Area Forecast Discussion
Issued by NWS Indianapolis, IN

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099
FXUS63 KIND 210651
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
251 AM EDT Wed Jun 21 2017

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

&&

.SYNOPSIS...
Issued at 251 AM EDT Wed Jun 21 2017

High pressure from Indiana to the southeast coast is going to rule
Hoosier weather through Thursday night. Friday we`ll be passed by a
cold front. Friday night high pressure should arrive from the
northwest.  The high is likely to dominate our weather for several
days as its center shifts to the eastern seaboard.

&&

.NEAR TERM (Today)...

Issued at 251 AM EDT Wed Jun 21 2017

The main issue is POPS.

The models tend to agree today will be dry. They also agree a weak
boundary and some moisture will remain over the area, on the day
with literally the highest sun angle of the year. We currently
have more rain than there `should` be.

There will need to be an early morning period with relatively high
POPs. For the actual today period, the comparatively moist MET,
which gives a chance or slight chance in the areas with the most
moisture, will be used.  Skies should be partly cloudy under diurnal
cumulus.

Given low confidence about POPs, there is limited confidence about
temperatures. Consensus should minimize errors. These may be 2-3
degrees based on the range between different forecast methods.

&&

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

Issued at 251 AM EDT Wed Jun 21 2017

POPs are the main forecast problem.

The models agree in many ways. However we are going to be affected
by a tropical system from the Gulf--very atypical so early in the
summer. Such systems are notoriously challenging for the models.

Currently there is no reason to deviate from the consensus POPs.
These have precipitation likely by Friday, with drier weather
afterward. However confidence is the forecast is low. POPs may
need to be adjusted by 20 percent from those issued today.

As with POPs, there is no reason to vary from consensus with
temperatures, and confidence in them is low. Potential errors are
2-4 degrees.

&&

.LONG TERM /Friday Night through Tuesday/...
Issued at 253 PM EDT Tue Jun 20 2017

Showers and a few thunderstorms will linger into Friday night as a
front across central Indiana moves on to the south.  The front will
be far enough south Saturday for Indiana to be dry.   Models...
especially the european indicate a weather disturbance may bring
chance POPS around Sunday...then mostly dry weather will occur
Sunday night through Tuesday as high pressure over the central
plains moves towards the Ohio valley.

Temperatures will be cooler than normal...especially Sunday and
Monday.
Highs will be in the upper 70s to lower 80s Saturday and again
Tuesday and in the 70s Sunday and Monday.  Lows will be in the lower
to middle 60s Friday night...around 60 Saturday night and 50s Sunday
and Monday night.  Generally stayed close to model initialized
temperatures.

&&

.AVIATION (Discussion for 210600Z TAFs)...

Issued at 1235 AM EDT Wed Jun 21 2017

Upper level vorticity lobe currently sagging southeast through
central Indiana is expected to pass off to the southeast of the
terminals by or shortly after issuance time. As a result, remaining
shower activity in the vicinity of the terminals should end over the
next couple of hours.

Otherwise, expecting diurnal cloud development based around 030
towards the midday hours of Wednesday. Light surface winds overnight
expected to become 250-290 degrees at 7-10 kts by midday Wednesday.


&&

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

$$

SYNOPSIS...JK
NEAR TERM...JK
SHORT TERM...JK
LONG TERM....JH
AVIATION...JS/JK



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