Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 180717
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
217 AM EST Wed Jan 18 2017

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

&&

.SYNOPSIS...
Issued at 216 AM EST Wed Jan 18 2017

High pressure over Missouri will push east across the Ohio Valley
today and tonight. This will result in dry weather today and
tonight across Central Indiana...with above normal temperatures.

By Thursday afternoon...the High pressure systems will have
exited to the east while a Low pressure system and warm front approach
the Wabash Valley from the southwest. This will bring yet another
shot of warm air to central Indiana along with showers and perhaps
a Thunderstorm Thursday night into Friday morning.

As the low departs to the north on Friday...Warm southerly winds
are expected to provide well above normal temperatures...with
mostly cloudy skies.

More Active weather with above normal temperatures look in store
for the weekend as quick southwest flow in place aloft pushes
several upper level weather disturbances across the Ohio Valley.

&&

.NEAR TERM /Today/...

Issued at 216 AM EST Wed Jan 18 2017

Surface Analysis early this morning shows high pressure in place
over Missouri. IR Images show extensive cloudiness on the north
side of the high...stretching from Indiana to Western Missouri.
Water Vapor Imagery shows a quick SW flow in place with a
tropical plume surging across eastern texas into the Tennessee
Valley. A quick moving short wave over over NE Indiana...exiting
rapidly.

Main forecast challenge today will be clouds. The high pressure
system is expected to build across Indiana today and tonight.
Ridging aloft is expected also. Furthermore...forecast soundings
show a very dry column as do the Time height sections. Both
suggest however that lower level saturation will linger across the
area through the day. Thus given the latest satellite trends will
keep much of the day cloudy...but trend toward a few peaks of sun
late in the day as the High builds along with subsidence in the
column. Given the expected clouds will keep temps close or
slightly below superblend.

&&

.SHORT TERM /Tonight through Friday night/...

Issued at 216 AM EST Wed Jan 18 2017

Quiet weather is expected to continue tonight as the models
suggest the surface high and ridging aloft pushing across the
state. Again...time heights and forecast soundings suggesting a
dry column and will expect some clearing as forecast soundings
show breaks in the lower level saturation. Thus partly cloudy
should work with a blend on Temps.

On Thursday...the high will be departing to the east along with
the ridging aloft. Meanwhile the models suggest a deep upper low
developing across the Central Plains and pushing an embedded short
wave toward the Ohio Valley within the SW flow aloft. Forecast
soundings quickly become saturated by late Thursday afternoon.
Meanwhile the GFS shows excellent isentropic lift on the 295K GFS
surface...with specific humidities surging to Over 8 g/kg into
Thursday Night. Furthermore Time Heights show a deeply Saturated column
with strong lift as this negatively tilted short wave approaches.
Thus will ramp up pops this Thursday afternoon and Thursday Night
as these dynamics pass. Forecast soundings only show elevated
convection possible...thus a rumble of thunder cannot be ruled out
but TStorms are not expected to be widespread. Will trend Highs on
Thursday at or above a blend given the very strong warm air
advection...and trend Thursday night lows toward expected
wetbulbs.

On Friday and Friday Night...the GFS and NAM suggest progressive
SW in place aloft...but little arriving in the way of forcing.
Forecast soundings suggest a mainly dry column Friday and Friday
Night...but do keep some lingering lower level moisture in place
trapped beneath a weak inversion. Meanwhile strong warm air
advection will be in place on Friday and Friday Night with 850mb
Temps surging toward spring like values of 7-8C. Thus given the
warm air and gulf flow...expect some clouds from time to time.
Partly Sunny to Mostly cloudy should work fine. Again given the
warm air advection will stick close or slightly above superblend
on Highs and lows.

&&

.LONG TERM /Friday night Through Monday night/...
Issued at 141 PM EST Tue Jan 17 2017

Well above normal temperatures and period rain showers will be
featured this weekend and early next week. Models are in pretty good
agreement on the overall synoptic features, so regional blend
looks good.

Negatively-tilted upper trough will be over the lower Great Lakes
Friday night, and a trailing upper low will lift north over the
Plains, well west of the forecast area. This should result in mostly
dry weather over central Indiana through Saturday. Still, would not
rule out a stray shower or two Saturday with good return flow and
impulses in southwest flow aloft. After that, a strong southern
Plains upper low will lift northeast across the Ohio Valley on
Monday. This will bring more shower chances to the area starting
Saturday night. Activity will be widespread over some locales by
Sunday and start to decrease in coverage Monday night in the wake of
the system.

&&

.AVIATION /Discussion for the 18/06Z TAFs/...
Issued at 1145 PM EST Tue Jan 17 2017

Ceilings will likely remain near the IFR/MVFR borderline much of the
night into Wednesday morning. Some drizzle can be expected at times
during the night.

Conditions will likely improve late morning into early afternoon
tomorrow across the area, with a return to VFR expected around 18-
20Z.

Winds will generally be out of the west from 250-280 around 5-11KT
throughout the period.

Brief periods of slightly reduced visibilities in patchy fog
cannot be entirely ruled out.


&&

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

$$

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



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