Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 282356
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
756 PM EDT Wed Sep 28 2016

.SYNOPSIS...
Issued at 755 PM EDT Wed Sep 28 2016

A slow moving upper level disturbance will persist across the
region through the first part of the weekend. This will lead to
periodic scattered rain showers through Saturday. Isolated
thunderstorms will also be possible each afternoon through Friday.
Mainly dry conditions are then expected for the second half of the
weekend. Low temperatures tonight will drop into the lower to mid
50s. High temperatures on Thursday will reach into the mid to
upper 60s.

&&

.SHORT TERM...(This Evening through Thursday)
Issued at 337 PM EDT Wed Sep 28 2016

Unsettled weather pattern to continue into at least first half of
the weekend as meandering upper low will persist across the region.

A series of disturbances will continue to rotate through broad upper
low level, with center of parent circulation centered across
northwest Indiana this afternoon. One of these short waves appears
to be nosing across north central Indiana at this time. DPVA
associated with this short wave combined with low level convergence
along low level trough axis has led to some renewed convection
across central Indiana into far south central portions of the
forecast area this afternoon. As this wave continues to progress
through parent circulation, low level cyclonic circulation axis will
gradually reorient more in a northwest to southeast fashion across
central portions of the forecast area. DPVA should also begin to
increase as aforementioned vort max wraps northward across the
southern Great Lakes. Given above evolution and establishment of
cold pool aloft, have maintained trend to scattered-numerous PoPs
across approximately northern half of the area by late
afternoon/early evening. Did maintain these mid range PoPs
through the night, especially north half, as low/mid level
moisture axis wraps cyclonically across the southern Great Lakes.
Have maintained isolated thunder mention through early evening,
mainly across the southeast half where axis of 100-300 J/kg
MLCAPES should reside. Some small hail will continue to be a
possibility through late this afternoon, particularly southeast
half of the area. Persistent cloud cover and moist air mass will
limit diurnal temp ranges tonight, and have maintained lows in
the lower to mid 50s.

A similar setup appear to be in store for Thursday as upper low
drops across the lower Ohio Valley. Upper speed max and associated
short wave rotating through the base of this trough across mid MS
Valley will begin to impact the area on Thursday with a renewed
chance of showers/iso storms. Orientation of more favorable deeper
moisture axis should support highest (likely) PoPs across the
northern half. Maintenance of steep low level lapse rats will make
thunder possible once again Thursday. Some small hail cannot be
ruled out given proximity of cold core aloft, but freezing levels
should be slightly higher on Thursday.

&&

.LONG TERM...(Thursday Night through Wednesday)
Issued at 337 PM EDT Wed Sep 28 2016

Chance of showers will continue Thursday night, although have
maintained somewhat lower chances for this period as some lull in
stronger forcing is expected. Yet another stronger vort lobe will
lift northeast through upper trough late Thursday night into
Friday causing mid/upper level height minimum to lift back
northward on Friday. Previous forecast already had likely PoPs for
Friday and see no reason to deviate at this time. Lapse rates may
not be quite as steep on Friday but plentiful moisture should
result in enough weak instability for iso thunder mention in the
afternoon. Scattered showers will likely persist into Saturday as
upper low lifts across the southern Great Lakes. This feature
should eventually get ingested by an upper level PV anomaly
dropping out of southeast Canada, resulting in diminishing rain
chances by Saturday night/Sunday. Moderating trend then expected
for early next week with highs back into the mid 70s by Tuesday.
Another chance of rain appears to be in store toward and just
beyond this forecast period due to next approaching front.

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday Evening)
Issued at 748 PM EDT Wed Sep 28 2016

Difficult forecast with low confidence with respect to ceiling
heights and timing of scattered showers beneath pinwheeling
vortex. Attempt to time period of tempo VFR ceilings at KSBN
toward daybreak per guidance trend and separate period during late
morning/early afternoon at KFWA before again lowering to below
fuel/alternate levels in shra by mid/late afternoon at peak of
instability.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...Small Craft Advisory until 5 PM EDT Friday for LMZ043-046.

&&

$$

SYNOPSIS...Murphy
SHORT TERM...Marsili
LONG TERM...Marsili
AVIATION...Murphy


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