Area Forecast Discussion
Issued by NWS Northern Indiana

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580
FXUS63 KIWX 240542
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
142 AM EDT Thu Aug 24 2017

.SYNOPSIS...
Issued at 750 PM EDT Wed Aug 23 2017

Primarily fair weather will continue through the weekend as high
pressure dominates the region. Expect a slight chance of rain
showers on Lake Michigan early Thursday, but overall conditions will
be dry. High temperatures will be in the 70`s through the weekend.
Lows will be chilly, ranging from the upper 40`s to the 50`s.

&&

.UPDATE...
Issued at 750 PM EDT Wed Aug 23 2017

Wind speeds beginning to drop off over past hour as decoupling
occurs, and speeds will continue to diminish to light northwest or
become calm through 02Z. The next upstream short wave of interest
is across northern Minnesota, and this wave will dive southeast
tonight into Thursday morning across the southern Great Lakes. A
band of rain is accompanying this feature this evening across
Minnesota where decent low/mid level baroclinicity exists. This
wave will not have this type of baroclinic zone to work with as it
drops southeast late tonight into tomorrow morning. However, as
previous discussion mentions, may need to watch for some isolated
shower development tomorrow morning as this forcing translates
southeast and some lake induced instability develops. A thermally
induced circulation is also being hinted at in higher res
guidance across southern Lake Michigan, and could also provide a
brief uptick in shower chances, mainly in the 12Z-18Z window
Thursday.

&&

.SHORT TERM...(This Evening through Thursday)
Issued at 211 PM EDT Wed Aug 23 2017

Water vapor imagery depicting short wave over southern Manitoba
that will drop down through the great lakes region in the short
term. Outside of a possible stray shower up near the lake...only
other sensible weather impact will be an increase in clouds as it
moves across the area. Cool...dry Canadian airmass will continue
to build into the region as lows tonight will drop down into the
lower 50s while added cloud cover will limit highs to upper 60s to
around 70 in NW CWA and lower 70s elsewhere on Thursday.

&&

.LONG TERM...(Thursday Night through Wednesday)
Issued at 211 PM EDT Wed Aug 23 2017

Surface high pressure will build into the great lakes region and
provide ideal weather through the weekend with low humidities and
seasonably cool temps with highs in the 70s and lows in the 50s.
Plenty of model uncertainty in a low confidence pattern heading
into next week with remnants of Harvey along the TX gulf coast and
a northern stream disturbance topping the western US ridge and
moving into the mid MS valley on Monday. Latest GFS now has the
northern stream wave deepening as it moves overhead on Monday
night into Tuesday. Expect limited moisture transport with this
feature as no indications at this time that it will be able to tap
into the remnants of Harvey that will still be hung up along gulf
coast. ECMWF offers a weaker and slower solution in comparison
but end result from model blend will be a weak but non-zero signal
for precip in our area which model discrepancies will only act to
spread spatially and temporally through the end of the long term
period. Will at least attempt to limit effects of overdone GFS and
remove POPs from Sunday night. Will also smooth out the spurious
looking bullseye POP areas in out periods as they have no physical
basis or validity.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday Night)
Issued at 137 AM EDT Thu Aug 24 2017

Potent short wave seen nicely on satellite IR and WV early this
morning moving into northern WI. This wave will continue to drop
southeast through the first part of Thursday. Minimal aviation
impacts expected with VFR conditions. A few isolated shra remains
possible but coverage too limited to include in point forecasts,
especially with little impact. Chances should be in the 12-18z
timeframe before wave exits the area and clearing skies return for
latter half of the valid period.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&

$$

UPDATE...Marsili
SYNOPSIS...MCD
SHORT TERM...JAL
LONG TERM...JAL
AVIATION...Lashley


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