Hoosier Posted March 18, 2020 Author Share Posted March 18, 2020 Day 2 marginal risk for a good part of the area with a slight on the western fringes. Link to comment Share on other sites More sharing options...
Chinook Posted March 18, 2020 Share Posted March 18, 2020 The SPC has increased the wind risk to 30% and tornado risk to 10% into southern Indiana and Illinois. Some of the convection-allowing models show updraft helicity tracks in IN/IL late at night, well after 00z. Link to comment Share on other sites More sharing options...
Hoosier Posted March 18, 2020 Author Share Posted March 18, 2020 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1238 PM CDT Wed Mar 18 2020 Valid 191200Z - 201200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF NORTHERN MO...EXTREME SOUTHEAST NE AND SOUTHERN IA AS WELL AS FROM CENTRAL AR INTO CENTRAL IN... ...SUMMARY... Severe thunderstorms are expected from the lower Missouri Valley and Ozarks vicinity into the middle Mississippi and lower Ohio Valleys on Thursday. Damaging gusts, isolated large hail and tornadoes are possible, mainly during the afternoon into the evening hours. ...Synopsis... A compact shortwave trough will eject northeast from the southern Plains to the Great Lakes on Thursday. As this occurs, intense deep layer southwesterly shear will overspread much of the Ozarks into the mid-MS and lower OH Valley vicinity while a deepening surface low develops east/northeast across KS to IA by 00z, to the Great Lakes/Canadian border by Friday morning. Showers and thunderstorms may be ongoing Thursday morning in a strong warm advection regime across the mid-MS Valley and lower OH Valley. A warm front extending from the NE/KS border area east/southeast to near St. Louis to southern IN early Thursday will steadily lift northward through the afternoon. By late afternoon/early evening, the surface low will be near the NE/IA/MO tri-state area with the warm front extending across central IA to near the WI/IL border eastward into northern IN/OH. A cold front will extend southward from the low into eastern OK and central/southern TX. 60s surface dewpoints will be common across much of the warm sector, with mid to upper 60s dewpoints possible from eastern OK/TX across the Ozark Plateau toward western KY/southern IL/MO Bootheel region. Cloud cover across the region will inhibit destabilization somewhat, but steep midlevel lapse rates and increasing low level moisture will result in MLCAPE values increasing to 1000-1500 J/kg by afternoon. 850-700 mb southwesterly flow will likewise increase to 45-55 kt as the upper trough shifts eastward during the afternoon and evening. Supercells will initially be possible ahead of the cold front, but may tend to grow upscale into bowing segments with time as deep layer shear will become more unidirectional into the evening hours. Nevertheless, conditions will be favorable for damaging gusts, large hail and tornadoes across portions of the Ozarks into the lower Ohio Valley. Further north near the surface low, effective SRH will be quite a bit stronger due to the influence of the deepening low and warm front. Backed low level flow in this vicinity and better directional shear will result in a corridor of greater tornado potential during the late afternoon/evening. Large hail and damaging gusts will also be possible as supercells and bowing segment shift northeast toward southern WI/northern IL during the evening. ..Leitman.. 03/18/2020 Link to comment Share on other sites More sharing options...
CheeselandSkies Posted March 18, 2020 Share Posted March 18, 2020 My interest in this setup has been piqued a tad over the last couple days, I might do some local spotting if something comes up toward WI. Was thinking about going into Iowa; but between the abrupt societal lockdown/economic disruption, disagreement among the CAMs on where the strongest storms will track, likelihood of having to contend with the MS River and the poor chasing terrain nearby, and Iowa's general track record with tornado threats (doesn't produce when you expect it do, does when you don't) I'm leaning against it at this point. Link to comment Share on other sites More sharing options...
frostfern Posted March 18, 2020 Share Posted March 18, 2020 54 minutes ago, CheeselandSkies said: My interest in this setup has been piqued a tad over the last couple days, I might do some local spotting if something comes up toward WI. Was thinking about going into Iowa; but between the abrupt societal lockdown/economic disruption, disagreement among the CAMs on where the strongest storms will track, likelihood of having to contend with the MS River and the poor chasing terrain nearby, and Iowa's general track record with tornado threats (doesn't produce when you expect it do, does when you don't) I'm leaning against it at this point. Yea. There might be an outbreak of low-topped supercell storms coming out of Iowa as the dry slot and upper low sweeps in from the west. Not a lot of CAPE needed because the tropopause/EL will be low. It's hard to predict if there will be any really persistent cells though. Updrafts might have a lot of spin but are usually kind of small and can be snuffed out pretty easily in the dry slot. 1 Link to comment Share on other sites More sharing options...
CheeselandSkies Posted March 18, 2020 Share Posted March 18, 2020 14 minutes ago, frostfern said: Yea. There might be an outbreak of low-topped supercell storms coming out of Iowa as the dry slot and upper low sweeps in from the west. Not a lot of CAPE needed because the tropopause/EL will be low. It's hard to predict if there will be any really persistent cells though. Updrafts might have a lot of spin but are usually kind of small and can be snuffed out pretty easily in the dry slot. Yep, therein lies the rub with this kind of setup. Link to comment Share on other sites More sharing options...
Chicago Storm Posted March 19, 2020 Share Posted March 19, 2020 Tomorrow will likely be mitigated by widespread areas of precip and lingering debris into the afternoon for most areas. Near the SLP in IA looks best as of now. Link to comment Share on other sites More sharing options...
snowlover2 Posted March 19, 2020 Share Posted March 19, 2020 10% tornado area expanded across the S IA area otherwise no other real changes on new day 1. Link to comment Share on other sites More sharing options...
Chicago Storm Posted March 19, 2020 Share Posted March 19, 2020 SPC is wayyy too overzealous, as seems to be par for the course these days. Link to comment Share on other sites More sharing options...
IMADreamer Posted March 19, 2020 Share Posted March 19, 2020 Still light/moderate rain here and over cast. Going to have to clear out and warm up fast I think for anything to get going now. Link to comment Share on other sites More sharing options...
Indystorm Posted March 19, 2020 Share Posted March 19, 2020 PAH now 70/64, cloudy with a south wind gusting to 24. The threat down that way and into sw to central IN has always been for late evening into the overnight hours and kinematically rather than instability driven. Will have to see how things progress today. Any scattered clearing could rev things up a bit. Link to comment Share on other sites More sharing options...
Chinook Posted March 19, 2020 Share Posted March 19, 2020 1 hour ago, Chicago Storm said: SPC is wayyy too overzealous, as seems to be par for the course these days. Why not use math? The 10% tornado area is 113,928 sq mi, the 5% tornado area is 140,381 sq mi, and the 2% tornado area is 168,806 sq mi. The SPC system forecasts a probability that any one point in a certain zone will see a report within 25 miles. That means that each point in space is something of a 25 mi radius storm-report-detector. A 25-mi radius circle takes up (pi)*(25)^2 square miles of area. Aside from using more advanced methods of statistics, let's just apply simple math. The number of 25 mile circles covered by the 10% outlook is 58.02, and likewise, 71.50 circles, and 85.97 circles. Then (58.02)*(0.10)+(71.50)*(0.05)+(85.97)*(0.02) = 11.1 tornadoes. 11 seems like a possible number of tornadoes. Qualitatively, I think it's reasonable to say the 10% risk for a large section of the Ohio Valley/Mississippi may seem too much. Otherwise, using real statistical methods may calculate a different number of expected tornadoes. 1 Link to comment Share on other sites More sharing options...
Spartman Posted March 19, 2020 Share Posted March 19, 2020 46 minutes ago, IMADreamer said: Still light/moderate rain here and over cast. Going to have to clear out and warm up fast I think for anything to get going now. Forecast high is in the upper 60's, but expected the warm-up to occur by midnight tonight. Link to comment Share on other sites More sharing options...
CheeselandSkies Posted March 19, 2020 Share Posted March 19, 2020 16Z HRRR is meh for anything east of I-35 in IA. That's at least a five hour drive for me after working 3AM-noon (actually 12:20, had to stay late today as with every day this week due to COVID social distancing and sanitizing precautions slowing down the workflow, among other things). The expansion of the northern 10% and 5% tornado areas eastward makes no sense to me. Trend of the strongest activity being further west (closer to the MO river than the MS, at least until well after dark) plus the societal lockdown/"avoid discretionary travel" guidelines will have me sitting this one out. I keep thinking one of these years we have to get a legit early season outbreak involving the upper Midwest again (3/13/90, 4/8/99, 3/12/06, etc) but it hasn't happened yet. Link to comment Share on other sites More sharing options...
frostfern Posted March 19, 2020 Share Posted March 19, 2020 The destabilization will be driven by cold air advection aloft more than surface heating. The upper low moving in was producing thundersnow showers over the southwestern US. These will be very low-topped cells. Less instability is needed. The bigger problem will be whether there's enough upward forcing to overcome dry air entertainment with such a big shear-to-instability ratio. I don't think CAMS really know how to handle these kind of small-scale details. Chasing small fast-moving cells that can poop out at any moment will be frustrating. It also gets dark early this time of year. If it's a late-evening event it will be mostly in the dark. Link to comment Share on other sites More sharing options...
CheeselandSkies Posted March 19, 2020 Share Posted March 19, 2020 21 minutes ago, frostfern said: The destabilization will be driven by cold air advection aloft more than surface heating. The upper low moving in was producing thundersnow showers over the southwestern US. These will be very low-topped cells. Less instability is needed. The bigger problem will be whether there's enough upward forcing to overcome dry air entertainment with such a big shear-to-instability ratio. I don't think CAMS really know how to handle these kind of small-scale details. Chasing small fast-moving cells that can poop out at any moment will be frustrating. It also gets dark early this time of year. If it's a late-evening event it will be mostly in the dark. Yep, been there, done that several times over the last several years. No thanks. Link to comment Share on other sites More sharing options...
Indystorm Posted March 19, 2020 Share Posted March 19, 2020 BULLETIN - EAS ACTIVATION REQUESTED TORNADO WARNING NATIONAL WEATHER SERVICE PADUCAH KY 332 PM CDT THU MAR 19 2020 THE NATIONAL WEATHER SERVICE IN PADUCAH HAS ISSUED A * TORNADO WARNING FOR... SOUTHEASTERN PERRY COUNTY IN SOUTH CENTRAL ILLINOIS... SOUTHWESTERN JEFFERSON COUNTY IN SOUTH CENTRAL ILLINOIS... NORTH CENTRAL JACKSON COUNTY IN SOUTHERN ILLINOIS... NORTHWESTERN FRANKLIN COUNTY IN SOUTH CENTRAL ILLINOIS... * UNTIL 415 PM CDT. * AT 332 PM CDT, A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO WAS LOCATED NEAR PINCKNEYVILLE, MOVING EAST AT 50 MPH. HAZARD...TORNADO AND QUARTER SIZE HAIL. SOURCE...RADAR INDICATED ROTATION. IMPACT...FLYING DEBRIS WILL BE DANGEROUS TO THOSE CAUGHT WITHOUT SHELTER. MOBILE HOMES WILL BE DAMAGED OR DESTROYED. DAMAGE TO ROOFS, WINDOWS, AND VEHICLES WILL OCCUR. TREE DAMAGE IS LIKELY. * LOCATIONS IMPACTED INCLUDE... DU QUOIN, PINCKNEYVILLE, REND LAKE AREA, SESSER, VALIER, TAMAROA, INA, NORTH CITY, WALTONVILLE, BONNIE, EWING, NASON AND ST. JOHNS. Link to comment Share on other sites More sharing options...
Indystorm Posted March 19, 2020 Share Posted March 19, 2020 Meso discussion out for probable tor watch for the lower Ohio Valley and adjacent areas. Very good shear and surface-3km helicity up to 500 or better. Gotta watch these warm fronts in spring especially.. Link to comment Share on other sites More sharing options...
cyclone77 Posted March 19, 2020 Share Posted March 19, 2020 If I had all the time in the world I likely would have chased today. But as per usual work limited my chance. Hopefully some storms can manage to make it in here later this evening for a little lightning. Link to comment Share on other sites More sharing options...
IMADreamer Posted March 19, 2020 Share Posted March 19, 2020 Strong sunshine here now, with the temp up a good 7 degrees in a few hours. Link to comment Share on other sites More sharing options...
Chicago Storm Posted March 19, 2020 Share Posted March 19, 2020 2 hours ago, cyclone77 said: If I had all the time in the world I likely would have chased today. But as per usual work limited my chance. Hopefully some storms can manage to make it in here later this evening for a little lightning. It's a good thing you didn't, as the cold front under-cut just about everything. Link to comment Share on other sites More sharing options...
CheeselandSkies Posted March 20, 2020 Share Posted March 20, 2020 1 hour ago, Chicago Storm said: It's a good thing you didn't, as the cold front under-cut just about everything. Yep. Glad I didn't get suckered again by Lie-owa today (although TBH, if the COVID outbreak weren't happening, there's a good chance I might have since I have tomorrow off). 1 Link to comment Share on other sites More sharing options...
cyclone77 Posted March 20, 2020 Share Posted March 20, 2020 1 hour ago, Chicago Storm said: It's a good thing you didn't, as the cold front under-cut just about everything. Yeah would have been a long ride back. Link to comment Share on other sites More sharing options...
cyclone77 Posted March 20, 2020 Share Posted March 20, 2020 Pretty lame event overall today. The DVN area getting decaying Iowa sloppy seconds per usual. Still waiting on first thunder since last fall or summer. 1 Link to comment Share on other sites More sharing options...
Jackstraw Posted March 20, 2020 Share Posted March 20, 2020 Gotta love a P&C like this lol..... 1 Link to comment Share on other sites More sharing options...
Indystorm Posted March 20, 2020 Share Posted March 20, 2020 It might as well be spring! Actually I have been watching the storms down in Arkansas in the central thread....new overnight watch raises EF 2 or greater tor probs to moderate from low. Link to comment Share on other sites More sharing options...
MIstorm97 Posted March 24, 2020 Share Posted March 24, 2020 Starting to be some general agreement on a potential severe event in the western lakes on Saturday. Specifics to be determined as the event draws closer, but right now there is potential for a pretty decent event. Guidance currently has an impressive upper level system moving into the region with a deep surface low (~990mb). Speed shear is off the charts, with at least some directional shear. Thermos don't look to be a problem either, with 60F dews being brought well north. Lapse rates appear to be decent as well, with thermo profiles generating 1000-2000 CAPE even on the coarse globals. I'm sure this will somehow trend to garbage, like pretty much every snow event this winter, but it's something to watch. Link to comment Share on other sites More sharing options...
Chicago Storm Posted March 24, 2020 Share Posted March 24, 2020 5 hours ago, MIstorm97 said: Starting to be some general agreement on a potential severe event in the western lakes on Saturday. Specifics to be determined as the event draws closer, but right now there is potential for a pretty decent event. Guidance currently has an impressive upper level system moving into the region with a deep surface low (~990mb). Speed shear is off the charts, with at least some directional shear. Thermos don't look to be a problem either, with 60F dews being brought well north. Lapse rates appear to be decent as well, with thermo profiles generating 1000-2000 CAPE even on the coarse globals. I'm sure this will somehow trend to garbage, like pretty much every snow event this winter, but it's something to watch. The rare IL dry-line is looking like a good possibility. However...lapse rates look poor and the potential for widespread warm sector debris is high. Link to comment Share on other sites More sharing options...
Stebo Posted March 25, 2020 Share Posted March 25, 2020 2 hours ago, Chicago Storm said: The rare IL dry-line is looking like a good possibility. However...lapse rates look poor and the potential for widespread warm sector debris is high. 7-7.5 c/km are not poor lapse rates, only the GFS is closer to 6.5 which is workable but also poorly underdone by a shitty model. 1 Link to comment Share on other sites More sharing options...
nwohweather Posted March 25, 2020 Share Posted March 25, 2020 35 minutes ago, Stebo said: 7-7.5 c/km are not poor lapse rates, only the GFS is closer to 6.5 which is workable but also poorly underdone by a shitty model. Right. This isn't the Plains where you get extremely unstable atmospheres. 10 C°/KM is completely unstable correct? Link to comment Share on other sites More sharing options...
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