Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 161941
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
241 PM EST Tue Jan 16 2018

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

&&

.SYNOPSIS...
Issued at 240 PM EST Tue Jan 16 2018

Cold and dry winter weather is expected to slow transition warmer
temperatures later this week. Strong High pressure over the
Central Plains is expected to drift southeast to the deep south by
Friday. This will allow a southwesterly flow of warmer air to
arrive with by Friday.

The next chance for precipitation will be Sunday and Monday...
when a frontal system will bring rain to the area.
A mix with snowflakes is possible by Monday.

&&

.NEAR TERM /Tonight/...

Issued at 240 PM EST Tue Jan 16 2018

Surface analysis early this afternoon shows strong high pressure
in place across the Central PLains. This was resulting in a cold
northerly flow of air to Central Indiana. A very cold air mass
remained in place across the area with temperatures mainly in the
single digits. GOES16 shows mainly some high cloud in place across
Illinois and Indiana...along with some lake clouds drifting off of
Lake Michigan in NW Indiana.

Time height sections across the area shows a mostly dry column
tonight with some saturation within lower levels. Subsidence
appears to be present within the column through the period.
Aloft...lee side ridging on the broad ridge in place over the
western United States continues to provide cold NW flow aloft
along with dry air.

GFS continues to hint at the dome of cold air remaining over
Central Indiana tonight as 850mb temps remain around -15C
overnight. Thus will again trend lows at or below the forecast
builder blend, Given the thin cloud cover across the area will
trend skies toward partly cloudy.

&&

.SHORT TERM /Tonight through Friday/...

Issued at 240 PM EST Tue Jan 16 2018

Quiet weather is expected to persist through Friday. GFS and NAM
finally shows the dome of cold air beginning to exit the area on
Wednesday as 850mb temps begin a ridge toward -4c by 00Z Thursday.
Meanwhile at the surface...the arctic surface high begins to push
southeast to the deep south and the lower level flow responds by
becoming more southwesterly. Time heights respond with slightly
more cloud cover within the mid levels on Wednesday. By Thursday
and Friday the upper flow reveals more weak ridging aloft while
mainly a zonal flow of Pacific air persists within the lower
levels. Forecast soundings through the period fail to show much
in the way of saturation...thus will mainly trend toward a partly
cloudy sky during this period. Furthermore with the gradual warm
air advection through the period will trend temps at or above the
forecast builder blend.

&&

.LONG TERM /Friday Night through Tuesday/...
Issued at 240 PM EST Tue Jan 16 2018

The long term portion of the forecast will be significantly warmer
as the west coast ridge breaks down and shifts eastward across the
country. This will allow a trailing trough axis to push into the
Rockies Saturday and induce cyclogenesis in the lee of the Rockies.
Warm advection and isentropic lift out ahead of this developing low
will necessitate low pops for rain showers early in the weekend,
with chances increasing late in the weekend into early next week as
a well developed low pressure system pushes northeast through the
Great Lakes and drags a cold front through the area. The vast
majority of precipitation with this system will fall as rain,
although it may turn just cold enough with the wrap around
precipitation behind the cold front for a few snow flurries.

Blended initialization handled things well and few significant
changes were required.

&&

.AVIATION /Discussion for the 16/18Z TAFs/...
Issued at 1208 PM EST Tue Jan 16 2018

MVFR likely much of the period.

MVFR ceilings with brief forays up into low end VFR will likely
persist much of the period as an upper trough axis moves through
the area. Cannot rule out a few flurries or snow showers,
particularly at LAF where lake enhancement is adding to the
situation. Will carry an explicit mention at LAF and leave out
elsewhere for now.

Winds through the period will become more northwesterly with time,
generally 8-11KT or less.


&&

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

$$

SYNOPSIS...Puma
NEAR TERM...Puma
SHORT TERM...Puma
LONG TERM...Nield
AVIATION...Nield



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