Area Forecast Discussion
Issued by NWS Northern Indiana

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445
FXUS63 KIWX 191846
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
246 PM EDT Thu Oct 19 2017

.SYNOPSIS...
Issued at 246 PM EDT Thu Oct 19 2017

Warm and pleasant weather will continue through Saturday with highs
in the 70s and lows in the mid 40s to lower 50s. The next chance of
rain will arrive on Sunday. Periodic showers will then be possible
through the middle of next week...along with much cooler
temperatures.

&&

.SHORT TERM...(This Evening through Friday)
Issued at 246 PM EDT Thu Oct 19 2017

Exceptionally high amplitude and large wavelength ridge is currently
building over the eastern CONUS as high latitude trough quickly
exits to the Canadian Maritimes and next large Pacific trough
crashes into the west coast. Net result is a continuation of
spectacular fall weather through Saturday. Thin cirrus shield
gradually dissipating and expect clear skies with generally light
winds overnight. Lows tonight will be similar to last night, though
a bit cooler in spots (especially across the north) given more ideal
radiational cooling conditions. Low level ridge axis does pass east
of our area late tonight. SW winds and WAA will ramp up tomorrow
(leading to afternoon highs in the mid/upper 70s under full sun) but
should not have too much impact on lows tonight.

&&

.LONG TERM...(Friday Night through Thursday)
Issued at 246 PM EDT Thu Oct 19 2017

Warm/moist air advection continues into Saturday as trough slowly
approaches. Expect a few more clouds on Sat that could keep highs a
degree or two lower but still a dry and pleasant day.

Forecast for Sunday and Monday still a little uncertain but a trend
to more progressive system may be emerging. Low confidence is due to
the fact that main shortwave will be lifting into Hudson Bay but
trough is so narrow that a substantial vort max gets cut off across
the Lower Mississippi Valley. Secondary jet streak/trough then dives
into the Great Lakes with some solutions (ECMWF in particular)
showing a phasing event directly over our area while other solutions
(Canadian, NAM, GFS, and ensembles) indicate a more progressive/
eastward phase. This mainly affects the forecast for Monday but
still some uncertainty on exact timing of rainfall with cold front
on Sunday/Sunday night. Good chance for rain when front does pass
though, given ample moisture and good low level convergence with
decent mid/upper level support. Trended the forecast toward a more
progressive solution but did keep some PoPs in for Monday. By
Tues/Wed good chance for some lake-enhanced rain showers as longwave
trough settles over the Great Lakes. Will be much cooler than
current conditions but should remain warm enough for an all liquid
forecast.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday Afternoon)
Issued at 1256 PM EDT Thu Oct 19 2017

VFR flight conditions expected for the period with winds this
afternoon around 10 kts. Winds overnight will become calm.

&&

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

$$

SYNOPSIS...AGD
SHORT TERM...AGD
LONG TERM...AGD
AVIATION...Heidelberger


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