IWX issues Area Forecast Discussion (AFD) at Nov 18, 3:49 AM EST348
FXUS63 KIWX 180849
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
349 AM EST Mon Nov 18 2024
.KEY MESSAGES...
- Chances for showers increase, focused on tonight into early
Tuesday and again by Wednesday night.
- Highs in the 60s Tuesday will be quickly replaced by much
cooler temperatures in the 30s and 40s by Thursday.
- While some snowflakes may occur Wednesday night into early
Thursday, accumulations are not expected given warm ground
temperatures.
&&
.DISCUSSION...
Issued at 343 AM EST Mon Nov 18 2024
Weak cool front was stalling/washing out across northern portions of
the area where KBEH and surrounding areas managed to pick up less
than a tenth of an inch of rain. The rainfall and lingering moisture
has allowed fog and stratus to rapidly develop with some
locations, especially north of the toll road at or below 1/4sm
at times. Have introduced patchy or areas of fog across far N
areas, but holding off on any headlines.
A strong upper level low and associated jet streak was aiding in
surface low pressure development across western TX. The upper level
energy and associated sfc low will move NNE into Minnesota by 12Z
Tue. The initial upper wave will be dampening somewhat, transferring
its energy into a northern stream trough that will quickly deepen
with a closed low taking shape by 18Z Tue over the Dakotas.
Surge of WAA will commence today, with plume of increasing low level
moisture advecting north courtesy of an unobstructed flow from the
GOM. The LLJ will remain focused to our west through the day,
helping to focus the greatest QPF potential into IL. Somewhat
skeptical that much rain will edge into western areas with current
QPF forecasts of around a tenth of an inch possibly overdone. By the
time you reach I-69, little or no rainfall is expected. Widely
scattered showers may start to edge into western areas after 03Z
Tue, but best chances exist between 6 and 15Z from SW to NE with a
few lingering showers possible until the warm front clears the area.
Overall QPF should be on the order of a quarter inch or so. Dry slot
quickly works in during the afternoon, likely lingering through at
least 12Z Wed with strong mixing allowing for a breezy day with
temperatures soaring into the 60s early, well above normal for
November, but still far shy of records in the 70s.
The upper low will continue to move east and deepen into Wednesday
with a 120 kt jet streak rounding the trough, eventually forcing
further cyclogenesis east of the area as the energy transfers east.
Some models bring some light precip in Wednesday as the nose of
stronger lift arrives ahead of the cold front, but concerned that
the disjointed setup of dynamics may lead to limited chances for
precip with the bulk of anything residing more north and east int
Thursday morning for most areas. Colder air will be rapidly moving
into SW areas Wed night into Thur with 850 mb temps dropping well
below zero celsius and Tw temps also dropping below 32 degrees. This
would yield a chance for some snow, but areas with highest pops
across the far north will have somewhat higher Tw temps resulting in
more of a mix. Also, despite the overnight occurrence of the colder
air, lack of high precip rates, combined with very warm ground temps
point towards no accumulation and little if any impacts on roads.
Better chances for more widespread precipitation looks to arrive
Thursday afternoon into night as energy wraps back around the
eastern low. Sub zero 850 mb temps will still exist, but a modifying
airmass will advect in from the north, yielding warmer Tw temps and
keeping precip in the form of rain. Gusty winds still appear to be
in store for Wed into Thu, but translation of much stronger winds
may end up more east of the area. Still expecting 20 to 30 mph with
some higher gusts possible.
The main upper low will move to New England but the strong NW flow
will remain in place with additional waves bringing chances for
mainly light showers into the weekend.
&&
.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1207 AM EST Mon Nov 18 2024
Weak/shallow cold front in association with low amplitude
shortwave spinning south of James Bay will stall out across the
terminals this morning. This frontal zone will mix back north
this aftn in response to strong upstream disturbance currently
ejecting out into w TX. Little sensible wx impact expected
however boundary layer moistening invof frontal zone may yield
a brief period of threshold MVFR/VFR cigs for a time around
daybreak.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...Small Craft Advisory from 10 PM this evening to noon EST
Tuesday for LMZ043-046.
&&
$$
DISCUSSION...Fisher
AVIATION...T
Source:
IWX issues Area Forecast Discussion (AFD) at Nov 18, 3:49 AM EST---------------
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