Sunday, May 31, 2009

Severe Weather Update #2 - May 31

A few severe thunderstorms, and even one tornado warning, was issued this evening across southeast Nebraska and southeast South Dakota. Warnings are still ongoing across parts of central/eastern Nebraska along the cold front, however, these storms are only capable of large hail at the moment. Other storms along the cold front in southern South Dakota and Minnesota are only capable of heavy rains and maybe some small hail currently. Although the low level jet should begin to ramp up, these storms do not look like they will be well-above severe limits tonight.

Enjoy the rain, maybe some small hail, and otherwise rumbles of thunder overnight...

Another update is likely early tomorrow with a quick discussion about the warm front across the central/southern thirds of the state tomorrow.

Severe Weather Update - May 31

A broken line of thunderstorms has erupted along the cold front across eastern/central South Dakota and into northern Nebraska. With surface winds from the southwest along the cold front, low level shear is pretty weak; combined with high LCL's due to only mid 50s dew points and you are left with fairly high based storms capable of mainly large hail. These storms should continue to develop and move southeast through the evening and into the overnight hours.

While additional thunderstorms may be able to develop during sunset along the warm front in eastern Nebraska, the most likely scenario will be for the storms along the cold front to evolve into a more linear system. These storms may be capable of damaging winds and isolated large hail as they move into northwest Iowa and adjacent areas. Additional updates are possible as storms continue to develop and move into/nearby Iowa...

Severe Weather - May 31

With the lack of an update last night and early this morning, you may have been able to tell that I am not too excited about the severe weather threat today. A warm front will likely push east/northeast through the afternoon into western Iowa by this evening. A cold front will also be located over portions of western Minnesota and across central/eastern Dakotas which will also be a trigger for thunderstorms this afternoon. Today is a combination of favorable shear and weak instability, and then strong instability and weak shear further south along the warm front. Chasers are torn between where to target, where storms are likely but not the greatest tornado chance; or where storms are not so likely but if something were to occur it would likely be the show of the day.

Thunderstorms should develop in the eastern half of South Dakota this afternoon, with the chance of a tornado or two as well as large hail and damaging winds. Forecasts appear to support the development of an MCS, which would likely be capable of damaging winds as it moves into southern Minnesota and northern Iowa tonight. Additional updates as storms form and congeal is likely...

Saturday, May 30, 2009

Severe Weather Potential - May 31

It would appear that surface features and upper air parameters will come into play for tomorrow and allow one of the better risks of severe weather across the plains in nearly two weeks! While surface moisture will still be fairly meager across the northern plains with surface dew points only in the 50s, upper air dynamics will be fairly strong and hopefully be able to overcome the lack of moisture. A shortwave will likely move across the new, more westerly, flow at 500hPa and combine with favorable low level flow to give sufficient shear values across much of western Minnesota and adjacent areas of extreme eastern Dakotas.

With sufficient shear values and modest instability present given meager dew point values for the last day of May we should see the initial development of supercells along the cold front and potentially in the warm sector over eastern SD and western MN. While initially the storms may be favorable for large hail and a tornado or two, it appears that with a strengthening low level jet during the evening and into the overnight that the development of an MCS is likely. This MCS would likely move southeast through southern Minnesota and potentially into extreme northern Iowa with the greatest threat being damaging winds. Expect additional updates on the severe weather threat later this evening and early tomorrow... While I currently do not have any chase plans, if significant severe weather does appear to be likely I may have a chase update as well.

Friday, May 29, 2009

Severe Weather Threat - May 29 (Update)

The latest SPC outlook for severe thunderstorms has greatly limited the potential for severe weather across the state this evening and overnight. This is likely due to the lack of convergence along the quasi-stationary front that is now over northern Missouri. With this front located that far south, and the lack of convergence along and especially north of the front it looks as if the likelihood of strong/severe storms anywhere in Iowa is going to be limited to extreme southern Iowa if any areas at all. A few scattered thunderstorms are still possible across portions of Iowa this evening/tonight, however, these should not be severe in nature.

Areas that may see severe weather this afternoon would be areas of the eastern Dakotas and extreme western Minnesota; as well as northern Missouri into Illinois along the stationary boundary. Marginally severe hail, and damaging wind gusts will be the main threats with the evening/overnight storms.

With today's severe weather threat becoming minimal if not obsolete, we'll look towards Sunday as the first day that Iowa can see severe weather since oh so long ago...

Severe Weather Threat - May 29

A weak cold front is positioned across northern Iowa this morning, and should slowly push southward through the morning hours to be positioned near/along the I-80 corridor by this afternoon. Areas along and south of this front will be in position to see strong/severe thunderstorms this afternoon and overnight. While some storm development along the front is possible during the evening hours, storms that develop across central NE/SD are likely to congeal into some form of MCS or cluster of storms. These clusters of storms should follow along/south of the cold front and be capable of damaging winds and/or large hail through the overnight hours across southern Iowa and northern Missouri.

Additional updates are possible this afternoon if development does occur this afternoon across Iowa, otherwise expect an update during the evening hours on the thunderstorm development across Nebraska/Dakotas and how those storms may evolve across Iowa overnight.

Otherwise expect partly cloudy to clear skies across the state, with temperatures in the mid 70s to upper 80s across the state. Additional strong/severe thunderstorms will once again be in the forecast for Sunday afternoon/evening...

Thursday, May 28, 2009

Feels like May!

After yesterday's high temperatures across the state in the 50s and 60s, along with cloudy and rainy skies, today is much of a relief for those wishing it would actually feel like May. Morning lows were on the chilly side in the mid 40s in the northwest, to the mid 50s across much of the southern tiers of the state. With clear skies overhead today, and only light northerly winds the temperatures will soar into the lower 80s across the western portions of the state and near 70 along the Mississippi River. Temperatures will only get warmer as we continue into the weekend, and the return of southerly flow will allow increased moisture as well. We'll see only partly cloudy skies through the rest of the week, leading to a wonderful start of the weekend.

Low temperatures tonight in the lower to mid 50s across the state, setting us up for highs on Friday from the mid 70s across the northeast quarter to the mid 80s across the southwest. Friday night lows from the lower 50s to upper 50s from north to south are expected as light southerly winds begin to pull in moisture from the south. Highs for the start of the weekend on Saturday will range from the upper 70s to upper 80s from east to west across the state. Lows overnight from the lower 50s to lower 60s from northeast to southwest... Previous forecasts had indicated the potential for thunderstorms on Saturday evening across parts of southern Iowa, however, current model trends continue to push the forecasted low pressure system and associated fronts further south into Missouri. If this model trend holds true then only a slight chance of a thunderstorm or two would see possible across southern Iowa.

Sunday should hold a different story, with a cold front beginning to work down from the northwest and warm/moist temperatures finally in place ahead of the front would lead to strong and potentially severe thunderstorm development during the afternoon/evening hours. Sunday's highs from near 80 to near 90 appears likely from east to west, with dew points approaching 60 across much of the state.

Thunderstorms would be likely along the cold front as it sweeps into northwest Iowa by the evening hours, and continued development would be likely across the state as the front continues to move southeast through the overnight hours. Moderate instability would appear to be present given warm temperatures and modest dew point values, however dew points would still appear to be too low to support strong surface-based development. For this reason it would appear that damaging winds be the main threat with storms along the cold front, with large hail being a secondary threat with any of the stronger storms. More updates on the potential for severe weather for this weekend and next week in later updates!

Tuesday, May 26, 2009

Return of Severe Weather?!?

A small area of 'See Text' as issued by the Storm Prediction Center covers extreme southeast Iowa today for the risk of an isolated brief tornado. This is in regards to a weak warm core low that has spun across Missouri the past two days, and is continuing to move northward near the Iowa/Missouri border by late this afternoon. The previous two days with this low have brought tornado warnings and even a couple of reports of tornadoes in extreme southeast Missouri on Sunday. Instability and shear are slightly weaker, thus we don't expect anything other than a storm or two that may be able to exhibit rotation across extreme southeast Iowa and adjacent areas. Other areas across the state should see isolated thunderstorms or showers through much of the day as they move northwest with the weak surface low. Temperatures will struggle with the cloudy and rainy conditions, only reaching the the lower 60s to lower 70s from northwest to southeast.

Lingering showers possible across western and central regions tonight, likely over the eastern third of the state. And then isolated showers across the state on Wednesday, and possibly into Wednesday night for the eastern sections of the state. We then look towards clear skies for the remainder of the week, with the only additional chance of thunderstorms coming into the forecast for western Iowa on Saturday. More details on these thunderstorm chances and the return of severe weather being possible for the plains states in later updates...

Wednesday highs in the 60s across the state; Thursday in the mid 70s to lower 80s from east to west; and Friday highs from the mid 70s to mid 80s from east to west as well. Tonight's lows in the from near 50 in the northwest to near 60 in the southeast; overnight lows on Wednesday night from the upper 40s to upper 50s from northwest to southeast. Lows on both Thursday and Friday night will be into the mid to upper 50s across the entire state, as moisture begins to be pushed into the state under stronger southerly winds.

Sunday, May 24, 2009

Severe Weather Drought

Today marked the eighth straight day in which the Storm Prediction Center had not issued a Severe Thunderstorm or Tornado watch over any part of the United States. This is essentially a May record, with eight days of minimal organized severe weather and even one day (May 21) in which not even a single severe weather report was received. For those that are interested in such major projects like VORTEX, this lack of significant severe weather is definitely putting a damper on any hype. At least many are hopeful for a strong start to June, that will hopefully continue through the rest of the month and have mother nature finally give us a good show in the beautiful northern plains states.

Several local chasers/spotters have been using the high plains as chase territory with times like these, minimal moisture is still sufficient at the higher elevations, and low level winds with an easterly component play into good up-slope flow to trigger the convection. A weak/shallow trough is currently over the northern plains, and will create some potential for severe weather across eastern Dakotas and western Minnesota on Memorial Day. However, even with sufficient wind shear over this area, the lack of moisture will likely create high based storms more likely of large hail and some strong wind gusts.

Once this small trough passes through, we'll once again see a ridge in the western half of the CONUS build. Continuing the lack of organized severe weather across the plains states... Forecast models are now beginning to hint at this ridge breaking down towards the last day or two of May and then continuing to support the threat of organized severe weather into the month of June. Once these threats really begin to crank up and enter the forecast, I'll hopefully be able to begin some organized severe weather forecasts for Iowa and adjacent areas.

Saturday, May 23, 2009

Wet Weekend

Memorial Weekend has been fairly wet and cool across northwest Iowa, as a cold front is draped across the state leading to showers/thunderstorms along and north of the boundary. Today's highs over northwest Iowa where rain and cloud cover dominated were only in the mid 60s to lower 70s. Other parts of the state saw plenty of sun and temperatures once again soared into the upper 70s to mid 80s.

These showers and thunderstorms will continue over northwest Iowa tonight, and a few sprinkles are also possible over the rest of western and northern Iowa. Lows from the mid 50s to mid 60s from northwest to southeast are expected. As the cold front works through the rest of the state, we'll see isolated showers over all but the southeast corner of the state on Saturday. High temperatures from the upper 60s in the north, to the lower 80s in the south are forecasted. A few isolated showers are going to be held in the forecast over the western third of the state through the remainder of the weekend; with high temperatures in the 70s through the state on Sunday. Lows on Saturday and Sunday will be in the 50s for the most part, a few 60s also will be seen.

We'll see showers and thunderstorms work back into the forecast for Memorial Day, and through Tuesday. Showers over the southern half of the state during the day on Monday, over the entire state for Monday night and Tuesday, and then over the eastern third on Tuesday night. A few stronger thunderstorms may be possible if moisture can be sufficient, more details on that may be available later this weekend. Look for high temperatures in the mid to upper 70s on Memorial Day for the state; low temperatures in the mid 50s to lower 60s overnight on Monday...

Sunday, May 17, 2009

Summer Arrives!!

After a weekend with near record lows, we now enter a couple of days with high temperatures that will be well above normal for late May. We saw our first hint of that today with temperatures across the state ranging from near 90 along the Missouri River, to only the upper 60s along the eastern portions of the state. We'll see the upper level ridge move further east over the next couple of days, allowing the entire state to see the well above normal temperatures. This will come with some negatives, as southerly winds will be gusty from 20-40 mph on both Tuesday and Wednesday. As for those highs, Tuesday will range from near 90 to near 80 from west to east; Wednesday from the lower 90s to lower 80s from west to east. Lows on Tuesday from the mid 60s to upper 50s from west to east.

A cold front will begin to drape into the state on Wednesday night, leading to some showers and isolated thunderstorms across northwest Iowa. This will also lead to some lower temperatures, with Wednesday night lows from the lower 50s to upper 50s from northwest to southeast. As the cold front slowly moves into the state it will begin to diffuse, and linger across the state for a few days. This will lead to sporadic chances of showers across portions of the state through the end of the week and into the weekend. High temperatures only in the upper 60s to upper 70s are expected; with lows in the upper 40s to upper 50s.

We'll see how the Memorial Weekend forecast plays out, but it looks to be around normal for temperatures; and we will be hopeful that we can clear out the skies for Sunday and Monday after a likely cloudy Saturday start.

In the even longer range, much of the talk between storm chasers is the lack of significant severe weather that appears to be forecasted for quite some time. Some chasers have even been canceling their latter half of May vacations that they were hopeful to chase on. We'll see if summer decides to show up early and end a lot of the significant severe weather chances over the central/southern plains.

Saturday, May 16, 2009

Freezing in May!?!

Unfortunately that statement above is likely going to come true tonight, as several National Weather Service offices have already issued Frost Advisories for parts of the state. Overnight lows last night ranged from the mid 30s across northwest Iowa to the mid 40s across southeast Iowa. Temperatures were able to stay slightly warmer due to the windy conditions and some scattered cloud cover. With clear skies and calmer winds today, temperatures will be able to warm nicely into the upper 50s to mid 60s across the state. While these temperatures are 10-15 degrees below average, the sun will at least provide some warmth for the state.

Under clear skies tonight, and unfortunately calming winds, the lows tonight will be able to drop into the 30s across the state. With much of the northern two-thirds of the state seeing temperatures at/below or near freezing. Record lows for tonight range from the upper 20s to mid 30s across the state, thus we should remain just above those record levels. Thankfully, this cold air won't stay too long as Sunday will warm up nicely into the mid 60s to lower 70s from northeast to southwest. The southerly winds will continue into next week and provide us with near average and even above average temperatures. A quick look at the highs/lows for early next week below:

Sunday Night - Low 50s to low 40s from west to east.
Monday - Mid 80s to lower 70s from west to east; southerly winds 15-25 mph.
Monday Night - Mid 50s to lower 50s from west to east.
Tuesday - Lower 80s to upper 60s from southwest to northeast; chance of thunderstorms.
Tuesday Night - Upper 40s to upper 50s from northeast to southwest; chance of thunderstorms.

Friday, May 15, 2009

May 15 Thunderstorms

The combination of a warm front lifting northward and a cold front sliding southeast will create the chance for thunderstorms across much of the state of Iowa from this afternoon through the overnight. A cold front is currently located over central SD/ND this morning, with a warm front draped across portions of northeast Kansas and northern Missouri. The warm front is currently being held fairly stationary by continued thunderstorm development across extreme northern Missouri and northeast Kansas; these storms should move northeast through the early afternoon with the chance of some isolated large hail reports. The warm front should slowly move northward, and may approach southern Iowa by this evening. Areas that are along and south of this warm front should see sufficient instability to promote severe thunderstorms, and given strong shear the storms may support tornadic development this afternoon/evening along/south of the front.

In addition to the warm front thunderstorms, western Iowa should see additional thunderstorm/shower development along the cold front that will move into the state this evening. Given such cold air aloft, some instability is expected despite meager surface moisture and temperatures. Given this instability, some isolated severe storms are possible with the cold front during the afternoon/evening across western Iowa and Minnesota.

Overall, it would appear that the state should miss the majority of severe weather, with only extreme southern Iowa being currently under a slight risk for the remainder of afternoon/evening for the thunderstorms north of the warm front. Areas of northern Missouri and eastern Kansas should be more favorable, with all modes of severe weather possible. Parts of southern Iowa may also deal with flooding given the heavy rains during the previous days, and the training of storms today north of the warm front.

Expect cooler conditions to prevail tonight and tomorrow, and near record lows being possible for Saturday night before we begin our warm-up for next week. Initial forecasts through mid-week next week indicate highs in the 70s and 80s across the state.

Tuesday, May 12, 2009

Sunday, May 10, 2009

Chilly Start

After the cold front and associated thunderstorms moved through parts of the state last night, temperatures were finally able to drop well below average across much of the state. Many woke up this morning to temperatures in the mid 30s in northwest Iowa, to the mid 40s across the south and east. The state won't warm up too much even today as cooler northwest flow continues over the state. Expect highs in lower to mid 60s across much of the state today, with low temperatures tonight falling back down into the upper 30s to mid 40s from north to south.

A slight warm up tomorrow, and continued warming trend through the week as thunderstorm chances are introduced beginning Tuesday night. More details on the thunderstorm threat and the chances of severe weather in later updates!

Friday, May 8, 2009

May 8 Severe Weather Update #2

The severe weather threat across the state is coming to an end, as the current line of severe warned storms is just entering Illinois. Other showers and isolated thunderstorms will continue during the overnight for much of the state as precipitation wraps around the low pressure system. Thus far it appears that the lack of instability over the state hindered the threat of severe weather...

The first reports came in just after 5 PM with damaging wind reports in Marion and Poweshiek counties, both of which in the 60-65 mph range. Additional reports at ~6:30 PM from Sigourney, IA where a semi-trailer was blown off the road. And the latest report near Muscatine, IA where ~65 mph winds have occurred with the storms now entering Illinois. One other rogue report came in from an Iowa DNR officer to the east of Spencer, IA where a brief tornado spin-up was reported; likely more of a landspot that was able to pick up some dirt and/or field debris.

This should end our chances of thunderstorms and severe weather until next week as a system on Tuesday may bring a chance of significant severe weather across the Plains.

May 8 Severe Weather Update #1

A Severe Thunderstorm Watch has been issued for much of Iowa that will be in effect until 8 PM. For more details please read the watch discussion via the SPC page:

This watch includes areas east of the low pressure system and cold front, and areas south of the now stationary front. The main threat with any storms that do develop will be the threat for large hail.

May 8 Severe Weather Threat

Once again a weak low pressure system is centered just southeast of Sioux City, with a warm front extending eastward parallel to Highways 20 and 30. This warm front and low pressure system already has a few clusters of isolated thunderstorms just north of the boundary and near the center of low pressure. These storms should continue to evolve and potentially become better defined through the afternoon hours. Additional development is expected through the afternoon to the south of the warm front in the warm sector where temperatures and into the 70s and dew points in the 50s. Areas of surface based instability have developed and should support surface based supercells within the next few hours. Supercells do appear to be the best threat for areas along and south of the warm front; current meso-analysis indicates that an enhanced area of shear and instability exists for areas along and just north of I-80 in western Iowa.

Storms currently developing near the surface low along the Missouri River should continue to move eastward into the area of enhanced shear/instability. If these storms are able to stay discrete over the next few hours, severe thunderstorms capable of large hail and an isolated tornado or two may also be possible.

Although I will not be chasing today, my virtual target area would be along I-80 in western Iowa; likely near Guthrie Center. Additional updates during the afternoon are likely...

Thursday, May 7, 2009

May 7 Severe Weather

A Tornado Watch is now in effect for portions of southwest Iowa and will remain in effect until 8:00 PM tonight. A weak surface low is positioned over northeast Nebraska, and a warm front appears to be draped along eastern Nebraska and southern Iowa. Areas along and south of this warm front will see convective development within the next few hours. Similar to yesterday, any storms which may be able to make a southward turn will enhance their shear values and be able to produce a tornado or two. The main threat with storms as they move east/southeast will be to produce large hail, up to 3 inches in diameter in the stronger supercells.

It does appear that initiation is beginning near the Missouri River near Omaha, NE. The tornado threat is expected to increase as the evening continues as more moisture is pulled northward and begins to lower the dew point depressions.

May 6, 2009 Chase Report

Had an impromptu chase yesterday evening as a weak cold front and associated disturbances kicked off thunderstorms yesterday afternoon over northwest Iowa. One cell was able to become severe warned over Osceola county, and within a few minutes was also tornado warned. At this point with the tornado warning I quickly gathered items into the vehicle, then myself along with my dad and fiance hopped in and began our quick chase. Our total path is shown below, under 2 hours of drive time and just under 80 miles round trip make this a very short and good warm-up chase for the northern plains this year.

Our chase led us to intercept the storm near Royal, IA where we encountered mainly nickel sized hail just ahead of the large rain/hail core. It was just about at this point where the storm really dropped all of the energy it had left before rapidly dissipating. Went ahead and drove south just ahead and then as confirmation was received that the tornado warning would be canceled dove back into the core to see if any hail was remaining, and none remained. All in all, a bunch of nickel sized hail and some impressive rainbows (shown below) and a nice impromptu chase in early May for northwest Iowa.

Tuesday, May 5, 2009

Unofficial Meteorologist

As mentioned in this mornings' update, I walked off of the Iowa State University campus a short time ago early this afternoon after my last final as a student here at ISU. This makes me for the time being, an unofficial meteorologist, not having my true degree in my hand until later this summer when they are mailed out. Nonetheless, I have made it through semester upon semester of Calculus, Calculus-based Physics, Dynamic Meteorology, and any other fun classes along the way. I managed to complete a senior thesis last fall, and even present it at a national conference! Better yet, I got to spend the past four years getting to know a few hundred people that I can recognize daily. Quite a few in which they can be called my friends... The end of an era I suppose, but definitely the start of another that can hopefully be just as good, if not a little bit better!!

Fairwell Ames, Iowa

In the same tune as Tony Laubach's last post, today is my last day of college at Iowa State University in Ames, IA. Spent the past four falls and springs on-campus, enjoying the college life and getting my work done. As of approximately 1:30 PM this afternoon I will be leaving the campus as a student for the last time, and an unofficial meteorologist. The only thing between me and my Bachelor's of Science in Meteorology is about a months wait until the university mails it out. With other obligations back home, I will also be leaving Ames this afternoon, with my vehicle packed full of things I have gathered down here for the past four years.

I know I will be back, but it simply is not the same when I'm not a student; rather a graduate. Let's hope this means a good season of severe weather in the northern plains, as I have a few things planned out for this first summer being a true meteorologist... I'll be filling in those details in the coming days! Stay tuned...

Sunday, May 3, 2009

Stormy Week Ahead

We've seen a few stormy days as of late, and this week looks to have at least two more days of storm weather for the state. The first chance of storms will come into the picture late Monday, more likely on Tuesday as a front passes over the state. Although a few showers/thunderstorms may linger into Wednesday, another good chance of thunderstorms will come into the state on Thursday! Currently the severe weather threat for both of these thunderstorm days is questionable, with Tuesday's event being before we get ample moisture return combined with the lack of good directional shear. Thursday may be more of a severe weather day, but it is still too far out to really pinpoint any specific risks and locations.

Other than the thunderstorm chances, it finally will feel like we are getting into summer with temperatures holding steady in the 60s and 70s across the state. Monday's highs in the low to mid 70s across the state; overnight lows in the upper 40s to mid 50s from east to west. Tuesday high temperatures should also range from near 70 to the mid 70s across the state, expect some clouds and thunderstorms to limit the highs in localized areas. Overnight lows from near 50 to the mid 50s are forecasted, once again showers/thunderstorms will fluctuate temperatures under heavy cloud cover. We'll slowly clear out on Wednesday from west to east, and high temperatures will reflect this as they range from the upper 60s in the east to the mid 70s in the west. This front won't effect temperatures greatly, overnight lows in the mid 40s to mid 50s from northwest to southeast. More details on the Tuesday thunderstorms and the latter half of the week's forecast in later updates.