000
FXUS63 KIND 021947
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
245 PM EST Wed Dec 2 2020

.UPDATE...
The LONG TERM Section has been updated below.

&&

.SYNOPSIS...
Issued at 211 PM EST Wed Dec 2 2020

Dry weather is expected tonight as high pressure over Kentucky and
Tennessee departs the area to the northeast. Dry and cold air in
place across Central Indiana associated with this high will keep
skies clear across Indiana tonight.

Low pressure over the southern plains is expected to push to
through the Tennessee River Valley on Thursday through
Friday...before reaching the middle Atlantic States by Saturday.
This will bring dry weather through the weekend.

Dry weather with near normal temperatures are expected for much of
next week.

&&

.NEAR TERM /Tonight/...

Issued at 211 PM EST Wed Dec 2 2020

Surface analysis early this afternoon shows high pressure in
place across KY with a surface ridge extending NW across IL to IA.
Low pressure was in place across TX/OK. Light NW surface flow was
in place across Indiana...with temps in the upper 30s and lower
40s. GOES16 shows high CI cloud streaming across the area. The
upper flow shown in the water vapor imagery shows a deep low in
place across TX and the SW states. Another upper low was found
over Quebec. Indiana was caught between these two systems with
weak ridging in place aloft.

Models tonight suggest a slow progression of the surface high to
the east while surface low pressure lingers across the Southern
Mississippi River Valley. Aloft...the GFS and NAM suggest the
upper low to the SW making little progress east as our weak
ridging in place slows its progress. No forcing is seen overnight.
Forecast soundings and Time heights show a dry column with
subsidence. Thus will trend toward a dry forecast overnight with
mostly clear skies. Given these ideal radiational cooling
conditions along with dew points in the teens across the
area...will trend overnight lows at or below the NBM.

&&

.SHORT TERM /Thursday through Saturday/...

Issued at 211 PM EST Wed Dec 2 2020

Models keep broad cyclonic flow in place aloft over the
northeastern United States and Ohio Valley through the period.
The upper low to the southwest is finally pushes east by
Friday...and absorbed somewhat by the broader upper flow. The
associated surface low with this feature passes through the gulf
states before reaching the Carolinas and NYC area by Saturday.
This southerly path of the system will keep Indiana on the cold
and dry side of the system...with mainly just some clouds expected
to arrive and pass. Time heights show the arrival of some clouds
with the system on Thursday night. Forecast soundings also show
some saturation at that time. Thus will trend toward increasing
clouds on Thursday and Mostly cloudy on Thursday Night.

As the cyclonic lower level flow continues on Friday
morning...forecast soundings continue to reveal saturation within
the lowest levels of the column...a trapped strato-cu deck.
However By Friday afternoon through Saturday subsidence wins out
as the column dries out due to cool and dry northerly flow on the
NW side of the low. Thus will trend toward decreasing cloudiness
for Friday with Mostly sunny skies on Saturday. Given the minimal
temperature advection...will trend temps close to the NBM.

&&

.LONG TERM /Saturday Night through Wednesday/...
Issued at 245 PM EST Wed Dec 2 2020

Models having issues coming to a consensus regarding timing and
strength of individual disturbances set to pass over or nearby
central Indiana late this weekend. The first one of these waves will
move from the Missouri Valley to near a Chicago to St. Louis line
Saturday night. After that, the models diverge, with the 12z GFS by
far the most aggressive, pushing it across central Indiana Sunday.
The others, especially the 12z Canadian, hold it further west with a
Great Lakes disturbance diving down south over the area Sunday
night.

Lack of moisture with these disturbances expected to keep the threat
of impactful weather low. In fact, the model blend came in with PoPs
below 10% over the period. After coordinating with adjacent offices
left PoPs out through Sunday night, although confidence is low. With
the two disturbances moving through a mean trough over us or nearby,
can not rule out eventually adding PoPs to the late weekend, the
close we get.

Model thickness and BUFKIT soundings suggest precipitation type be
mostly snow except for perhaps Sunday afternoon as low levels warm
well above freezing.

After that, another weak wave in northwest flow will move through
the area or nearby on Tuesday. However, again, moisture is lacking,
so will keep it dry for now through the entire long term.

Model thermals support slightly below normal temperatures to start
off but west or southwest winds hint at a modest warmup by the
middle of the week with afternoon highs in the upper 30s and lower
40s Sunday warming the middle and upper 40s by next Wednesday.

&&

.AVIATION /Discussion for the 021800Z IND TAF Issuance/...
Issued at 1200 PM EST Thu Dec 3 2020

IMPACTS: No impacts expected.

DISCUSSION: Very dry column below cirrus level and under the
influence of surface high pressure will lead to VFR conditions with
just some passing cirrus through tonight. After 12z Thursday, will
see an increase in cirrus and perhaps mid level clouds ahead of a
southern Plains system.

Winds 230-270 degrees up to 7 knots through 22z. Then, calm or very
light southwest winds through 15z or so Thursday and then southwest
winds to 6 knots Thursday afternoon.

CONFIDENCE: High confidence in VFR conditions. High confidence in
wind trends.


&&

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

$$

SYNOPSIS...Puma
NEAR TERM...Puma
SHORT TERM...Puma
LONG TERM....MK
AVIATION...MK