IWX issues Area Forecast Discussion (AFD) at Sep 27, 2:08 AM EDT881
FXUS63 KIWX 270608
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
208 AM EDT Fri Sep 27 2024
.KEY MESSAGES...
- Windy conditions are expected Friday into Friday evening,
especially south of US 30 in Indiana where northeast winds may
gust in excess of 45 mph Friday afternoon into Friday
evening.
- Showers overspread the area from southeast to northwest
Friday afternoon into Friday evening.
- Chances for scattered rain showers linger through this
weekend.
&&
.DISCUSSION...
Issued at 228 PM EDT Thu Sep 26 2024
An upper low over the western TN Valley, and Hurricane Helene over
the eastern Gulf of Mexico, will be the features of interest later
tonight through this weekend. The center of Helene is still on
target to continue northward, making landfall near the big bend area
of Florida this evening, reaching the southern Appalachians by 12z
Friday. The Fujiwara interaction with the western TN upper low then
takes over Friday into Friday night with Helene's low center
retrograding north-northwest to near or just south of Evansville
IN by 00z Sat.
The quick movement of Helene's remnants, and eventual merging with
the aformentioned upper low will allow for a slower weakening trend
than normally observed with tropical remnants reaching the TN
and/or lower OH Valleys. NAEFS return intervals for MSLP outside
of the CFSR climate database, with ensemble guidance in good
agreement in a low center nearly 6 standard deviations below
average lend increased ensemble support for this anomalous
synoptic evolution.
The impacts locally will be increasing east-northeast winds
late tonight into Friday on its northern fringe thanks to a
tightening low level height gradient (925 mb winds peaking 45-55
knots Friday afternoon-evening). HREF/NBM probabilistic data
suggests high confidence in gusts in the 35-45 mph range during
this time, with a 12z HREF increase to 50-60 percent probs for
headline level gusts (45 mph plus) in the south. Low level
lapse rates and mixing depths look limited and may keep the bulk
of gusts below 45 mph, though the stronger solutions and
unusual setup mentioned above are worth mentioning for what
could be a least a brief period of advisory level gusts, best
chances south of US 30 in Indiana Friday afternoon and early
evening on the leading edge of rain. Per collaboration, did opt
for a Wind Advisory mid Friday afternoon through Friday evening
in our southwest. Have gusts mainly in the 30-45 mph range
elsewhere with some northward expansion potentially needed.
A narrowing band of rain should also accompany the system warm
conveyor and associated plume of deeper moisture/isentropic upglide.
Guidance remained in general agreement in this precip shield lifting
into areas along/south of US 24 Friday afternoon, then narrowing and
slowly drying up with its pivot into our north-northwest zones
Friday night. No hydro concerns are anticipated.
Big closed low after the full merger does fill and attempt to wobble
slowly east in the vicinity of the Ohio River Valley this weekend
into early next week. This will keep clouds and chances for showers
in the forecast, though winds will diminish and temperatures will be
pleasant. Mainly quiet/dry otherwise next week with temp
fluctuations as a more active high-lat northern stream drops a cold
front through around mid week, and possibly another just beyond this
forecast period.
&&
.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 200 AM EDT Fri Sep 27 2024
The period begins with a focus on strengthening winds Friday
with VFR cigs/vis, then we deal with deteriorating conditions to
MVFR and possibly IFR at times. The first is the wind gusts,
which look to be out of the NE at a maximum around 35-40 knots
late this afternoon. Right now, have capped gusts around 37
knots for TAF sites but wouldn't be surprised to see some
isolated higher gusts towards 00z. Rain will lift north through
the afternoon and into the evening, with showers beginning at
KFWA this afternoon and then closer to late afternoon/early
evening at KSBN. For now kept things MVFR, but model guidance
hints at KFWA seeing some higher-end IFR ceilings (700-900 ft)
towards the end of the period. LLWS signal wasn't quite there
yet, so opted to leave out for this issuance.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Wind Advisory from 2 PM this afternoon to 11 PM EDT this
evening for INZ013-015-020-022>026-032>034.
Beach Hazards Statement from this afternoon through late
tonight for INZ103.
OH...None.
MI...Beach Hazards Statement from this afternoon through late
tonight for MIZ177-277.
MARINE...Small Craft Advisory from 8 AM this morning to 8 AM EDT
Saturday for LMZ043-046.
&&
$$
DISCUSSION...Steinwedel
AVIATION...MCD
Source:
IWX issues Area Forecast Discussion (AFD) at Sep 27, 2:08 AM EDT---------------
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