Temps | Gusts | WU KORD KPWK

CLICK for this month's BIG night sky ...




Cardinal SAT


MOBILE DEVICE? Turn sideways. Weather conditions directly above are near Lakefront. Top tabs refer to O'Hare (official).

Archives for the SPC Convective Outlook are updated daily (approximately) with a live map at the beginning of each article. Follow the link at the end of the article to check for current updates on the NOAA/NWS Storm Prediction Center website. Also, see Archives for Chicago's hourly weather data on CARDINAL NEWS Magazine.


Tuesday, February 21, 2023

SPC Feb 21, 2023 0600 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1142 PM CST Mon Feb 20 2023 Valid 211200Z - 221200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON ACROSS PARTS OF THE NORTHERN MID ATLANTIC AND LATE TONIGHT ACROSS PARTS THE SOUTHERN GREAT PLAINS... ...SUMMARY... A few strong thunderstorms with gusty winds and small hail are possible across parts of the northern Mid Atlantic this afternoon, mainly across eastern Pennsylvania into New Jersey. Additional strong thunderstorms posing at least some risk for severe weather are possible across northwest Texas and southwestern Oklahoma by early Wednesday. ...Synopsis... Blocking will remain prominent within the mid/upper flow across the mid-latitude eastern Pacific, with the northern branch of the evolving split flow becoming increasingly amplified across much of the Pacific into western North America during this period. This will include building mid-level ridging to the north of the high, and the evolution of a large deepening trough near and inland the U.S. Pacific coast, as an intense north-northwesterly jet digs offshore. Farther downstream, strong mid-level height rises are forecast across much of the eastern U.S. by early this evening, as large-scale ridging builds within the westerlies, to the north of persistent subtropical ridging centered over the Caribbean. Before the ridge builds into the Northeast, mid-level troughing is forecast to rapidly shift east-southeast of the Great Lakes/Upper Ohio Valley and offshore of the northern Atlantic Seaboard. In higher latitudes, a deep mid-level low of Arctic origins, initially digging across Hudson Bay, likely will begin to turn eastward toward northern Quebec. However, associated cold surface air, which has worked its way toward the Canadian Rockies, is forecast to surge across the international border through much of the northern U.S. Great Plains and Upper Midwest, while substantive lower/mid-tropospheric warming occurs across the southern Great Plains, lower/middle Mississippi and Ohio Valleys. By 12Z Wednesday, the primary strengthening low-level baroclinc zone will extend across the central Great Plains into the Ohio Valley and Mid Atlantic. However, in the wake of prior cold intrusions into the Gulf of Mexico, and beneath warm and dry layers aloft, low-level moistening to the south of the front will remain modest and strongly capped across most areas. ...Northern Gulf States into Middle Mississippi/Ohio Valleys... A rather large area with a 10 percent risk for thunderstorms remains indicated. It is possible that a corridor of weak thunderstorm development may linger beyond 12Z this morning across parts of the northern Gulf Coast states/Tennessee Valley vicinity. Otherwise, as mid-level inhibition increases with warming aloft, the risk for thunderstorms may be rather negligible until early Wednesday, across parts of the lower Ohio Valley, in response to elevated moisture return and warm advection, to the north of the stronger capping. ....Northern Mid Atlantic... In the wake of an initial frontal wave migrating offshore, models indicate that boundary-layer warming and mixing with insolation along and east of the Allegheny Mountains, coupled with modest residual low-level moisture, may contribute to weak destabilization ahead of an occluding surface low migrating east-northeast of the lower Great Lakes. Beneath very cold mid-level air (including 500 mb temps at or below -30 C), it appears that the environment may become conducive to scattered low-topped thunderstorms capable of producing small hail/graupel. Some of this activity, mainly across parts of eastern Pennsylvania into New Jersey, may also aid the downward transfer of momentum associated with 40-50+ kt west-southwesterly flow in the 850-500 mb layer, contributing to a risk for damaging surface gusts during the mid to late afternoon hours. ...Southern Great Plains... Models indicate a narrow corridor of weak boundary-layer destabilization (including CAPE to around 500 J/kg) across northwest Texas into southwestern and central Oklahoma as early as the 06-12Z time frame late tonight. This is forecast to occur near/just ahead of a weak surface cold front accompanying the leading edge of stronger mid-level cooling, associated with the perturbation emerging from the subtropical eastern Pacific. In the presence of intensifying south-southwesterly deep-layer mean flow (including 50+ kt in the lowest 6 km AGL), it appears that forcing for ascent may become sufficient to overcome relatively warm, dry and well-mixed air in the 850-700 mb layer, and support increasing thunderstorm development. If this occurs, strong deep-layer shear may contribute to an organizing line with potential to produce severe wind gusts. ..Kerr/Wendt.. 02/21/2023 Read more CHECK UPDATE ZOOM GRAPHIC
SUNRISE AND SUNSET TIMES IN UTC (if you're not logged in to Google)
CHICAGO UTC-6 during CST (Central Standard Time, e.g., winter)
CHICAGO UTC-5 during CDT (Daylight Savings Time, e.g., summer)