Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 260043

Area Forecast Discussion
National Weather Service Northern Indiana
843 PM EDT Thu May 25 2017

Issued at 131 PM EDT Thu May 25 2017

An upper low pressure system continues to pivot away from the
region allowing showers to push away during the early overnight.
Scattered showers and perhaps a few thunderstorms are once again
possible Friday afternoon into Friday night as a low pressure
system approaches the region. Showers are still possible during
the holiday weekend, but for the most part we`ll stay dry. Highs
will stay around average for this time of year as we reach into
the 70s this holiday weekend.


Issued at 840 PM EDT Thu May 25 2017

Remnants of TROWAL should gradually shift east of the forecast
area later this evening. Until this time, a few light rain showers
are possible through late evening across south central Lower
Michigan and northwest Ohio. Starting to see some clearing across
southwest Lower Michigan and northwest Indiana which should work
across portions of north central Indiana over next few hours. Loss
of weak diurnal mixing and lingering low level inversion beneath
developing subsidence inversion will pose fog/stratus chances late
this evening into the overnight. Low level flow may be just strong
enough east of approaching low level ridge axis to promote stratus
vs fog, but may consider patchy fog mention across central/western
portions of the area late evening/overnight. Otherwise, no
significant changes to going forecast are anticipated at this


.SHORT TERM...(This Evening through Sunday)
Issued at 237 PM EDT Thu May 25 2017

Scattered showers/drizzle in deformation axis on the backside of a
stacked low over central OH will continue into the late afternoon
hours mainly east of I-69. Any additional rainfall should be
light. Rain chances quickly diminish/end this evening into Friday
morning as low finally gets a kick east toward southern New
England. Expect significant height rises/drying aloft with
shortwave ridging in wake of this system, though low clouds and
possibly some fog will likely be slow to dissipate as moisture
lingers within subsidence inversion.

A transition to more zonal flow is expected into Friday and Saturday
as deep circulation opens toward the Canadian Maritimes and the next
longwave trough edges east into the Northern Plains/south-central
Canada. Several low amplitude/convectively enhanced shortwaves are
expected to move through this westerly flow, one more compact wave
late Friday/Friday night and a separate/more pronounced shortwave
around Saturday night/Sunday morning. A convective complex will
likely accompany each wave as it feeds on a developing baroclinic
zone/instability gradient across the Mid MS Valley-northern OH
Valley. Details on timing/track of these features at this range
remain rather sketchy as models normally struggle with
convection/Lower amplitude flow. For now will continue to carry
chance PoPs (highest Friday night and later Saturday night/Sunday
morning) with better severe/heavy rain chances with each wave being
just south of the forecast area, though close enough to closely
monitor going forward given saturated soils and the potential for a
more northerly track of MCV`s. Shortwave ridging with boundary
forced south in between waves should lead to a mainly dry/mild
Saturday and Sunday afternoon.


.LONG TERM...(Monday through Thursday)
Issued at 237 PM EDT Thu May 25 2017

Eastward release of the upper low/trough into the Great
Lakes/Ontario will set up cooler/cyclonic flow into next week.
Smaller scale perturbations rotating around the upper low, in
concert with some diurnal heating, may generate some mainly
afternoon/early evening showers under cold pocket aloft. No washouts
are expected but don`t be surprised if there are a few showers
(maybe a few storms) in the area each afternoon.


.AVIATION...(For the 00Z TAFS through 00Z Friday Evening)
Issued at 840 PM EDT Thu May 25 2017

Any light rain showers for the remaining of the evening hours will
remain east of the terminals across northwest Ohio. Back edge of
MVFR deck appears to be making some progress eastward and has
cleared KSBN and may make it to KFWA over next few hours. Concern
for tonight will be potential redevelopment of fog/stratus given
approaching low level ridge axis, weakening flow, and trapped low
level moisture beneath the inversion. Flow just above the surface
may be strong enough to promote more in the way of stratus
development vs fog, but will hedge with combo of IFR vsbys/cigs at
terminals overnight. Sfc winds will become light overnight and
then light south/southeast on Friday as sfc low pressure tracks
across west central Illinois. A convectively enhanced vort max is
expected to approach the area from the Mid MS Rvr Valley late this
period, with chances of showers and thunderstorms increasing
mainly just beyond this forecast valid period Friday evening.


IN...Beach Hazards Statement until 10 PM CDT this evening for INZ003.

MI...Beach Hazards Statement until 11 PM EDT this evening for MIZ077.

LM...Small Craft Advisory until 11 PM EDT this evening for LMZ043-046.



SHORT TERM...Steinwedel
LONG TERM...Steinwedel

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