Friday, June 26, 2009

Severe Squall Line

A mature squall line that continues to be capable of damaging winds in excess of 60 mph and the potential for quarter sized hail is moving swiftly to the east across South Dakota and northeast Nebraska. Current warnings cover the entire length of this line from DeSmet, SD to Pierce, NE...

Along its' current track the line would likely enter southwest Minnesota and northwest Iowa just after 1 AM this morning. Northwest Iowa is most likely to see any damaging winds from this squall line as it enters the state. Those in northwest Iowa should monitor conditions with their weather radio as damaging winds can often cause trees to fall which can produce damage to homes, especially upper levels.

My current plan will be to grab a few hours rest before getting up and heading out ahead of this squall line if it is still in tact as it nears Dickinson/Clay counties. More than likely I will attempt some lightning photography as it nears...

Wednesday, June 24, 2009

Severe Weather Potential - June 24

Quick update from the road today as I am returning from a trip to Ames to visit a few friends. Thunderstorms were widespread yesterday as they continued to move in from NE/SD during the early afternoon hours. Although a few tornado warnings were issued, these tornado warnings were for small vorticies that were confined within the larger line of storms as it moved across the state. No reports were confirmed of a tornado in the state yesterday, but wind damage was widespread through nearly the entire state with wind gusts nearing 80 mph in a few of the stronger storms during the afternoon.

Today's severe weather threat would appear to exist during mainly the late evening and overnight hours as storms once again move out of SD/NE and into western Iowa. A few rogue thunderstorms may develop in localized areas of convergence this evening and have the potential for damaging winds, hail and an isolated tornado. Otherwise it is likely that an MCS will form over eastern SD and continue east/southeast into northwestern Iowa during the early overnight hours. This MCS will likely contain damaging winds and perhaps some small hail as it moves across the state.

Tuesday, June 23, 2009

Welcome Summer...

Apparently summer did not want to show up until it was officially ready, with Sunday being the first day of summer the state sure has heated up since. High temperatures yesterday ranged from the lower to mid 90s across the entire state, with plenty of moisture across a majority of the state to make it feel like temperatures were close to triple digits. Today will be similar, with highs actually getting a few degrees higher than yesterday in most locations. With high continuing in the lower to mid 90s, and even more moisture present today, heat indices will range across the lower 100s. This has prompted a majority of the state to be put under a heat advisory for this afternoons' heat.

Thunderstorms are a possibility across the state tonight and tomorrow, with a chance of a few storms even being near or above severe limits overnight tonight across western and central Iowa. These thunderstorms should be fairly isolated in nature, with marginal hail and damaging winds as the main threats. Temperatures will cool some on Wednesday with the passing of this system, but temperatures should still remain in the 80s across the state. Those temperatures in the 80s should continue through the remainder of the week, with continued high moisture leading to the warm/sticky days and enjoyable nights.

Sunday, June 21, 2009

Severe Weather Potential - June 21

More of a summer-like pattern has pushed into the central plains, with a weak ridge trying to work into the plains states. This has left us with southwest flow aloft through the state of Iowa, and with a low pressure system working off of the high plains and into Nebraska this morning will set us up for a round of severe weather this afternoon. This low pressure system should work into the four corners area of NE/SD/IA/MN by mid-afternoon, with a well defined warm front to its' east/southeast and a trough of lower pressure to its' south/southwest. Along and south of the warm front should have clear skies through the afternoon, with strong heating near 90 and dew points surging into the lower 70s across the area. This should provide us with moderate to strong instability across the state, and with little in the way of inhibition it would likely to see storm initiation fairly early in the afternoon in areas that clear and develop this instability.

Given decent southeasterly flow within the warm sector, low level shear should be sufficient to warrant a tornadic risk. Combined with the very low LCL levels thanks to good heating and moisture present, this tornadic risk seems to be fairly significant. Storms that do develop and move east/southeast nearly parallel to the warm front would have favorable conditions to be tornadic. Thus, would expect areas of northern Iowa, and eastern Iowa where the warm front is more southeast oriented to see the greatest risk of severe weather including tornadoes.

It is Father's Day, thus a lot of people likely enjoying the day outside. It will be important to pay attention to the weather this afternoon due to the risk of severe weather, specifically tornadoes. An additional update near Noon is expected, this will be a brief update in regards to any change in potential.

Friday, June 19, 2009

Iowa Upsets Chasers

Once again the state of Iowa has upset the chasing community with its' lack of cooperation over the past two days. Two straight days of moderate risk, and two straight days of utter disappointment for any storm chaser that was in the state. Both setups featured their own caveats, and both featured the opportunities for greatness, but both days have their caveats win out with no tornado reports and perhaps the highlight of a shelf cloud and some impressive winds this afternoon in southeast Iowa.

Thursday's setup featured a warm front which pushed well north of the state, leaving the state under a heavy capping inhibition between 850 hPa and 700 hPa. With no warm front to help trigger thunderstorms, only a weak remnant outflow boundary had an opportunity for greatness. Although it tried with several cumulus fields attempting to bubble up through the capping inversion, none would ever succeed. Thus, tack a point up for capping inversions with 12C temperatures at 700 hPa over Iowa as a bad chase day.

Today's (Friday) setup finally featured a strong trigger for convection as a cold front moved through the state, and an outflow boundary once again was expected to allow low level winds to remain southeasterly and aid in low level shear. The disappointment would come with winds remaining southwesterly ahead of the cold front, and the lack of a capping inversion allowing the whole cold front to be socked in with showers/storms from Noon onward. At least there were thunderstorms, albeit outflow dominant, that would let you chase something! Wind reports were consistent with at least three separate thunderstorms today, with winds ranging from 60-85 mph across eastern Iowa. Still, a day that would have offered tornado potential for the state would be ruined by a cold front with little inhibition and the lack of cooperation of the surface winds.

If anything can be learned from the past two days, trust instincts that a 12-13C temperature at 700hPa and no strong convergence in the lower levels will lead to nothing but struggling cumulus or blue skies. And, when a cold front comes into the state then you need the 12C temperature at 700hPa along with some southeast if not at least south winds to provide low level shear.

Here's to the hope that the more summer-like thunderstorms can provide some punch for the state with at least some great lightning and supercellular structure!!

Severe Weather Threat - June 19

While yesterday turned out to be another cap bust in Iowa that makes all those out-of-state chasers absolutely hate chasing in Iowa, today will definitely not be the same. Must cooler temperatures just above the surface in the lower levels will provide much less of a capping inversion, and with a must stronger wave in the mid-levels combined with significantly more convergence at the lower levels as well with a cold front moving southeastward. All of this will provide the southeast half of the state to see numerous thunderstorms, many of which may be severe with damaging winds and large hail.

Be sure to pay attention to the latest weather information via TV/Radio as thunderstorms near your area. While the risk of tornadoes is forecasted, it would appear that surface winds quickly turning southwesterly will decrease the low level shear dramatically, thus inhibiting the strong low level shear that was expected to aid in tornadic development.

Thursday, June 18, 2009

Cap Bust??

With 700hPa temperatures in vicinity of the 12C range, the cap over central Iowa is quite strong... And with the ever decreasing convergence along any portion of the state it looks less and less likely that storms will fire before dark. I've decided to slowly work back westward towards home with an eye on the sky/radar if something does try to develop.

For now it appears that the Iowa cap will once again win over another fantastic parameter day in June...

Did manage to meet up with the TWISTEX crew and spend some time chatting with them, and grabbed a few pictures with the TIV2 as they were with the TWISTEX crew today. It was good to see all of them and hope to see you guys again!!

Chasing Live!!

Currently on Highway 18 just east of Cylinder, IA and will likely continue east towards Algona before sitting and waiting for a bit longer. Parameters look amazing, and once the cap is able to go then we should see very explosive development of supercells capable of significant tornadoes and hail.

Be sure to watch the chase live via the spotter network maps, the latest radar update from my laptop, and live video from my dash on the Iowa Chaser Live Chase Page!!

Significant Severe Weather - June 18

The updated SPC Day 1 outlook will continue the moderate risk of severe weather across much of northern Iowa and southern Minnesota. There is a significant risk of damaging winds, very large hail, and tornadoes across the area today. In fact, the updated outlook has increased the probability of tornadoes over northern Iowa and southern Minnesota. The morning thunderstorms will actually help increase the risk of tornadoes this afternoon/evening as the outflow boundary left in its' wake will interact with the warm front to create substantial low level shear. This would appear to once again be a very dangerous and life threatening situation over areas of the plains states today.

I will be chasing today across northwest Iowa, this blog will have the latest updates as I can provide them. As we near the afternoon initiation you may be able to view live video from my vehicle as well as track my location via the Iowa Chaser LIVE Chase Page.

Next update in regards to afternoon chasing and severe weather is expected in the early afternoon hours.

Morning Severe

The SPC has issued a new severe thunderstorm watch for northern Iowa as a line of thunderstorms with a history of large hail and damaging winds is moving across northwest Iowa currently and is expected to remain severe through the morning hours. This watch will be in effect until 11:00 AM and cover the areas shown below:

Morning Bow Echo

Thunderstorms cleared the state during the overnight hours, but not before providing several reports of hail and damaging winds as well as a tornado report in northeastern Iowa during yesterday evening.

Early this morning there is a bow echo that is entering northwest Iowa with the potential for damaging winds in excess of 60 mph. This storm has had a history of damaging wind gusts as well as marginally severe hail. The bow echo is a line of storms extending from near Beresford, SD southwards to near Pender, NE; and is moving east/northeast at 35 mph. A Severe Thunderstorm Watch has been issued for portions of northwest Iowa until 9 am for this line of thunderstorms.

This line of storms does appear to travel towards my location, thus will plan for its' arrival between 8:30 and 9:00 AM with the likelihood of a photogenic shelf cloud.

Wednesday, June 17, 2009

Severe Weather Update #2 - June 17

The weak boundary is responsible for several ongoing tornadic storms over north-central and northeast Iowa as well as southern Minnesota. Currently Chickasaw county has a tornado warned storm that has produced a tornado before within the past hour, and this storm may continue to produce tornadoes as it moves to the southeast. Another, perhaps more dangerous storm, is moving into Mitchell and Howard counties in Iowa. This storm has produced a large and dangerous tornado that is responsible for injuries across Austin, MN and nearby areas. These storms are likely to continue to be tornadic in nature for at least the next hour or two. After which the instability may begin to weaken in those areas and we may see the storms weaken... Persons in those areas should be very aware of the conditions and take shelter if any storms approach.

Additional thunderstorms have fired across northeast Nebraska and into southeast South Dakota. Given environmental conditions ahead of these thunderstorms, they are likely to maintain a severe weather threat into the overnight hours. Areas of west-central and northwest Iowa are likely to see these storms as they have the potential to produce significant severe weather. Additional updates are likely as storms continue to threaten areas of the state.

Severe Weather Update #1 - June 17

Severe and now tornadic thunderstorms are ongoing with the stronger warm front located along the Kansas/Nebraska border. Additional storms are likely as we continue through the afternoon and eventually congeal into more of a cluster or MCS of storms moving into west-central and southwest Iowa.

The other area of concern for severe weather, including tornadoes, will be over northwest/north-central Iowa where a convergent low level boundary associated with a weak low pressure system over South Dakota may trigger thunderstorms this afternoon/evening. Latest analysis indicates this wind shift is becoming very defined with strong instability along and east of the boundary. Effective wind shear values above 40 kts will support supercells when initiation occurs, and likely support tornadic storms through the evening hours.

I plan on chasing any development along this wind shift and weak boundary in northwest Iowa, thus stay tuned for additional updates!

Severe Weather Potential - June 17

The potential is there for significant severe weather across the western half of Iowa this afternoon and into the overnight hours. All modes of severe weather appear possible, including damaging winds, very large hail, and tornadoes. There are two areas of concern for severe weather today, both of which cover western Iowa...

The first and most likely concern will be over much of western Iowa, and likely be during the late evening or overnight hours. This severe weather threat will likely be for damaging winds and large hail, although a risk of tornadoes will exist, a more linear nature of thunderstorms may be expected. These thunderstorms will evolve from central Nebraska this afternoon as they initiate due to a shortwave and frontal system interaction. As the thunderstorms continue to evolve eastward they are likely to congeal into a more linear MCS capable of large hail and damaging winds as they enter into western Iowa.

Another threat for severe weather will exist during the afternoon/evening hours over mainly northwest Iowa, as well as southwest Minnesota. Similar to yesterday afternoon over South Dakota, a weak low pressure system in conjunction with a trough of low pressure and low level convergence may lead to thunderstorm development along a weak wind shift line. With even higher temperatures and dew points this afternoon yielding even higher instability amounts this will come as no surprise to see even stronger supercells off of this setup. These storms will be capable of all modes of severe weather through the evening hours, but similar to yesterday they should begin to weaken after sunset.

Additional updates are likely this afternoon as the severe weather threat evolves, I am watching the potential across northwest Iowa for the tornadic supercells similar to yesterday...

Tuesday, June 16, 2009

Severe Weather Update #1 - June 16

Although severe weather is not immediately affecting any portion of the state, ongoing and developing thunderstorms appear to be moving towards northwest Iowa and may enter the state in the coming hours. The most immediate danger would appear to effect Plymouth and Sioux counties in Iowa over the next two hours. The NWS in Sioux Falls has extended the tornado watch that was in effect for eastern South Dakota to include those counties that are in the direct path of a strong tornadic supercell that has had a history of producing tornadoes, some of which have appeared to be strong, over southeast South Dakota. Currently this tornadic storm is east of Yankton, SD and is moving southeast at 30 mph. This path would likely effect Vermillion, SD and eventually towards Sioux City, IA by approximately 10:30 PM. While the tornadic threat may not continue through this time, it would appear that at least damaging winds and large hail would be an issue for areas of Plymouth and Sioux counties.

Additional updates are possible if this continues on its' track towards northwest Iowa.

Severe Weather Threat - June 16

While some thunderstorms move across parts of central/eastern Iowa this morning, and some lingering showers/cloud cover continue across western Iowa, we are likely to see clearing skies and an increased chance of thunderstorms once again this afternoon/evening and potentially into the overnight hours. Temperatures not only today, but through the remainder of the week are likely to rebound nicely after morning convection and/or cloud cover. Highs into the 80s and 90s over the state are likely through Thursday...

A weak surface low is positioned across central South Dakota this morning, and is likely to only move slightly as we continue into the afternoon hours. Two troughs of low pressure are likely to extend from this low pressure system and create a moderately unstable warm sector for this afternoon across eastern Nebraska, eastern South Dakota, western Iowa and other adjacent areas. Moderately instability combined with a weakly capped environment should create ample development by the afternoon hours along both troughs in SD/NE and perhaps across Minnesota and extreme northern Iowa. While moderate bulk shear is present across the entire warm sector, directional shear appears to be limited over SD/NE/MN/IA where development is likely. Thus it would appear as if the main threats of severe weather will be for large hail and damaging winds with the strongest and more organized storm clusters this afternoon. Additional update are possible if the severe weather threat warrants...

The severe weather threat will likely continue for the northern plains on Wednesday, and continue through Friday. Both Wednesday and Thursday have warm fronts that will likely be positioned across Iowa or just south of the state warranting the risk for severe weather. Thursday will also have a cold front finally pushing eastward over the plains states with an increased risk of severe weather; a similar threat exists on Friday. Additional updates on these risks as the week continues.

Monday, June 15, 2009

Overnight Thunderstorms

Severe and tornadic thunderstorms continue to move across much of the northern and central plains states. Some of these storms may enter the western portions of Iowa within the next few hours, mainly over southwest Iowa where a Severe Thunderstorm Watch is in effect. Currently, a line of thunderstorms is moving into southeast Nebraska and will continue to move northeastward into southwest Iowa likely by 10:30 PM capable of large hail and damaging winds. Other storms over central Nebraska and South Dakota will likely congeal into more of an MCS as the low level jet continues to increase and organize storms and produces additional development. These storms are not as likely to be severe, rather with a continued heavy rain threat over parts of the state which saw heavy rains over the past few days.

Thunderstorms will likely linger across the state tomorrow, with additional development of severe/tornadic thunderstorms possible to move into the state during the evening hours. Additional updates on tomorrow's severe weather threat over the southwestern half of the state is likely tomorrow morning.

The forecast will continue to warm up as well as moisten to allow more chances of thunderstorms later in the week, with another round of severe weather being likely on Thursday across much of the state.

Friday, June 12, 2009

Warming Weekend

After below normal temperatures and an end of the week that was both cool and wet we will begin a weekend that will start us on a warming trend! Rainfall totals across the state appeared heaviest across western Iowa where just over an inch fell in areas such as Sioux City and LeMars. Other areas of the state, especially the southeast, did not see nearly as much with only a few hundredths to a few tenths in the heaviest areas. Expect a few lingering showers over central and eastern Iowa tonight, and mainly cloudy skies over those same areas while parts of western Iowa begins to see some clearing skies.

Lows overnight tonight from near 50 in the northwest to near 60 in the southeast. Partly cloudy skies will prevail for Saturday, and with the sunshine we'll see highs in the mid 70s throughout the entire state. Saturday night will remain partly cloudy across the state, with increasing clouds over the west as we near sunrise on Sunday. Low temperatures will range from the lower to mid 50s from northeast to southwest. A weak frontal system will approach the state from the southwest on Sunday, bringing in more chances of showers and an isolated thunderstorm over the southwest half of the state on Sunday and Sunday evening. Highs on Sunday should be fairly consistent across the state near the mid 70s; with overnight lows in the mid to upper 50s from northeast to south. Our frontal system stalls out and begins to become diffuse which will decrease our chances of showers overnight on Sunday.

In the long range, it would appear that mainly zonal flow with embedded shortwaves will prevail over the plains states through the week. This will bring us off and on showers/thunderstorms throughout the week. Some slight ridging is expected to begin towards next weekend, with this expect an increase in temperatures as we near the upper 80s and finally the 90s across parts of Iowa. More details on this true southern warmth in next weeks' forecast updates.

Tuesday, June 9, 2009

TWISTEX & Other Chasers

Today was forecasted to be another potentially significant day of severe weather with an increased tornado potential across the plains states. Unfortunately for all of the groups out there that are doing research, from my TWISTEX buddies, to VORTEX2, and to all of the other chasers out there, today once again turned to be a big disappointment from a tornadoes standpoint.

The tornado reports today came across eastern Kansas during the early afternoon storms that were likely triggered and aided by the morning MCS. Other reports came across the high plains of Colorado where little risk was expected, and even a stray report in Nebraska that was a very brief and likely a landspout. Sunday was expected to be a strong day for thunderstorms and tornado potential, while the thunderstorm aspect wasn't a disappointment with hail larger than 5 inches in diameter, the tornado reports that may have verified were all brief and weak. This year is the lowest since 2005 as far as tornado reports, and is nearly 200 tornadoes below the last 4-year average. While there are plenty of chasers who have still had a good year, most are still very disappointed in the year thus far.

Thus, I am not too disappointed that I have had to miss this years' activities due to the birth of my first little boy. Here's to a hope that we can continue the mediocre year well into June and into this fall over the northern plains.

While I'm on the context of other chasers including TWISTEX, I would like to give my little shout-out to the group that is chasing as a part of the Discovery Channel Storm Chasers crew. TWISTEX is being displayed as a professional and pure scientific research group, as that is what they are! Tim Samaras, Dr. Bruce Lee, Dr. Cathy Finley, and Tony Laubach among others have had some luck this year; they were able to have a successful mission out in Wyoming last week as well as many others. Be sure to follow their updates as I post them on their website:

Monday, June 8, 2009

June 7 Tornado/Wind Survey for Dallas/Polk Counties

The National Weather Service office out of Des Moines issued their public information statement regarding the tornado reports and damaging wind reports that were received as a severe and tornadic thunderstorm moved across Dallas and Polk counties on Sunday evening. The results of the survey indicated that a brief EF-0 tornado occurred south/southeast of Dallas Center. The tornado length was 1.5 miles long, with an average width of 100 yards; the tornado damage path was concentrated within a path of straight line winds which began near Adel and continued northeast. The reports of a tornado near the town of Grimes was investigated and the NWS determined that this was a results of straight line winds that occurred on the southern periphery of the supercell's mesocyclone. A nice image that the Des Moines NWS has posted to their website is below:

To read more details and the complete public information statement please view the survey link: Adel to Grimes Wind Damage Survey

Another Cool Week

Over the past couple of days I couldn't help but hear people whine about how 'cold' it was across northwest Iowa and adjacent areas that were north of the warm front that sparked off several rounds of thunderstorms. It is always ironic to me how people use the word 'cold' to describe the weather; if it was anytime between October and March then people would be very pleased and say that the past couple of days of weather has been 'warm'. Instead, just because we want to see temperatures in the 70s and 80s or even higher we start complaining that it is 'cold' outside. Thus, this posts title will be in regards to the continued cool weather that is expected for what looks to be the remainder of this week.

Today's temperatures range from the upper 50s to mid 60s across a majority of the state, while extreme southeast Iowa was able to stay in the warm sector for a while and saw highs in the 70s and lower 80s. We'll dry off tonight with low temperatures ranging from the mid 40s to mid 50s from north to south. The showers/thunderstorms will return to western Iowa during the evening hours on Tuesday; with highs in the mid 60s to mid 70s from northwest to southeast. The showers/thunderstorms will overspread much of the state overnight on Tuesday, with low temperatures in the 50s throughout the state. Scattered showers are likely to continue over the state on Wednesday, hindering high temperatures to the mid 60s to lower 70s from north to south.

Although there are a few rogue chances of a shower/thunderstorm, we should stay dry through the rest of the work week. High temperatures for Thursday and Friday should range from the lower to mid 70s. Low temperatures in the lower to upper 50s on Thursday night will increase a few degrees to the mid to upper 50s for Friday night.

Sunday, June 7, 2009

Severe Weather Update #2 - June 7

Three storms have formed in vicinity of the warm front across both Iowa and Nebraska, one of which has been tornado warned for over a half-hour now. The tornadic portion of the storm passed just 15 miles south of my previously mentioned virtual target area. This storm has yet to produce a tornado, although a few reports of a roughly organized wall cloud have came into the NWS. This storm continues to move east just north of the Kansas/Nebraska border, and a second storm that is severe warned near Falls City, NE capable of large hail. A third storm along the warm front that is severe warned is much further east in Iowa, near Adair, that is capable of large hail near quarters in size. This storm is moving in more of a northeast fashion.

It would appear that much of Iowa will see isolated thunderstorms this evening and overnight; the best areas for severe weather are likely to be over areas along/south of I-80. Thunderstorms appear to be forming rapidly near the Iowa/Missouri border and will likely be the start of an MCS that will move over southern and eastern Iowa capable of large hail and damaging winds.

No additional updates are likely this evening as the severe weather threat is playing out similar to forecasted.

Severe Weather Update #1- June 7

Just a quick update beings I have had a chance to look over the latest mesoscale analysis from the SPC. The warm front is very well defined across Nebraska and Iowa, with strong frontogenesis also occurring across southeast Nebraska and southwest Iowa. There is fairly high temperatures at 700hPa which is likely leading to some pretty good capping across much of eastern Kansas and into adjacent areas of NE/IA/MO. The vorticity maxima associated with the shortwave is now across central NE/KS and this may provide sufficient forcing to begin forming a cumulus field along the warm front. It would appear that all other factors are sufficient for strong supercellular storms this afternoon, wind shear greater than 40 kts, moderate to strong instability, and the good focus for thunderstorms.

We do have cloud cover and a few showers associated with the shortwave, and these may be a hindrance or a help to convective development. My current virtual chase target would be for Tecumseh, Nebraska...

Severe Weather - June 7

Once again a warm front will be draped across the plains states, from northern Kansas through southeast Nebraska and then across parts of southern/central Iowa. Areas along and south of this front are likely to see temperatures near/above 80 degrees this afternoon with surface dew points into the lower 60s. This will provide moderate to strong instability, and combined with ~40 knots of 0-3km wind shear across this sames area of eastern KS/NE and southern IA will provide an environment for supercells. The potential for supercells will be enhanced by an increasing low level jet across the plains states, and any outflow boundaries that may be situated in this warm sector. Thunderstorms should develop along these outflow boundaries in vicinity of the warm front, indicating likely areas of initiation to northeast Kansas, southeast Nebraska and potentially into southwest Iowa. Thunderstorms in the early stages are likely to contain very large hail and the potential for tornadoes; as storms continue into the overnight we could see one or more clusters of storms. These clusters are likely to continue the threat of large hail and especially damaging winds across the remainder of southern/eastern Iowa.

Additional updates are possible this afternoon as storms begin to develop...

Saturday, June 6, 2009

Severe Weather - June 6

Overnight convection associated with an MCS has continued to move through the state of Iowa this morning, and another cluster of precipitation is also moving across extreme northeast Nebraska and eastern South Dakota as well. This precipitation and its' evolution was a big question mark as to how it would affect the forecast for today's severe weather as it would influence the location of the warm front. It would appear that a cold pool has setup across parts of southeast South Dakota and adjacent areas of Minnesota and Iowa, however, areas behind this convection are already clearing indicating that there may only be a minimal effect from this mornings' precipitation across much of eastern Nebraska and western Iowa. In fact, elevated instability is already showing up across much of eastern Nebraska where clearing is already occurring.

Current SPC forecasts still indicate that they do not expect the front to have much of a northward surge at all today, leaving the primary focus for severe weather across southeast Nebraska and extreme northern Kansas. Once storms fire over that region this evening, they would then propagate northeastward along the warm front into western Iowa with the threats of damaging winds and large hail. This may be the more likely scenario, however, an eye will likely be kept on this front and its' northward progression throughout the day.

Severe weather will definitely be a possibility for areas south of a Kearney, NE to Sioux City, IA to Fort Dodge, IA line. All modes of severe weather would appear likely south of this line, including the threat of tornadoes in both discrete supercells and even in a more linear segments given strong shear values across the region. Once again however if the warm front is able to surge north across any portion of Nebraska/Iowa the threat of severe weather may move northward... Additional updates this afternoon may address this if it does indeed look to be occurring.

With prior plans in Vermillion, SD until ~7 PM I don't see any chasing occurring today unless the front can surge well north of its' current forecast. Tomorrow may be another chance with those details later tonight...

Friday, June 5, 2009

Severe Weekend Weather!

One of the more impressive setups for severe weather will take place beginning today and continue through the weekend for the northern/central Plains states. A broad western trough has finally moved into position to create southwesterly flow across the high plains today, and will make progress eastward over the next two days to continue this southwest flow into the central US. Today's severe weather threat will be held to the high plains due to meager moisture in place, and the more favorable upper level support is located across the high plains as well. Today's area of interest will include western Nebraska, northeast Colorado, and nearby adjacent areas including eastern Wyoming. The main threats with today's storms in the high plains will be very large hail and tornadoes given a strengthening low-level jet in the evening hours.

Tomorrow (Saturday) the lee cyclone begins to move off of the high plains and further east into Nebraska, with the aid of strong southerly jets just above the surface and an open Gulf of Mexico even at the surface we will see strong moisture return through the day and into the overnight. Moisture return will likely make it to near 60 or just above by Saturday evening, leading to only moderate instability across Nebraska and into western Iowa along/south of a warm front. The warm front location is somewhat in question, although this mornings' models locate this front from near Lincoln, NE to Clear Lake, IA and eastward towards Dubuque, IA. A dryline also situates itself southward from the low in central Nebraska, leading to other favorable areas for severe weather along this dryline through central Kansas. Shear values are favorable throughout this region, and initiation of storms appears likely nearest to the low pressure system in Nebraska and along/north of the warm front in NE/IA. Further south along the dryline could have explosive development if 700hPa temperatures well above 10C do not cap the convection. Storms that do develop and remain somewhat discrete will be supercellular in nature capable of large hail, damaging winds, and tornadoes. The more likely scenario will be for the storms to develop near the surface low and near the warm front, these storms will be capable of large hail/damaging winds. Given moderate moisture, storms may become surface based and definitely become capable of tornadoes as storms move along the warm front. An additional update on tomorrow may be posted later today if necessary...

Sunday is another day that holds very high potential for severe weather, given deeper and more sufficient moisture return south of the warm front that is once again expected to be draped from northern Nebraska through central/northern Iowa (Norfolk, NE to Sioux City, and near Clear Lake). While the warm front doesn't appear as defined on Sunday, likely due to convection debris/cloud cover from Saturday night, sufficient instability and lift would appear strong enough to erode the capping inversion that is once again present south of the warm front (10-12C 700 hPa temperatures). Once again storms should develop near the low pressure and near the warm front, capable of large hail/damaging winds/tornadoes given increasing shear values throughout the evening. As storms continue to develop near the low and further south along the dryline, it would appear that an MCS will once again develop and push east/northeast through Iowa capable of hail/winds. An update will be posted for Sunday either tonight/early tomorrow or potentially early Sunday.

I'm currently scheduled to photograph a wedding in Vermillion, SD on Saturday afternoon and early evening. Meaning I'm already in position for the potential on Saturday along the warm front and perhaps in position for Sunday in northeast Nebraska given an overnight stay. All of my chase gear will be with me needless to say...

Tuesday, June 2, 2009

Cooler Weather

Lows over the next few nights will be a ways below normal, while highs struggle and remain just below normal. Overnight lows tonight across the state will range from the lower 40s in the extreme northwest part of the state to the lower 50s across the southeast portions of the state. While partly to mostly cloudy skies remain across the state tomorrow we'll see highs ranging from from the upper 60s to lower 70s and northerly winds from 5-15 mph. Another chilly night is in store for Wednesday night, with skies clearing the lows will drop into the 40s for nearly the entire state.

Winds will begin to turn to the south once again on Thursday, and with partly cloudy skies highs will be back to near-normal from the lower 70s along the Mississippi to highs near 80 along the Missouri River. With meager moisture returning, lows overnight on Thursday will only drop into the lower to mid 50s from east to west across the state. We'll also see some slight chances of showers/thunderstorms move into the state for the overnight and continue through Friday night. Friday's highs will range from the lower 70s to the mid 70s, and overnight lows from near 50 in the north to the mid 50s in the south.

A blast of colder air will return for the weekend, and with that comes showers/thunderstorms across the state. More details on the weekend precipitation chances in the next update!

Monday, June 1, 2009

Weather Update - June 1

Despite a severe thunderstorm watch being issued for portions of southern Iowa, the severe weather threat has never really ramped up due to continue cloud cover and the lack of organized convection. The Storm Prediction Center has chosen to continue the watch over southern Iowa, but it would appear that storms will remain very unorganized through the evening hours.

Thunderstorms are likely to continue over much of southern Iowa, thus despite the lack of severe weather, the likelihood of flooding is fairly high due to the training of storms over the same areas. As the storms continue across the state tonight and into tomorrow, we'll finally clear off on Tuesday afternoon and stay that way until later this week. The next update will contain the forecast for the remainder of the week to see how warm or how cold we can manage to get!

Severe Weather Forecast - June 1

Welcome to June! Our first day will be welcomed with a warm front draped across the state, which will trigger afternoon/evening thunderstorms capable of large hail, damaging winds and even a tornado or two! After the cold front slid through parts of the state last night, the front will continue to slowly progress southward and may even stall out somewhat this afternoon with the warming air mass to its' south. Current forecasts indicate it to position itself near the I-80 corridor by 7 PM tonight.

For those that are along this front, just south/north of the boundary are going to be in a favorable position for thunderstorms this afternoon. Today is one of those warm front days where the instability is all south of the front, but the shear is mainly north. Which means any storms that are able to ride along the boundary to get the best of both sides will be the strongest and most organized of the day, and will be the most likely storms capable of a tornado or two. With flow otherwise parallel to the front, expect storms to eventually congeal into broken lines or clusters capable of large hail and a few wind gusts. Once again expect the thunderstorms to persist into the early nighttime hours with some severe potential.

As the low level jet increases tonight, this will push some elevated instability north of the boundary, likely over much of Iowa. This will also bring the chance for at least elevated storms capable of some large hail given this strong overrunning of moisture across the front in southern/central Iowa. These storms will likely be in clusters or broken lines given the better shear values that are north of the front.

I begin my part-time job this morning, thus am not expecting to chase today along the stalled boundary. Although if any significant changes in the tornado chances occur by early this afternoon I may have to take the quick dive south into the favorable chase area... Another update is possible early this afternoon...