Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 252020
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
420 PM EDT Tue Apr 25 2017

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

&&

.SYNOPSIS...
Issued at 240 PM EDT Tue Apr 25 2017

A frontal system is expected to move through the area Wednesday
night or Thursday morning. Another frontal system may affect
the area towards the end of the week, and on into next weekend.

&&

.NEAR TERM /Rest of This Afternoon and Tonight/...
Issued at 240 PM EDT Tue Apr 25 2017

Dry weather expected through tonight as surface high pressure ridge
hold over the area. Some passing high level cloud expected from time
to time.

Low level thicknesses suggest the GFS MOS lows for tonight look OK
for the most part.

&&

.SHORT TERM /Wednesday through Friday/...
Issued at 240 PM EDT Tue Apr 25 2017

Model data in general agreement on frontal passage occurring either
Wednesday night or Thursday morning. Lift appears to mainly located
in the vicinity of the front and in the post frontal zone, so don`t
think there will be much activity in the warm sector ahead of cold
front. For this reason, think most of Wednesday will be dry, with
the precipitation threat arriving in the western zones towards
evening. Will go with PoPs for mostly Wednesday night and Thursday
morning coinciding with the best lift. Precipitation threat should
diminish by Thursday afternoon as main lift and upper trough move
off to the northeast.

Will keep Thursday night dry with surface high pressure moving over
the area.

Models suggest decent warm advection will develop by Friday
afternoon in advance of the next upper disturbance rounding the
Plains long wave trough. Will go with chance PoPs on Friday
afternoon.

Given a continued trend of slowing the midweek frontal system down,
will raise the GFS MOS highs and lows for Wednesday and Wednesday
night about a category. Progged low level thicknesses also suggest
the lows Thursday night are probably too cool. Will raise the
guidance lows 3-5 degrees in that period.

&&

.LONG TERM /Friday Night through Tuesday/...

Issued at 201 PM EDT Tue Apr 25 2017

ECMWF suggests active weather ongoing on Friday night through
Sunday night. The lower levels feature a stalled frontal boundary
lingering across Indiana through at least Sunday. Meanwhile Low
pressure begins to develop in the central plains states along
with a strong upper wave suggested to arrive on Sunday. With Warm
and moist southerly flow headed into the Ohio Valley Through The
weekend...good moisture will be available for precip. For
now...the ECMWF suggests a weak wave passing on Saturday and due
to the poor organization....confidence here is low. However best
forcing really appears on Sunday afternoon/evening with expected
frontal passage. Confidence with this second system is much
higher.

The ECMWF suggests the upper low pulls quickly northeast on late
sunday night along with the cold front pushing well to the east.
This should bring about dry and cooler weather for the start of
the next work week.

&&

.AVIATION /Discussion for the 25/2100Z TAF Update/...

Issued at 418 PM EDT Tue Apr 25 2017

UPDATE...
No flight category changes.

PREVIOUS DISCUSSION...
VFR Conditions will continue this period.

Weak high pressure across the area will remain in place through
the period. Forecast soundings and time height sections remain
dry. Models suggest that stronger forcing associated with an
approaching front will begin to push in to the area after 00Z
Thursday...at which point we should begin to see a deterioration
of flying conditions.

&&

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

&&

$$

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



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