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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, July 1, 2024

SPC Jul 1, 2024 1630 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1630Z Day 1 Outlook

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1130 AM CDT Mon Jul 01 2024

Valid 011630Z - 021200Z


Severe thunderstorms should occur this afternoon and tonight across
parts of the northern/central Plains, especially portions of
Nebraska and the Dakotas. Scattered severe/damaging winds, large
hail, and a few tornadoes all appear possible.

...Northern/Central Plains...
A notable upper trough across the northern Rockies will advance
eastward today over the northern/central Plains. Related low-level
mass response will encourage multiple surface lows to slowly deepen
across the northern/central High Plains. An occluded/cold front will
move eastward across the western/central Dakotas through this
evening, while a warm front attempts to lift northward across
northern KS into NE. Current expectations are for robust convection
to develop along both the front in the western Dakotas, and the
higher terrain of WY/CO as large-scale ascent associated with the
upper trough overspreads the warm sector. Low-level moisture will
remain more limited with northward extent into the Dakotas. But,
sufficient instability in a narrow corridor, along with strong
deep-layer shear, is still anticipated. Initial supercells over
western ND/SD should pose a threat for large hail, before convection
quickly grows upscale into a bowing cluster towards central ND/SD
with a greater threat for severe/damaging winds. With sufficient
ambient near-surface vorticity along the front, a brief tornado or
two also appears possible with initially more cellular development.
This activity should weaken with eastward extent tonight as it
encounters much weaker instability towards the MN border.

Initially high-based convection over central CO may pose an isolated
threat for severe wind gusts as it moves into eastern CO/western KS
and encounters a very well mixed boundary layer. The Marginal Risk
has been expanded westward and southward a bit in CO to account for
this potential. Otherwise, thunderstorms should eventually develop
and strengthen by late this afternoon along/east of a surface low
centered over northeast CO. Deep-layer shear will be strong enough
to support supercells, but convective mode may quickly become messy
as activity moves eastward along/near the northward-advancing warm
front in NE. Large hail may occur with any sustained supercell, and
sufficient low-level shear will be present along/near the warm front
to support a threat for a few tornadoes. Even so, a more
clustery/linear mode may become dominant fairly soon after initial
development. This would support a greater threat for severe/damaging
winds, and perhaps isolated gusts up to about 75 mph. Regardless of
continued uncertainty over what the dominant convective mode will
be, the severe threat will likely persist into eastern NE/western IA
this evening and tonight before thunderstorms eventually weaken.

Scattered to numerous thunderstorms should develop this afternoon
along and south of a cold front draped east to west across parts of
the Southeast. Although mid-level flow and related deep-layer shear
will remain modest, steepened low-level lapse rates though daytime
heating and plentiful low-level moisture will easily support
moderate to strong instability. Occasional strong to damaging winds
may occur with the more robust cores and loosely organized clusters
as they move generally southward through the early evening before
eventually weakening.

..Gleason/Thornton.. 07/01/2024

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)