Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 161910
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
210 PM EST Thu Nov 16 2017

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

&&

.SYNOPSIS...
Issued at 210 PM EST Thu Nov 16 2017

High pressure is going to be over Indiana into Friday, with a
strong cold front expected to cross Friday night and Saturday.
High pressure is going to return by Sunday. Another cold front
should pass Indiana Tuesday. Wednesday and Thursday the Hoosier
state will be once again under high pressure.

&&

.NEAR TERM (Tonight and Friday)...

Issued at 210 PM EST Thu Nov 16 2017

High pressure is going to cause dry weather, except for a small
chance for showers in the northwest late Friday.

Clouds have been eroding in the southwest today. Once the sun goes
down, that area should be clear the rest of the night. While the
northeast should eventually clear, boundary layer moisture forecasts
suggest this will take time. Partly cloudy is a better forecast
there. The entire CWA is likely to see sun in the morning Friday,
with increasing clouds in the afternoon ahead of the next system.

Considering last nights lows and that there will be less cloudiness
tonight, a MOS consensus looks OK for lows. A MOS consensus also
looks good for highs Friday allowing for morning sun and rather
strong warm advection ahead of the approaching powerful system.

&&

.SHORT TERM (Friday night through Sunday)...

Issued at 210 PM EST Thu Nov 16 2017

There is good model agreement on the basic fields.

Confidence is high with the POPs. Showers are on tap Friday night
and Saturday.

Both the GFS and the NAM bring in a lot of CAPE aloft. Thunderstorms
may occur as soon as Friday night. It is likely we will see them
Saturday. With a very strong flow aloft, some storms could bring
gusty winds to the surface.

There is good confidence precipitation will end before midnight
Saturday. There is less confidence about what it will be as it ends.
Considering incoming temperatures, showers of either rain or snow
are possible. There is little or no chance of snow accumulation.

Despite model agreement, there is limited confidence with the
temperature forecast. Friday night and Saturday minor timing
differences with a strong front could make a big difference in highs
and lows. Errors of 6 degrees are possible. Potential errors drop to
4 degrees Saturday night and Sunday when the front will be to the
east.

The blend wind forecast for Saturday was adjusted upward.
Considering the blend often has a low bias, and the strength of the
pressure gradient, MOS winds were preferred.

&&

.LONG TERM /Sunday through Thursday/...

Issued at 245 AM EST Thu Nov 16 2017

Main pattern will remain west/northwesterly aloft and resulting in
dry conditions until towards the end of the period. Several mid/
upper level troughs will skirt eastward off to the north of the
forecast area mainly over the Great Lakes.

High pressure will be over the southern Plains eastward across the
southeast states efficiently blocking any low level moisture
northward. As that high moves off the southern Atlantic coast, a
dry southwesterly flow out of the southern and central Plains
will warm the area to near 50 across the southern parts of the
area before the next cold front drops in Tuesday afternoon.

Looks like the next chance for precipitation will not be until
early Thursday morning (Thanksgiving) as a frontal system comes
into the area with the chance for snow flurries/light rain.
Confidence is low at this time being so late in the period and
will have to see how this develops over the next several days.

&&

.AVIATION /Discussion for the 161800Z Tafs/...

Issued at 1226 PM EST Thu Nov 16 2017

MVFR Cigs are expected to improve to VFR Cigs leading to VFR
conditions late tonight and Friday.

High pressure over the middle Mississippi Valley will build east
across Indiana today. GOES16 shows abundant MVFR clouds across
Illinois and Indiana. There has been little improvement in
clearing as mid level ridging remains to the west. Thus will keep
the clouds lingering this afternoon until this anticyclonic
feature arrives this evening. Daytime heating may provide some
brief breaks of MVFR later this afternoon.

Forecast soundings and Time heights go dry tonight as the ridge
arrives...supporting the current forecast thinking.


&&

.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SYNOPSIS...JK
NEAR TERM...JK
SHORT TERM...JK
LONG TERM....DM
AVIATION...JP



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