Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 232259

Area Forecast Discussion
National Weather Service Northern Indiana
659 PM EDT Tue May 23 2017

Issued at 317 PM EDT Tue May 23 2017

Scattered showers will remain possible west of Route 31 into
tonight. Mainly dry otherwise tonight with lows dropping into the
50s. Rain will expand over the area Wednesday into Wednesday night
with highs into the mid to upper 60s. An isolated thunderstorm
will also be possible. Clouds and a few showers will linger into
Thursday behind this system. Friday into the holiday weekend will
feature periodic chances for showers and near normal temperatures.


.SHORT TERM...(This Evening through Thursday)
Issued at 317 PM EDT Tue May 23 2017

An upper level low will dive southeast from the Upper Midwest late
this afternoon to the OH/TN Valleys by Wednesday night. Showers late
this afternoon into tonight will generally remain confined to IL/nw
IN/sw Lower MI near pivoting/pronounced low level moisture
convergence axis on eastern fringe of height falls. Best chances
will remain west across IL near stronger area of sfc-850 mb
fgen...with activity more scattered (chance PoPs) into our nw IN/sw
Lower MI zones. There may be just enough weak instability to support
of isolated thunderstorm here into the early afternoon, though
chances are rather low.

A widespread rainfall should spread into the entire area during the
day Wednesday/Wednesday night as TROWAL/deep deformation sets up on
north-northeast flank of upper low. A smaller scale vort max and
strong left exit upper jet support rounding the base of the
deepening longwave trough will also provide good chances for
rain...especially Wednesday afternoon and evening. Most locations
will likely end up with a half inch to 1 inch of rain...with a
narrow swatch of 1" plus possible into nw IN/nw OH where deformation
axis pivots. Some embedded thunder/locally heavy rainfall rates is
not out of the question as some weak MLCAPE possibly  develops
under cool pocket aloft. Will continue to highlight potential for
lowland/river flooding in the ESF (Hydrologic Outlook).

Light showers and low clouds will linger into Thursday,
especially along/east of I-69, on the backside of exiting low
pressure lifting northeast to near Lake Erie by later in the day.
Turning cooler otherwise Wednesday into Thursday.


.LONG TERM...(Thursday Night through Tuesday)
Issued at 317 PM EDT Tue May 23 2017

More seasonable and at times unsettled weather will be the story
Friday into the upcoming holiday weekend as the flow pattern
flattens out a bit in wake of the Wed/Thur system. Will have to
monitor a couple shortwaves to eject east under the next upper low
modeled to take residence into Manitoba/sw Ontario. These
convectively enhanced features will likely feed on a developing
baroclinic zone, with the strongest signal for a period of
rain/thunder locally being Friday night/Saturday morning and
again Saturday night/early Sunday. Mainly dry otherwise with
temps near normal.


.AVIATION...(For the 00Z TAFS through 00Z Wednesday Evening)
Issued at 651 PM EDT Tue May 23 2017

Wk vort max lifting nne into lwr MI resulting in diminishing
coverage of SHRA in SBN vcnty this eve, but more SHRA east of upr
low centered over central IA may impact the terminal overnight.
Combination of diurnal heating/destabilization and increased low
level moisture wrapping around deepening sfc/h85 low centered
over the OH valley should cause SHRA to become widespread with a
few TS across nrn IN Wed aftn. Given expectation of limited TS
coverage, didn`t add mention to TAFS attm. VFR flight conditions
overnight should lower to MVFR at SBN Wed morning and at FWA Wed




SHORT TERM...Steinwedel
LONG TERM...Steinwedel

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