Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 190551
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
151 AM EDT Sat May 19 2018

.UPDATE...
The SYNOPSIS...NEAR TERM and SHORT TERM Sections have been updated below.

&&

.SYNOPSIS...
Issued at 152 AM EDT Sat May 19 2018

The same frontal system will linger over or near Indiana until the
middle of next week.  High pressure to the southeast should
gradually take control of our weather from Wednesday into Friday.


&&

.NEAR TERM (Today)...

Issued at 152 AM EDT Sat May 19 2018

The main forecast issue is rain chances.

The models are close. They agree the day should be mostly cloudy
with a chance for rain as a frontal boundary remains over Indiana.
Consensus should work fairly well for both POPs and temperature.

However, there is considerable uncertainty.  Frontal situations are
difficult to forecast. This is reflected in the POPS, which indicate
any one spot may or may not get rain. Where rain falls amounts are
apt to be variable.

Based on the history of the air that will be over Indiana, most rain
today should be from showers, but scattered locations could get a
thunderstorm.

Uncertainty about precipitation leads to uncertainty about
temperatures. Possible forecast errors about 4 degrees.

&&

.SHORT TERM (Tonight through MOnday night)...

Issued at 152 AM EDT Sat May 19 2018

Rain chances continue as the main forecast problem.

The models are close with their deterministic fields, keeping a
frontal boundary over the area.  This introduces uncertainty. Small
differences could have a large impact on shower and storm formation.

Use of consensus will minimize POP errors. There is greater
confidence in trends than predictions for specific times. In
particular,tonight should be relatively dry. and Sunday night should
be relatively wet. The models concur there will be enough
instability for both showers and thunderstorms, with the best chance
for thunder in the afternoons and evenings.

Even when it doesn`t rain, skies should be mostly cloudy.

With overall model agreement, consensus temperatures look
reasonable. Confidence in the temperature forecast is low because of
uncertainty in the precipitation forecast. Possible errors are 4
degrees.

&&

.LONG TERM /Monday night Through Friday/...
Issued at 302 PM EDT Fri May 18 2018

A cold front will drop southeast across central Indiana sometime
early next week before likely becoming quasi-stationary. Confidence
in this exact timing is low, but with the front nearby, will accept
the blend which has chance PoPs over all or parts of the area at
times with the best chance Monday night.

Looking at low level thermal progs, look for above normal
temperatures but confidence is low to within a few degrees due to
not having confidence in the frontal position through time.

&&

.AVIATION /Discussion for 190600z TAF issuance/...

Issued at 1129 PM EDT Fri May 18 2018

MVFR and IFR ceilings can be expected through the overnight hours.
KLAF and KHUF may still have a few showers impacting them by
issuance time but these should move away from the sites with time.
There is potential for redevelopment but lower confidence on
timing/placement. Ceilings should improve back to MVFR by mid to
late morning but chances for thunderstorms will develop then as
well. These are low enough confidence to leave out at this point
beyond a possible PROB30 mention. Winds will mainly be out of the
east through the overnight around 4 to 8 kts and then veer to
southwesterly by Saturday afternoon around 8 to 12 kts. Should see
VFR ceilings return between 18 and 23z Saturday.


&&

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

$$

SYNOPSIS...JK
NEAR TERM...JK
SHORT TERM...JK
LONG TERM....MK
AVIATION...CP


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