Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 201738

Area Forecast Discussion
National Weather Service Northern Indiana
138 PM EDT Mon Mar 20 2017

Issued at 1120 AM EDT Mon Mar 20 2017

Scattered showers and thunderstorms are expected again this
afternoon. Hail and locally heavy rainfall will be possible with
the stronger storms. It will turn colder midweek with highs on
Wednesday only in the middle to upper 30s. A warmup is expected by
Friday with temperatures climbing into the 60s but rain chances
return for late week and the weekend with this warmup.


Issued at 1120 AM EDT Mon Mar 20 2017

Regional radar mosaic shows secondary wave of convection beginning
to develop over northeast IL. Mesoanalysis shows largest MUCAPE
over NW IN and NE IL into west central IN. Mid level lapse rates
on the order of impressive 8-9 C/KM in this region along with bulk
shear of 30-40 knots. Impressive 12z soundings this morning
showing elevated mixed layer over stout low level inversion. All
this sets the stage for hail potential this afternoon with any
storm development and marginal severe hail possible with stronger
updrafts. PWATs also over an inch and earlier convection laid down
1 to 2 inches of rainfall in our southeast. Locally heavy rainfall
possible this afternoon as well and some flooding potential if
training develops in areas hit with earlier heavy rainfall. Will
be monitoring all of this through the day but in agreement with
SPC marginal risk as well as marginal excessive rainfall outlook
for the area. Latest CAMs showing convective development near
approaching boundary with strongest cells in our west to
southwest and latest radar trends support this.


.SHORT TERM...(Today and Tonight)
Issued at 351 AM EDT Mon Mar 20 2017

A couple of upper level disturbances will move across the forecast
area today. Given the elevated nature of the convection with the
colder layer below the inversion and given the arrival of an
elevated mixed layer with steep mid level lapse rates, storms with
hail are favorable today. Hail size up to an inch appear likely
today; both early this morning with the initial short wave, but also
this afternoon with the second short wave. Hail sizes above 1 inch
are also possible. This second system should move through this
evening with the hail potential diminishing rapidly this evening.


.LONG TERM...(Tuesday through Sunday)
Issued at 351 AM EDT Mon Mar 20 2017

The Tuesday system is expected to track farther south than earlier
expected, so have greatly limited rain chances over southern areas.
Otherwise, a large Canadian high pressure area will build into the
Great Lakes region Wednesday and bring much colder air to the
area. Highs Wednesday will only be in the 30s to around 40 with
lows Tuesday and Wednesday nights falling to around 20. Chances
for rain will increase with the next system Thursday night into
Saturday. Heavy rain is possible with this late week system,
although wintry weather is not expected.


.AVIATION...(For the 18Z TAFS through 18Z Tuesday Afternoon)
Issued at 134 PM EDT Mon Mar 20 2017

Thunderstorms with possibility of small hail nearing KFWA at
issuance time. Likely only about an hour or two at most of
convection with hail possibility. In wake of this current activity
on radar...not much happening as best instability aloft is being
robbed by convection entering west central IN. Mid level lapse
rates also become less favorable as afternoon progresses.
However...main front/wind shift still to move through along with
good deep layer shear. Could still see some additional shower and
isolated tsra development later this afternoon but having doubts.
Will monitor but confined convection to next few hours. Clearing
works into KSBN this evening but low clouds may redevelop and
linger at KFWA. Some guidance wants to develop IFR and LIFR fog at
KFWA but would only expect this if skies clear temporarily there.
Hedged for now but did drop into IFR range.




SHORT TERM...Skipper
LONG TERM...Skipper

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