Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 151650
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1150 AM EST Wed Nov 15 2017

.UPDATE...
The AVIATION Section has been updated below.

&&

.SYNOPSIS...
Issued at 243 AM EST Wed Nov 15 2017

A cold front will bring rain to central Indiana today. Dry weather
briefly returns for Thursday, then a low pressure system will bring
more rain for Friday & Saturday. Dry weather then rule for early
next week. Temperatures will generally be below normal, with well
below normal conditions expected for Sunday.

&&

.NEAR TERM /Today/...
Issued at 952 AM EST Wed Nov 15 2017

Widespread rain has now encompassed most of the forecast area as
of mid morning. Have seen a few lightning strikes periodically...
largely focused over the lower Wabash Valley. 1430Z temperatures
were mainly in the low and mid 40s.

A wet...raw and gray day on tap for central Indiana as rain will
continue to track east through the area ahead of a cold front
currently located from western Illinois back into central
Missouri. Have maintained a low mention for thunder over far
southern counties through early afternoon but overall
thermodynamic profiles are largely becoming less and less
supportive for thunder.

High confidence forecast for the rest of the day with rain ending
from west to east during the second half of the afternoon as the
cold front sweeps through. CAMs guidance has a nice handle on
current activity and overall timing going forward through the rest
of the day. Even though rain should hamper temp rises over the
next several hours...potential does exist for temps to rise prior
to the cold frontal passage which will hold off until late day for
most of the area. Current forecast highs in the upper 40s to
lower 50s from northeast to southwest still appear reasonable and
made no changes at this time. Already getting breezy in western
counties and expect this to continue and expand across the rest of
the forecast area into the afternoon.

Should see some scattering of lower clouds in western counties
late...but overall will be a cloudy day. Lingering moisture in the
boundary layer and the development of an inversion this evening
may serve to redevelop and/or maintain lower stratus over much of
the area tonight as well.

Zone and grid updates out.

&&

.SHORT TERM.../Tonight through Friday night/
Issued at 243 AM EST Wed Nov 15 2017

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

Tonight through Thursday night will be dry with high pressure moving
across the area.

Some concern that there will be more clouds tonight into Thursday
than the models suggest with moisture perhaps becoming trapped
underneath an inversion (typical for November). Will raise the
blend`s sky cover tonight most areas, going partly cloudy for mainly
the northeast forecast area. Will have to watch Thursday for the
need for more clouds.

Lift will increase Friday afternoon into Friday night as a low
pressure system organizes to the west. A 50kt 850mb jet will bring
in moisture and forcing, mainly Friday night. Thus low PoPs can be
expected Friday afternoon with high PoPs Friday night as the better
forcing moves in.

By Friday night enough instability moves into the area to mention
some isolated thunderstorms. An inversion should keep the stronger
winds aloft from mixing down Friday night. However, some gusts near
25kt are possible with the pressure gradient tightening up.

The blend`s temperatures look reasonable.

&&

.LONG TERM /Saturday through Wednesday/...
Issued at 230 AM EST Wed Nov 15 2017

A warm and stormy start then a cold tranquil end to this period.

Model timing differences for stormy start are still present but
diminishing while decent agreement occurs Sunday onward. Model blend
on timing and temperatures was followed.

Thanksgiving travel period early look shows no major weather systems
for the U.S.

Saturday...models still show a strengthening low pressure system
tracking northeast from Illinois to the eastern Great Lakes sweeping
a strong cold front across Indiana. With only elevated instability
to work with, severe weather threat no longer appears to be a factor
but with strong wind fields, would not rule out some gusts to 40 mph
in heavier downpours. Models pretty well agree with rainfall on the
order of one inch, falling mainly 3am- 3pm Saturday time frame.

Saturday night...much colder air builds in on gusty northwest winds.
A fetch off Lake Michigan may bring some scattered rain showers to
northeast counties Saturday evening which could transition to snow
showers before ending, but with no snowfall accumulation.

Sunday through Wednesday...Cold high pressure builds in with
conditions similar to last Friday...brisk sunshine with temperatures
remaining in the 30s Sunday. The high and cold core will move
quickly east as a weak low pressure system tracks east across
southern Canada. This system will sweep a weak cold front across our
area Tuesday night. Gulf moisture will be cut off for this system so
clouds, and no more than a few sprinkles are expected, if at all.

Temperatures...a model blend appeared reasonable and was followed
trending from a little above normal Saturday to well below normal
Sunday before moderating back towards normal for the rest of next
week.

&&

.AVIATION /Discussion for 151800Z TAF Issuance/...
Issued at 1150 AM EST Wed Nov 15 2017

Poor flying conditions expected through the rest of the afternoon.
Low ceilings may redevelop late tonight into Thursday morning.

Rain continues to impact the terminals late this morning ahead of
an approaching cold front located over western Illinois. Steadier
and more widespread rainfall will move east of the terminals
around or shortly after issuance time...but scattered showers will
linger through much of the afternoon. Visibilities will
sporadically drop within the showers but the overall trend
through the afternoon will be a return to VFR visibilities.

Ceilings will remain mired largely in the IFR category for the
rest of the day with any improvements likely holding off until
near or just after sunset once the front passes through the area.
Expect some clearing this evening as the dry slot rotates through
behind the front. However...the presence of lingering low level
moisture and a developing inversion will lead to a reexpansion of
MVFR stratus tonight...especially at KIND and KLAF and possibly at
KBMG and KHUF as well. Model soundings hint at the lower stratus
lingering through midday Thursday before the inversion weakens
substantially.

Southwest winds ahead of the front this afternoon will
periodically gust to around 20kts. Winds will veer to westerly and
diminish this evening but the passage of an upper wave through
northern Indiana overnight will likely lead to a 4-6 hour period
with a resumption of gusts from the northwest. N?NW winds will
slacken again Thursday morning as high pressure builds in.

&&

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

&&

$$

SYNOPSIS...50
NEAR TERM...Ryan
SHORT TERM...50
LONG TERM...Tucek
AVIATION...Ryan



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