Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 252317
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
717 PM EDT Sun Sep 25 2016

.SYNOPSIS...
Issued at 710 PM EDT Sun Sep 25 2016

Rain showers will accompany a strong cold front tonight into
early Monday morning. Lows tonight will be in the upper 50s to
lower 60s. Cooler and drier air will settle in Monday afternoon
through Tuesday. Highs on Monday will be in the mid 60s to around
70 and a few degrees cooler on Tuesday. An upper level low will
then bring renewed rain chances Tuesday night into Wednesday.

&&

.UPDATE...
Issued at 705 PM EDT Sun Sep 25 2016

Evening update to further minimize TSRA chances and relegate only
to western CWA this evening as only narrow upstream surface
dewpoint plume and soon to diminish surface based lapse rates with
loss of diurnal heating. Lagged height falls and upstream
shortwave approach following frontal passage still should aid in
anafrontal precipitation shield expansion across the area, however
this not totally assured with slight lowering to hourly pops per
blend with latest short term consensus. With nominal MUCAPE and
poor low level jet placement do not antcipate additional TSRA
beyond next couple hours and isold/slight chance at best.

&&

.SHORT TERM...(This Evening through Monday)
Issued at 341 PM EDT Sun Sep 25 2016

The upper level trof across the Upper Midwest was becoming
negatively tilted this afternoon. A cold front associated with this
system was over extreme east Iowa and was moving east. Scattered
showers and thunderstorms had formed over the northern half of
Illinois. There is some risk for gusty winds in the 40-50 mph range
with DCAPE near 1000 J/Km per SPC mesoanalysis over areas west of
highway 31. Also, there is some support for isolated weak tornadoes
given favorable low level helicity, daytime heating with upstream
temperatures topping 90 degrees with dew points near 70, the
approach of the upper level trof. The 4Km NAM indicates 0-1Km shear
over 30 m/s with helicity approaching 300 m2/s2. However, it appears
the limiting tornadic factor will be relatively high LCLs around
1500 meters.

This system will trigger a round of showers and scattered storms as
the front moves east. Precipitable water values per BUFKIT will top
2.0 inches as an axis of moisture spreads northeast ahead of the
front. The precipitable values are near the climatological maximum
for this time of year.  The ongoing timing of the showers and storms
appears on track for tonight, so have made few changes. Showers
should end except possibly the far north as much cooler air spreads
into the area.

&&
Evening update to further minimize TSRA chances and relegate only
to western CWA this evening as only narrow upstream surface
dewpoint plume and soon to diminish surface based lapse rates with
loss of diurnal heating. Lagged height falls and upstream
shortwave approach following frontal passage still should aid in
anafrontal precipitation shield expansion across the area,
however this not totally assured with slight lowering to hourly
pops per blend with latest short term consensus. With nominal
MUCAPE and poor low level jet placement do not antcipate
additional TSRA beyond next couple hours and isold/slight chance
at best.

.LONG TERM...(Monday Night through Sunday)
Issued at 341 PM EDT Sun Sep 25 2016

Chilly air will spread south behind a cold front with
temperatures below normal during the middle of the week. An upper
level low will move into the area and bring a chance for showers
especially from Tuesday evening into Wednesday. Very warm lake
temperatures will favor lake enhancement of showers as delta T
values approach or exceed 15C. The period Thursday through Sunday
should be mainly dry with temperatures recovering above normal
into the mid 70s by Sunday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday Afternoon)
Issued at 148 PM EDT Sun Sep 25 2016

Main focus still on cold front passage tonight with VFR until
then. Left in VCTS mention at KSBN due to slight chance for a
storm in the 00-04Z timeframe but low level moisture and
instability are fairly limited and coverage is expected to remain
low. Rain will cross the area overnight and expect at least MVFR
conditions along and behind front in CAA regime. Brief fuel
alternate, possibly IFR, conditions not out of the question but
not expected to persist given strong dry air advection and will
leave out any mention for now due to some lingering uncertainty
on exact timing. VFR will return by late Monday morning but
westerly winds will gust in the 20-25 kt range.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...Small Craft Advisory from 11 PM this evening to 11 PM EDT
     Wednesday for LMZ043-046.

&&

$$

UPDATE...Murphy
SYNOPSIS...Murphy
SHORT TERM...Skipper
LONG TERM...Skipper
AVIATION...AGD


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