IWX issues Area Forecast Discussion (AFD) at Nov 12, 11:32 AM EST979
FXUS63 KIWX 121632
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
1132 AM EST Tue Nov 12 2024
.KEY MESSAGES...
- Cooler over the next few days closer to seasonable normals with
dry conditions today into the first part of Wednesday.
- Rain is expected Wednesday evening into Thursday. Storm total rainfall
amounts expected to be in the one quarter to three quarters
of an inch range.
- Little day to day temperature change Thursday through the
weekend, with temperatures a little above normal for mid
November.
&&
.DISCUSSION...
Issued at 355 AM EST Tue Nov 12 2024
An upper level trough shifting across the eastern Great Lakes this
morning has driven a low level front southward across the southern
Great Lakes. Cold advection with this front has supported southward
building low cloud deck across much of NE Indiana/NW Ohio. Mid
level ridging will build in quickly on the heels of this eastern
Great Lakes wave today, with not much additional southward
progression of the low level front expected. Increasing deep
layer subsidence and some diurnal mixing later this morning
into early this afternoon should gradually erode these low
clouds, but confidence still on the low side regarding exact
details with sky cover trends. Easterly flow and lowering
inversion heights will result in poor/shallow mixing today that
should limit high temperatures to around 50.
For tonight, a neutral low level temperature advection pattern
will shift to warm advection during the overnight hours due to
progressive nature of the Great Lakes anticyclone. Mainly clear
skies tonight should support good radiative losses this evening
with better boundary layer decoupling compared to previous
night. A few negative factors for much colder temperatures
tonight include maintenance of some low level height gradient
given departure of the high and expected increase in high clouds
overnight. Have not made much change from previous forecast
with lows from the upper 20s to mid 30s.
Mid level warm advection and upper trough ejecting out of the
Rockies will support increase in mid and high clouds during the
day Wednesday. Highs Wednesday should be just a bit above
normal despite the WAA considering mixed layer depths should be
quite shallow as low level inversion sharpens. Surface gradient
should still be strong enough for somewhat breezy conditions
however.
Wednesday night into Thursday still shaping up as best rain
prospects this period as a low level jet provides more substantial
moisture transport. A fairly impressive axis of moisture wrapping
around southern periphery of western Atlantic anticyclone will get
drawn northward into Lower MS Valley Wednesday night, but still some
concern that gradual veering of low level flow will cut-off best
moisture return to lower Ohio Valley and points south. Categorical
pops still seem in order given strong upper forcing, pre-frontal
trough forcing, and anomalous moisture for mid November. Deep
layer unidirectional flow characterized by good speed shear
could be supportive once again for localized bands of enhanced
rainfall amounts in the 0.5-1.00" range with expectation of more
general storm total in the 0.25-0.75" range. Pattern across the
Atlantic should become a bit more blocky in nature heading into
Thursday, so slow departure of this upper trough locally will
prolong rain chances into Thursday, possibly ending as some
pockets of drizzle late Thursday. The bulk of rainfall should
occur in the 00Z-12Z timeframe however.
Dry conditions are expected Friday and Saturday with little day to
day temperature variations expected just above climatological
normals as amplifying upstream ridge only exhibits modest
eastward progression. Medium range guidance still suggests a
more active eastern Pacific pattern taking shape late work
week/next weekend with a lead upper level short wave topping the
ridge Sunday. This may eventually drive another cold front
southward late weekend. Large scale pattern with western CONUS
longwave troughing would support additional rain chances early
next week
&&
.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1132 AM EST Tue Nov 12 2024
MVFR stratocu deck continues to erode with both terminals
already VFR. High pressure will continue to keep VFR conditions
in place through the remainder of the period with an increase in
high clouds later tonight into tomorrow. Easterly winds persist
near 10 knots otherwise.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.
&&
$$
DISCUSSION...Marsili
AVIATION...Steinwedel
Source:
IWX issues Area Forecast Discussion (AFD) at Nov 12, 11:32 AM EST---------------
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