Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 231800
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
200 PM EDT Fri Jun 23 2017

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

&&

.SYNOPSIS...
Issued at 200 PM EDT Fri Jun 23 2017

A Cold front over Central Indiana will push east and exit the
state tonight. Rain will end late this afternoon and evening as
the front passes. High pressure centered over the western plains
states will then build across the Indiana and the Great
Lakes...providing cooler and drier NW flow. This will result in
dry and pleasant weather this weekend...with below normal
temperatures and comfortable humidities.

Dry weather and below normal temperatures will be expected for
much of next week due to the strong high pressure system to the
west.

&&

.NEAR TERM /Tonight/...

Issued at 200 PM EDT Fri Jun 23 2017

Surface analysis shows a Cold front across NW Indiana stretching
to East Central Illinois to SE Missouri. Radar trends show a band
of showers ahead of the front across central Indiana. Some of the
showers continue to produce very heavy rain with the very moist
tropical air mass in place.

GFS and NAM continue to suggest a SE progression of the surface
cold front which will effectively push the stream of moisture SE
and out of Central Indiana. Rapid refresh suggests that by
00Z...only the far southeastern parts of the forecast area will
still be impacted by rain. HRRR progression after that suggests
the forecast area should be rain free by 03Z. Time heights show a
complete loss of forcing and strong drying within the column after
00Z with subsidence. Significant air mass change is also expected
as dew points in the lower 60s and upper 50s...as seen in NRN
Illinois...are set to arrive in the wake of the front.

Thus will trend toward a dry forecast tonight...especially across
the NW where Rain will have ended. May need to keep some pops for
the first 1-2 hours after 00Z across the SE where rain may not
have exited yet. Models suggest strong cold air advection tonight
and will trend lows at or below the expected forecast builder
blend.

&&

.SHORT TERM /Saturday through Monday/...

Issued at 200 PM EDT Fri Jun 23 2017

GFS and NAM suggest a large broad trough in place across the
Great lakes and Ohio valley through Monday. Several weak...poorly
organized disturbances look to pass within the flow...but best
dynamics look to remain well north of Central Indiana. Time
height sections continue to show a dry column through Monday.
Forecast soundings through Monday also show a dry column...but
attainable convective temperatures in the upper 60s to near 70.
However on both Saturday and Sunday afternoons...forecast
soundings show a good mid level inversion that should just result
in some flat topped CU. Furthermore CAPE appears really limited
with values less than 300 J/KG. Thus with dew points in the 50s
and high in the 70s expected for this
period...comfortable...pleasant and not humid weather is expected.
Thus will trend toward Partly cloudy days and Mostly clear nights.

Forecast soundings hint at slightly more CAPE on Monday afternoon
and less of a mid level cap. Forecast blender may try to insert
pops here...however...confidence remains very low at this point
given the NW flow expected and a lack of deep moisture.

&&

.LONG TERM /Monday through Thursday/...
Issued at 302 AM EDT Thu Jun 22 2017

A strong upper trough over the great lakes will dominate our weather
early next week as high pressure over the middle Mississippi valley
builds east across Kentucky and Tennessee.  The GFS and Euro models
indicate a few showers are possible part of our area Monday
afternoon and evening as a weak upper disturbance moves our way.
Will mention a slight chance of showers north and central sections
Monday afternoon and a slight chance of evening showers west half
Monday evening.   Otherwise...high pressure will bring dry and quiet
weather through Wednesday as it moves on to the east.

High pressure will move on to the east coast and an increasing
southerly flow will allow Gulf moisture to spread north into our
region by Thursday.  Models indicate an unstable air mass by then
and will mention a chance of thunderstorms after the middle of next
week.

Temperatures will be cooler than normal early next week warming to
near normal by days 6 and 7 as the upper trough moves on to.
the east.  Overall Superblend temperatures seem reasonable.

&&

.AVIATION /Discussion for the 231800Z IND TAFs/...

Issued at 1253 PM EDT Fri Jun 23 2017

MVFR Conditions will improve to VFR during the TAF period.

Cold front over NW Central Indiana will sag southeast during the
first 1-3 hours of the TAF period...ending the precipitation
threat as it passes southeast. In the meantime ample moisture and
lower level convergence will result in showers and storms ahead of
the front...producing mainly MVFR conditions...but IFR will be
possible with some of the heavier rain showers.

High pressure centered over western plains will then build across
the region tonight...leading to VFR CIGS. Unlimited CIGS will be
expected by Saturday morning as forecast soundings suggest a very
dry column.


&&

.IND WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch until 8 PM EDT this evening for INZ052>057-
060>065-067>072.

&&

$$

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



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