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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.

Thursday, April 14, 2022

SPC Apr 14, 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 Thu Apr 14 2022 Valid 142000Z - 151200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER A SMALL PART OF THE MID ATLANTIC... ...SUMMARY... Thunderstorms capable of strong wind gusts and marginal hail remain possible across parts of the Mid Atlantic. Little change was made to the outlook other than sharpening probabilities along the advancing cold front. ...Discussion... Storms are increasing in coverage along the cold front, primarily from MD into southern NY. Deep-layer shear appears favorable for primarily cellular storm mode, in which case marginal hail will be possible given MLCAPE values of 200-500 J/kg. A few strong to severe gusts may occur as well given timing of the storms with peak heating and steep boundary-layer lapse rates. Farther south into VA and NC, slightly stronger instability, though also weaker shear, may also favor a few marginally severe storms capable of hail or wind prior through early evening. For more information, see mesoscale discussion 494. ..Jewell.. 04/14/2022 .PREV DISCUSSION... /ISSUED 1121 AM CDT Thu Apr 14 2022/ ...Mid-Atlantic to Hudson Valley this afternoon/evening... A deep occluded low over northern MN will move slowly east-northeastward into ON as an embedded shortwave trough rotates northeastward over the lower Great Lakes and Northeast. The shortwave trough is accompanied by a surface cold front that will cross the Appalachian crest early this afternoon and reach the Mid-Atlantic coast this evening. Surface heating to the east of a cloud band along the front will result in afternoon temperatures of 75-80 F inland from the coast, with boundary-layer dewpoints in the 55-60 F range across eastern PA/NJ to the Hudson Valley (west of the cool air wedge across eastern New England). Midlevel lapse rates will be poor, but the surface heating/mixing will drive steep low-level lapse rates and MLCAPE of 500-1000 J/kg in the pre-frontal warm sector. Relatively straight hodographs with 35-45 kt effective bulk shear will support a mix of multicell clusters/line segments, and perhaps some low-end supercell structures this afternoon, with a primary threat of damaging outflow gusts. The severe threat should be limited to a roughly four-hour window from about 19-23z, after which convection will move offshore or weaken while encountering the cool air wedge lingering across VT/MA/CT. ...VA to GA this afternoon/evening... A remnant MCV from convection yesterday across MS/AL is now moving northeastward into VA from NC, and will likely approach Chesapeake Bay by mid afternoon. A few storms with strong outflow gusts may form along or just ahead of the cold front from NC into VA this afternoon where temperatures warm to near 80 F with dewpoints near or above 60 F. However, the potential for organized storms will diminish from southwest-to-northeast as midlevel flow weakens in the wake of the remnant MCV. Farther south toward GA, severe storms are not expected as a result of high-level cloud debris slowing surface heating, in combination with weak vertical shear and only minimal forcing for ascent. Read more CHECK UPDATE ZOOM GRAPHIC