A-L-E-K Posted July 15 Share Posted July 15 finger crossed Quote given the presence of a convergent, moisture-rich, broad gradient of instability north of the boundary aligned strongly parallel to favorably strong mid/upper winds, large low/middle-level lapse rates, and a related reservoir of high buoyancy (MLCAPE of 3000-5000 J/kg) this activity should evolve quickly upscale to an MCS with severe gusts (some over 75 mph) becoming the greatest hazard. With a vorticity-laden boundary, and potential for backed surface winds and vertical-shear/hodograph enhancement to its north, a corridor of relatively maximized tornado potential (from supercells and/or QLCS-embedded circulations) also exists -- likely narrower than depicted here due to current boundary-position uncertainty. Uncertainty exists also on how far the MCS will travel (and whether far enough to qualify as a derecho) before weakening tonight. Link to comment Share on other sites More sharing options...
sbnwx85 Posted July 15 Share Posted July 15 Feeling better about tonight's potential out here. I'll plan to stay awake for it. 1 Link to comment Share on other sites More sharing options...
SchaumburgStormer Posted July 15 Share Posted July 15 Things really came together overhead last night for a good burst of straight line winds. Sounds like damage from Dekalb through the St Charles/Geneva area before the punch started to wimp out. 1 Link to comment Share on other sites More sharing options...
MidwestChaser Posted July 15 Share Posted July 15 12 HRRR/4kNAM has a spicy bow going through the metro after 7. 4 Link to comment Share on other sites More sharing options...
Cary67 Posted July 15 Share Posted July 15 1 Link to comment Share on other sites More sharing options...
MidwestChaser Posted July 15 Share Posted July 15 1 Link to comment Share on other sites More sharing options...
A-L-E-K Posted July 15 Share Posted July 15 rip cary#s 1 Link to comment Share on other sites More sharing options...
mjwise Posted July 15 Share Posted July 15 2 hours ago, SchaumburgStormer said: Things really came together overhead last night for a good burst of straight line winds. Sounds like damage from Dekalb through the St Charles/Geneva area before the punch started to wimp out. Enough tree limbs down here to crush about half of my garden. It just has not been a good garden year. 1 Link to comment Share on other sites More sharing options...
Cary67 Posted July 15 Share Posted July 15 34 minutes ago, A-L-E-K said: rip cary#s Hard pass on that. Loss of power no bueno Link to comment Share on other sites More sharing options...
RCNYILWX Posted July 15 Share Posted July 15 Wonder if there's a play for semi discrete mode for longer this evening. Not like it's unheard of in these setups. And if that were to happen, the forecast soundings are favorable for strong tornadoes. Sent from my SM-G998U using Tapatalk 3 Link to comment Share on other sites More sharing options...
CheeselandSkies Posted July 15 Share Posted July 15 Majority of CAM solutions are leaning toward a miss south for most of Wisconsin, thus SPC having the Enhanced where it is.More recent runs of the HRRR ticking north a bit...Sent from my Pixel 8 using Tapatalk Link to comment Share on other sites More sharing options...
sbnwx85 Posted July 15 Share Posted July 15 Wa wa wee wa! Link to comment Share on other sites More sharing options...
SchaumburgStormer Posted July 15 Share Posted July 15 5 minutes ago, sbnwx85 said: Wa wa wee wa! Looking like a copy/paste of the past couple days. 1 Link to comment Share on other sites More sharing options...
hawkeye_wx Posted July 15 Share Posted July 15 The morning storms over southern Minnesota pushed a boundary down into Iowa. The boundary stalled wnw-ese through the Cedar Rapids area. 80º dews are piling up along the boundary this afternoon and there is a fair amount of agitation on satellite. 2 Link to comment Share on other sites More sharing options...
hawkeye_wx Posted July 15 Share Posted July 15 SUMMARY...A severe thunderstorm watch is likely later this afternoon for portions of Iowa into Northern Illinois and Southern Wisconsin in anticipation of convective initiation, forecast to occur between 19-21Z. Thunderstorms are expected to grow upscale quickly into a bowing line, which will be capable of 80+ MPH winds, though 1.00+ inch hail and embedded tornadoes are also possible. DISCUSSION...A subtle shortwave trough evident in both water vapor channel satellite imagery and RAP analyses is progressing eastward across southwest Minnesota. This shortwave is expected to provide additional ascent for convective initiation between 19-21Z over what is already a moist and unstable airmass, with widespread areas of MLCAPE > 3500 J/kg. This convective initiation is expected to occur anywhere from southern Minnesota, along the existing band of cloudiness, to central Iowa, where MLCINH has already eroded. Forecast profiles in north-central Iowa around the time of convective initiation show some slight curvature of the hodograph, resulting in modest 0-3km SRH of around 120 m^2/s^2. This will support the potential for tornadoes with any storms that remain isolated/discrete, but the overall expectation is for rapid upscale growth into a bowing MCS. The primary concern this evening is for damaging straight-line winds in excess of 80 MPH associated with this MCS, in addition to 1.00+ inch hail. Further east into Illinois, forecast hodographs show more favorable curvature and streamwise vorticity along and south of the surface boundary. Given the environment and expected storm mode, embedded QLCS tornadoes appear possible. 1 1 Link to comment Share on other sites More sharing options...
SchaumburgStormer Posted July 15 Share Posted July 15 LOT has confirmed 3 EF-0's so far with last nights storm. 2 Link to comment Share on other sites More sharing options...
A-L-E-K Posted July 15 Share Posted July 15 Quote Conditions continue to look favorable for a QLCS with damaging winds across much of the CWA this evening. Given combination of extreme instability and moderate shear, cannot rule out some swaths of significant wind damage with gusts over 75mph in spots. In addition, strengthening low level jet this evening should result in favorable environment for QLCS type tornadoes as well. Finally, PWATs over 2" and very high freezing levels will result in storms being extreme efficient heavy rainfall producers capable of hourly rainfall rates of 2-3" per hour. Should any "warm air advection" wing type cells develop ahead of the approaching QLCS or upwind propagating storms develop on the tail end of the QLCS, then they would pose a potentially significant flash flood threat. Think it is likely that a (flash) flood watch will eventually be needed for portions of the CWA once the mesoscale evolution of things becomes clearer this afternoon. Of particular concern would be areas near and north of I-88, from the Rockford into the Chicago metro where there have been multiple rounds of heavy rain over the weekend, making them particularly susceptible to flash flooding with any heavy rainfall. - Izzi Link to comment Share on other sites More sharing options...
mjwise Posted July 15 Share Posted July 15 Upgrade to moderate flash flooding risk this evening for Rockford and Chicago. It will all depend on how progressive this evening's line is and if we see a significant WAA wing and/or training occurring on the back end. Quote In coordination with the local Chicago WFO, a targeted upgrade to a Moderate Risk was made to encompass much of Northern IL, including the Rockford and Chicago metro areas. Previous 48 hrs have been impactful across the aforementioned area with locally 5-10" of rainfall from a succession of three MCS as they moved through the area. Despite the overall progressive nature of the expected complex later today, the antecedent conditions coupled with rates of 1-3"/hr over very saturated soils and flood prone urban corridors were enough to warrant a targeted upgrade to the MDT risk across that area. 1 Link to comment Share on other sites More sharing options...
MidwestChaser Posted July 15 Share Posted July 15 Moderate risk here we go. 2 Link to comment Share on other sites More sharing options...
yoda Posted July 15 Share Posted July 15 1 minute ago, MidwestChaser said: Moderate risk here we go. Link to comment Share on other sites More sharing options...
yoda Posted July 15 Share Posted July 15 Link to comment Share on other sites More sharing options...
yoda Posted July 15 Share Posted July 15 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0300 PM CDT Mon Jul 15 2024 Valid 152000Z - 161200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF EASTERN IOWA...EXTREME SOUTHERN WISCONSIN...NORTHERN ILLINOIS...AND FAR NORTHWEST INDIANA... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE CENTRAL PLAINS...AND ACROSS PARTS OF NEW YORK...PENNSYLVANIA AND FAR NORTHERN NEW JERSEY... ...SUMMARY... Severe thunderstorms are expected through this evening across portions of the Midwest, central High Plains, lower Great Lakes, and Arizona. The greatest potential for severe gusts is over eastern Iowa into Illinois and Indiana. ...Midwest... Both tornado and wind probabilities have been increased with the 20z update to 10 percent, and 45 percent SIG, respectively. Latest satellite imagery shows a modified outflow boundary draped across far eastern IA into northern IL. A very moist airmass with dewpoints in the mid/upper 70s amid strong heating is resulting in a corridor or strong to extreme instability across the region. Favorable vertical shear will support initial supercells, organizing into a bowing MCS with time as low-level flow remains orthogonal to the developing band of storms. The greatest severe wind potential is expected along the instability gradient in the vicinity of the remnant outflow boundary, extending from far eastern IA into extreme southern WI, northern IL, and far northwest IN into this evening. Widespread gusts of 60-70 mph are expected, with some gusts to 85 mph possible. Given favorable low-level shear, mesovortex tornadoes are likely along and near the apex of the developing bow late this afternoon into evening. For short term details on severe potential across this area, reference MCD 1630. Link to comment Share on other sites More sharing options...
Chicago Storm Posted July 15 Author Share Posted July 15 Moderate is the way to go for sure. Everything is there for a high end event, with widespread/significant damaging winds and QLCS tornadoes. 1 1 Link to comment Share on other sites More sharing options...
MidwestChaser Posted July 15 Share Posted July 15 I wonder if the watch will be PDS. Link to comment Share on other sites More sharing options...
yoda Posted July 15 Share Posted July 15 15 minutes ago, MidwestChaser said: I wonder if the watch will be PDS. Regular URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 539 NWS Storm Prediction Center Norman OK 320 PM CDT Mon Jul 15 2024 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Central and Eastern Iowa Northwest Illinois Northeast Missouri Southwest Wisconsin * Effective this Monday afternoon and evening from 320 PM until 1100 PM CDT. * Primary threats include... Widespread damaging winds and isolated significant gusts to 85 mph likely Scattered large hail likely with isolated very large hail events to 2.5 inches in diameter possible A tornado or two possible SUMMARY...Intense thunderstorms will soon develop across Iowa in a very moist and unstable air mass. Activity will track eastward and organize into a fast-moving bowing cluster, capable of very damaging wind gusts and large hail. A tornado or two is also possible across this region. The severe thunderstorm watch area is approximately along and 85 statute miles north and south of a line from 25 miles west of Des Moines IA to 5 miles east southeast of Rockford IL. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU9). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Severe Thunderstorm Watch means conditions are favorable for severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. Severe thunderstorms can and occasionally do produce tornadoes. && Link to comment Share on other sites More sharing options...
yoda Posted July 15 Share Posted July 15 Link to comment Share on other sites More sharing options...
mjwise Posted July 15 Share Posted July 15 19Z special sounding at DVN, Powder keg ready to blow. 1 1 Link to comment Share on other sites More sharing options...
hawkeye_wx Posted July 15 Share Posted July 15 Link to comment Share on other sites More sharing options...
frostfern Posted July 15 Share Posted July 15 Nudged enough N to get me excited. Link to comment Share on other sites More sharing options...
MidwestChaser Posted July 15 Share Posted July 15 Is LOT not doing an afternoon AFD for tonight? Link to comment Share on other sites More sharing options...
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