Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 221817
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
217 PM EDT Tue Aug 22 2017

.SYNOPSIS...
Issued at 351 AM EDT Tue Aug 22 2017

Showers and isolated thunderstorms will impact the area until the
passage of a cold front today. Drier, cooler and less humid
conditions will arrive and lingering into the weekend with a slow
warm up into next week.

&&

.SHORT TERM...(This Evening through Wednesday)
Issued at 211 PM EDT Tue Aug 22 2017

KIWX radar continuing to show weakening trends in precip as it
has now exited the eastern CWA. Cold front moving into NW CWA has
decent mass convergence and combining with lake breeze to generate
a broken line of showers across the northern CWA while pocket of
weak diurnal instability ahead of the front has widely scattered
showers over the north central CWA. Cold front should keep this
activity pushing E/SE and diminishing later in the afternoon with
loss of daytime heating. This will set the stage for a cooler and
drier Canadian airmass to begin building into the region behind
the cold front tonight. Surface analysis has low pressure up in
southern Canada along the Ontario/Quebec border with high pressure
still back to the west centered over the Dakotas. Decent gradient
in between sets up over the area and will generate some gusty
winds through the early evening hours until boundary layer
decouples. Clearing skies can be expected overnight with lows in
the mid 50s. Cooler and less humid conditions on Wednesday with
highs in the mid 70s. Surface high pressure only slides eastward
to the mid MS valley keeping a modest gradient over the area and
have winds gusting to 15-20mph by Wednesday afternoon. Some
residual low level moisture lingering over the area will generate
a decent diurnal cu field...especially in NE CWA.

&&

.LONG TERM...(Wednesday Night through Tuesday)
Issued at 211 PM EDT Tue Aug 22 2017

Surface high pressure builds into the western great lakes region
on Thursday. NW flow aloft will send weak disturbance down into
the area bringing additional cloud cover with it but expect to
maintain a dry forecast. High pressure remains in control through
the weekend and will bring ideal weather to the region with lots
of sunshine...low humidities...and highs in the mid 70s. Clear
skies and calm winds will provide optimal radiational cooling at
night and have lows dropping to near 50...10F below normal...with
some areas dipping into the upper 40s. Meanwhile...a tropical
disturbance associated with the remnants of Harvey is expected to
re-organize as it moves into the gulf of Mexico...eventually
making landfall in SE TX. As expected...models struggling with the
extratropical remains and if/when it will phase into the northern
stream flow. Latest model trends have upper ridge building in the
western US leaving remnants detached from northern stream and
stalled in TX/LA through beginning of next week before finally
lifting northward into the TN valley by midweek. GFS also bringing
northern stream wave sliding down the eastern edge of upper ridge
into the mid MS valley Mon/Tue timeframe with resulting guidance
blend introducing small chance POPs. Given rather weak
signal...will limit values on Mon and keep forecast dry but go
along with blend for chance of showers on Tue. Temperatures remain
pleasant through the entire period with highs in the 70s and lows
in the 50s along with comfortably low humidities for late August.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday Afternoon)
Issued at 125 PM EDT Tue Aug 22 2017

5h trof moving across the gtlks region this aftn. sfc boundary has
moved into far nw IN at 17Z. shra from this morning has shifted
into OH while a secondary band of precip has developed across far
srn MI. Expect this line of precip to impact both terminal sites
this aftn as short range models depicted this fairly well.expect
cigs to improve during the aftn to vfr conds and continue through
the night. winds will turn more nwly this aftn and become gusty
until about 02-03Z.


&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Beach Hazards Statement through Wednesday afternoon for INZ003.

MI...Beach Hazards Statement through Wednesday afternoon for MIZ077.

OH...NONE.
LM...Small Craft Advisory until 5 PM EDT Wednesday for LMZ043-046.

&&

$$

SYNOPSIS...Marsili/T
SHORT TERM...Logsdon
LONG TERM...Logsdon
AVIATION...Frazier


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