Tim from Springfield (IL) Posted May 13, 2020 Share Posted May 13, 2020 From ChicagoStorm in the general severe thread regarding tomorrow: "Tomorrow definitely holds potential, but all hinges on tonight/tomorrow mornings activity. SGT risk looks good for now, but could need upgrade to ENH in the morning once everything becomes clear." Going to take the bait and start a thread for the upcoming storm system including tomorrow's severe threat. This thread can also be a catch-all for other threats including the heavy rain expected in parts of the sub (especially MO/IL) through Sunday, as the system stalls. Today's threat far west of the sub but SPC's Day 1 has consistently had a marginal up to along and west of the Illinois River: https://www.spc.noaa.gov/products/outlook/day1otlk.html Link to comment Share on other sites More sharing options...
Tim from Springfield (IL) Posted May 13, 2020 Author Share Posted May 13, 2020 Day 2 for tomorrow:https://www.spc.noaa.gov/products/outlook/day2otlk.html ...Eastern Kansas into the Mid Mississippi Valley, Midwest, Ohio Valley, and Lower Great Lakes... Showers and thunderstorms will likely be ongoing Thursday morning in a low-level warm advection regime across parts of the mid MS Valley into the Midwest and lower Great Lakes. A weak mid-level perturbation associated with this convection should continue to shift eastward across these regions through the day. In its wake, a more amplified shortwave trough should progress over the northern Plains to the Upper Midwest by Thursday evening. At the surface, a weak low initially over IA Thursday morning should develop northeastward to lower MI by the early evening, with a warm front lifting northward across much of the Midwest/OH Valley into the lower Great Lakes. A trailing cold front across the mid MS Valley into the central Plains is forecast to make only slow southeastward progress through the period. In the wake of the morning convection, low-level moistening, diurnal heating, and steepening mid-level lapse rates owing to an EML advecting eastward from the Plains will contribute to a destabilizing airmass by Thursday afternoon along/south of both the warm and cold fronts. Instability should be stronger from eastern KS into the mid MS Valley and perhaps IL, where MLCAPE may reach 2000-3000+ J/kg before convective initiation. Storms should form along/near the cold front by mid to late afternoon, with large-scale ascent possibly being aided by another weak mid-level perturbation. The stronger mid-level flow associated with the northern Plains/Upper Midwest shortwave trough may remain generally displaced to the north of the warm sector. Still, there should be enough of a veering/strengthening wind profile through the low/mid levels to support organized storms. Initial convective development along or just south of the front may pose a large hail threat given the steep mid-level lapse rates and marginal effective bulk shear values (around 30-35 kt) supporting occasional supercells. Although low-level flow is not forecast to be particularly strong, a couple tornadoes may also occur with these any semi-discrete storms. The Slight Risk has been expanded slightly northward across MO/IA/IL to account for better model agreement in the placement of the front Thursday afternoon. Damaging winds should become the primary threat with time as storms congeal into multiple east-southeastward moving clusters/bows through the evening. By late Thursday evening/overnight, this activity should weaken as it encounters increasing convective inhibition with southeastward extent across the warm sector. From roughly IN eastward into Lower MI and OH, low-level moisture and diurnal heating will probably remain more limited owing to morning convection. Still, enough instability should develop by late afternoon to pose some large hail/damaging wind threat along and south of the northward-moving warm front. Latest guidance suggests this front will probably extend across southern Lower MI by Thursday evening, with one or more clusters potentially moving eastward along or just south of this boundary. The Slight Risk for damaging winds has been extended eastward across more of northern/central IN, southern Lower MI, and into northwestern OH to account for this threat. Also Heavy Rain this weekend including in central Illinois. ILX's take: Link to comment Share on other sites More sharing options...
Moosey2323 Posted May 13, 2020 Share Posted May 13, 2020 NAM 3km (18z) shows an interesting feature along the Michigan-Indiana border. Looks like a bowing segment. Will have to keep an eye on that. Link to comment Share on other sites More sharing options...
Hoosier Posted May 14, 2020 Share Posted May 14, 2020 We'll see what happens but imo the better threat is roughly along/south of I-80. Link to comment Share on other sites More sharing options...
A-L-E-K Posted May 14, 2020 Share Posted May 14, 2020 getting quality garden variety this am, amazing how through all the ups and downs, consistently wet remains the name of the game Link to comment Share on other sites More sharing options...
RyanDe680 Posted May 14, 2020 Share Posted May 14, 2020 morning convection never really a good thing for afternoon convection Link to comment Share on other sites More sharing options...
A-L-E-K Posted May 14, 2020 Share Posted May 14, 2020 5 minutes ago, RyanDe680 said: morning convection never really a good thing for afternoon convection not nec, stuff over the area now is irrelevant evolution of N MO stuff and wf position is what matters, everything looks as expected to me Link to comment Share on other sites More sharing options...
cyclone77 Posted May 14, 2020 Share Posted May 14, 2020 Nice soaker this morning with thunder for hours. Picked up 1.27" and counting. 1 1 Link to comment Share on other sites More sharing options...
CheeselandSkies Posted May 14, 2020 Share Posted May 14, 2020 Not even a flash/rumble here yet again... I. Just. Want. To. Hear. Thunder. Once more in my life. 1 Link to comment Share on other sites More sharing options...
SchaumburgStormer Posted May 14, 2020 Share Posted May 14, 2020 Some big bangers this morning. Nice to get woken up by thunder. 1 Link to comment Share on other sites More sharing options...
A-L-E-K Posted May 14, 2020 Share Posted May 14, 2020 yeah, booms have been loud and plentiful all morning 1 Link to comment Share on other sites More sharing options...
hawkeye_wx Posted May 14, 2020 Share Posted May 14, 2020 57 minutes ago, CheeselandSkies said: Not even a flash/rumble here yet again... I. Just. Want. To. Hear. Thunder. Once more in my life. Same here. I picked up 0.43" of rain, but the totals fell short of expectation as much of the action developed east and south. There was no lightning/thunder here. Much of today's action should also be south and east. 1 Link to comment Share on other sites More sharing options...
Chicago Storm Posted May 14, 2020 Share Posted May 14, 2020 Quality storms this morning around here. 1.28” rain at ORD this morning and 2.04” here. . Link to comment Share on other sites More sharing options...
Moosey2323 Posted May 14, 2020 Share Posted May 14, 2020 Detroit Update to the AFD: Quote Late morning satellite imagery indicates a perishable look to the low clouds over that area which leans expectations toward the higher end of CAPE estimates for this afternoon into early evening as the warm front makes northward progress into Lower Michigan. Convection building in from the west could then become surface based and present severe weather potential to that portion of SE Michigan in the current Slight Risk area. Damaging wind remains the primary hazard and the currently advertised time period of 2 to 8 PM still looks on target. Link to comment Share on other sites More sharing options...
IMADreamer Posted May 14, 2020 Share Posted May 14, 2020 .62in this morning. Nice thunder, a little small hail. It is soupy right now out. Definitely feels like more is in the offering later. Link to comment Share on other sites More sharing options...
wisconsinwx Posted May 14, 2020 Share Posted May 14, 2020 4 hours ago, CheeselandSkies said: Not even a flash/rumble here yet again... I. Just. Want. To. Hear. Thunder. Once more in my life. Until this morning, Madison hadn't recorded a thunderstorm since March. Meanwhile, Rockford just to the south, has had a half dozen days of thunder since March. Time for this endless early/mid spring weather to turn more summery. 2 Link to comment Share on other sites More sharing options...
Hoosier Posted May 14, 2020 Share Posted May 14, 2020 Looks like the new outlook trimmed the northern edge of the slight risk. Link to comment Share on other sites More sharing options...
RyanDe680 Posted May 14, 2020 Share Posted May 14, 2020 9 minutes ago, Hoosier said: Looks like the new outlook trimmed the northern edge of the slight risk. Classic case of how morning convection screws up the possibility for anything fun in the afternoon. Looks like a nighttime soaker. Link to comment Share on other sites More sharing options...
Chicago Storm Posted May 14, 2020 Share Posted May 14, 2020 While there is a still a SLGT worthy severe risk for the area (even if SPC did trim it, they have been meh), the flood threat looks to steal the show overall. Upwards of 1.00-2.50" of rain fell across a corridor within N Illinois last night/this morning. It looks like a good portion of that corridor will overlap with the heaviest for this afternoon/tonight, with upwards of another 2-5" of rain possible. Could be seeing final totals in that overlap region in excess of 6"...if things line up correctly. Link to comment Share on other sites More sharing options...
madwx Posted May 14, 2020 Share Posted May 14, 2020 Midwestern farmers should invest in hydroponics the way rainfall has trended in the area the past 2 decades 2 Link to comment Share on other sites More sharing options...
Tim from Springfield (IL) Posted May 14, 2020 Author Share Posted May 14, 2020 The latest Day 2 for tomorrow extends the slight back to central OH, and marginal to C/S IN. Also a 5/30/15 Enhanced north of NYC: https://www.spc.noaa.gov/products/outlook/day2otlk.html ...Northeast States and Ohio Valley regions... Shortwave trough now situated over ND near the international border will continue into the Great Lakes Friday, reaching the northeast states later Friday afternoon and evening. A low amplitude impulse may precede this feature. By late afternoon the accompanying cold front should extend from a surface low in upstate NY southwest into the lower Great Lakes and OH Valley. Warm front will extend from the surface low through southern New England. Modest low-level moisture with upper 50s to around 60 F dewpoints will advect through the pre-frontal warm sector and contribute to 1000-1500 J/kg MLCAPE as the surface layer warms during the afternoon. Thunderstorms are expected to redevelop along and ahead of the front by early to mid afternoon within the weakly capped, destabilizing warm sector. A mid-level jet within the base of the approaching shortwave trough will contribute to 35-45 kt effective bulk shear over the northeast U.S. supporting organized storms including a few supercells and bowing segments with damaging wind the main threat. The low-level jet is forecast to strengthen by late afternoon into early evening across the northeast U.S. with 0-1 km hodographs becoming sufficient for isolated tornadoes, especially with any storms interacting with the warm front across southern New England. Farther west across OH, deep-layer shear will be weaker, but wind profiles with 40-45 kt flow in the 700-500 mb layer will be supportive of a few damaging wind gusts as the boundary layer destabilizes during the afternoon. Link to comment Share on other sites More sharing options...
sbnwx85 Posted May 14, 2020 Share Posted May 14, 2020 WPC expanded the excessive rainfall moderate risk into southeast Iowa and basically the northern half of IL. Good write-up below. Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 1223 PM EDT Thu May 14 2020 Day 1 Valid 12Z Thu May 14 2020 - 12Z Fri May 15 2020 ...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FROM CHICAGOLAND TO NORTHERN MISSOURI... ...Moderate Risk Area... A northern stream system skirting across the Midwest, with a developing upper level jet streak during convective maximum, 21-06Z, will interact moderate instability along a slow moving frontal zone, to produce a multi-hour heavy rain event this afternoon/evening. Synoptic deep layer forcing becomes maximized along a zone from northern Missouri and southern Iowa toward northern Illinois and southwest lower Michigan. Many model QPFs align here, such as the NAM, NAM Nest, WRF-NMMB, and recent HRRR runs. The WRF-ARW is a bit of an outlier in how much southward propagation it produces, ending up considerably south of the rest... but the WRF-ARW2 perhaps represents a more resonable southward adjustment that may occur as a result of outflow from early-morning convection. Thus, there are still some placement challenges, especially toward Chicago where the lake breeze may also act to inhibit the northward rebound of instability later on today. Northern Illinois is, however, more hydrologically vulnerable - having received 0.50 to 1.50 inches of rain this morning. Parts of the Davenport area also received some local amounts up to two inches. Aside from the early-day event, much of the region has been running below normal on precipitation recently, with fairly dry soils. Thus a second challenge is whether the evening event is likely to produce impacts consistent with the Moderate Risk category. But there do appear to be enough overlapping factors to support Moderate Risk. Inflow of unstable low level air near and atop the effective surface front and other outflow boundaries will increase to 30-40 knots late this afternoon, with deep layer flow becoming quite parallel to the boundaries. We could see a several hour period of training, causing what is otherwise an average combination of PW and CAPE to produce a few spots of higher-end rainfall totals. The NMMB even signals a small 3-inch / 1-hour amount in Illinois, and the NAM Nest signals local 3 to 4 inch in 3 hour totals, indicative of what could occur. This may lead to numerous flash floods and isolated higher-end impacts. Thanks to the WFOs and RFCs for helping shape the updated Moderate Risk contour. 1 Link to comment Share on other sites More sharing options...
CheeselandSkies Posted May 14, 2020 Share Posted May 14, 2020 1 hour ago, wisconsinwx said: Until this morning, Madison hadn't recorded a thunderstorm since March. Meanwhile, Rockford just to the south, has had a half dozen days of thunder since March. Time for this endless early/mid spring weather to turn more summery. We did record one this morning? Not in my part of town. Link to comment Share on other sites More sharing options...
CheeselandSkies Posted May 14, 2020 Share Posted May 14, 2020 5 hours ago, SchaumburgStormer said: Some big bangers this morning. Nice to get woken up by thunder. Lucky you. And lucky @A-L-E-K Link to comment Share on other sites More sharing options...
Hoosier Posted May 14, 2020 Share Posted May 14, 2020 1 hour ago, RyanDe680 said: Classic case of how morning convection screws up the possibility for anything fun in the afternoon. Looks like a nighttime soaker. imo, could still have some severe threat north of I-80, pending ability to recover. I do think blaming the morning/current stuff is a bit simplistic because it has been happening south of I-80 too, where the SLGT still exists. 2 Link to comment Share on other sites More sharing options...
RyanDe680 Posted May 14, 2020 Share Posted May 14, 2020 I think the best chance for development remains in MO, with the ability to ride NE into central IL. Wouldn't be shocked to see the slight risk trimmed further south. CAPE isn't currently anywhere near substantial unless you are Springfield or south and the wind field is a mess. We're gonna ride an axis with a crap ton of rain though. Link to comment Share on other sites More sharing options...
Indystorm Posted May 14, 2020 Share Posted May 14, 2020 Garden variety t storm here just before 3 p.m. EDT. Now to watch sw MO for the MCV's to see if storms develop and migrate ne there. Link to comment Share on other sites More sharing options...
pen_artist Posted May 14, 2020 Share Posted May 14, 2020 Can't say I have seen such a small hatched area before but there is one for hail in texas panhandle Link to comment Share on other sites More sharing options...
Chicago Storm Posted May 14, 2020 Share Posted May 14, 2020 23 minutes ago, RyanDe680 said: I think the best chance for development remains in MO, with the ability to ride NE into central IL. Wouldn't be shocked to see the slight risk trimmed further south. CAPE isn't currently anywhere near substantial unless you are Springfield or south and the wind field is a mess. We're gonna ride an axis with a crap ton of rain though. The whole area has the same kind of threat...No matter if you're in ORD, IKK or GBG. Link to comment Share on other sites More sharing options...
wisconsinwx Posted May 14, 2020 Share Posted May 14, 2020 56 minutes ago, CheeselandSkies said: We did record one this morning? Not in my part of town. One of the airport's morning obs reported, but that was the southeast part of town per lightning data. Link to comment Share on other sites More sharing options...
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