April 29 Chse Recap

Took a trip back home for the weekend, thus the late response to recap last Thursday's storm chase which yielded two tornadoes that have both been confirmed by the NWS offices. A complete recap will be posted later today, with images likely being available sometime later...

For more information regarding updates while on the chase last Thursday, please visit the new blog site for Severe Plains:

http://www.severeplains.com/blog

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April 29, 2010 Chase Forecast

Chase #1 of 2010!

Time of Departure: ~12:30PM
Initial Target: Herington, KS

Discussion: Initial low pressure system over Nebraska will swiftly progress northeast into northern Minnesota by late evening. A trailing cold front will surge east/southeast over MN/IA/NE and into northern Kansas during the evening, intersecting with a dryline positioned over central Kansas/Oklahoma. Largely linear forcing expected along the cold front in the Northern Plains preludes any significant tornado risk despite very strong shear values given the howling winds throughout all levels. Thunderstorms should initiate along this cold front during the evening hours, likely unzipping the front the entire way from southern Minnesota into southern Nebraska and along the Kansas/Nebraska border. As this occurs a secondary low is forecast to form in central Kansas, enforcing the dryline and providing a source for some localized backing of the winds. As this occurs it would appear likely that convective initiation should ensue given enhanced convergence. Bulk shear values are undoubtedly sufficient for supercells during the evening with an increase in shear likely with the low level jet increasing and proving south-southeast winds at the surface during the early overnight. Moisture is a concern given only mid to upper 40s exist widely in the area of interest, however continued strong southerly flow should provide ~60 surface dew points by 00z tomorrow. Widespread 1000-1500 J/kg of mixed-layer CAPE should exist, however fairly substantial capping inversion should limit any development without the aid of at least moderate surface convergence. Given surface temperatures of mid 80s and dew points ~60, high LCL values are also of concern for tornado potential. Nonetheless, the risk is there for at least a storm or two to develop along the dryline or for the cold front to initialize a storm near the intersection of the two boundaries.

It is for this purpose that the initial target be just south of the expected cold front and dryline intersection, being close enough for a tail-end charlie situation along the front or close enough to close quickly on any development to the south along the dryline. Will update by early afternoon with additional thoughts after viewing the 00z runs tonight and the 12z runs tomorrow morning; along with a look at the current conditions as a fellow co-worker and I depart.

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April 29 Severe Weather Forecast #1

A nice and cool day today with temperatures only into the low to mid 60s over the region. A few showers were able to develop thanks to the abundant sunshine and cool temperatures aloft, however nothing widespread or too significant. We'll see the winds turn to the south during the overnight tonight, beginning to bring back the warm and moist air that was shunted southeast with the cold front this past weekend. This will set the stage for a severe weather event Thursday evening and overnight as a large trough moves eastward onto the Plains.

Details are still sketchy despite being only 2 1/2 days out, with the GFS still playing catch-up with the NAM and especially the ECMWF/GEM models. Strong southerly flow at the surface and above the surface should yield sufficient moisture return with ~60 surface dew points to the Central Plains by Thursday evening. This southerly flow will continue into the evening hours, and combined with strong flow in the mid-levels from the west-southwest will yield strong shear values over the area of interest. The combination of instability and shear does yield 0-3km EHI values of 3-4 which given a surface based storm would likely be more than sufficient for rotation in the lowest portions of the storm. Other parameters to note would be mixed layer CAPE of 1000-1500 J/kg, deep layer (0-6km) shear of 45-55 knots with a vector more normal than not to the boundary over south-central Kansas and Oklahoma. Such strong wind fields throughout all of the levels will end up giving fairly quick storm motions of 30-40 mph to the northeast, which would be favorable for any storms moving off of the dryline and into an even higher dew point environment.

All of the above parameters would be more than sufficient for strong rotating supercells likely capable of tornadoes given the strong deep layer and storm-relative shear. However, there are definitely some negatives at this point with the setup on Thursday. Moisture return will be sufficient for thunderstorms, however given surface temperatures of 80+ degrees F will give way to ~20 degree F dew point depressions and LCL heights of 1500 meters or higher. This decreases the tornado potential initially, but with storm modification of the surrounding environment could definitely still yield tornadoes. A pronounced warm nose in the lower levels will also give way to some substantial inhibition for surface based parcels to initially develop. There are of course many other details which will hopefully become better defined by tomorrow night, but for now it does appear that the positives outweigh the negatives on this setup for severe weather.

An additional update is likely by tomorrow night, with the final details regarding my chasing opportunities with this setup. A quick glance beyond Thursday doesn't give much model consensus, but it would appear that a continued threat of showers and thunderstorms would appear likely.

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A Few Nice Days Ahead

A few showers remained in the area today with the upper level low still hanging around over Iowa. These showers pivoted around the low this evening and will continue to do so overnight, giving areas a few hundredths to a tenth of an inch of rain in the heavier bands. A nice scene this evening in Kansas City with the showers moving through as the sun was lowering, created both some high contrast dark clouds and a nice sunset scene (including a brief rainbow). We'll dry out tomorrow and continue to remain dry with warming temperatures for Wednesday and Thursday.

The next chance for rain and severe weather for that matter will come on Thursday for the Central Plains. A deepening trough in the west will eject several waves of energy for late this week and through the weekend. Model forecasts have been very inconsistent in what the system will do in regards to a cold front Thursday night. This will have dramatic affects on both precipitation and especially severe weather chances for Friday and the weekend. A quick look at the potential on Thursday shows a great chance of thunderstorms given the strength of the forcing along the cold front that will likely be sweeping southeast across the Plains. A lot of questions still need to be answered regarding the specifics, but it would appear likely that at least a strong line of thunderstorms would sweep over parts of the Northern and Central Plains Thursday evening and overnight. Additional details regarding the severe weather potential on Thursday and the remainder of the week will be addressed in later updates. Finally have a few days off with what looks to be an active pattern, so may finally get a chase day in as well!

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Severe Weather Potential - April 23

Another day with potentially significant severe weather across both the Central Plains and into the Gulf Coast. Yesterday was quite impressive, with multiple cyclic tornadic storms over eastern Colorado and western Kansas, and several tornadic storms in the Texas Panhandle. Another severe weather setup is available today with a surface low located along the western Kansas/Nebraska borders, a warm front extends eastward across southern Nebraska and into southeast Iowa; and a dryline ahead of the cold front should be positioned over far eastern Kansas by this evening. The dryline should extend well south into the Arklatex region, providing a trigger for development from southern Nebraska to as far as northeast Texas. There is very good agreement that thunderstorms initiating in the Arklatex region will move eastward off of the boundary, but continue to pose a significant threat of severe weather given parcel profiles and strong shear present throughout the overnight. However, in the interest of forecasting sake I am focusing on the northern potential given its' likelihood to affect the Kansas City Metro this evening.

Morning convection is currently on its' way out of eastern Kansas, with cloud cover extending back further west to encompass much of eastern Kansas. This should clear out over the next few hours, allowing for sufficient destabilization ahead of the dryline and south of the warm front. This should yield 2000-2500 J/kg of surface based CAPE, and mixed-layer CAPE nearing 2000 J/kg. Deep layer shear values of 40-50 kts with a vector out of the west-southwest should allow for fairly discrete storm development along the dryline in extreme southeast Nebraska and northeast Kansas. As these storms move off of the dryline they will continue to encounter a favorable air mass and likely even better low level shear given stronger backing of the winds. A mid-level jet (500 hPa) will enter the area during the evening hours, likely increasing the deep layer sheer values and providing support for additional storm development. Storm motion given the storm relative wind fields should be to the northeast at 20-35 mph, with any right-movement yielding motions of east-northeast around 25 mph. Storms will likely have enough directional shear to rotate, yielding sufficient tornado potential to mention tornadoes possible with any supercells that do develop in this area. In addition to the tornado potential, ample instability will be available for large hail growth.

Storm initiation should occur by 00z (7pm) in eastern Kansas along or just ahead of the dryline, with storms continuing well into the overnight as they move northeast. Based upon current forecasts, thunderstorms should enter the Kansas City metro ~10pm and exit by 2am. Severe weather is likely with any thunderstorm this evening and into the early overnight. I work the evening shift at work, thus will not be chasing or be able to provide updates. `

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Severe Weather Recap - April 4-6

The large trough and associated low pressure system and other surface features that had been in the eyes of chasers for nearly a week before even coming onshore has come and gone over the Plains. This past Sunday (April 4) through Tuesday (April 6) all had the potential to be some of the best days of chasing thus far for 2010. Now I realize given the way the early season (January-March) have turned out this isn't saying a whole lot, but comparatively many chasers were quite excited about the prospects. There were obviously some concerns with the setups on each day, as it is often hard to find a day that doesn't have some sort of concern. The lack of upper level support for Sunday and Monday were hard to miss, and with such a stout elevated mixed layer (EML) this allowed for a pretty good lack of significant storms until during/after sunset. The upper level support did arrive for Tuesday, but winds became largely unidirectional for most areas with only a narrow axis of good directional shear along the warm front in Iowa. The moisture concern which was largely discussed didn't show itself at the surface, but given the impressive EML that was in place the moisture just wasn't deep enough in my opinion. I could go on with a few more concerns and of course mention the positives that were in place for the events, but we'll continue on into what actually occurred each day.

In the end I can somewhat luckily say that I had to work throughout all three potential chase days, thus was not active in chasing any of the storms. I think it is fairly safe to say though that if I wasn't working that I would have likely favored going chasing for at least 1 or 2 of the days.

Sunday will actually be credited with the only tornado reports on the Plains, although not yet confirmed to my knowledge by the Kansas City or St. Louis NWS offices. (Note: There was a tornado report on Monday 4/5 in western Illinois) These tornado reports came from a rather impressive supercell that began its' life ~40 miles northeast of Kansas City and continued into western Illinois during the early overnight hours. A total of 4 tornado reports came from this storm as it passed through Howard, Randolph & Audrain counties between 7pm and 8:15pm. This storm also produced some of the largest hail reports (2.5" in diameter) and damaging winds. The storm was fairly photogenic, although any tornadoes were likely hidden within shrouds of rain. The worst part of this storm was likely its' speed (45 mph) and location within the hilly/winding roads of central Missouri. There were additional storms across parts of northern Oklahoma that came after dark and produced some large hail and damaging winds, but nothing of tornadic nature and largely photogenic.

Monday and another day featuring a warm front draped along the Iowa/Missouri borders and then a dryline play in Kansas/Oklahoma. No tornado reports and no significant severe weather to speak of out of the entire day/night with a majority of storms occurring across southern/central Iowa and only producing 1.0-1.75" diameter hail and some wind gusts of 60-70 mph. This will largely go down as a bust for most people as the only storms were well out of any target area by chasers.

Tuesday was turning out to be the day, with upper level support finally arriving and significant surface moisture still in place the hopes were high for most people. The SPC had targeted the warm front with a 10% tornado risk and kept the conditional hope of 5% tornado risk for the remainder of the dryline in Kansas/Oklahoma. Storms did initiate along the dryline/pre-frontal trough and the warm front in Iowa; however once again there were no tornadoes to speak of. Several tornado warnings were issued in Iowa, with there being some impressive damage that has been surveyed to be damaging straight-line winds of 95-105 mph! Other reports of damaging winds and large hail occurred across eastern Kansas and parts of Oklahoma, although storm motions of 45 mph were a disadvantage along with largely linear storm mode with embedded supercells over Kansas. The storms over Oklahoma came after dark once again given the strong inhibition (EML) that continued to be in place. Although not a lot of reports from chasers have came in regarding the storms on Tuesday, I think it'll be hard to get any highly photogenic storms out of what occurred.

With what is likely one of the worst starts in regards to tornadoes in several years, the largely linear and high precipitation storms thus far haven't produced anything amazing to my knowledge. The Kansas City metro has been off to a pretty good start in regards to just severe/strong thunderstorms with several days of morning and afternoon convection with some marginal hail and strong winds. Even today we managed to pull off a severe thunderstorm and 1.75" hail in Platte County with little instability and a surface observation of 58/44. Can't say I'm dissapointed in hearing the thunder multiple times thus far, and I'll look forward to warmer temperatures and an eventual return to slower moving and more discrete storms later in the Spring!

Now all eyes can turn to the next trough to enter the Plains, which should come sometime early next week! In the meantime, we'll focus on sunny skies and warming temperatures for Kansas City.

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Severe Weather - Apr. 5

A recap of any severe weather will likely be posted once this system has exited the Plains entirely, as a round of severe/tornadic thunderstorms occurred yesterday afternoon/evening and additional rounds of thunderstorms are occurring this morning with more expected this afternoon.

Currently, elevated thunderstorms capable of producing large hail have been ongoing across parts of northeast Kansas and northwest Missouri, especially near the Kansas City Metro area.  A severe thunderstorm watch was issued for portions of the states through Noon today.  These storms are being fed by a strong southerly low level jet that continues to push moisture northward and will begin to push a warm front to the north today, likely situating near the Iowa/Missouri border this afternoon. In addition to the warm front, a dryline will be situated across central Kanas southward into Oklahoma which may be another focus for thunderstorm development.  Thunderstorm development along both frontal boundaries is somewhat in question due to a substantial capping inversion and elevated mixed-layer that will overspread the Plains states. 

Despite this, thunderstorm development should occur along the warm front this evening (7-9pm).  Given moderate instability and sufficient deep layer shear, supercells will be likely capable of producing very large hail, damaging winds, and tornadoes.  Storms should move along the warm front, continuing to be capable of all modes of severe weather through the evening and into the early overnight.  Additional storms will continue along the warm front into Illinois and other portions of the Midwest during the overnight hours continuing the severe weather threat of mainly damaging winds and large hail, although a tornado or two is still likely with any storms that continue along the warm front.

Development along the dryline across central Kansas into Oklahoma is very conditional given the substantial elevated mixed-layer and associated temperature inversion in the lower levels.  Strong instability should be present along/just ahead of the dryline this afternoon, however without continued convergence along the boundary there may not be sufficient lift for development of thunderstorms.  If an area of enhanced convergence can occur along the dryline and thunderstorm development can occur, there is no doubt that supercell(s) would be likely.  Once again all modes of severe weather will be likely with strong deep layer shear resulting in the potential for very large hail, damaging winds, and tornadoes.

Essentially a conditional, but very volatile severe weather setup today across parts of central Kansas, extreme southeast Nebraska, extreme southern Iowa and extreme northern Missouri.  The potential is there for a very strong supercell capable of significant hail, winds, and tornadoes.  I'm sure there will be plenty of storm chasers out to keep track of the situation live.  I once again am working the evening shift, thus will not be chasing this event (I keep telling myself it is only early April, plenty more opportunities).

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Severe Weather - Apr. 4

A true convergence of air masses will lead to severe weather potential stretching from extreme eastern Kansas to the northeast across northern Missouri, southeast Iowa and Illinois.  A cold front will slowly drift southeastward during the day today, at the same time a strong southerly flow will continue the return of warm air and moisture to the Central Plains.  By late this afternoon or early this evening a good bulk of warm air and moisture will begin to bisect the cold front, aiding in destabilization and convergence along the front.  A meager shortwave is shown in model forecasts, and should give at least a glancing blow to aid in storm initiation this evening, especially along the northeastward extent of the front in northeast Missouri and adjacent areas of IA/IL.  Further southwest, instability should be higher due to slightly higher moisture return by this evening, with SBCAPE values of 1000-1500 J/kg and MUCAPE values even higher (~2000 J/kg).  This may be enough when combined with the convergence along the front to initiate storms this evening which may be surface based for a short time as well.  If surface based storms can develop, they will be able to take advantage of some low level shear which will aid in the organization of supercells.  This may open up a small window of opportunity for a tornadic storm or two, however those risks at the moment seem quite low.  More likely scenario will be for elevated storms to develop along the front this evening over northern Missouri as the low level jet provides additional lift and support to parcels ~1km above the surface.  Elevated supercells are possible across northern Missouri, with the potential for large hail and a few damaging wind gusts.  Individual storms will move east/northeast oriented with the cold front, thus the potential will also be there for training storms capable of some localized flooding concerns.  The cold front will drift slowly southward overnight continuing the risk of thunderstorms into central Missouri and adjacent areas, before lifting back to the north Monday morning.

As I've mentioned before I work throughout the weekend and into next week, thus no chasing is planned.  For a local chase today I would suggest a target in northern Missouri, perhaps along a Macon to Moberly line dependent on where the front is when initiation occurs.  A brief update may be posted around Noon, otherwise any additional updates will be later tonight.

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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!

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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. 

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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.

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Severe Weather Potential - August 7 Update #3

Despite the hopes for convection before sunset, it does not appear likely as sunset is within an hour or two and there is not even a watch issued for potential development. Some cumulus is occurring in the warm sector, however, temperatures at 700hPa have increased to 14C directly over the most likely area for development. This is suppressing any chance of convection until at least after sundown across the area...

Thunderstorm development is still possible along the front as the low level jet increases slightly and we see the decoupling of the boundary layer. The tornadic threat with this development will be fairly minimal, with a large hail threat, and a more likely damaging wind threat across portions of southeast South Dakota and then across northern Iowa and southern Minnesota. An additional update is possible, but only if development can actually occur.

Once again Iowa has went and gone off to disappoint the severe weather lovers across the northern plains!

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Severe Weather Potential - August 7 Update #2

Convective inhibition remains strong, however, confidence has increased that the inhibition will yield to convection during the late afternoon or evening hours across portions of the warm front in South Dakota and Iowa. Thunderstorms that do develop are likely to be supercellular with the threat for very large hail, damaging winds, and tornadoes given good low level shear and strong instability.

Just a short update... Expect to leave for a chase target in vicinity of Storm Lake, IA in approximately an hour. Storm initiation by 7 PM along the warm front in vicinity of prolonged strong low level convergence that is occurring in this area. Storms should follow this warm front, tapping into strong instability and good shear parameters leading to a continued tornado threat through 9 PM. Eventual evolution to a cluster or linear segments is expected beyond 10 PM with more of a damaging wind threat.

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Severe Weather Potential - August 7 Update #1

Not much for changes in the going forecast or in the current analysis of things across the plains states. Watching clearing skies across the Dakotas and Nebraska, which should also work into western Iowa during the early afternoon hours. Warm front currently located along and just east of the Missouri River from South Dakota into western Iowa. This front should slowly move a bit northward, currently inhibited due to cold pool left from cloud cover and showers this morning. Strong instability and good inhibition is still in the forecast for the warm sector through this evening. A shortwave currently over eastern Colorado should move over the corner regions of SD/NE/MN/IA during the evening hours and should provide enough support for the formation of isolated thunderstorms.

Thunderstorms forming along the warm front would appear to be supercellular in nature during the evening hours, with the threat of very large hail, damaging winds, and the potential for a tornado given favorable storm motion. Storms should merge in the early nighttime hours, and begin more of a damaging wind threat across northern Iowa and southern Minnesota. This is confirmed with the latest SPC outlook upgrading the probabilities for damaging winds across this region...

Will watch the warm front evolution, as well as the 700hPa temperatures that will be inhibiting development until the Colorado shortwave makes its' way over during the evening hours.

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Severe Weather Threat - August 7

Morning convection continues across southwest Iowa, with additional showers/thunderstorms spread throughout the state and spreading eastward at approximately 30-40 mph. These thunderstorms and showers should continue through the morning hours across much of the state, with cloud cover also remaining through 10 AM across the entire state. Look for a gradual decrease in coverage in both showers and cloud cover through the Noon hour and into the afternoon. Skies should begin to clear from west to east through the Noon hour as well, beginning to leave portions of western Iowa under warm and sunny skies by early afternoon. A warm front currently positioned south of the thunderstorm activity this morning should make its' way northward as the lee cyclone moves out of eastern Colorado and into the plains this afternoon. The warm front should become positioned parallel to I90 across southern Minnesota and likely through South Dakota, with a very warm/moist and unstable air mass to its' south.

Instability values should become quite high (3000-4000 j/kg) given surface temperatures near/above 90 degrees and dew point values well into the 60s and perhaps 70s along/south of the warm front. Strong surface convergence as well as theta-e should be taking place along the warm front, with aid from a subtle disturbance in the mid-levels also arriving during the evening hours across northwest Iowa. The combination of strong instability and continued convergence along the boundary may have the potential to break a cap that is likely to be in place throughout the afternoon south of the warm front. Temperatures at 700hPa are likely to be in the 11-13C range, with temperatures at 850hPa above 20C. Despite the warm temperatures aloft, models continue to indicate surface heating is enough to overcome the cap in areas that have this strong convergence along the warm front.

If the cap is overcome within the warm sector across northwest Iowa or South Dakota, expect rapid intensification of updrafts leading to large hail becoming a likely threat. Given strong shear values, especially for the late evening and early nighttime hours as the low level jet begins to aid the low level flow, a tornadic potential will exist with any development. Expect storms to begin to form into somewhat of a cluster or MCS after 10 PM and continue across the state, with perhaps an additional MCS moving out of the Dakotas and into MN/IA during the nighttime hours. An additional update is likely near the Noon hour, and once again through the afternoon and convective inhibition and the location of boundaries, etc. becomes more defined.

Storm Chasing Status: With a conditional threat, I will likely be sitting in the comfortable confines of home through the afternoon. However, with the threat likely evolving within an hours drive will be watching conditions closely. Current four county target area is Lyon and Osceola counties in northwest Iowa, and Nobles and Rock counties in southwest Minnesota.

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A Quick Recap

Busy days ongoing for me has created a good lack of updates on my part. Just to review back to July 14, the severe weather threat did materialize, although much weaker than initially thought due to only convection along the front firing during the evening hours. Did manage to punch through a severe warned cell between Wallingford and Ringsted on the way back from a playoff baseball game. This cell didn't really back much punch in regards to wind, and no hail was found. A weakly photogenic shelf cloud was noted, but not captured...

After the cold front passed through the state we were left with some below average temperatures that have continued into tonight. Current temperatures early this morning range from the mid 50s to the upper 40s! High temperatures for Friday should range from the upper 60s to the mid 70s across the state from northeast to southwest; lows overnight will drop into the upper 40s to mid 50s across the state once again. The weekend will stay dry with highs in the upper 60s to mid 70s from east to west on Saturday, then from mid 70s to mid 80s by Sunday. Low to mid 50s for Saturday night temperatures, and mid 50s to lower 60s from east to west for lows on Sunday night.

We'll return to chances of thunderstorms and showers for the work week, with the best chances on Monday night in the west; Tuesday and Tuesday night for the central and eastern thirds, and the potential for a lingering shower or storm in the east on Wednesday. High temperatures in the upper 70s to mid 80s from east to west for the first half of the work week; with lows in the upper 50s to mid 60s. Look for an update on these chances of thunderstorms come early next week!

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Severe Weather Potential - July 14

The potential for a significant severe weather event over portions of the central/northern plains is there for tomorrow, as potent surface features will be supported by strong upper air parameters. Two areas of interest are going to come into play, both of which have some very big question as to its' potential to produce significant severe weather. A lot of the questions may be answered tomorrow morning once the evolution of the MCS(s) from current severe/tornadic convection across SD/NE is known. An update during the overnight hours or during the early morning will hopefully give an idea as to which area of concern is greatest.

The most favorable target will likely be along a reinforced warm front or outflow boundary following tonights' convection that will setup across southeast Nebraska, southwest Iowa and across northern/western Missouri. Strong heating and moisture return will be in place for this area, providing extreme instability and likely strong lift. Upper air features better align with this area of instability and lift, aided by a shortwave that would likely aid in development. As with the case with most late season events with such extreme parameters in place is the capping concerns... Temperatures at 700hPa near the 12C mark will likely cap thing well into the afternoon, however, there is support with the models indicating that this capping inversion will be broken before 00z. A target in this area could come with some significant rewards, or you could end up with nice blue skies as the cap holds.

Another target area will be further north along the cold front which is forecasted to move into western Minnesota and near the SD/NE/IA/MN corners and into eastern Nebraska. Capping will be less of a concern here with a strong mechanism for storm development (cold front) and 700hPa temperatures less than 12C. Development is likely by the evening hours along the cold front throughout western Minnesota and into SD/IA/NE. The problem with the setup here arises with the displacement of instability and shear parameters, with strong instability present along/ahead of the cold front (especially at low levels), but the best shear further ahead of the front. Any development just ahead of the cold front may be able to tap into both instability and shear, thus able to put on a show... This would rely on any outflow boundaries from morning convection...

Additional updates likely within the next 8-12 hours... I will likely favor the secondary target area as it is quite local.

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Chase Account - July 9

Several rounds of severe weather swept across portions of northwest Iowa yesterday, from mid-afternoon hail to evening and overnight storms that left hail, winds, and heavy rainfall across parts of the state. I made a trip out to view the storms on two occasions yesterday, once during the mid-afternoon hours between 3:30 and 4:30 PM. This was the initial round of storms that produced some large hail from the SD/IA borders eastward to near Highway 71. Upon arrival to the storms, they were weakening significantly and led to only heavy rains that would obscure your view pretty good. On this trip we would also arrive upon an accident that occurred just west of Ruthven, IA where it appeared a vehicle may have been pulling out of a private lane onto the highway and did not see the cross traffic. A bad scene there as both vehicles were badly damaged, however, have not heard any news about this accident and how either drivers/passengers fared.

The second chase came during the waning daytime hours, from ~8:30 PM to after 10 PM across portions along the Dickinson/Clay county lines and back towards Wallingford in Emmet county. Several occasions of strong lightning strikes, and torrential/blinding rains with the multiple storm cells that we crossed paths with. On the backside of the last cell to be severe warned across these counties we were able to capture several occasions of 3/4" hail and strong east-southeast winds of 40+ mph. Video was captured from the dash cam for the entire trip, however, nothing significant to really note and share... A nice local chase/spot to add on for the year; now we'll wait for some true summer isolated cells to actually have some photogenic quality to the storms!

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Severe Weather Potential - July 9

A complicated forecast is in the works for the next 36 hours, and perhaps even longer, for Iowa and adjacent areas. A strong wave will initiate thunderstorms this afternoon across the western Dakotas and areas of Montana/Wyoming. These storms should develop into a large MCS, possible derecho, during the evening and overnight hours traversing the Dakotas and moving into western Minnesota by sunrise on Thursday. This MCS will likely be making a right turn throughout the night as the low level jet veers, making the projected path perhaps into northern Iowa between 6-10 AM tomorrow. While the severe weather threat would seem minimal, gusty winds nearing severe criteria is a definite possibility.

As this MCS clears, a stable layer will be left over and likely inhibit additional development until the later afternoon hours. With a cold front and strong disturbance coordinate to create sufficient lift to break and inhibition that will be present across northern Iowa and southern Minnesota. With wind fields increasing in strength throughout the lower and mid-levels, expect deep layer shear to be sufficient for supercells as the initial storm mode with damaging winds, large hail, and isoalted tornadoes all being possible. However, with time and more forcing along the cold front it would appear that the growth of another MCS is likely, yielding a damaging wind threat across the central portions of the state. More details into the forecast will be clear tomorrow morning when the extent of the morning MCS is known... Expect an additional update late tonight and early tomorrow as to the possibilities of severe weather across portions of Iowa.

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Severe Weather Recap - July 7

A cluster of thunderstorms developed in eastern South Dakota during the afternoon hours yesterday, and entered into northwest Iowa during the evening hours. These clusters of storms were at times severe warned with the potential for both damaging winds and large hail, estimated 60 mph winds were reported and hail up to 1.5" in diameter also occurred. The severe weather was intermittent at best, with little in the way of damage reported.

I ventured outside of home for a short while as the leading edge of what was a bow echo entered the state in northern Emmet county. Upon arriving outside of Wallingford I did capture very brief video of a gustnado on this leading edge. I estimate the location of this gustnado near Dolliver, IA given its' distance away from me at that time. An otherwise uneventful night as gusty winds and heavy rains were all that occurred...

I will try to get a vidcap of the gustnado up at a later time... Along with a few panoramic images of the shelf as it entered Emmet county.

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