Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 092302
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
602 PM EST Fri Dec 9 2016

.UPDATE...

The Near Term and Aviation section has been updated below.

&&

.SYNOPSIS...
Issued at 241 PM EST Fri Dec 9 2016

High pressure over the Missouri Valley will build in across central
Indiana tonight and Saturday and result in dry and cold weather.
However, that will be short lived as a southern Plains system is
expected to bring a variety of winter weather to central Indiana
Saturday night through Monday.

Two more quick moving systems next week will bring light snow to the
area and reinforce the cold air.

&&

.NEAR TERM /Today and Saturday/...
Issued at 602 PM EST Fri Dec 9 2016

Will add a flurries mention for the first few hours of the evening.
HRRR shows a shallow saturated dendritic growth zone...similar to
but much shallower and shorter lived than last night. Remainder of
forecast in good shape. Previous discussion follows.

Issued at 241 PM EST Fri Dec 9 2016

Models in good agreement that strong high pressure over the Missouri
Valley will build in across central Indiana tonight. Model rh time
sections, soundings, low level rh progs and satellite trends all
favor keeping plenty of stratocu around tonight. In addition, winds
will become light. This suggests temperatures will not drop too much
tonight, so will go a few degrees above MOS with lows in the upper
teens and lower 20s.

With high pressure starting off over top of central Indiana,
Saturday should be dry. As the high moves off to Appalachia Saturday
afternoon, should see the low clouds depart but AC increase as
isentropic lift commences. Could see a few breaks in the cloud
cover. Plus, low level flow will become southwest. This should allow
temperatures to warm back up to the upper 20s and lower 30s or near
a MOS blend.

&&

.SHORT TERM /Saturday night through Monday/...
Issued at 241 PM EST Fri Dec 9 2016

Main challenge for the short term will be precipitation type,
amounts and timing as a low pressure system lifts northeast over the
region Sunday night.

Models in much agreement that a Rockies system will strengthen over
the Texas and Oklahoma panhandles by 12z Sunday and then lift
northeast to Lake Huron by 12z Monday. As it does it will drag a
cold front across central Indiana overnight Sunday night. This
system is expected to bring a variety of winter weather to central
Indiana starting Saturday night with far northern sections expecting
to see a few inches of snow and the south to see mainly rain. Warm
advection will start gearing up Saturday night ahead of the
aforementioned system and in the wake of departing high pressure.
The GFS was the one model that may be too quick to saturate the
column as seen in low condensation pressure deficits Saturday
evening. Prefer blend of the other short term models that are slower
to moisten things up. At any rate, can not rule out some light snow
north of Interstate 70 Saturday night. Small chance pops look good
there.

By Sunday, isentropic lifts really gets going, and the atmosphere
quickly saturates down. 140 plus upper jet will move across southern
lower Michigan, enhancing the lift. Precipitation will become
widespread Sunday afternoon and night before the precipitation ends
Monday morning in the wake of the cold front.

Precipitation should start off as snow Saturday night and Sunday
morning and gradually transition to a mix of freezing rain, sleet
and rain from south to north. By 00z Monday, it should be rain over
all but extreme northern parts of the forecast area, where some snow
and sleet could mix in. Finally, the precipitation will exit
Randolph county Monday morning before ending.

Snow totals could reach 3 plus inches in the Kokomo and Delphi areas
by Monday morning and quickly drop off to an inch or less from
Indianapolis to the south. Total ice accumulation is expected to be
less than a tenth of an inch.

With models continuing their warming trends, not confident we will
see enough snow or ice to warrant a Winter Storm Watch at this
point. Watches from adjacent offices are also north of our border
counties.

&&

.LONG TERM /Monday night through Friday/...
Issued at 214 PM EST Fri Dec 9 2016

The long term pattern looks somewhat active with mostly zonal flow
across the area. For Tuesday into Wednesday central Indiana is
pinched between building high pressure from the northwest and a
surface low moving northeast out of the Gulf. Latest ECMWF and GFS
keep an qpf out of the area until Wednesday and removed some pops
in the southwest from midday Tuesday through some of the overnight
considering that and collaboration. See some potential for a rain
snow mix in the south at onset, if any precip occurs Tuesday
evening. On Wednesday an upper wave will move through as well, and
see some chances for snow with this. Fairly dry as far as moisture
is concerned so pops are midrange at best. Temperatures will drop
pretty rapidly with northwesterly winds and cold Canadian air
spilling down of the back side of the large upper low moving east
across Ontario. Wind chills in the single digits Wednesday morning
and below zero Wednesday night, Thursday morning and possibly
Friday morning.

&&

.AVIATION /Discussion for the 10/00Z TAFs/...
Issued at 602 PM EST Fri Dec 9 2016

Mainly VFR through the period, although some brief MVFR ceilings
will be possible at times early in the period as ceilings are within
a few hundred feet of the borderline.

Winds will generally be less than 10kt through the period, remaining
northwesterly overnight, and then backing to southeasterly by the
end of the period.

No significant obstructions to visiblity are expected through the
period.

&&

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

&&

$$

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



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