Tuesday, March 30, 2010

Warm Temperatures... Thunderstorms by Friday!

There has been much discussion in the chase community about the upcoming trough and its' associated features and its' severe weather potential. This discussion has been ongoing since the trough was a gleam in the GFS way back at 300+ hours. This would appear to be the first trough in perhaps many that is signaling the idea of switching out of winter and into a spring pattern. This pattern change is welcomed in such a year that thus far has been terribly slow in severe weather per SPC yearly climatology. Many questions remain about this first trough and still being 3.5 days as of this mornings (12z) model run this isn't necessarily unusual. I do hope that by tomorrow evening the models were at least begin to agree upon the more synoptic features of the event. Many questions have been brought forth regarding this Friday and while a few of them will likely not be answered until the morning of, we can at least speculate to what the results will be given certain conditions.

Moisture was an initial concern, and while the moisture is not expected to be significant there would still appear to be sufficient surface and mixed-layer moisture available for severe weather given the strong dynamics. Wind shear was a concern and still is a large concern given model forecasts of south-southwest winds from 850hPa through 500hPa. Latest trends have at least backed surface winds to a southeast direction during the afternoon Friday, which is dramatically helping the 0-1km shear values. However, given the highly uniform wind speeds without some additional turning in the 850-700hPa layer the surface winds may not be much of a factor. Instability has become somewhat of an issue given such dynamic cooling takes place ahead of the trough that there will not be a sufficient cap to allow for clear skies into the afternoon. A resulting precipitation/cloud shield in conjunction with warm temperatures ~800hPa would appear to be limiting the overall instability. This last detail is a question that may not be answered until the morning of, given the highly questionable model forecast cloud cover and precipitation. Nonetheless with all of the questions abound it would still appear that a severe weather event may likely unfold across the Southern Plains and perhaps even parts of the Central Plains. There is no doubt that with such a slow season ongoing and the location of the setup that many chasers will be out regardless.

In the meantime it is time to enjoy some very warm weather! High temperatures today ranged from the lower 70s along the Mississippi to the mid 80s along the western High Plains. Warm air and moisture will continue to stream northward as south winds continue to be sustained 10-20 mph with gusts to 30 mph both Wednesday and Thursday. Expect temperatures tomorrow to be a few degrees warmer than today, and Thursday's high once again be well above normal for most areas.

Additional updates will be likely tomorrow and through the remainder of the week in regards to the upcoming potential for severe weather.

Monday, March 29, 2010

Warming Quickly!! Late-Week Potential...

As we enter the work week we can look forward to seeing bright sunny skies and knowing that temperatures will be above to well above average for this last week of March and beginning of April. A weak upper level ridge will be placed over the Plains states for much of the week, leading to clear skies and fairly strong southerly winds. High temperatures will be in the 50s and 60s from east to west over the Central Plains tomorrow with a steady increase expected through Wednesday. Tuesday's highs will range from the mid 60s to ~80 from east to west, and even a few more degrees warmer on Wednesday (from 70 to mid 80s). Highs on Thursday will likely be fairly close to those on Wednesday, but our upper level ridge will no longer be centered across the Plains. We'll be in the process of ushering in a fairly robust trough and potentially closed upper level low onto the Plains on Thursday.

This will be the main focus of the rest of the updates this week, as the potent trough given the right set of features may be one of the first widespread severe weather events of the year.  Currently the mid-range models are having problems deciding what to do with the trough late this week, differing as to either keeping it as a progressive wave across the Plains or to bring it into Texas as a cut-off low.  Additional updates this week will keep track as to the latest model trends with this system and a quick review of the warm temperatures outside.

Saturday, March 27, 2010

Severe Weather Threat - Mar. 27

 An upper level low will become closed for a short period of time today, and in conjunction with a surface low will create the potential for thunderstorms and a few severe thunderstorms this afternoon/evening over the Central Plains.  The area of interest for severe weather will be over extreme southeast Kansas, extreme southern Missouri, extreme eastern Oklahoma, and Arkansas.  Surface moisture will be meager over the area of interest, with dew points only reaching near 50F by this evening. However, the low level temperature profile will be sufficient given the cooling mid-levels associated with the closed upper low.  This will result in low level instability sufficient for numerous thunderstorms across the area, with a low level wind field especially favorable for low level wind shear.  The best mid-level and upper-level wind shear will be offset from this best low-level wind shear, thus limiting the overall tornado potential.  However, there will be enough to uphold a marginal tornado threat across mainly extreme southern Missouri and northern Arkansas.  Large hail and damaging winds will of course also be a threat with any strong/severe thunderstorms that occur this afternoon as well...

The threat is marginal enough and in an unfavorable chase terrain to not warrant a chase day for me.  There will be several chasers out taking the chance however, and will likely have their live video available on ChaserTV this afternoon/evening.  For the Kansas City area, expect showers/thunderstorms to continue off/on through much of the afternoon, becoming widespread by evening.  The severe weather threat is very low, but thunderstorms are expected.

Beyond this storm system we can look forward to one of the first good upper level ridges across the Plains for much of the week ahead.  This will bring temperatures warming dramatically to the highest we've seen yet this year, likely into the 70s and 80s across the Central Plains.  This will hopefully increase the moisture content across the Plains as well, setting us up for the potential for one of the first significant severe weather events of the year...  More details on the warming weather and the round of severe weather that may be in the forecast tomorrow!

Tuesday, March 23, 2010

A Rainy Period...

Another storm system is impacting the Rockies already this evening, likely to bring snowfall amounts greater than a foot in many areas along the foothills in Colorado. A low pressure system will also be created that will quickly move out onto the Plains states and establish itself by tomorrow morning. A stationary front will be draped from southwest Oklahoma to the northeast across Oklahoma, Kansas and into northern Missouri by tomorrow morning. We'll see widespread rain showers by tomorrow morning over central Kansas into southeast Nebraska and southwest Iowa with these areas being just north of the stationary boundary. As the low pressure system continues slowly eastward and the upper level low dig onto the Plains this stationary boundary will slide to the south. Leaving much of Kansas, northern Missouri, southern Iowa and parts of southeast Nebraska in a favorable location for widespread rain showers through the day on Wednesday. This feature will slide eastward during the overnight hours, with additional rain showers and thunderstorms occurring over parts of Oklahoma and Texas. These thunderstorms will work northeast along with the surface low pressure system, making their way into southern Missouri for Wednesday night. Despite the strengthening system at all levels, the storm system will be picked up by an upper level jet streak which will thankfully move this system out of the Plains by Thursday night. Although much of Missouri and adjacent areas will be left under frequent showers and cloud cover through Thursday, the Plains will be dry by dawn on Friday.

We won't have too long to dry out though, as the next storm system will make its' way off of the Rockies and into the Plains by Saturday. This will travel across the Plains over the weekend, and unfortunately with some northern stream energy to work with it will likely feature a decent cold front that will sweep across the area. This will likely lead to a couple of days of below average temperatures, which really is nothing new for the way this year has gone. Luckily the upper level ridge looks to build quickly which will allow the temperatures to rise quickly back to normal and potentially above normal levels for much of next week.

So to recap, two low pressure systems coming off of the Rockies look to affect the Plains states. The first of which for Wednesday and Thursday will bring steady rains and isolated thunderstorms. Perhaps some severe weather with a marginal setup over parts of Texas and Oklahoma. We'll take a day to dry off on Friday before the next system brings more steady rain, becoming a cold rain late, for the weekend. Despite a day or two of chilly temperatures, we'll be quick to warm back up come next week...

Sunday, March 21, 2010

March 20 Winter Storm Video

I finished a quick edit of my video I captured yesterday both in the early morning and during the late morning/early afternoon hours around the Kansas City area.  You can find it available on YouTube and YouTube HD at the following url:  http://www.youtube.com/watch?v=sUtv6DlGJns

Or it is embedded below for you view here:

Winter Storm: Mar. 19/20 Recap

A long duration and dynamic winter storm struck portions of the Central and Southern Plains this past weekend, bringing with it nearly a foot of snow for parts of Kansas and Missouri. While snowfall did fall at a moderate to heavy intensity at times, the main culprit for the significant snowfall amounts was the long duration of the snowfall.  To think, the ground was so warm from the previous two days of sunny and 60s that there was a portion of the snow that melted instead of accumulating.  The first round of snow came with post-frontal precipitation across parts of Iowa, Nebraska and then into Kansas and Missouri during Friday evening and early overnight. As the early nighttime hours progressed, the first band of snow was enhanced by the developing upper level low to the south across Oklahoma/Texas resulting in increased coverage and intensities across Kansas and Missouri.  There were even reports of thundersnow with lightning strikes across parts of northeast Kansas around the Midnight time frame.

A short break in the snow for Kansas City came during the morning hours on Saturday, as the post-frontal precipitation had moved into central Missouri.  The low pressure system both in the lower and mid levels quickly deepened during the day, causing a large swath of deformation snow to occur over parts of eastern Kansas and western Missouri.  This snowfall came down long and steady and caused a majority of the accumulations over the Southern Plains and for areas south of I70 in Kansas and Missouri.  A very tight temperature gradient still existed across central/western Missouri which during the day on Saturday which kept the precipitation as rain over many areas including Springfield, Jefferson City, and especially St. Louis (which never saw any snow).  As the sun set on Saturday evening, a battle between the air masses resumed in which a cooling air mass due to the setting sun was being warmed by the strong southerly flow ahead of the low pressure system. This did allow some areas to see quick accumulations of snowfall, such as Springfield as the air mass cooled quick enough just before the warm air arrived.  Reports were also received of both sleet and ice accumulations where the air mass wasn't quite cold enough for snow at the lower levels.

For a full look at your local area's snowfall amounts as well as a write up from a few of the NWS offices please select one of the links below.  Additional links may be added as they become available.

Kansas City NWS -  Snowfall Maps & Recap
Wichita NWS - Snowfall Map
Springfield NWS - Snowfall Map 

Saturday, March 20, 2010

Winter Storm: Mar. 19/20 Update #8

Moderate snow ongoing over the Kansas City metro with strong north-northwest winds of 15-25 mph with some higher gusts as well. This snow should continue for the next few hours before tapering to light snow for the remainder of the afternoon and evening. Areas just southeast of the metro areas may continue to see moderate snow through the evening hours...

I've made it back home and am already watching basketball and preparing some dinner.  Pretty fun morning heading out and checking out some of the rural areas, watching the snow fall and the traffic come by.  The highlight of the live stream may have actually been the large group of deer that showed up across a field that I had parked by!  Hopefully you caught that...

Going to relax and watch some basketball.  Next post will likely be the recap of the event sometime tomorrow unless something new develops this afternoon.

Live Winter Storm Video Continues

Currently located on the southern edge of Johnson county Kansas, just south of the Kansas City metro area with a view of I35 on the live camera.  Expect a band of moderate to heavy snow to move into the area shortly and expect visibilities to fall to a half-mile or less at times...  Check out the current stream for your view of winter weather!  And keep in mind the stream is available for media use by contacting me at the number below the video...

Live Streaming Video:  http://www.severeplains.com/live.html


Live Winter Storm Video

Watching the next swath of snowfall making its' way northeast and will be entering the Kansas City area withing the next hour or so...  Am preparing everything and will be running the live stream as I head southward out of the Kansas City area and down toward the Johnson/Miami county lines.  Will watch the initial band come through and perhaps travel a bit of the countryside down there to view any blowing snow and drifting that is occurring.

To view the live stream please visit the following link:  http://www.severeplains.com/live.html

Please be patient as the stream will not likely be going until ~10AM this morning, but will likely continue to stream until I arrive back home around the Noon hour or so for some lunch, and for some of the true march madness to get underway this afternoon.

Winter Storm: Mar. 19/20 Update #7

A nice lull in the snowfall this morning as the frontal precipitation has moved off to the east, and the first indications of a deformation/trowal band are taking shape across north-central Oklahoma into southeast Kansas and moving northeast.  This will be the next round of snow that will likely enter the area after 10am and continue into a good portion of the afternoon hours.  Will monitor this band of snow which will likely be several more inches of snow to areas along/south of I35/I335 and I70 in Kansas, and along/south of I70 in western Missouri.

Current snowfall totals vary across the region, and stretch from the Texas panhandle and southwest Oklahoma clear up into southern Wisconsin!  A widespread 2.5-4" occurred over the Kansas City Metro area, with areas just southeast receiving less amounts as the change from rain/sleet to snow occurred later and the heavier band of precipitation were north. For a graphical look at the local storm reports from Midnight until 8am select the link below:

IEM Local Storm Reports (3/20 @ 12AM-8AM)

Live stream will likely begin ~11AM this morning as the next round of snow moves into the area. Details regarding locations are still unknown at this time as I'm taking a wait and see approach to how this next band develops.  An additional update is likely when I prepare to head out the door and begin Live streaming.

Winter Storm: Mar. 19/20 Update #6

Snow continues through the overnight hours and will likely continue for the Kansas City Metro before some subsiding occurs near 4-6am.  Snowfall accumulations of 1-2" are common across the metro region, with some higher amounts just north in areas of Leavenworth county and near St. Joseph, MO.  A brief period of thundersnow was reported and confirmed via ASOS reports of lightning just to the east of Topeka and continued into parts of Leavenworth county.

Been a long day and I aim to be up early in the morning to once again provide some live video of the Kansas City area.  With some light there will be some better views and hopefully a little better road conditions!  Keep track here for the latest updates on when the live streaming will begin and what locations I will likely be streaming from as the trowal axis of the low pressure system skirts by the Kansas City area. 

Friday, March 19, 2010

Winter Storm: Streaming Live!

With a band of moderate to heavy snow likely entering southwest portions of Kansas City I am going to do a little test run and grab some video of the heavy snow and blowing snow around the Shawnee, KS area.  I'll likely be live around 12:10AM, select the link below to view the stream:


Winter Storm: Mar. 19/20 Update #5

Snow has quickly overspread the Kansas City metro tonight, with a short period of both light rain and sleet occurring this evening areas at least on the Kansas side have switched to moderate snow around 11pm.  Snowfall is already beginning to accumulate on roadways, and strong northwest winds is blowing the snow around as it falls to the ground. Currently getting all of the equipment ready and may head out for a short period of time to grab some nighttime video of the start of the storm. Tomorrow morning I will likely also be out and around the Kansas City area barring decent snowfall is ongoing for some live video and for perhaps a small package of video.  I'll update here as necessary if I am going mobile...

Current expectation is for 4-6" of snow here in Johnson County Kansas, with a widespread 2-5" across the metro with higher amounts of ~6" towards the southern edges.  May not have to go too far further to see snowfall amounts of 6-8" and even higher dependent upon the trowal axis tomorrow afternoon.

Winter Storm: Mar. 19/20 Update #4

Just a quick update with the 12z model runs...  Amazing to think I'm sitting with the sliding door wide open letting the great outdoor air in at the moment, give another 12 hours and we'll be nearing 32 degrees and snow!!

The 12z NAM stays consistent with the frontal passage across Kansas and Missouri during the overnight hours, however, has changed the trowel strength and maximums once again.  With a surface low path further south compared to previous runs the best area for significant snow will be over parts of Oklahoma into extreme southeast Kansas and perhaps into portions of southwest/western Missouri. The 12z GFS is similar with a surface low track through Arkansas just a little further southeast, thus the best trowal now located a little further southeast away from the Kansas City Metro. 

Will likely get the 'live' setup going late tonight after I arrive home from work, but may not turn it on until the early morning hours so that there is truly something to view besides a dark view of the ground.  Expect to see white ground by sunrise Saturday over Kansas City, with total accumulations of ~4" along and south of I70, with 2-4" for the areas north of I70.  An additional update is likely tonight ~11PM or shortly thereafter...

Winter Storm: Mar. 19/20 Update #3

The off-hour model runs (06z) last night kept some consistency, although they both once again depicted some areas seeing over 18" of snowfall in eastern Oklahoma.  No drastic changes nonetheless, and we have Winter Storm Watches now posted for large areas of northern Oklahoma, southern Kansas, and western Missouri. Areas currently under the Winter Storm Watch are expected to see at least 6" of snow through Saturday evening. This heaviest swath is fairly consistent with my wording last night of where the heaviest snowfall is likely to occur, south of I35/I335 and I70 in Kansas and then between I70 and I44 in western Missouri.

I work this afternoon, thus will not be able to update during the afternoon hours as the cold front begins to dive into the area and we finally start to find out how quickly the change-over from rain to snow will occur.  Current indications are that a few hours of rain in Kansas City before we see snow mixing in and a change over to all snow just after Midnight tonight. The heaviest snow will not likely come with this first band of frontal precipitation, but rather the trowal development that will occur on Saturday and likely skirt the southern portions of the Kansas City Metro.  Will post another update after the 12z runs are available and hopeful confirm the going forecast, but would expect to see at least 4-6" of snow for areas of Kansas City south of I70.  The heaviest snowfall totals still look to occur over portions of Oklahoma and Kansas, but the remaining areas under the Winter Storm Watch aren't going to escape without some hefty amounts as well.

Additional update expected ~11AM...

Winter Storm: Mar. 19/20 Update #2

Just a quick update to post two model images from tonight, both the NAM and GFS 00z snowfall forecasts courtesy of Earl Barker's Model Page.  The snow algorithm used here is a max-temp in profile, although not as high as an omega or Cobb algorithm output, it is still likely higher than what you will actually see. This will be due to melting that will initially occur with any snowfall (due to warm ground temperatures), but then also compaction as the snow is expected to be quite wet and heavy at times.  With that, the two images are below (NAM above, GFS below):

Thursday, March 18, 2010

The Madness Continues... Winter Storm: Mar. 19/20

In the NCAA Tournament there is still plenty of good games with a Tennessee vs San Diego State game going down to the wire, and a Texas vs Wake Forest game going into overtime.  This has been one of the best first days of the tournament that I can remember...

In other madness, there is very high confidence of a winter storm taking shape over parts of the Central/Southern Plains with the potential for 8"+ of localized snowfall and sustained winds of 25-35 mph and gusts of 45 mph. The question has been on the exact location of this heaviest band, which has been hindered not only by model differences but by run-to-run differences as well.  The latest NAM (00z) has continued its' idea of a frontal passage over Kansas and northwest Missouri Friday night continuing into central Missouri during the day on Saturday. As this front continues into central Missouri the upper low deepens dramatically over Oklahoma and into Arkansas while the surface low tracks over northern Arkansas and then into the Tennessee Valley by Sunday.  This sets up the trowal axis over parts of extreme eastern Kansas and into western Missouri with the potential for over 12" of snow!  The NAM has been the outlier and was widely discounted, but the latest solution is quite similar to the latest run (00z) of the GFS.  The difference lies within the trowal location, as the GFS has the precipitation wrapped tighter/closer to the surface low.  The difference is less than 100 miles between the two, but the question remains on the solution to the ECMWF which has been the preferred model as of late.  I do feel confident enough to indicate that the heaviest swath of snow is likely to fall between I70 and I44 in Missouri, back into areas of eastern Kansas south of I70 & I335/I35.

I have a few errands to do tomorrow morning, but will try and take a quick look at the 12z runs and make a quick update here.  I will likely have a live stream running locally by tomorrow evening with a view out into the yard...  Am still entertaining the possibility of a mobile live stream depending upon the location of the heaviest band of snow. 

March (Model) Madness

The NCAA tournament got underway with some great games in the first round, including a few upsets and a few other games that went down to the wire. I have a few brackets that are still looking pretty good through the afternoon/evening games. But, the true madness is that of the forecast models and their differing solutions regarding the upcoming storm system for the Central and Southern Plains this weekend.

As previously mentioned it appeared that we were beginning to trend towards a solution, however, we definitely didn't improve upon the agreement this afternoon. The ECMWF would appear to have the best run-to-run consistency compared to the GFS and NAM, and it also has the furthest south track with the initial shortwave and the eventual closed low over the Southern Plains. The 12z GFS run had similarities, but the 18z also came up with a differing solution in regards to the initial frontal band of precipitation. Thus far the NAM has been thrown to the side for the most part, especially after the 12z run indicated a foot or two possible across Kansas/Missouri.

The storm system is very complicated in itself, dealing with the timing of an initial frontal passage and then the closing of the low somewhere over Oklahoma/Texas. Add in the problem of warm vs cold air and its' timing and we are looking at a sharp gradient between over 1" of rain and upwards of 6" of snow. A lot of questions may not likely be answered until the event gets underway and you can watch the lower level winds and temperature profiles to determine how much and if any is going to fall over certain locations. It still would appear that an area of Kansas/Missouri will see a swath of 6"+ through the day on Saturday; and the heaviest may very well occur over eastern Oklahoma with potentially 12"+ possible. Tomorrow morning after viewing the 12z model runs I will hopefully feel confident enough to say where this heaviest swath is likely to occur...

An additional update is possible late tonight after the 00z model runs are completed (~11pm) otherwise a quick update tomorrow morning can be expected.

Weekend Snow Storm?!?

Models had continued their questionable outputs in regards to snowfall and transition of rain to snow over the Central Plains on Friday night and Saturday, but are once again coming into a trend towards a solution. This mornings' GFS and NAM both had a fairly similar solution in regards to snow amounts over Kansas/Missouri, but still having slightly different tracks in regards to speed and north/south variability in the surface low. The ECMWF has been fairly consistent in a solution for the past few runs, and via current NWS discussions it would appear that it has the slight edge in regards to forecasting value.

I'll have a better chance during the afternoon today to look at the various models and see what the 18z and early indications of the 00z models have to say.  An update later this evening/tonight will be likely...

Looks like we'll see the change from rain to snow during the overnight Friday, and there should be enough cold air spilling in that we keep the precipitation as snow even as we hit the daylight hours Saturday. A lot of questions regarding snowfall amounts not only because of the model variability, but the fact that we will have temperatures in the 60s and sunny skies for today and Friday and we'll see rain before the change which will allow the wet surfaces to melt the initial snow as well.  If we had cold ground and no initial rainfall we could easily be looking at 6-12" with even higher isolated amounts across portions of Kansas/Missouri. However, with the questions raised above it would appear that we will struggle to see anything higher than a 4-6" widespread swath.  Again, I'll update more later on this evening.

In regards to the weekend event, I'm entertaining the idea of setting up a live stream for the duration of the storm.  For the most part this would be at a stagnant location, but if requested by any local media sources could become a live mobile stream.

Tuesday, March 16, 2010

Where's the Sun?!?

We've been going the past several days with mornings' filled with low level clouds and high moisture values leading to sprinkles and mist. Today is no exception, and it looks to continue tomorrow morning as well.  Yesterday during the late afternoon hours we were able to see the sunshine in Kansas City as the low level stratus finally cleared out, but the clouds made their return during the overnight.

A disturbance is going to slide north to south across the Northern Plains today, and over along the Missouri/Kansas border overnight tonight arriving into the Southern Plains by Wednesday morning. This disturbance does not have much for dynamics, and even less in regards to moisture to use for precipitation. This means we'll mainly see the cloud cover continuing, with a few rounds of sprinkles or light showers across  western Iowa, and Western Missouri. This will be out of the area by Wednesday morning, and we should dry out and clear out by Wednesday evening.  The clear skies will continue into Thursday and through most of Friday before out next storm system will bring in the next round of clouds and definitely a round of heaviest precipitation for the Central Plains.

This storm system for Friday and into the weekend is something to keep an eye on, as of yesterday morning it was the operational GFS that was the outlier showing a decent storm system. However, several models by the afternoon hours were showing a trend towards the operational GFS solution and the last 4 runs of the operational GFS have all continued with a similar solution. The surprising and questionable solution at this point is the amounts of snowfall that is forecasted with the operational GFS on the cold side of the system. Just for humor, last nights 00z operational GFS showed a surface low tracking along southern Kansas/Missouri leading to a swath of snow across western and central Kansas, into northeast Kansas and into northwest Missouri. With ~18" of snow in Russell as the maximum, but a solid swath of 6-10" across the remainder of the locations named above. For the Kansas City Metro this meant a gradient of 1-8" from south-to-north across the metro area.  Now keep in mind that I am not saying that this is going to be correct, as there is a lot of questions regarding the track and amount of cold air that can influx into the region. Also the ground temperatures are going to be quite warm after seeing temperatures near the 60 degree mark on Friday, thus if snow did fall how much of it would melt trying to get the surface temperature down to the freezing mark.  I'll continue to update this week as we near this storm system, the first one of Spring that has the potential to give us snow!!

Wednesday, March 10, 2010

Thunderstorms to Snow?!?

Numerous clusters of thunderstorms continue across portions of the Central and Southern Plains tonight, with a continued risk of a few severe/tornadic storms through the early overnight. The tornadic threat today across much of the risk area in Kansas, Oklahoma and Missouri was hindered by shallow moisture layer. Which when subjected to continued mixing during the afternoon led to marginal dew points in the 40s for most areas, and even meager dew point depressions. With the addition of early showers and cloud cover to areas just ahead of the low pressure system, little instability, especially in the lower levels, was present to aid in the development of strong convection. Nonetheless convection was able to fire, especially just ahead of the scattered showers/sprinkles in extreme northeast Oklahoma into southwest Missouri during the evening. Marginally severe hail and some rotation was noted on the stronger cells, and although tornadoes were reported thus far no damage reports have been received.

This current storm system is sliding to the north and will become vertically stacked over Iowa. Leading to continued wrap-around moisture and thus ongoing scattered showers through the day on Friday. Cold air advection will also be present to the west and southwest of the vertically stacked low, thus conditions may become favorable for at least a wintery mix of precipitation during the overnight Thursday into Friday for parts of northern Kansas and Missouri. Areas including the Kansas City Metro may see a few hours of a rain/snow mix early Friday, although with current surface temperatures there will not likely be any accumulation. Areas of northeast Kansas, northwest Missouri and southeast Nebraska and adjacent areas of extreme southwest Iowa may not be quite as lucky with snowfall becoming heavy enough for accumulations at least on grassy surfaces. Models are having a hard time depicting the magnitude of cold air and its' association with any lift to aid in snowflake development, in addition to warm surface temperatures will lead to models likely overestimating the accumulated snowfall.

Temperatures a little below average through the weekend, but we'll at least start to dry off after a decent amount of spring rainfall. The other story to watch through the weekend will by the flooding on several rivers in the Northern and Central Plains. Making matters worse in a high number of ice jams that are also occurring thanks to rapid melting. These ice jams can create rapidly rising waters and are very hard to forecast, thus anyone in flood prone areas should pay close attention to water levels through the weekend and beyond.

Got to hear a few rumbles of thunder in Kansas City, nothing overly impressive but it was a nice sound to hear. Wait and see about a few snowflakes and then hopefully get back on track towards spring!!

Severe Weather - Mar. 10

Models continue to indicate the potential for severe weather across portions of the Central and Southern Plains for this afternoon, evening, and overnight.  A low pressure system currently ejecting onto the Plains will continue to trek east-northeast across Oklahoma and into the southeast corner of Kansas by 6pm this evening.  The low is then expected to move nearly northward as it gets ingested by the upper level system located over the northern Plains.  Moisture return is ongoing this morning ahead of the surface low pressure and will continue through this evening, however, dew point values along the surface warm front and near the surface low are likely to only reach near 50F.  Slightly higher dew points are possible further south along the dryline in eastern Oklahoma, however, surface temperatures are also expected to be higher resulting in similar LCL's across the region.

Sufficient surface based cape, at or above 1000 J/kg, will be present in the warm sector resulting in surface based convection around or just after 3pm near the surface low and southward along the dryline.  Additional convection along the warm front will also likely develop during the late afternoon and move northeast along the warm front and surface low track during the overnight. These storms along the warm front will likely be a broken line and/or linear clusters therefore the severe weather threat is lower.  However, an isolated large hail or damaging wind gusts cannot be ruled out with these storms which may move into the Kansas City area after 10pm.

The storms along the low pressure system and especially the dryline will be a slightly different story, with the ability for surface based storms to remain somewhat discrete.  Given strong low level shear and sufficient instability, storm type will likely be supercellular with the potential for very large hail and isolated tornadoes. The tornado threat may continue into the overnight across Arkansas where storms may be able to stay somewhat discrete, whereas further north storms will likely congeal and continue their potential for large hail and perhaps an isolated damaging wind gusts over southern Missouri.  Many storm chasers are heading out today, with the majority of targets being the southeast corner of Kansas or northeast Oklahoma.  As mentioned last night with my target area along Highway 169 at the Kansas/Oklahoma border; this hasn't appeared to change to much with this mornings' NAM.

I'll be in the office working this afternoon and evening, likely getting off just before our round of thunderstorms arrive in the Kansas City area. I'll be watching the storms initiate across the warm sector, however, no updates on the blog are expected until early tonight if at all. 

Tuesday, March 9, 2010

Severe Thunderstorm Potential - Mar. 9

A quick morning update on the potential for severe weather today as the surface low currently located over south-central Kansas will move northeastward and create the potential for severe weather this afternoon for areas of eastern Kansas and western Missouri.  The low pressure system has become vertically stacked overnight, creating a true cold-core thunderstorm setup over the Central Plains.

Moisture is still somewhat meager with dew points nearing 50 over much of the area this morning, while a few more degrees of moisture can be expected before this afternoon to bring dew points into the lower 50s the key for thunderstorm development today will likely be the instability.  Some instability will be present simply due to the steep lapse rates created by the vertically stacked low, however, we will likely need to see some sunshine over the area to give us better low-level instability.  Current satellite trends do not bode well for sunshine with a cluster of thunderstorms located just east of the surface low in Kansas, and its' associated cloud shield covering much of eastern Kansas under thick cumulus.  We'll have to watch trends to see if we can get a dry/clear slot to rotate around the low pressure system late this morning or early this afternoon to give us a chance, but currently conditions don't bode well for our thunderstorm risk.

If we are able to see a few hours of sunshine to enhance the low level instability then we could see an enhanced risk for low topped supercells.  This would create the potential for some brief cold air funnels and perhaps a quick cold core tornado or two given strong low level wind shear and vorticity present with the low pressure system.  This currently seems to be at rather low probability, thus not too excited on the potential.  Will try to update if anything changes this morning before I get into the office...

Monday, March 8, 2010

Thunderstorm Potential - Mar. 9

There are a handful of storm chasers that made the trek down into western Oklahoma and Texas today for a marginal severe weather setup.  Low-level wind shear is good in vicinity of the surface low, and while some cirrus has hindered full heating there does appear to at least be marginal instability for thunderstorms over the next few hours.  Marginal hail and perhaps a brief tornado would appear possible given the latest parameters on the SPC Mesoanalysis page.

Looking ahead to tomorrow this surface low will continue to move northeast, into south-central Kansas during the overnight and then across into northwest Missouri during the day tomorrow before moving into Iowa by tomorrow night. The low pressure system will continue to be vertically stacked, creating steep lapse rates and the potential for thunderstorms. Per the 12z NAM it would appear that during the early afternoon hours given diurnal heating that some surface instability and especially mixed layer instability would be present across parts of eastern Kansas and western Missouri.  Given marginal instability and strong low level vorticity given the proximity to vertically stacked low pressure system that a brief window of development for low-topped supercells would exist. Given cold temperatures aloft, marginal hail would be a threat; in addition to strong low level shear that would warrant the potential for a tornado or two as well.

An additional update is possible either late tonight or early tomorrow regarding any changes to the potential for severe weather for the Central Plains.  I work during the afternoon tomorrow, thus no chase activities are planned and blog updates are not expected.

Thursday, March 4, 2010

Ahhh... Sunshine!!

Another bright and sunshine filled day today, with surface winds becoming southerly in the afternoon to aid in our warming temperatures. Highs today were widely in the 50s for areas without snow cover, even well into the 40s for those on the southern portions of the snowpack. Areas further north across Iowa were still held into the 30s due to the large snow pack in their area, plus the surrounding. Nonetheless the warm air temperature and unabated sun did allow for melting which showed up as some dense fog during the morning hours. We'll look for another day of warming temperatures and clear skies for a majority of the Central Plains tomorrow, just ahead of a disturbance that will be developing in the lee of the Rockies.

This upper level system is a fairly compact, but strong system that will bring a good chance of rain and even isolated thunderstorms to portions of the central Plains. Latest model tracks have continued the trend of a cut-off low pressure system moving east/northeast from eastern Colorado into central Nebraska Friday night, then slowly meandering eastward across Iowa through Saturday night. This will lead to a good chance of rain showers for areas north of I70 in both Kansas and Missouri and as far north as the Dakota borders and central Minnesota. Most of this precipitation should fall as rain, however, as the upper level low continues to deepend and cool areas north of Highway 30 in northeast Nebraska and Iowa as well as adjacent areas of southeast South Dakota and southern Minnesota may be able to see some mixed precipitation and snowfall. The wintery precipitation will have its' best chance late Saturday through early Sunday with accumulations remaining minimal for most areas. Decent amounts of rain are possible for the remainder of the area, including those that have several inches of water frozen in their snowpacks. This will amount to some rapid rises in rivers over the weekend and may in turn cause flooding concerns for areas of Iowa and places downstream.

Many people are still watching the stronger system for early next week, with many eyes on it for the first severe weather event for the Plains states. Moisture return is weak thus far, but there is still several days of warming and moistening to go for many areas of the southern Plains. The latest GFS and its' ensembles have taken the further south track today with the center of the 500hPa low tracking along the Oklahoma/Kansas border into Arkansas on Tuesday. This is seemingly becoming the favorite solution of the models, at least until the disturbance comes ashore and the models actually get a good look at its' dynamics. Nonetheless, expect rain to dominate the forecast for the southern and central Plains for early next week. With the best chance of thunder coming for areas of Texas and Oklahoma, however areas of Kansas/Missouri can't rule out the thunder given intense lapse rates under the closed low aloft. One of the best highlights with this southern track is that there is really no cold air to be advected south, thus we'll keep temperatures near normal for most of next week. Could we be looking at a sign that spring may actually be arriving?!?

An additional update is possible tomorrow, however a 3-day weekend and continued warm weather will hopefully keep me busy with other things!

Tuesday, March 2, 2010

Quiet Weather Continues...

Mainly sunny skies and slowly warming temperatures have been the story thus far this week. And this looks to continue through the remainder of the week given current forecasts. A disturbance is expected to develop in the lee of the Rockies on Friday, leaving areas of Kansas, Nebraska, and South Dakota with a chance of showers through the day on Friday. This low will push off into the Plains on Saturday, continuing the chance of showers for areas of Kansas, Missouri, and southern portions of Nebraska and Iowa. There will be enough cold air to see more wintery precipitation for areas of northern Nebraska and northern Iowa, along with adjacent areas of the Dakotas and Minnesota.

As this system exits to the Great Lakes, our next wave of energy will moving across the Rockies and likely resulting in a new low pressure along the front range in Colorado. With the previous low sliding well north compared to previous storms, ample southerly flow is expected across the southern and central Plains. This means warm temperatures and increasing moisture across much of the Plains. Temperatures may reach above normal levels for the first time in several months for areas of the central Plains, with 50s and 60s likely on Sunday and Monday. These above average temperatures may be short-lived as the low pressure will begin to enter the Plains and bring widespread precipitation chances. The timing and exact track of the surface low, along with the strength of the upper-level features continue to be in question. The latest GFS runs have actually began to decrease the intensity of the closed low aloft.  Nonetheless, discussion continues about the potential for the first good severe weather event for the Plains states which at this time would appear to occur over portions of western Texas/Oklahoma, and perhaps Kansas depending upon the surface low track. The talk also continues about the potential for a strong winter storm, with ample moisture if the low can bring down enough cold air we could see a strong deformation zone filled with snowfall across parts of the northern Plains. Given a forecasted strong pressure gradient, wind speeds would also be in the 20+ mph range and likely result in widespread blowing snow. Many questions remain for this storm system, and as mentioned previously is the main talk as we enjoy sunny skies and warm temperatures.