Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 211812

Area Forecast Discussion
National Weather Service Indianapolis IN
212 PM EDT Wed Mar 21 2018

The AVIATION Section has been updated below.


Issued at 358 AM EDT Wed Mar 21 2018

Snow will move out of the area later this morning and then expect
dry conditions as high pressure quickly moves through. More
chances for precipitation return for the weekend, with some
potential for a wintry mix and some snow Friday night. Saturday
could see some rain in the afternoon before changing back to snow
Saturday night before dry weather comes in for Sunday.
Temperatures should warm back to near normal to start the work


.NEAR TERM /This afternoon/...

Issued at 929 AM EDT Wed Mar 21 2018

Surface analysis late this morning shows Low pressure in place
across Virginia...with cyclonic flow in place across Central
Indiana. Radar shows back-side wrap-around snow fall across the
eastern 1/2 of the forecast area. Cold Northerly surface flow was
in place across the forecast area.

Models suggest the low pressure system will continue to progress
eastward this afternoon...taking the associated wrap around snow
bands with it. In the meantime...snow will likely continue late
this morning across Eastern parts of the forecast area before
beginning to diminish from west to east as the Low moves away.
HRRR radar trends also suggest this...showing the snow bands
exiting the area by 17Z-18Z. Up to an additional inch will be
possible across the eastern parts of the forecast area. Time
Heights keep cloud cover in place across much of the forecast
area...showing saturation within the lower levels. Thus a trend
toward mainly cloudy skies will be expected through the afternoon.
With cool north flow and precipitation in place...we trended high
temperatures at or below the forecast builder blends.


.SHORT TERM /Tonight through Friday Night/...

Issued at 358 AM EDT Wed Mar 21 2018

Tonight skies will clear across central Indiana and this will allow
temperatures to drop into the low to mid 20s, with the lower 20s
occurring over eastern Indiana where snow cover will be in place.
Thursday temperatures will slowly warm with highs in the low 50s
southwest to low 40s northeast. A weak upper wave and a surface
warm front will start to approach central Indiana and bring low
chances for precipitation in the southwest overnight Thursday, but
forcing and moisture with this wave are weak so probabilities
will remain low.

Friday afternoon the warm front will get a bit closer and bring a
small chance into the southwest counties. The front enters the
area Friday night and an upper wave will interact with it,
providing better forcing and thus much higher probabilities for
initially rain but then transitioning to a wintry mix and then
snow during the overnight hours. At this time around an inch of
snow looks possible in parts of central Indiana, and light icing
is possible as well. Confidence regarding exact precip type late
Friday night is low considering the marginal sounding profiles.


.LONG TERM /Saturday Night through Wednesday/...
Issued at 212 AM EDT Wed Mar 21 2018

ECMWF suggests the rain/snow system will departing the area on
Saturday night as a short wave and associated surface low drifts
southeast of Indiana. This should bring precip to an end on
Saturday Night as dry air returns to the column on northeast
winds. Confidence for precip on Saturday and early Saturday
evening remains high...but confidence on precipitation type is
low. Again a sharp cut-off looks to exist between rain and snow

Sunday Night and Monday look dry as ridging remains in place
across the area. However more wet weather looks to return on
Monday night through Wednesday as the ECMWF suggests several short
waves pushing into the Ohio Valley ahead of a deeper low over the
western plains. ECMWF suggests ample moisture accompanying these
waves...along with the arrival of a warm front on Tuesday and a
surface low on Wednesday. Thus forecast builders suggestion of
pops during this period seems reasonable.


.AVIATION /Discussion for the 211800Z Tafs/...

Issued at 1238 PM EDT Wed Mar 21 2018

Improvement toward VFR Conditions is expected at the TAF sites
within the first 1-2 hours of issuance.

Low pressure over the Virginias is expected to continue to slide
east and exit the area. Cyclonic flow will remain across
Indiana...and some clouds will linger...particularly across the
east...but a gradual trend toward unlimited CIGs is expected.
Tonight...High pressure amid NW flow will begin to arrive. Models
show forecast soundings and time heights trending toward a dry
column. This is expected to persist into Thursday. Thus...trending
toward VFR conditions with NW flow will continue to be expected.





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