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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.


Monday, November 27, 2023

SPC Nov 27, 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
1100 PM CST Sun Nov 26 2023

Valid 271200Z - 281200Z


The risk of thunderstorms appears negligible across much of the U.S.
today, although some lightning is possible in developing bands of
snow across parts of the upper into lower Great Lakes vicinity by

Split westerlies emanating from the mid-latitude Pacific continue to
converge east of the Rockies, where some further amplification of
northern branch large-scale troughing is possible, toward the
southern mid latitudes. As this troughing slowly shifts east of the
Mississippi Valley, through the Canadian Maritimes and waters
offshore of the Atlantic Seaboard, at least some suppression of
mid-level heights is forecast on the northern periphery of
subtropical ridging centered over the Caribbean.

Beneath this regime, a significant cold front, trailing a deepening
occluded surface cyclone migrating to the east and northeast of
James Bay, is forecast to advance into the Bahamas, northwest
Caribbean and southwestern Gulf of Mexico before stalling. In its
wake, generally dry/stable conditions will be maintained across much
of the U.S. into 12Z Tuesday.

...Lake Superior into lower Great Lakes...
While stronger mid-level height falls (associated with a pair of
short wave perturbations embedded within the larger-scale cyclonic
flow), spread eastward and northeastward, away from the Great Lakes
region, models indicate that another consolidating short wave
perturbation will dig southeast of the Upper Midwest through the
upper Ohio Valley/Mid Atlantic by late Monday night. As it does,
deep-layer cyclonic flow likely will be maintained across much of
Lake Superior through the lower Great Lakes vicinity, where the
southeastward advecting lower/mid-tropospheric cold core (including
-20 to -24C around 700 mb) will contribute to steepening lapse rates
above the relatively warm lake waters. Associated destabilization
is forecast to support developing bands of snow, with forecast
soundings indicating the evolution of thermodynamic profiles which
could potentially become conducive to lightning, particularly by
tonight across and to the immediate lee of the lower Great Lakes.

..Kerr/Weinman.. 11/27/2023

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)