Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 200811
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
312 AM EST Fri Jan 20 2017

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

&&

.SYNOPSIS...
Issued at 312 AM EST Fri Jan 20 2017

It will be mild with periodic shower chances through the middle of
next week. Then, more seasonable weather will return to the Ohio
valley late next week.

&&

.NEAR TERM /Today/...
Issued at 312 AM EST Fri Jan 20 2017

Solid area of showers was lifting northeast across the Ohio Valley
and Great Lakes overnight along and north of a warm front that
extended from southeastern Illinois to the Smokies to the Atlantic
Ocean. Aloft, a negatively-tilted trough was pivoting northeast
across the Missouri and Tennessee Valleys.

Models in good agreement that the upper trough will lift northeast
into the lower Great Lakes this afternoon as the warm front moves to
northern Indiana. As this occurs, model time rh sections are showing
nice drying above 850 millibars with precipitable water numbers
dropping to three quarters of an inch, down from 1 to 1.2 inches
overnight. Thus, rain will be ending from southwest to northeast
noon or earlier. Areas of fog will dissipate behind the warm front
this afternoon.

Upstream temperatures and low level thermal progs support mild highs
in the 50s per MOS blend despite thick clouds.

&&

.SHORT TERM /Tonight through Sunday night/...
Issued at 312 AM EST Fri Jan 20 2017

Precipitation chances and temperatures will continue to be the main
short term issues.

Models are handling the main synoptic features rather well this
weekend, so model blend is preferred. Yet another southwestern upper
system will rotate northeast tonight. However, this one will be a
bit further to the west than the previous ones and not have as much
moisture to work with. Thus, went with a slight chance of showers
tonight near and north of a Terre Haute to Evansville line. The
clouds will hang around tonight under an inversion per model rh time
sections and soundings. With thick clouds and mild low level thermal
progs, will go warmer than MOS blend with overnight temperatures
only dropping to the upper 40s to lower 50s.

Yet another southwestern upper low will move to the Texas and
Oklahoma panhandles late Saturday. An impulse or two will eject
northeast ahead of this feature across the Ohio Valley Saturday
afternoon and night. This could result in scattered showers and
possibly even a thunderstorm or two over south central Indiana.

Finally, this upper low will move east across the southern states
Sunday and Sunday night. Moisture and warmer temperatures will be
drawn north ahead of the low and bring more shower chances to the
area through the weekend along with afternoon highs in the upper 50s
and mid 60s on Saturday. Sunday will not be much cooler than
Saturday. Normal highs for this time of year are only in the mid 30s.

&&

.LONG TERM /Sunday night through Thursday/...
Issued at 146 PM EST Thu Jan 19 2017

An upper low will move across the southeast U.S. and then slowly
move up the east coast through the extended. NAM is a distinct
outlier in its treatment of the low early in the extended so
disregarded it. GFS/ECMWF in pretty good agreement and generally
used the Superblend without much deviation.

Temperatures will generally remain above normal through the period,
although not quite as far above as this weekend. This effectively
means all precipitation chances through the extended, with the
exception of the very end, are for rain. The pattern shows little
in the way of strong forcing until Tuesday night when an upper
wave and cold front move through. Otherwise small chances for rain
off and on through the end of the period with little shortwaves
moving through the flow.

Included some rain/snow mix late Wednesday night/early Thursday

&&

.AVIATION /Discussion for the 20/06Z TAFs/...
Issued at 1145 PM EST Thu Jan 19 2017

Flying conditions remain poor...IFR or worse...throughout the
night. Some modest improvement may occur Friday.

Ample low level moisture wil remain in place as low pressure passes
through the area tonight into Friday. Ceilings and visibilities will
likely remain poor in rain showers and fog...although fluctuations
are likely to occur.

Winds through the period will be less than 10KT...initially out of
the east much of the night, becoming southerly after warm frontal
passage late tonight into Friday morning.

Poor conditions appear likely to persist much of the period as a
strong low level inversion remains in place.

While isolated thunder cannot be ruled out, this probability is too
low for inclusion in the TAF.

&&

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

&&

$$

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



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