Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 300710

Area Forecast Discussion
National Weather Service Northern Indiana
310 AM EDT Fri Sep 30 2016

Issued at 310 AM EDT Fri Sep 30 2016

A stalled upper level disturbance will bring periods of rain to the
area through the weekend. A few embedded thunderstorms are also
possible. Highs through the weekend will be in the 60s with lows in
the 50s. High pressure will bring slowly improving conditions early
next week.


.SHORT TERM...(Today and Tonight)
Issued at 310 AM EDT Fri Sep 30 2016

Latest water vapor imagery clearly shows cutoff upper low
continues to wobble just south of our area, allowing continuous
feed of Atlantic moisture and shortwaves embedded in deep cyclonic
flow to maintain areas of rain and abundant clouds across the
southern Great Lakes. SCT/NUM showers will continue through at
least Saturday along with mostly cloudy skies and limited diurnal
temp ranges. Position of upper low continues to favor main axis of
steadier/heavier rain across southern Michigan where best
850-700mb theta-e ridge resides, along with better 295K system
relative isentropic ascent, midlevel deformation, and upper level
divergence. There is also a secondary area of fgen/deformation
across central IN/OH on immediate northern flank of cyclone.
Current regional radar mosaic shows these axes of better forcing
and moisture quite well and will continue to pivot eastward this
morning. Even outside of these two areas, the chance for SCT
showers will exist throughout the CWA given abundant moisture and
deep cyclonic flow. Best chances for most of the area will
probably be this afternoon and into the evening/early overnight.
Height fall centroid will begin to lift north during this time
given slow approach of west coast trough. Combination of robust
midlevel CVA and increasing instability due to cold pool aloft
will likely support numerous/widespread showers. A few embedded
thunderstorms certainly possible given around 500 J/kg of SBCAPE
during diurnal peak. Chance of thunder could even persist after
sunset given surface dewpoints around 60F and 500mb temps dropping
below -20C. No severe weather is anticipated. Locally
moderate/heavy rain may be possible if weak instability is
realized and any training develops with PW values around 1.25
inches and decent synoptic forcing, but not expecting any real
impacts. Basin-average QPF amounts expected to be around 0.25-0.5
inches through tonight. Expect high temps to remain in the
mid/upper 60s (assuming no breaks in the clouds) with lows tonight
generally in the mid 50s.


.LONG TERM...(Saturday through Thursday)
Issued at 310 AM EDT Fri Sep 30 2016

Midlevel cold pool will be directly overhead on Saturday and this
will support another day of showers, and possibly thunderstorms,
given 500 J/kg SBCAPE and pinwheeling vort lobe overhead. Best
chances will likely be in the afternoon, during peak heating, but
again, no severe weather is expected given limited instability.
Activity will diminish overnight as instability wanes and upper low
begins to lift NE. Precip chances are lower on Sunday but can`t
completely rule out shower chances as several models indicate weak
vorticity spoke rotating through the area on backside of exiting
low. Deep/moist cyclonic flow will at least support mostly cloudy
skies and a few stray showers certainly possible in our N/NE
counties. Some peaks of sun possible in our south and could see some
lower 70s for max temps.

Improving conditions expected during the first half of next week.
Monday appears mainly dry, though still some residual cyclonic flow
so could still be a fair amount of clouds and a very low chance for
a sprinkle in our north. Ill effects of upper low will be fully
vanquished by Tuesday as longwave ridge develops over the Great
Lakes in response to deep trough over the Rockies/Central Plains.
Eventually this will send a cold front through our area but likely
not until Wednesday night/Thursday with questionable precip chances
based on latest GFS. Until then, expect slowly moderating temps and
mostly sunny conditions Tues and Wed.


.AVIATION...(For the 06Z TAFS through 06Z Friday Night)
Issued at 1237 AM EDT Fri Sep 30 2016

Widespread mvfr/ifr conditions over nrn IN and upstream across srn
MI/nw OH attm. Not expecting any sgfnt improvement to conditions
early this morning, with upstream cigs/vsbys suggesting some
potential for further deterioration. Ocnl areas of shra should cont
to rotate around strong upr low now centered over nrn KY and fcst to
lift slowly north today/tonight. Some diurnal improvement to flight
conditions psbl today, but latest HRRR suggests another band of shra
will move through the area this aftn suggesting any improvement will
be fairly brief.


LM...Small Craft Advisory until 6 PM EDT this evening for LMZ043-046.




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