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Weather conditions on bar directly above are near Lakefront. Tabs under Moon Phases refer to O'Hare (official).

Archives for SPC Convective outlook are updated daily with a live map a the beginning of the article. Touch or click map to get possible update, and follow link at end of article for referral to NOAA/NWS Storm Prediction Center. Archives for Chicago's hourly weather data were updated 24-48 hours after end of each day prior to Dec. 2020.

Wednesday, April 13, 2022

SPC Apr 13, 2022 2000 UTC Day 1 Convective Outlook

SPC 2000Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Wed Apr 13 2022 Valid 132000Z - 141200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF SOUTHEASTERN MISSOURI...SOUTHERN ILLINOIS...WESTERN KENTUCKY...WESTERN TENNESSEE...EASTERN ARKANSAS...NORTHEASTERN LOUISIANA...AND NORTHERN MISSISSIPPI... ...SUMMARY... Numerous severe thunderstorms are expected this afternoon and evening across the Mid-South, lower/middle Mississippi Valley, and Lower Ohio Valley. Tornadoes, some of which will be strong, along with widespread and potentially significant damaging wind gusts and large hail, remain likely especially within the Moderate and Enhanced Risk areas. ...Discussion... Few changes appear necessary to the ongoing outlook at this time, aside from trimming western fringes of thunder and severe-risk areas due to progression of the surface front and associated/ongoing convection. Along with a couple of loosely organized bands of strong to severe storms ongoing from southeastern Missouri to East Texas, development of anticipated/more isolated storms ahead of the line appears to be occurring now over the northern Louisiana vicinity. These storms -- should continued development indeed occur -- would likely be accompanied by more substantial tornado potential over the next few hours. Otherwise, risk for several -- potentially strong -- tornadoes, along with strong/damaging winds and large hail -- remain likely through this afternoon and evening, and into the overnight hours mainly across the central Gulf Coast area. ..Goss.. 04/13/2022 .PREV DISCUSSION... /ISSUED 1126 AM CDT Wed Apr 13 2022/ ...Synopsis... An upper-level trough over the OK/TX Panhandle this morning will become negatively tilted as it amplifies and shifts northeastward through the day today and into the Great Lakes tonight. This will deepen the surface low across the Upper Midwest and tighten the frontal boundary from northern Illinois to eastern Texas this afternoon and accelerate the front east to the western Appalachians by Thursday morning. ...Lower Ohio Valley into the Lower/Mid Mississippi Valley... Convection this morning will have significant ramifications on the severe weather risk throughout the day. Thunderstorms have formed along and ahead of the cold front from southern Missouri across Arkansas and into northeast Texas. This front (or convectively enhanced effective front) should mark the northwestern periphery of the severe weather threat today. East of this front, widespread convection has also developed across eastern Missouri and into Illinois in the uncapped airmass sampled by the 12Z ILX RAOB. Continued convection through the morning and early afternoon across this region will likely limit destabilization and northward moisture transport, stunting storm intensity with northern extent. Farther south, a significant severe weather threat remains. An EML across this region (sampled by the KLZK 12Z RAOB) should permit more robust low-level heating. Currently there is a drier surface airmass in this region in the wake of the morning MCV which has since moved into central Kentucky. However, northward low-level moisture advection is already underway with mid 60s dewpoints into southern Arkansas and upper 60s dewpoints in Louisiana and southern Mississippi. The severe weather threat across this region will be bi-modal. The organizing squall line from the Ozarks to northeast Texas will accelerate east during the afternoon/evening hours. This will pose a threat for both damaging winds and QLCS/embedded supercell tornadoes. Additional convection is expected to develop ahead of this line during peak heating. This activity will likely pose the greatest strong tornado threat with the potential for an intense tornado or two. Forecast hodographs show the majority of the shear in the lowest 1.5 km with nearly uniform flow in the cloud bearing layer. This may reduce hydrometeor venting in the mid-upper levels and result in messier updrafts and HP supercell mode. This could partially explain the strong, but shorter track, updraft helicity swaths shown by most 12Z CAM guidance. However, despite this, some longer track storms are likely across southeast Arkansas and northwestern Mississippi where greater low-level moisture and instability is forecast. The severe threat will gradually reduce with southern extent where mid-level flow will be weaker and low-level flow will veer as the upper trough moves away. ...Portions of the Northeast... Isolated strong to severe storms may occur from western Maryland/eastern West Virginia across Pennsylvania and into central New York. Limited moisture will keep instability on the lower side, but enough heating is forecast for MLCAPE in the 500 to 750 J/kg range with supercell wind profiles. Therefore, occasional weakly rotating updrafts could produce marginally severe hail/damaging wind gusts across the region. Read more CHECK UPDATE ZOOM GRAPHIC
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