Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 010743

Area Forecast Discussion
National Weather Service Indianapolis IN
243 AM EST Thu Dec 1 2016

The SYNOPSIS...NEAR TERM and SHORT TERM Sections have been updated


Issued at 239 AM EST Thu Dec 1 2016

High pressure is expected across the area through the end of the
week. A weak upper trough is expected to move across the area around
Sunday. A low pressure system may affect the area around next


.NEAR TERM /Today/...
Issued at 239 AM EST Thu Dec 1 2016

Been some sprinkles and flurries across the area, probably
associated with a vorticity lobe currently pushing through northern
Indiana and southern Michigan. Short term models suggest this
feature will pass off to the east by sunrise, so any lingering
light precipitation expected to end by that time.

Otherwise, quite a bit of cloud cover expected today, especially
over the northern zones, as an 850mb cold pocket holds over the
Great Lakes.

Low level thicknesses suggest the GFS MOS highs for today look


.SHORT TERM /Tonight through Saturday night/...
Issued at 239 AM EST Thu Dec 1 2016

Dry weather expected for most of this period as upper low over the
Great Lakes gradually shears out to the east, leaving a split flow
in its wake. At the surface, high pressure will build into the area
by the weekend.

The 850mb cold pocket looks like it will hold over the Great Lakes
until around Saturday, before lifting off to the northeast. As a
result, it may be until Friday night before significant clearing
takes place, especially over the northern zones.

By Saturday night, models suggest an upper trough in the northern
stream may approach the area from the west. At this time, it appears
main precipitation threat from this system will be after this
forecast period. Will bring in some small chance PoPs for light
mixed precipitation late Saturday night over the far southwest zones.

Progged low level thicknesses and expected cloud cover suggest the
GFS MOS highs for the next couple of days are probably too warm.
Will cut about 2-5 degrees off of the guidance highs Friday and
Saturday. Guidance lows look OK for now.


.LONG TERM (Sunday through Thursday)...
Issued at 224 AM EST Thu Dec 1 2016

Significant model discrepancies exist regarding handling of multiple
systems expected to impact central Indiana during the long term
portion of the forecast, which may have a major impact on
precipitation types and timing. See little reason to make
significant deviations from blended initialization as a result.

At least 3 separate systems look poised to bring at least a chance
of precipitation to the area during the week, with low level
thermals borderline for a few snowflakes at times.


.AVIATION (Discussion for 010600Z TAF Issuance)...
Issued at 1142 PM EST Wed Nov 30 2016

The SREF and GFS LAMP favor ceilings returning to VFR until after
12z. Then, they bring back good chances of MVFR to all but BMG 12z-
15z. Having said that, observational trends suggest ceilings will
continue to be around the border of VFR and MVFR. So, confidence is
not great with ceiling Category or timing through Thursday night.
Will have to take a last second look to determine which way to go
for the first few hours but generally will go with the models.

Winds will be west 8 to 12 knots through the period with gusty winds
possible to near 20 knots at LAF, where the pressure gradient was
slightly tighter.




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