Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 281523

Area Forecast Discussion
National Weather Service Northern Indiana
1123 AM EDT Sun May 28 2017

Issued at 336 AM EDT Sun May 28 2017

A low pressure system is expected to cause thunderstorms as it lifts
northeast across our area this afternoon. Storms will move out of
the area tonight but a few more may develop Memorial Day afternoon
as another weak trough moves through. After highs in the 70s today,
temperatures will be a little cooler than normal Monday through
Wednesday as northwest flow on the backside of the slowly departing
low pressure system persists across the western Great Lakes. A few
showers are possible again Tuesday and Wednesday afternoons as a
couple more weak troughs rotate around the slowly departing low.
Temperatures will warm a bit late week but there will also be
increasing chances of showers and thunderstorms as a cold front
slowly approaches from the north.


Issued at 1117 AM EDT Sun May 28 2017

Atmosphere beginning to destabilize as clouds have thinned and
diurnal heating is underway. CAMs all in decent agreement on
thunderstorms developing in the 17-20z time frame and moving out
of the east this evening. MLCAPE expected in the 1500-2500 j/kg
range with mid level lapse rates around 7c/km. Models only
showing 0-3km shear of 20-30 knots but deeper 0-6km shear more
favorable around 40 knots as upper level jet streak moves through.
Expecting broken line of storms to develop with stronger updrafts
having potential for damaging winds and large hail this afternoon
and early evening. Forecast on track but did make some minor
tweeks to pops and timing.


.SHORT TERM...(Today and Tonight)
Issued at 336 AM EDT Sun May 28 2017

Airmass over our area will destabilize today as an upr trof moves
east to the wrn Grtlks. This should allow tstms to develop over
wrn portions of our area early this aftn and spread east across
ern portions later this aftn. Given forecast of moderate
instability with cape apchg 1500j/kg and modest deep layer shear
near 30kt, some potential for a few storms with damaging winds and
large hail in our area. Decent mixing and a warm start to the day
should allow temps to top out in the m70s despite considerable
cloudiness and dvlpg storms/cold pools this aftn.

Storms expected to move east out of the cwa early this eve
as cdfnt moves through. WSW gradient should keep some mixing
going overnight limiting temp falls despite clearing skies with
lows expected in the m50s.


.LONG TERM...(Monday through Saturday)
Issued at 336 AM EDT Sun May 28 2017

Upr low over srn Manitoba expected to move to the upr Grtlks Monday
and then lift slowly ne Tue/Wed. Mainly a cool/dry period, but
shrtwv`s rotating around this low may cause a few showers in the
area each day. Another upr low expected to track slowly se across
srn Ontario Thu-Fri and to Quebec Saturday. Swly low level flow
should develop ahead of this system allowing for some
destabilization in our area by Fri as cdfnt approaches which may
allow tstms to develop. This front expected to move slowly south
across the cwa keeping a chc of showers in the area through
Saturday, with temps turning cooler after a brief/modest late week


.AVIATION...(For the 12Z TAFS through 12Z Sunday Morning)
Issued at 640 AM EDT Sun May 28 2017

Massive storm complex through the lower MS valley this morning
finally beginning to weaken as large scale outflow continues to push
swd. Extensive cloud debris to the north across the srn great
lakes/OH valley continues to thin and expect robust destabilization
to ensue through early aftn ahead of approaching sfc trough
extending swd from vigorous upper disturbance over nrn MN. Primary
question is swd extent of stronger forcing into what should be a
sizable CAPE reservoir mid to late aftn as mid 70 temps over mid 60
dewpoints yields 2K j/kg while effective shear broaches 30kts.
Trends in CAMS guidance fleeting at best and have yet to lock onto a
more definitive time period and have kept with prior VCTS mention.
Nonetheless sct severe storms are likely from mid to late aftn
especially invof the KFWA terminal.





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