Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 222323

Area Forecast Discussion
National Weather Service Northern Indiana
722 PM EDT Thu Jun 22 2017

Issued at 722 PM EDT Thu Jun 22 2017

Chances of showers and thunderstorms will increase overnight into
Friday morning as a low pressure system and associated cold front
tracks across the Great Lakes region. Cooler and drier conditions
are then expected behind this system for the upcoming weekend.


.SHORT TERM...(This Evening through Friday)
Issued at 212 PM EDT Thu Jun 22 2017

KIWX radar indicating a few weak returns otherwise early shower
activity has exited the area as warm front continues to lift
northward through lower Michigan. Convective complex moving across
the upper MS valley toward western great lakes aided by good
forcing as 60-80kt mid level speed max rounds base of upper
trough. Water vapor imagery depicting northern stream closed low
over Manitoba with circulation associated with Cindy now along
TX/LA border. Fast moving northern stream will become more
amplified in the short term as closed low expected to phase with
remnants of Cindy as it moves into SW Ontario. Thunderstorm
chances will increase tonight as cold front approaches the area.
While this afternoons convective complex expected to continue
eastward following the mean cloud bearing wind...additional
convection possible with arrival of cold front late tonight.
Unfavorable diurnal timing will limit instability and more
favorable forcing/dynamics detached to the north so severe
potential will be reduced and only potential in far northwest
CWA. As front moves through the area on Friday expect limited
instability in anticipation of debris clouds and any ongoing
precip...but will still be sufficient for potential of heavy rain
producing strong storms as enhanced moisture with Cindy remnants
will have PW value around 2 inches in the far SE CWA. Warm and
muggy conditions tonight will have lows around 70 while
clouds...precip...and frontal passage will keep highs 75-80


.LONG TERM...(Friday Night through Thursday)
Issued at 212 PM EDT Thu Jun 22 2017

Cooler and less humid conditions to begin the long term period.
Upper level trough will carve out over the great lakes as surface
high pressure settles into the northern plains Saturday. NW flow
pattern sets up through Monday and will bring a series of
shortwaves through the great lakes region. While moisture will be
limited...diurnal instability along with -20C to -24C cold pool
warrants small chances for precip. Pleasant weather for Tuesday-
Wednesday as trof axis shifts east and surface high moves over the
region. Upper level ridging and return flow will see moderating
temps back toward 80 Wed-Thu. Surface high pressure moves off to
the east by day 7 which will put our area in a good return flow
but medium range models trending toward a closed system well to
the northwest yielding a very weak signal for precip chances. As
usual blend too aggressive temporally in bringing POPs back so
will trend toward dry forecast.


.AVIATION...(For the 00Z TAFS through 00Z Friday Evening)
Issued at 722 PM EDT Thu Jun 22 2017

A cold front in association with low pressure skirting through
Ontario Canada is expected to generate a progressive line of
shra/tsra late tonight...aft 06Z primarily before ending late Fri
morning. Sub-tropical moisture remnants from depression Cindy in the
process of entraining into this sys and especially so overnight as
LLJ ramps. Thus VFR flight rule early on will deteriorate late
tonight as precip develops eventually into widespread MVFR

 A low pressure trough and associated cold front will swing
through the TAF sites tonight into Friday. As a result, winds will
increase to 15 to 25 kts out of the south-southwest this afternoon,
and then veer to the northwest by Friday afternoon. Abundant
moisture will lift into the region ahead of the front during the TAF
period, partially associated with the remnants of tropical storm
Cindy. The abundant moisture, and lift associated with the front
gives higher confidence for rain and thunderstorms starting this
evening and continuing through Friday morning/afternoon. Have
conditions dropping from VFR/MVFR this afternoon to IFR as the
stronger forcing/deeper moisture arrive. Would not be surprised to
see lower ceilings in any stronger thunderstorms, but didn`t feel
confident enough to include in the TAF at this time.


LM...Small Craft Advisory until 8 PM EDT this evening for LMZ043-046.




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