Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 080448
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1150 PM EST Wed Dec 7 2016

.UPDATE...

The Aviation section has been updated below.

&&

.SYNOPSIS...
Issued at 157 PM EST Wed Dec 7 2016

Winter pattern takes hold this period and intensifies next week.

First arctic air of the season arrives Thursday, possibly with a few
flurries.

All models in agreement with first widespread snow for
all of central Indiana late Saturday evening into midday Sunday.
Models diverge from there however, with amount of rain-snow mix
or complete changeover to rain Sunday afternoon in question. Thus
uncertainty in final snow amounts when precipitation finally ends
but at least an inch or more snowfall should occur before any
changeover.

Below normal temperatures and dry high pressure to follow this
weather system early next. By midweek a reinforcing and more
significant arctic blast arrives with light but measurable snows,
single digit low temperatures and subzero wind chills.

&&

.NEAR TERM /Tonight/...
Issued at 948 PM EST Wed Dec 7 2016

Going forecast is in excellent shape. Continue to see no
observations of precipitation in the vicinity with light echoes on
regional radar mosaics, as expected given substantial surface temp
dewpoint spreads. Previous discussion follows.

Issued at 157 PM EST Wed Dec 7 2016

A general increase in cloudiness is expected this evening
followed by some clearing late night as much drier arctic air
arrives. Radar is showing some weak echoes aloft but evaporation
in drier air below snow has prevented any from reaching the
ground. Will not include any flurries in the forecast but would
not rule out a few flakes from 20dbz echoes. Light snow back near
Kansas City is moving southeast and projected to weaken
overnight.

A mix of model temps still indicate min temps near 20.

&&

.SHORT TERM /Thursday through Saturday/...
Issued at 157 PM EST Wed Dec 7 2016

Models are close enough that the SuperBlend initialization
was accepted.

Thursday...wrap around deck of lower clouds across Great Lakes
impinges into our northern counties as afternoon wears on. Again
would not be surprised to see a few flakes from these clouds but
not enough to warrant a mention. Under cold advection and gusty
winds,do not expect much of a warm-up and thus current 25-30 max
temps forecast still appear pretty good.

Thursday night into Saturday...stayed with a model blend for
temperatures and weather. Wrap-around clouds exit Thursday night
as upper low departs and surface high pressure continues
building in. A weak wave in the flow brings some cloudiness late
Friday into early Saturday but column is too dry for any
precipitation to reach the surface. Clouds will thicken late
Saturday as snow-making system organizes in central Plains. Again
diverging solutions with the evolution of this system make final
outcome in the extended period uncertain.

Have stayed with a blend of model temperature solutions with lows
upper teens to lower 20s and highs 25 to near 30. Single digit
wind chills can be expected Thursday and Friday morning.

&&

.LONG TERM (Saturday night through Wednesday)...
Issued at 138 PM EST Wed Dec 7 2016

There is high confidence for the first significant snow of the
season Sunday into Monday. A major winter storms is possible, but
much less certain.

The models disagree about many features with this forecast. This
results in different predictions about snow timing and amount.
However no matter which model you believe, sometime from Sunday into
Monday there should be at least 1 to 3 inches. In the worst case
scenario, snowfall could be near 6 inches.

Even after Monday, there is a lot of uncertainty in this forecast as
different models have very different predictions. The blended
forecast from the regional initialization will be used because it
will minimize errors.

&&

.AVIATION /Discussion for the 08/06Z TAFs/...
Issued at 1150 PM EST Wed Dec 7 2016

VFR likely overnight and into tomorrow. MVFR ceilings may overspread
the northern three sites beginning Thursday afternoon.

Winds throughout the period will be northwesterly, generally 10KT or
less overnight. From mid morning on Thursday, expect gusts into the
low 20KT range.

No significant obstructions to visibility are anticipated during the
period.

&&

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

&&

$$

SYNOPSIS...TUCEK
NEAR TERM...TUCEK/NIELD
SHORT TERM...TUCEK
LONG TERM...JK
AVIATION...NIELD



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