Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 200230
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
930 PM EST Sun Nov 19 2017

.UPDATE...

The Near Term section has been updated below.

&&

.SYNOPSIS...
Issued at 235 PM EST Sun Nov 19 2017

High pressure will keep most of the next 7 days dry. However, a
frontal system will bring a chance for showers to the area Friday
night and Saturday.  Temperatures will be near to below normal
through the Thanksgiving weekend.

&&

.NEAR TERM.../Tonight/
Issued at 930 PM EST Sun Nov 19 2017

Temperatures at 02Z were already at or slightly below prior min
temp forecast, particularly in the LAF and IND areas. While near
term models do show some weak low level warm advection as the high
approaches and winds turn more southerly, dewpoints are well into
the low 20s and winds, while not calm, remain relatively light
overnight. Thus, expect more radiational cooling and will adjust
min temps down 1-4 degrees depending on location. Previous
discussion follows.

Issued at 235 PM EST Sun Nov 19 2017

Clearing trend and temperatures will be the main focus for tonight,

Models in good agreement that surface high pressure over eastern
Texas will move to the Tennessee Valley tonight. Model rh time
sections were showing a dry column save some high level moisture.
Satellite was showing the clearing line making progress across west
central Indiana in the wake of an upper trough. Thus, should see
clear or mostly clear skies tonight. Winds will shift to southwest
overnight as the high shifts to the Tennessee Valley. Despite this
modest warm air advection, the clear skies should allow temperatures
to drop to the mid and upper 20s for overnight lows per the
Superblend.

&&

.SHORT TERM.../Monday through Wednesday/
Issued at 235 PM EST Sun Nov 19 2017

The main focus for the short term will be on shower potential
Tuesday.

Models in good agreement that a cold front will drop southeast
across central Indiana Tuesday afternoon. Ribbon of 70 plus 1000-500
millibar mean level rh will be along and ahead of the front with the
deepest moisture across our northeastern counties, where Forecast
Builder places slight chance pops. With moisture marginal, will
leave the small blend pops over our far north, though would not be
surprised to see a little more coverage. Otherwise, a weak upper
waves will move across Monday and Monday night. However, models were
only showing high level moisture suggests just some passing cirrus.
Finally, surface high pressure will gradually build in from the west
Tuesday night, which should result in clearing skies.

Low level thermal progs and only high clouds support temperatures
climbing to near normal Monday and Tuesday. Colder air will move in
again behind the front Tuesday night. Blend temperatures capture
this well, so good confidence in temperatures to within a few
degrees with highs in the mid 40s to lower 50s Monday and Tuesday
but only 35 to 40 Wednesday.

Models are close enough that the model blend initialization was
accepted for most items.

The short term will remain quiet. High pressure will remain in
control through Monday. A cold front will move through on Tuesday,
but moisture is lacking. Thus do not expect any precipitation with
it.

Tuesday will be breezy with wind gusts of 20-30 mph across the area
as the cold front passes.

The model blend looks good for temperatures given expected
conditions.

&&

.LONG TERM /Wednesday night through Sunday/...
Issued at 127 PM EST Sun Nov 19 2017

Models and ensembles in good agreement that high pressure will
result in dry weather through Friday. Then, a frontal system and
upper wave will bring the threat for showers to all or parts of
central Indiana Friday night and Saturday. Forecast builder suggests
precipitation type Friday night and Saturday morning as rain. This
looks reasonable with surface temperatures well above freezing.

Temperatures will warm to near normal Friday and Saturday,
otherwise, below normal temperatures are expected well ahead of the
frontal system on Thursday and behind the system on Sunday per the
blend.

&&

.AVIATION /Discussion for the 20/00Z TAFs/...
Issued at 605 PM EST Sun Nov 19 2017

VFR through the period.

High pressure will move across the region through the period, with
clear or mostly clear skies expected.

Winds will be westerly initially less than 10KT. Overnight into
Monday winds will become more southwesterly. Expect some gusts to
around 20KT at the sites Monday mid morning on.

No significant obstructions to visibility anticipated during the
period.

&&

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

&&

$$

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



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