Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 192030

Area Forecast Discussion
National Weather Service Indianapolis IN
432 PM EDT Tue Sep 19 2017

Aviation Sections has been updated below.


Issued at 235 PM EDT Tue Sep 19 2017

A weak surface and upper trough will exit Indiana this evening and
the few remaining showers and storms will dissipate around dusk.
Strong upper ridging will build in its wake and provide a warm and
mostly dry period from Wednesday into early next week. The front
currently in the northern Plains will run into this ridge Thursday
and bring a low chance for showers here but otherwise dry weather
will be the rule. With upper heights quite high, temperatures above
normal will prevail.

Model solutions were in fairly good agreement and followed.


.NEAR TERM /Tonight/...

Issued at 235 PM EDT Tue Sep 19 2017

Upper and surface trough is moving slowly east and the few afternoon
showers they have triggered will diminish and dissipate by dark.
Light winds and mostly clear skies should prevail overnight. With
recent rain moistening the surface, the light wind clear sky
expected tonight will lead to locally dense fog in spots. Its
possible fog could become widespread so that will bear watching.

Model blend min temps looked good and were used.


.SHORT TERM /Wednesday into Friday/...

Issued at 235 PM EDT Tue Sep 19 2017

Upper level ridging will dominate this period. With warming
subsidence occurring, the above normal temperature regime will
continue. Storms along a cold front today will approach Indiana
Thursday. Overall, the ridge should prevail and keep us dry but with
some uncertainty, will keep a low chance of precipitation with this
feature as it moves across our area early Thursday. Once this threat
leaves, no chance for rain is expected again before next week.

Guidance temperature blends, above normal, appeared reasonable and
were used.


.LONG TERM /Friday through Monday/...
Issued at 228 AM EDT Tue Sep 19 2017

ECMWF suggests dry weather with above normal temperatures through
this period. ECWMF shows strong ridging in place aloft across the
eastern half of the country. The strong ridge looks to keep Indiana
protected from passing dynamics...keeping them well northwest of
Indiana. Meanwhile at the surface strong subsidence beneath the
ridge results in surface High pressure across the eastern Great
Lakes that keep as dry Easterly flow across Indiana through the
weekend. thus have trended toward a dry forecast. With little to no
change in air mass...have trended highs at or above the forecast
builder blend as warm air reigns supreme under the ridge.


.AVIATION.../Discussion for 21z KIND TAF Update/...
Issued at 432 PM EDT Tue Sep 19 2017

Downplayed VCTS threat as a only a few light showers occurring north
and northwest. signficant changes are needed at this
time.  Previous aviation discussion follows...

Low stratus from morning rains is still slowly lifting and breaking
up but should lift to VFR by 191800z as broken cumulus field around
3000 feet. Current scattered band of showers between KLAF and KIND
WILL fill in some and probably develops thunder as atmosphere
destabilizes. Cumulus will gradually dissipate by late afternoon as
weak high pressure slowly builds in.

Other question is given clearing skies this evening, rains of this
morning wetting the ground, and light wind overnight, whether fog or
stratus develops towards daybreak. Model solutions vary and MOS
varies as well. For now carrying MVFR ceiling and/or fog but
potential for IFR stratus or fog certainly bears watching.





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