IWX issues Area Forecast Discussion (AFD) at Feb 3, 11:34 AM EST479
FXUS63 KIWX 031634
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
1134 AM EST Mon Feb 3 2025
.KEY MESSAGES...
- Rain moves into the area Wednesday afternoon and may start as
some brief freezing rain. The best chance for ice
accumulations will be in Hillsdale and surrounding counties.
- Another system could bring a mix of precipitation types over
the weekend.
&&
.DISCUSSION...
Issued at 325 AM EST Mon Feb 3 2025
Challenging fog forecast this morning as WAA over cold ground has
supported patches of dense fog at times but visibilities are highly
variable. Generally following latest hi-res/rapid update guidance
which shows areas of dense fog slowly lifting north through the
early morning as surface winds increase and veer with next
approaching shortwave. Currently there is dense fog holding in our
NE CWA but visibilities elsewhere are generally 2SM or more. Hi-res
guidance suggests these lower visibilities may hold in the NE
through sunrise and then improve rapidly 13-14Z. Will therefore
trim some counties off the south and west sides of the advisory
and cut 3 hours off the end time for the counties that remain.
Further updates are certainly possible given highly variable
conditions.
WAA will continue through the day ahead of a cold front associated
with aformentioned shortwave crossing the northern Lakes. Concensus
guidance places highs well into the 50s today despite ample mid and
high level clouds. Held with a mostly dry forecast based on lack of
appreciable forcing and dry low levels but wouldn't be surprised to
see a few sprinkles in our eastern zones late today as the front
passes. Temps return much closer to normal behind this front with
lows tonight in the 20s for most areas and highs Tue only in the
30s.
The forecast for Wed remains a challenging one. A pair of weak
shortwaves will eject out of the Rockies during this time and
support another period of strong WAA/isentropic ascent across our
area. Much better moisture available with this round given strong SW
low level flow extending from the Southern Plains. The issue of
course will be precip type. 1035mb surface high extending from the
Canadian Prairies will support temps well into the 20s Wed AM and may
only climb into the mid 30s at best by Wed afternoon. Surface high
does exit off the New England coast by Wed evening but cool/dry
easterly flow is maintained until then. Surface warm front doesn't
lift through our area until mid Wed night (at best). However WAA
aloft is strong, pushing 850mb temps to around 5C and possibly
higher. This sets the stage for a period of freezing rain but the
question is how long and how much ice accretion. Pattern recognition
does not favor significant icing (save perhaps for our far NE).
First of all, while I did maintain some chance PoP's prior to 21Z
given some timing uncertainty in 00Z models I do believe the
substantive precip will not begin until 21-00Z in our SW (03Z or
later in our far NE) thus limiting the duration of precip falling
into the truly cold/dry surface air and allowing temps to recover a
bit in at least our SW half. Second, freezing rain is always a self-
limiting process that requires a steady feed of cold/dry air to
offset the latent heat released during freezing. This usually
requires a strong blocking high to the N/NE to provide that strong
surface CAA. We don't have that in this case and expect most areas
will just see some brief freezing rain (perhaps impacting the roads
given cold ground temps) with minimal ice accretion on trees and
powerlines before changing over to just rain. However, the exception
will be in the far NE counties where there does appear to be a
longer duration of cooler and drier air advecting into the area.
Angola-Hillsdale and points east are climatologically favored areas
for freezing rain with some minor terrain influences likely at play.
Here ice accumulation around a tenth is possible and may cause more
significant impacts but confidence is not high this far out.
Thu and Fri will be quiet but another system (fairly similar to Wed)
will cross the region on Sat. Here again, precip looks to be
primarily rain but can't rule out a possible mix, particularly in
our northern zones.
&&
.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1133 AM EST Mon Feb 3 2025
VFR with southwest winds near 10 knots this afternoon before a
cold front drops through KSBN around 21z, and KFWA around 00z.
Post-frontal saturation/cooling will allow for a period of IFR
to MVFR restrictions this evening into the overnight before
improving into MVFR/VFR under a drying north wind into Tuesday
morning.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.
&&
$$
DISCUSSION...AGD
AVIATION...Steinwedel
Source:
IWX issues Area Forecast Discussion (AFD) at Feb 3, 11:34 AM EST---------------
If I'm using your data in a way that is against your terms please email the team at "threatweb@pupswoof117.com"! I am a bot who will not respond in the comments at all and is only designed to post RSS feeds!
