Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 151940

Area Forecast Discussion
National Weather Service Indianapolis IN
240 PM EST Fri Dec 15 2017

The LONG TERM Section has been updated below.


Issued at 243 AM EST Fri Dec 15 2017

This period we will see a pattern change from the recent cold
troughing and frequent clipper systems to a milder ridging with
pieces of energy sweeping in from the southwest. Models are in
relatively good agreement with this shift. Below normal
temperatures of the past week will shift to above normal
starting Saturday and remaining so into next Friday.

The last of the clipper systems moves out of the Upper Great
Lakes today. One piece of upper energy in the southwest will eject
northeast to bring light rain to our area Sunday. A more
substantial trough will drop into the Plains Thursday and deepen
as it tracks into the Great Lakes Friday. All models lift this low
up to our northwest keeping us on the milder and showery side
late Thursday into Friday before a shift back to a colder pattern.


.NEAR TERM /This afternoon/...

Issued at 1008 AM EST Fri Dec 15 2017

Surface analysis late this morning shows strong low pressure over
the Great Lakes with cyclonic flow across Indiana. A ridge of
high pressure was found across Oklahoma and western Missouri.
GOES16 shows areas of stratus across Central Indiana as a upper
short wave was exiting the area. Surface flow was from the

Forecast soundings and time height sections across the area show
lower level saturation continuing over through the afternoon...and
giving the upstream satellite trends and the weak cyclonic
flow...this appears reasonable. Some breaks in the cloud will be
possible late this afternoon as the lower level flow becomes more
anticyclonic. Given the cloud cover have trended highs slightly
below the forecast builder blend.


.SHORT TERM /Tonight through Sunday night/...

Issued at 243 AM EST Fri Dec 15 2017

Tonight...will be dry with variable cloud cover as heights rise with
the upper trough lifting into New England and a surface
trough/warm front sets up to our northwest. With the periodic
cloud cover and light southwest wind...minimum temperatures will
be a category the middle 20s.

Saturday and Saturday night...continued southwest flow and the
surface boundary shifting further north in the Great Lakes will
result in sunnier skies for all areas by Saturday afternoon.
Temperatures top out from 45 to line with blended
guidance. Saturday night lows will be at or above freezing as
southwest winds continue and high clouds overspread the area after
midnight from the approaching system ejecting this way from the
southern Rockies.

Sunday and Sunday night...the upper trough dampens some as it moves
into the upper ridge over our area. Still, the moisture it pulls
northward will bring overcast skies Sunday. Light rain will also
overspread the area during the morning and continue into the
afternoon. The cloud cover and rain will hold back max
temperatures Sunday in the lower to middle 40s but that will
still feel mild compared to recent days. Rain amounts will be
less than a quarter inch.

Continued southwest flow Sunday night and dewpoints above freezing
will translate to minimal temperature drops Sunday night with
lows in the mid to upper 30s. Some light rain or drizzle will be
possible as more moisture transports into our area from a deep
trough in the southwest US.


.LONG TERM /Monday Night through Friday/...

Issued at 240 PM EST Fri Dec 15 2017

ECMWF keeps mainly high pressure in place from the upper midwest
across Indiana from Monday through Thursday. This will keep a
cool Northeasterly flow in place across the region for much of the
week. Meanwhile...a frontal boundary will be stalled out across
Kentucky and the Tennessee River Valley through Much of next week.
A low pressure system is expected to track along this boundary
from Tuesday Night through Thursday. At this time best moisture
and forcing looks to remains south of Indiana...and will keep the
forecast dry.

Best chance for precip in this period will be Friday as the
stalled boundary is pulled north into Indiana by and approaching
Low pressure system. Forecast builder has inserted mixed
precipitation chances for that time.


.AVIATION /Discussion for 15/18Z TAF Issuance/...

Issued at 1234 PM EST Fri Dec 15 2017

MVFR ceilings through 21Z, VFR after.

MVFR ceilings will slowly rise through the afternoon and become
VFR by late this evening as a trough exits the region. Winds will
gust at times during the afternoon today and will weaken after
sunset. Through the night winds will shift to become more




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