IWX issues Area Forecast Discussion (AFD) at Nov 11, 6:36 AM EST715
FXUS63 KIWX 111136
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
636 AM EST Mon Nov 11 2024
.KEY MESSAGES...
- Another cold front drops into the area today with windy
conditions once again. Peak gusts up to around 35 mph are
possible today.
- Return to near or slightly above normal temperatures today into
Thursday with another chance for showers Wednesday night.
- A return of highs in the upper 50s to lower 60s expected for
Sunday with another cold front expected to increase light rain
chances again for late weekend.
&&
.DISCUSSION...
Issued at 345 AM EST Mon Nov 11 2024
A well defined upper level vort max is evident on water vapor
imagery this morning across the Upper MS Valley. An associated cold
front with this compact vort will drop across the region this
afternoon. Some very brief, weak warm advection is preceding this
short wave this morning across the southern Great Lakes, and
this may tend to slow southward advance of stratocu deck across
far northern Indiana and southern Lower Michigan until later
this morning or midday. Low level westerlies will ramp up again
today with near term forecast soundings indicating top of the
boundary layer wind speeds on the order of 30-35 knots. These
low level winds and steep low level lapse rates should support
another afternoon of peak afternoon wind gusts in the 30-40 mph
range with higher resolution ensemble guidance indicating
approximately 40 percent chance of peak gusts exceeding 35 mph
across southern Lower Michigan into portions of extreme NE
Indiana/NW Ohio this afternoon. Moisture availability is limited
with this front, although cannot completely rule out some
scattered sprinkles briefly across south central Lower MI this
afternoon in closer proximity to colder mid level profiles.
Onset of stronger cold advection this afternoon and expanding
stratocu deck should limit highs to the mid 50s, but if low
clouds are more delayed across the south, could see a potential
of highs reaching around 60 south of US 24.
For tonight, a low level anticyclone will build eastward across the
Great Lakes region, with a period of time of favorable low level
trajectories down the long axis of Lake Michigan before winds veer
northeasterly late night. Inversion heights could be high enough (~4-
5k feet) to support some shallow convection with a few sprinkles or
light rain showers possible briefly downwind of Lake Michigan.
Veering of the low level flow and low level dry air intrusion should
result in decreasing clouds late night, but always some concern with
low level easterlies and lingering near sfc moisture that stratocu
could linger a bit longer. Forecast soundings do suggest maintenance
of steeper low level lapse rates overnight without full decoupling.
Given these factors will remain conservative with lows tonight,
generally in the mid 30s.
For Tuesday, pattern will remain progressive as the broad
anticyclone shifts east of the area. Persistent easterly flow and
neutral temperature advection will promote limited mixing heights on
Tuesday as low level thermal troughing lingers across the
southern/eastern Great Lakes. Previous forecast highs in upper 40s
to around 50 still appear reasonable at this time.
For Wednesday/Wednesday night, deterministic and ensemble
solutions are starting to show a bit better convergence in
solutions regarding another progressive eastern Pacific wave
approaching the region for late Wednesday. Moderately strong low
level moisture transport will build northward into the region
late Wednesday in advance of this feature with some accompanying
pre- frontal low level moisture convergence Wednesday evening.
Magnitude of moisture tongue is not as significant as last
event, and overall forcing mechanisms appear progressive. This
should keep storm total rainfall amounts generally less than one
half inch most locations. Given tendency to some better
guidance agreement, have nudged up PoPs to low end likely for
late Wednesday.
For Thursday through Saturday, little day to day temperature change
is anticipated with better low level warm advection looking more
likely for second half of the weekend. Eastern Pacific pattern looks
to become more active for next weekend, with EC/GFS indicating
fairly strong lead mid/upper level wave ejecting northeast into
Upper Midwest Sunday. This should eventually drive another frontal
boundary southward late weekend/early next week with some additional
light rain chances. Late weekend may also feature some pre-frontal
warming taking highs back into the upper 50s to lower 60s.
&&
.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 626 AM EST Mon Nov 11 2024
A deep low had moved northeast of Georgian Bay overnight, but a
secondary low upstream and about to move over Lake Superior.
This second low will race southeast in tandem with a secondary
cold front and bring gusty winds to the terminals. Winds will
shift to the northwest and eventually north. MVFR challenges
persist as these low clouds undulate over northern Indiana.
Went with a TEMPO group for 3 hours for now, but may be too
optimistic at SBN as winds become northwest which should be more
favorable for influx of long fetch lake moisture into the cloud
layer.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...Small Craft Advisory until 10 AM EST Tuesday for LMZ043-046.
&&
$$
DISCUSSION...Marsili
AVIATION...Skipper
Source:
IWX issues Area Forecast Discussion (AFD) at Nov 11, 6:36 AM EST---------------
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