Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 101733

Area Forecast Discussion
National Weather Service Northern Indiana
133 PM EDT Thu Aug 10 2017

Issued at 326 AM EDT Thu Aug 10 2017

Fair weather will continue today as high pressure moves slowly
east away from the area. Scattered showers are possible tonight as
a cold front approaches from the west. This front will move
through the area Friday bringing a chance of thunderstorms. High
pressure will build in from the northwest Saturday providing fair
weather and a little cooler temperatures. Low pressure is expected
to move east from the central or southern Plains Sunday and
Monday bringing a slight chance of showers to southern portions of
our area. This will be followed by high pressure moving slowly
east across the Great Lakes providing fair weather Tuesday and
Wednesday. and Wednesday.


.SHORT TERM...(Today and Tonight)
Issued at 326 AM EDT Thu Aug 10 2017

Low pressure system over srn MN will move east to nrn lwr MI by
12z Friday with trailing cdfnt entering nw portion of our cwa at
that time. Moisture will grdly increase across our area in advance
of the front, but only wk elevated instability expected by
tonight so just expecting sct wkng convection to move into the
area overnight. Wk waa today/tngt should result in a little
warmer temps with highs today in the l-m80s and lows tonight in
the l-m60s.


.LONG TERM...(Friday through Wednesday)
Issued at 326 AM EDT Thu Aug 10 2017

Cdfnt will progress across the cwa Friday/Friday night. Diurnal
heating/destabilization should allow scattered thunderstorms
to develop along the front Friday, especially se portions where
fropa will be later. 0-6km shear is fcst in the 30-35kt range, so
if sufficient destabilization occurs, a few strong storms are
psbl. Widely scattered storms may linger into Fri eve se as front
conts to move through but heating/instability wane. Some wk lake
induced instability should also develop in the caa regime behind
the front, but fcst soundings suggest this instability is rather
shallow with a low inversion, so models light lake effect qpf late
Friday night and Saturday was disregarded. Some post frontal
strato cu is likely in this timeframe but by Saturday aftn with
high pressure ridging in, sunshine should return providing
sufficient heating for temps to reach the l-m70s.

Medium range models continue to be erratic on handling of shrtwv
diving se down back of longwave trof Sun-Mon. Latest ECMWF
considerably farther north with this system than GFS/GEM. Followed
model blend approach which yields just slight chc pops mainly
across srn portions of the area. Fairly cool temps should cont
into early next week. High pressure should move slowly east across
the area Tue-Wed providing fair wx with a slow warming trend.


.AVIATION...(For the 18Z TAFS through 18Z Friday Afternoon)
Issued at 104 PM EDT Thu Aug 10 2017

Low pressure system in the High Plains enters the Northern Great
Lakes dragging a cold front through the forecast region. This will
keep the TAF sites dry heading towards evening tonight, but as the
front gets closer, chances for showers and possibly storms
increase. CAMs guidance like the HRRR and the NAM3k indicate that
afternoon convection in the Midwest and Northern Plains will
approach our northwest before midnight, which would include SBN.
With weak leftover instability and shear around, this appears
possible and would agree that it should continue to dissipate as
it moves through.

Friday morning, TAF models are showing the potential for a reduction
in conditions after the convection moves through. Appears the
most likely source will be from stratus into MVFR CIGs with winds
remaining at or around 5kts, but should winds go lighter, fog
could become a possibility as well. Thereafter, we`ll have to
watch for more showers and storms Friday.





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