Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 140501

Area Forecast Discussion
National Weather Service Indianapolis IN
1201 AM EST Tue Nov 14 2017

The AVIATION Section has been updated below.


Issued at 313 PM EST Mon Nov 13 2017

Dry weather will stay in place over central Indiana until early
Wednesday morning when a low pressure system approaches from the
west, bringing rain to the area through the day on Wednesday.
After a dry Thursday, a stronger system will arrive on Friday
bringing rain and chances for thunderstorms, some of which could
be strong, to the area through Friday night, with rain moving out
slowly on Saturday.


.NEAR TERM /Rest of Tonight/...

Issued at 930 PM EST Mon Nov 13 2017

Clouds will linger into the night across the eastern half of the
forecast area, but the western counties will experience clearing.
Overnight lows are still progged to bottom out in the low 30s, so
no changes needed. Updated grids have been sent.

Previous Discussion...
High confidence in dry conditions overnight. Forecast focus then
is on whether or not cloud cover will scatter and clear out or
hang around through the night. Low confidence forecast due to
uncertainty with models not in good agreement, and also their
tendency to move stratus out too quickly. High pressure is
building in from the west, but low level moisture is still in
place and is evident in time heights through the night. Think
western counties could see clearing that may not fill back in
since they`ve seen more sun through the day and are closer to the
high center, but elsewhere think anything that scatters over the
next couple of hours will fill back in later. Thus will go with
cloudy to mostly cloudy skies over much of the area through the
night, except perhaps the far western counties. Lows should run
around 32 to 34 given the cloud cover.


.SHORT TERM /Tuesday through Thursday/...

Issued at 313 PM EST Mon Nov 13 2017

High pressure crossing the area Tuesday should finally allow
clouds to scatter and skies to clear. Even so temperatures will
only warm to the upper 40s to lower 50s. Tuesday night warm
advection will start to ramp up and bring in chances for rain into
the western counties late. A cold front will move through the area
during the day on Wednesday and rain will be in place ahead of the
front, as well as some scattered showers in the wake of the
frontal passage. Considered addition of thunder for Wednesday, but
only NAM shows any instability (even elevated) over the area, and
highs barely make it into the 50s, so decided to leave out any
thunder mention at this time.

By Wednesday night, dry conditions will be filling in behind the
front, and temperatures should drop into the low 30s. Thursday
should see some sunshine but with cold advection highs will remain
in the upper 40s.


.LONG TERM /Thursday Night Through Monday/...

Issued at 224 PM EST Mon Nov 13 2017

ECMWF suggests a strong strong system moving through the Ohio
valley and Great lakes on Thursday night through Saturday morning.

A strong warm front will arrive ahead of a strong low pressure
pressure system. This will result in rain chances arriving late on
thursday night into Friday. Much of Friday will be spent within
the warm sector and the ECMWF and GFS suggest favorable
shear...but little in the way of instability and upper support.
However models do suggest ample moisture in the area. Thus we will
continue to go with a wet Friday...and watch for the potential for
severe weather also.

The associated strong cold front will pass on Saturday and this
will again require chances for precip. However as colder and drier
Canadian air arrives on Saturday night and Sunday. Dry and cold
weather should return for the end of the weekend and the start of
the next workweek.


.AVIATION /Discussion for the 04/06Z TAF Issuance/...

Issued at 1155 PM EST Mon Nov 13 2017

The main challenge for the TAF period will be the threat for fog
formation. Clearing has already commenced at the western TAF
sites, and MVFR fog is currently impacting KLAF and KIND but not
KHUF. Elsewhere, clouds have been slow to move out of KBMG, and
MVFR ceilings are still lingering. For now, will hold off on fog
mention at KHUF and KBMG, but these may need to be updated.
Elsewhere, will stick with MVFR fog at KHUF and KIND for now, too,
but that is a low confidence forecast. Would not be surprised if
there was a sudden drop to IFR or worse late in the night. After
the threat for any fog subsides, VFR will be the prevailing flight
category through the end of the TAF period. Meanwhile, winds will
be light and variable and conducive to fog formation.





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