Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
1236 PM CDT Wed Oct 2 2024
KEY MESSAGES...
- While a series of cold fronts will move through the region
through the weekend, at or above average temperatures are
expected to prevail.
- There is no meaningful signal for widespread, soaking rainfall
through at least the first half of the month.
&&
DISCUSSION...
Issued at 203 AM CDT Wed Oct 2 2024
Through Thursday:
Surface high pressure is shifting into the Mid-Mississippi Valley
region early this morning. While light winds and very dry airmass
associated with this high will foster a chilly start to day, a
high-level deck of cirrus overhead is likely to keep early
morning lows a couple of degrees warmer than previously though. In
spite of the chilly start to day, pleasant weather conditions are
expected today. Winds will shift to the southwest during the day
following a quick eastward passage of the surface high. This will
allow a warmer airmass to work back northward into the region
today and especially by Thursday. Accordingly, expect high
temperatures to rebound back into the lower 70s this afternoon
under mainly sunny skies. Sunny skies continue on Thursday, and
so too does the warming trend. This will result in highs on
Thursday reaching well into the 70s, to near 80 degrees (warmest
across interior sections of northern IL).
A weak surface cold front will be approaching the WI state line
later in the day. This front is likely to shift southward into our
area into Thursday night.
KJB
Thursday Night through Tuesday:
A broad longwave trough crossing southern Canada and the
northern Great Plains Thursday into Friday will induce a weak
surface trough/cold front across the Upper Mississippi River
Valley. This front will cross the forecast area late Thursday
night into Friday morning. Guidance continues to favor a dry
frontal passage, though cannot completely rule out a couple
rogue showers or elevated storms across northern Illinois if a
weak residual mid-level EML erodes more than expected on the
southern periphery of the trough.
Expansive high pressure will settle over the region later
Friday through Saturday. Another trough will cross far southern
Canada this weekend, with more prominent forcing remaining well
to the north Saturday night before a cold front crosses the area
early Sunday. Profiles continue to look rather dry ahead of the
front as Gulf moisture remains cutoff from potential tropical
activity. Signs point to another dry frontal passage, with only
some mid-level Pacific-based moisture brushing the area to the
north.
Continuing to see signals of a potential critical fire weather
day for brush and field fires across at least portions of our
area on Sunday. A well-mixed post-frontal airmass aided by gusty
westerly winds will be capable of lowering RH values near or
below 25%. With fine fuels and crops expected to further dry
over the next several days, all three critical values (wind, RH,
fuel moisture) may be met. We will continue to gradually
increase messaging for this period, especially as the signal in
lower RH grows within the ensemble suite each day.
Appreciable rain looks unlikely through at least late next week
with sprawling high pressure early next week being replaced by
a stout mid-level ridge mid to late week. Temps will run near
normal to above normal through this period.
Kluber
&&
AVIATION /18Z TAFS THROUGH 00Z FRIDAY/...
Issued at 1236 PM CDT Wed Oct 2 2024
Key Messages:
- Northeasterly wind shift behind lake breeze late tomorrow
afternoon
Winds are generally expected to remain out of the southwest
through most of the TAF period, with occasional gusts to 15-20
kts possible this afternoon. Winds should gradually become
lighter going into tomorrow, which will allow for a lake breeze
to push inland and cause the prevailing wind direction to shift
around to northeasterly at ORD and MDW towards the end of their
current 30-hour TAF period. Otherwise, expect VFR conditions to
prevail with occasional tufts of cirrus likely to be the only
observed cloud cover during the TAF period.
Ogorek
&&
LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
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