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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 0600 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1259 AM CDT Mon Jul 01 2024

Valid 011200Z - 021200Z


Severe thunderstorms will be possible today across the
northern/central Plains centered over Nebraska and South Dakota.
Areas of damaging winds and sporadic hail will be possible.

An upper-level trough will progress eastward into the northern and
central Plains today. The upper-level ridge within the southern
Plains will weaken in response and shift gradually eastward as well.
At the surface, the anticyclone within the East will broaden,
pushing a surface boundary farther into Southeast. Within the
broader lee trough, a surface low is forecast to deepen near the
CO/KS/NE border region and shift eastward through the afternoon. The
combination of the surface high to the east and the deepening
surface cyclone in the central Plains will advect rich low-level
moisture northward through the day into south-central and southeast
Nebraska and perhaps somewhat farther northwestward. Southerly flow
within the northern Plains will also move low 60s F dewpoints
currently in Kansas into the Dakotas.

...Central Plains...
Based on surface observations Sunday evening, upper 60s to low 70s F
dewpoints appear probable to reach portions of Nebraska (potentially
as far west as the Panhandle). Though some form of convection
currently in eastern Colorado/western Nebraska may be ongoing early
in the day Monday, this activity is forecast to weaken and move east
by early afternoon. Thereafter, very strong heating is expected west
of a dryline feature. Modest height falls should aid in thunderstorm
development near the surface low and northward-advancing warm front.
Initial development should be supercellular given large buoyancy
(2500-3000 J/kg MLCAPE) and 45-55 kts of effective shear. Low-level
shear enhancement near the warm front will promote some risk of
tornadoes so long as convection remains discrete. Large hail and
severe winds will also be possible. 2+ inch hail could occur, but
probability appears low due to warm temperatures within the hail
growth zone and high freezing levels. Weaker shear near the anvil
levels as well as somewhat high temperature-dewpoint spreads should
lead to quick upscale growth. This transition to linear mode will be
accompanied by an increase in severe wind threat, some potentially
75+ mph.

There is potential for storm development along the remnant surface
front/outflow boundary into eastern Kansas. Should a storm form, it
would likely be severe. With limited background ascent this far
south, confidence in storm initiation is quite low.

...Northern Plains...
Stronger mid-level ascent in combination with a north-south oriented
boundary will promote scattered storms across the region. Surface
heating will be less on account of cloud cover, but sufficient
low-level moisture will bring around 1500 J/kg MLCAPE. Though 40-45
kts of shear will be across the boundary, forcing should promote
decidedly more linear storm modes than farther south. Large hail and
severe winds will the be primary threats. A tornado or two could
occur given the ambient vorticity along the boundary.

...North Florida into Georgia and coastal South Carolina...
Ongoing convection Sunday evening may leave some cloud debris
present into Monday morning. Surface heating will be most pronounced
north of the remaining clouds. MLCAPE of perhaps near 3000 J/kg
appears possible by the afternoon. Mid-level lapse rates will be
weak, as will effective shear (around 20-25 kts), but a few damaging
gusts are possible especially with any clusters that may form.

..Wendt/Squitieri.. 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)