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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, February 16, 2022

SPC Feb 16, 2022 1730 UTC Day 2 Convective Outlook

SPC 1730Z Day 2 Outlook Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1128 AM CST Wed Feb 16 2022 Valid 171200Z - 181200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM THE MISSISSIPPI DELTA REGION EASTWARD ACROSS THE TENNESSEE VALLEY... ...SUMMARY... Severe thunderstorms are expected across portions of the Lower Mississippi Valley, Mid-South, and Southeast on Thursday. ...Synopsis... Phasing of a northern-stream upper trough crossing central Canada and the north-central U.S. with a southern-stream trough crossing the southern Rockies/southern Plains will occur Thursday, with eastward progression of the consolidating feature expected. This system will be characterized by very strong deep-layer flow on its southeast flank, across the south central into the eastern CONUS. At the surface, a deepening low is progged to be shifting eastward out of Oklahoma across the northern Arkansas/far southern Missouri region through the day, and then northeastward along the Ohio Valley into the evening hours. A broad, moistening warm sector will exist across the Mid South and Southeast, until a cold front, advancing eastward with time, ushers in colder/drier air. This front is expected to reach the Mississippi Delta region during the afternoon, the Appalachian crest overnight, and then extend from the Mid-Atlantic region to the Florida Panhandle by 18/12Z. ...Arklatex region eastward across the Mid South and central Gulf Coast region... Widespread showers and embedded thunderstorms will be ongoing at the start of the period from southeastern Kansas southward to eastern Oklahoma and Arkansas and into northeastern Texas at the start of the period, near and ahead of the advancing surface low/cold front. Meanwhile, largely elevated, warm advection-induced convection will extend northeastward across the Mid Mississippi and Ohio Valleys and vicinity. While meager CAPE is expected early in the period, strong flow aloft suggests that locally damaging wind gusts will be a possibility from the Arklatex region eastward toward the Mississippi Delta area through mid afternoon. With time, deepening of the low and associated strengthening of low-level southerlies will allow persistent northward theta-e advection to combine with modest/local diurnal warming, eventually yielding evolution of mixed-layer CAPE up to about 500 J/kg. Across Kentucky and areas north, a cool boundary layer should persist, resulting in slightly stable conditions beneath evolving, modest instability. However, this thermodynamic concern is partially offset by stronger ascent aloft spreading across this region -- along with the deepening low expected to track along roughly the Ohio River through late afternoon and into the evening. With this ascent likely to maintain partially forced convection, and given exceptionally strong/veering flow with height across this region, potential for locally damaging winds and a couple of tornadoes remains a possibility. Farther south, greater low-level theta-e advection suggests that the boundary layer will become at least neutral, and therefore greater certainty of surface- or near-surface-based storms exists -- both near the advancing cold front, and also with associated warm advection-driven bands of convection in the free warm sector. As noted above, very strong shear -- with south-southwesterly 850 mb winds in excess of 50 to 60 kt increasing to west-southwesterly at 70 to 90 kt at mid levels -- is suggestive of supercells, and attendant risk for damaging winds and several -- and possibly locally strong/damaging -- tornadoes. As such, an upgrade to enhanced risk is being introduced, centered across the Tennessee Valley area from late afternoon through the evening hours. ..Goss.. 02/16/2022 Read more CHECK UPDATE ZOOM GRAPHIC