Area Forecast Discussion
Issued by NWS Indianapolis, IN

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369
FXUS63 KIND 110736
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
236 AM EST Mon Dec 11 2017

.UPDATE...
The LONG TERM Section has been updated below.

&&

.SYNOPSIS...
Issued at 311 PM EST Sun Dec 10 2017

Dry conditions will prevail tonight, but another quick upper low
will bring snow showers to portions of central Indiana tomorrow
evening and night.  Further out, additional upper waves will
continue to rotate through the area in the wake of the main upper
trough. So, additional chances for snow showers (N) and rain/snow
showers (S) will be possible Thursday, and then rain showers on
Saturday.  Meanwhile, temperatures through the period will
generally be below normal for the short term period, then near
normal in the extended period.

&&

.NEAR TERM /Tonight/...
Issued at 635 PM EST Sun Dec 10 2017

With little cloud cover expected tonight and winds becoming light to
calm, lowered overnight lows a coouple of degrees. This also matched
better adjacent offices. One caveat would be if the low clouds
overning northern Indiana make it into our northern counties. If so,
temperatures will have a hard time reaching forecasted lows.

Previous discussion follows...
Issued at 311 PM EST Sun Dec 10 2017

Ridging will strengthen at the surface tonight in the wake of
today`s surface trough. As a result, it will be a mostly clear
and cold night with temperatures plummeting into the low to mid
20s. Nonetheless, clouds will start to increase a bit over the
northern half of the forecast area though by daybreak as the next
upper level low approaches the region.

&&

.SHORT TERM /Tomorrow through Wednesday/...

Issued at 311 PM EST Sun Dec 10 2017

The main focus of the short term period will be snow showers with
a quick upper low on Monday evening and night.

Time cross sections indicate best upward vertical velocity during
the Tue 03-09Z time frame over the northern half of central
Indiana with aforementioned upper low. The environment is now
conducive to an all snow event, but limited moisture will result
in little to no snow accumulation.

Light snow showers will linger across the northeastern counties
into Tuesday as an additional upper wave clips northwest Indiana.
However, dry conditions will then prevail from that point on with
weak ridging aloft. Meanwhile, temperatures through the period
will generally be below normal, especially on Tuesday when a surge
of colder air keeps high temperatures in the mid 20s to low 30s.

&&

.LONG TERM /Thursday through Sunday/...
Issued at 235 AM EST Mon Dec 11 2017

Ensembles in good agreement with the overall pattern during this
period. Long wave troughing over the eastern parts of the country
is expected to move off to the east, with the flow becoming more
zonal by the end of the week.

A short wave trough is expected to pass over the Great Lakes
around Thursday. Will go with small chance PoPs for mixed
precipitation on Thursday, mainly over the northern zones.

The rest of the extended looks dry at this time as heights rise
with the lifting out of the long wave trough. Ensembles suggest
the next system probably won`t affect the area until after this
period.

&&

.AVIATION /Discussion for the 11/06Z TAF Issuance/...
Issued at 1138 PM EST Sun Dec 10 2017

Good confidence in VFR conditions through most of the TAF period.
However, the SREF and GFS LAMP suggest there could be some MVFR
stratocu in the wake of another cold front after 05z.

Winds will be light to calm overnight. Then winds will veer from
south to northwest 10 knots or less in the wake of the late night
cold front. Winds will pick up at IND toward 12z Tuesday, however.

&&

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

$$

SYNOPSIS...TDUD
NEAR TERM...TDUD/MK
SHORT TERM...TDUD
LONG TERM....JAS
AVIATION...MK



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