Area Forecast Discussion
Issued by NWS Indianapolis, IN

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727
FXUS63 KIND 291826
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
226 PM EDT Mon May 29 2017

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

&&

.SYNOPSIS...
Issued at 224 PM EDT Mon May 29 2017

A couple of weak weather disturbances are expected to move through
the area, one late this afternoon and tonight, and another around
Tuesday night. A frontal system may affect the area towards the end
of the week.

&&

.NEAR TERM /Rest of This Afternoon and Tonight/...
Issued at 224 PM EDT Mon May 29 2017

Short term model guidance suggests lift from a mid level speed max
dropping southeast out of the northern Midwest, will begin moving
into the local area around 292000Z, so expecting scattered
convection to develop after that time. A possible vorticity center
moving out of Missouri may also help to enhance activity this
evening, especially over southern Indiana. Lapse rates are quite
weak, however deep layer shear is adequate for the potential for
some gusty winds in the vicinity of any stronger cells.

These features should move off to the east around 300700Z, so will
cut off PoPs by that time.

Low level thicknesses suggest the GFS MOS lows for tonight are
reasonable, so only minor adjustments planned.

&&

.SHORT TERM /Tuesday through Thursday/...
Issued at 224 PM EDT Mon May 29 2017

Model guidance suggests upper low over the northern Great Lakes will
slowly drift off to the east during this period, with west to
northwest upper flow locally.

Models continue to be quite aggressive with warm advection and
precipitation potential with the next upper disturbance that is
expected to pass through the area around Tuesday night. Will go with
chance PoPs during that period to cover this feature.

Another upper disturbance may approach the area from the northern
Plains as early as Thursday, but ensembles suggest the better
precipitation threat with this feature will be after this forecast
period. Will go with chance PoPs during the day on Thursday.

Progged low level thicknesses suggest the GFS MOS temperature
guidance for the next couple of days look OK for the most part.
Little, if any, adjustments will be made.

&&

.LONG TERM /Thursday Night through Monday/...

Issued at 220 PM EDT Mon May 29 2017

ECMWF suggests cool and dry NW flow continuing aloft through the
period. Meanwhile the ECMWF shows a warm front surging into the
area by Thursday evening and allowing warmer and more moist air
to push into the area on southwest winds. With the front lingering
in the area...and weak disturbances expected to pass in addition
to instability provided by daytime heating...daily shower and
thunderstorm chances seem reasonable.

We should be able to return dry weather to the forecast on Late
Sunday night and Monday as the ECMWF suggest the frontal boundary
sagging south to the Ohio river as a cold front...allowing HIgh
pressure over the Great Lakes to build across Indiana for the
Monday.

&&

.AVIATION /Discussion for the 291800Z Tafs/...

Issued at 100 PM EDT Mon May 29 2017

VFR Conditions will be expected this afternoon. Some brief MVFR
conditions will be possible with around 23Z-02Z at the TAF sites.
A quick return to VFR is expected thereafter.

Visible pictures show mostly sunny skies across central Indiana
with unlimited Cigs. Surface analysis shows a weak trough of low
pressure in place across Central Illinois...streaming eastward
within the broad cyclonic flow across the area. HRRR suggest this
wave should pass across the tAF sites near 00Z...thus some
mentions of VCTS will be expected. However confidence and coverage
remains too low to be worthy of a prevailing mention.

Dry air and subsidence quickly settle across the area in the wake
of the short wave...thus a quick return to VFR.

&&

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

$$

SYNOPSIS...JAS
NEAR TERM...JAS
SHORT TERM...JAS
LONG TERM....Puma
AVIATION...JP



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