Area Forecast Discussion Issued by NWS Chicago, IL
000
FXUS63 KLOT 151134
AFDLOT
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
634 AM CDT Fri Mar 15 2024
.KEY MESSAGES...
- Mild and breezy on Saturday with gusts to 35 mph
- Turning colder early next week with periods of snow showers
possible (20-30% chance)
&&
.DISCUSSION...
Issued at 303 AM CDT Fri Mar 15 2024
All is quiet across the Upper Midwest early this morning with
the surface front and associated convection well to the south,
currently extending from northeast Texas up toward West
Virginia. The broad upper trough is beginning to cut off across
the southwest which will set up a Rex block pattern across the
western CONUS as upper ridging builds into Canada. This will
place the Great Lakes region under a generally northwest flow
pattern with multiple disturbances moving across the region
ushering in a stretch of cooler and continued breezy conditions
early next week.
Today will begin mostly cloudy across the area with decreasing
cloudiness during the day, likely hanging on the longest near
the lake and into northwest Indiana. North to northwest winds
ease during the afternoon which will allow a lake breeze to
begin pushing land and turn winds easterly near the lake,
potentially aided by a weak mesohigh briefly developing over the
southern end of the lake. Expect highs to warm into the lower
50s, with 40s expected near the lake in Illinois and further
inland across northwest Indiana.
Breezy westerly winds develop on Saturday as the surface
pressure gradient tightens in response to a surface low diving
southeast across Ontario. Deep mixing into a strong low-level
jet could also tap into higher gusts to 35+ mph late morning
through the afternoon. Cooler temperatures then advect into the
region in the wake of the attendant cold front. This cooler air
will be reinforced by a trailing short-wave that dives across
the region Sunday into Monday with highs near 40 on Sunday and
mid 30s on Monday and overnight lows in the 20s. In addition to
the colder conditions, a few snow showers also can`t be ruled
out. There is perhaps a bit better signal during the Sunday
night into Monday period though really any time early next week
could feature a few snowflakes near the lake and into northwest
Indiana.
Toward the middle of next week temperatures begin to moderate
back to near normal to slightly above normal as the upper trough
shifts slightly east and the western CONUS Rex block begins to
break down, with highs back in the mid 40s to lower 50s. This
could result in additional rain chances later in the week, the
timing of which will depend on when the resultant southern
stream wave reaches the region.
Petr
&&
.AVIATION /12Z TAFS THROUGH 18Z SATURDAY/...
Issued at 630 AM CDT Fri Mar 15 2024
- MVFR/IFR CIGS linger this morning
- NNE winds trend NNW late morning then flip to east with a lake
breeze this afternoon at ORD/MDW
- Strong WSW to W winds develop on Saturday with gusts to 30kt
CIGS:
Lingering IFR to low-end MVFR stratus persists this morning at
the Chicago are terminals. This back edge will very gradually
shift southeast with time with sites scattering out to VFR by
late morning/early afternoon, earliest at DPA and latest at
GYY.
WINDS:
Winds remain out of the N to NNE this morning around 10-15 kt.
Speeds will gradually ease after daybreak, eventually backing
NNW by late morning. A weak lake breeze is expected to move
inland during the mid-late afternoon turning winds east at
ORD/MDW before settling into a prevailing southwest direction
this evening. Nudged up the east wind shift at ORD to 22Z to
match MDW based on the latest hi-res guidance trends. Strong
winds then develop Saturday morning with gusts to 30 kt
possible by the end of the 30-hr TAF period.
Petr
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory until 7 PM CDT this evening for the IL
and IN nearshore waters.
&&
$$
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