Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 250745

Area Forecast Discussion
National Weather Service Indianapolis IN
245 AM EST Sat Feb 25 2017

The LONG TERM section has been updated below.


Issued at 348 PM EST Fri Feb 24 2017

A strong cold front will seep across the Ohio Valley this evening
bringing thunderstorms and the threat for severe weather. Much
colder air will expand into the area behind the front overnight and
into the weekend with scattered snow showers on Saturday. After a
dry Sunday...unsettled weather will return for the first half of
next week along with warmer temperatures.


.NEAR TERM /Rest of Tonight/...
Issued at 1000 PM EST Fri Feb 24 2017

Showers will end most areas by midnight as cold front moves
on to the east.   Satellite indicated band of temporary
clearing across Illinois will push east across central Indiana
later tonight and then wrap around clouds over the upper midwest
will spread back in late tonight.   Lowered temperatures slightly
over western sections....otherwise current forecast is on track.

Temps by 12Z Saturday will be in the upper 20s to lower 30s...a
solid 40 degree drop from highs Friday.


.SHORT TERM /Saturday through Sunday Night/...
Issued at 348 PM EST Fri Feb 24 2017

After our late February spring preview...winter returns abruptly for
the weekend. Forecast challenges focus on precip chances Saturday in
the wraparound moisture behind the departing low...and temperatures
throughout the weekend.

The low pressure will continue to lift out to the north-northeast
through the Great Lakes on Saturday as colder air continues to flood
the Midwest in its wake. Wraparound moisture pool in the vicinity of
the upper low will lift across the region through the first half of
the day Saturday. Deeper moisture over the northern half of the
forecast area with scattered light snow showers expected through
early afternoon. Not expecting any accums as ground temps remain far
too warm to support. Moisture will remain trapped beneath an
inversion for much of the day and with the addition of cold
advection...skies will remain mostly cloudy for much of the day with
improvements by late afternoon as drier air builds in from the west.
Gusty west-northwest winds will continue all day with the tight
pressure gradient across the region.

With the departure of the upper low off to the northeast by Saturday
evening...the rest of the short term will be quiet and cold as high
pressure  passing through the Tennessee Valley becomes the primary
influence for central Indiana. Expect skies to become mostly clear
Saturday night and remain that way for much of the day Sunday as
surface ridging passes through. Winds will finally relax Saturday
evening as well. Will start to see increasing clouds late Sunday
along with an uptick in winds as return flow develops on the back
side of the ridge and moisture advects into the Ohio Valley ahead of
the next storm system. Any precipitation though will hold off until
after dark Sunday.

Temps...coldest temperatures in over 2 weeks for most of the region
as temps remain in the 30s on Saturday then recover somewhat into
the 40s on Sunday as warm advection commences later in the day. An
overall model blend looked quite reasonable for high temps. Lows
will fall into the lower and middle 20s Saturday night...the coldest
night since February 13th.


.LONG TERM /Monday through Friday/...
Issued at 245 AM EST Sat Feb 25 2017

Forecast confidence will start off good as models agree that a cold
front will move east across central Indiana Wednesday. Deep moisture
advected in off the Gulf ahead of the system, along with waves
moving along the front, suggest high pops per the Superblend are a
good bet. In addition, operational 00z GFS and ECMWF both have
decent instability Tuesday through Wednesday. So, have thunder in
the grids in that time period. Kept shower chances in through
Wednesday night, as a trailing upper trough moves through. Could see
some snow mix in overnight across our northern counties as the
roller coaster weather continues.

Less confidence the remainder of the long term as models handle the
next system differently. The 00z has a well defined frontal system
moving through the area Thursday night. The 00z ECMWF has much less
of a surface reflection. However, both have an cyclonic flow over
the area, so small superblend pops are justified Thursday night.
Left small pops in the extreme northeast Friday morning as the
system moves out. Could once again see some snow mix in, mainly over
the northeastern half. Accumulation is not expected at this time.

Superblend looks to be handling the temperature trends well, so no
reason to make any changes. Highs could once again reach the 60s on
Monday with highs in the 40s to follow late week.


.AVIATION /Discussion for 25060Z KIND TAF Issuance/...
Issued at 1140 PM EST Fri Feb 24 2017

MVFR ceilings at times late tonight and Saturday morning.

Strong low pressure centered over lake Huron will move to the
northeast as high pressure over the central plains moves to
Tennessee by Saturday evening.

A dry slot was spreading east across the Ohio valley and may
cause clouds to scatter out for a few hours central and south
sections.  Wrap around clouds over the middle and upper Mississippi
valley will push across central Indiana towards morning and scattered
sprinkles or flurries are possible over northern sections.  Main
impact will be a period of MVFR ceilings.   These clouds will
break up late Saturday as high pressure builds eastward.

West winds up to 15 knots and gusts up to 25 knots will occur
overnight and Saturday.  Winds will decrease to 10 to 15 knots
Saturday evening and 8 knots or less by end of forecast period.





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