Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 191729

Area Forecast Discussion
National Weather Service Northern Indiana
129 PM EDT Wed Apr 19 2017

Issued at 245 AM EDT Wed Apr 19 2017

Low pressure developing across Iowa today will promote isolated
to scattered thunderstorms along a frontal boundary draped across
the area this afternoon. As this system lifts northeast across
the upper Great Lakes Thursday, the accompanying cold front will
move across our area, likely causing thunderstorms. Isolated
severe storms are possible Thursday afternoon. Temperatures will
remain well above normal through Thursday, cooling off to a bit
below normal behind the cold front on Friday.


.SHORT TERM...(Today and Tonight)
Issued at 245 AM EDT Wed Apr 19 2017

Large scale warm advection ongoing ewd of vigorous sw disturbance
ejecting through the cntrl Rockies this morning. Ern extent of warm
frontal zone quite attm yet expected to change into this aftn as
boundary sharpens swd through nrn IN. As this occurs newd advance of
plains EML overtop ewd fold of substantial low level theta-e ridge
will yield increasing chcs for thunderstorm initiation invof of warm
frontal boundary. Hwvr given modest sfc based moisture return within
generally poor mid level flow aloft little svr risk if any

LLJ ramps appreciably later this evening tied to newd ejection of
Rockies disturbance into the upper midwest. Given intensity of H85
flow within left over theta-e ridge suspect additional storm
development along nwd retreating warm front psbl esp with ne extent.
Some isolated risk for a marginal hail producing elevated storm
present late tonight through far nrn zones yet limited in time.


.LONG TERM...(Thursday through Tuesday)
Issued at 245 AM EDT Wed Apr 19 2017

Ewd progression of aforementioned sw disturbance and attendant sfc
cold front through the nrn lakes expected Thu. Similar implied model
timing/placement of fntl zone lends credence to prior sharp w-e pop
gradient. While mid level flow certainly better Thu aftn... overall
svr risk remains tepid owing to poor quality GOMEX moisture
return... nrn track of mid level sw trough limiting frontal based
forcing and dilution of EML. Nonetheless zealous concensus based
pops appear fine attm.

Thereafter fairly strong sfc ridging will build south across the wrn
lakes as next vigorous sw disturbance digging through the Rockies
ejects out through the TN valley. Per indicated swd trending model
guidance here see little reason to entertain any pop mention through
the remainder of the period. Seasonably cool temps Fri-Sat will
moderate strongly into early next week timed with low amplitude
ridging developing ewd of next nrn stream disturbance indicated
through the nrn plains.


.AVIATION...(For the 18Z TAFS through 18Z Thursday Afternoon)
Issued at 128 PM EDT Wed Apr 19 2017

A front has stalled just north of Indiana as a low pressure
system approaches the region from the Central Plains.
Thunderstorms and showers are possible along the front especially
this afternoon and evening and separate time tomorrow afternoon
and evening as a cold front pushes through. The lowest levels of
the atmosphere are still fairly dry today, but any thunderstorm
does have the potential to reduce CIGs within heavy rain. At this
point, don`t have enough confidence to reduce CIGs into MVFR so
will keep it above 3kft this afternoon and again tomorrow
afternoon. Additionally, expecting LL shear overnight tonight
especially at SBN and wind gusts 25 to 30 kts Thursday as a low
level jet passes through.





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