Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 212327 CCA

Area Forecast Discussion
National Weather Service Northern Indiana
720 PM EDT Mon May 21 2018

Issued at 313 PM EDT Mon May 21 2018

Showers and thunderstorms will impact the area through tonight
with a threat for strong to severe storms existing mainly south of
Route 24. Drier weather will arrive Tuesday and continue through
the work week with highs climbing to into the 80s by Wednesday and


Issued at 508 PM EDT Mon May 21 2018

Thunderstorms have begun to develop over the past hour from
Bloomington IN to Lima OH with some cells, especially SW of Indy
showing attempts to organize. After coordination with SPC, it was
decided that with a mainly NE movement to the storms our CWA would
likely be missed or only see brief impacts, not enough to warrant
addition of 1 or 2 counties to the watch that was recently issued.
However, just because we are not in the watch doesn`t mean the
risk for severe is nil. Locations generally southeast of a
Portland to Lima line could be grazed by a strong to locally
severe storm, especially over the next couple of hours.

As for the rest of the forecast, will start trimming pops further
in the NW with at best scattered showers/isol thunder looking to


.SHORT TERM...(This Evening through Tuesday)
Issued at 313 PM EDT Mon May 21 2018

Elevated (850 mb) warm front has moved into Lower Michigan with sfc
warm front across southern portions of the forecast area with moist
and unstable atmosphere along and south of the front. Slight risk
was shifted a bit further NE earlier today to reflect increased
potential for destabilization with vis sat showing decent clearing
at this point across portions of eastern Indiana with cu field now
starting to develop. Influx of mid to upper 60s dewpoints south of
the front and clearing was allowing CAPE values to start to
increase. Shear profiles aren`t the best but may be sufficient for
at least some organization of storms. A few of the CAMs not only
develop scattered to numerous storms in eastern areas, but also
attempt to develop a line of convection across NE IL into NW IN.
Confidence in evolution warrants holding with likely pops across
the area into early evening before slowly lowering pops from west
to east. Main risk for severe will be damaging winds and large
hail, but stray tornado threat is non-zero. Could be some training
of storms with localized ponding/flooding as PWATs remain around
1.5 inches.

Showers will linger overnight into Tuesday morning in SE sections
with a chance for a storm until the front fully clears the area. In
the NW will have to watch for some patchy fog, especially closer to
Lake Michigan until departure of the trough.


.LONG TERM...(Tuesday Night through Monday)
Issued at 313 PM EDT Mon May 21 2018

Dry and warmer conditions still on tap through Friday as high
pressure dominates, keeping any precip north of the area. Temps
Thursday and Friday will reach at least the mid 80s in many areas
with MEX/ECE guidance indicating upper 80s possible.

Trough still set to move in over the weekend, but timing and
strength differences still exist warranting slgt chc to chc pops at
best for now.


.AVIATION...(For the 00Z TAFS through 00Z Tuesday Evening)
Issued at 720 PM EDT Mon May 21 2018

VFR conditions to briefly prevail over both TAF sites to begin this
cycle. KIWX and surrounding radars indicating broken line of showers
developing in advance of approaching surface low and trailing cold
front...extending from just west of KSBN back down into central
Illinois. Loss of daytime heating and lack of supporting flow aloft
will have precip struggling to maintain going into tonight. Will
handle with just VCSH for now. Saturated layer beneath low level
inversion tonight will bring MVFR/IFR cigs to KFWA and KSBN
respectively. Potential for LIFR at KSBN by the early morning hours
Tuesday but will stay with prevailing IFR and wait for 06Z cycle to
adjust as needed. Surface low tracks northeast into the eastern
great lakes as cold front pushes through the area during the day
Tuesday. Weak high pressure building in behind it will bring a slow
improvement back to VFR by late afternoon.


LM...Dense Fog Advisory from 2 AM to 11 AM EDT Tuesday for LMZ043-



LONG TERM...Fisher

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