IWX issues Area Forecast Discussion (AFD) at Sep 28, 2:07 AM EDT014
FXUS63 KIWX 280607
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
207 AM EDT Sat Sep 28 2024
.KEY MESSAGES...
-Periods of rain are expected through next Tuesday, with a
slight chance for thunderstorms on Sunday afternoon and
evening. Dry conditions return for the latter half of the work
week.
-Dangerous swimming conditions persist on Lake Michigan today,
particularly along the southern Berrien and La Porte County
shorelines.
-High temperatures this weekend into next Friday will be in the
upper 60s and 70s. Lows will range from the mid to upper 40s to
low 60s.
&&
.DISCUSSION...
Issued at 208 PM EDT Fri Sep 27 2024
Helene's remnants, with the center of low pressure (~985 mb) just
into se KY, is in the process of getting absorbed nwwd on the ne
fringe of a stalled western TN Valley upper low. This phasing is
helping to maintain the system strength with only slow weakening of
a sub ~990 mb low into western KY and far sw IN late this afternoon
and evening. The resulting tightening of the low level height field
(925 mb easterlies maxing out at 50-55 knots) will at least clip
southern portions of the forecast area mid afternoon through mid
evening. Lacking low level lapse rates with the incoming tropical
airmass a definite limiting factor for higher end gusts at the
surface, though a few gusts up to 50 mph remain possible for areas
mainly south of US 30. Frequent gusts in the 35-45 mph range
can be expected elsewhere. Pressure gradient then weakens with
time tonight through the weekend as the system fills with
lighter northeast winds.
The other aspect to this system will be rain chances. Arcing
tropical plume with the system warm front does lift through from se
to nw late this afternoon into tonight with a period of
widespread light to moderate rain. The deeper moisture does
struggle to reach our far nw which may result in lesser rain
coverage with time tonight, with more focused fgen/deformation
forcing likely shifting west of the area by later tonight and
Saturday morning.
Filling/stacked low center over the western OH Valley by Saturday
will continue to gradually become more ill-defined into Sunday and
Monday as it wobbles slowly east near or just south of the Ohio
River. Moisture axis and weak deformation forcing on its northern
fringe will keep clouds and times of mainly light showers in the
forecast through the weekend, and possibly into Monday. Saturday
aftn-eve appears to be the best chances for measurable rain before
the circulation unravels and deeper moisture shifts off to the
southeast.
This system will finally get a push out of the region by Tuesday
with the transition to a more progressive northern stream flow
regime. This forces a dry cold frontal passage through around
Tuesday night with a brief cooldown into Wednesday. Mainly dry/quiet
otherwise next week.
&&
.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 157 AM EDT Sat Sep 28 2024
Predominantly VFR to MVFR conditions at the TAF sites, with
periods of IFR likely. We will continue to see intermittent
shower activity as we deal with Helene's remnants. There is one
more defined back near KSBN, and one just south of KFWA (dry air
is lifting in from dry slot to the SE). This may limit some of
the activity, so kept some periods either dry or confined to
VCSH. Blustery NE winds continue over KSBN, and pick up somewhat
again this afternoon at KFWA (we're decoupling). Ceilings look
to be higher than what much of the guidance suggests so kept it
optimistic for now, with KFWA having potential to see more IFR
than what is currently in the TAF. Opted to hold off as
conditions haven't materialized yet--and stayed conservative
with the forecast.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Beach Hazards Statement through this evening for INZ103.
OH...None.
MI...Beach Hazards Statement until 5 AM EDT early this morning for
MIZ177.
Beach Hazards Statement until 8 AM EDT this morning for MIZ277.
MARINE...Small Craft Advisory until 8 AM EDT this morning for LMZ043-
046.
&&
$$
DISCUSSION...Steinwedel
AVIATION...MCD
Source:
IWX issues Area Forecast Discussion (AFD) at Sep 28, 2:07 AM EDT---------------
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