Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 251725

Area Forecast Discussion
National Weather Service Northern Indiana
125 PM EDT WED MAY 25 2016

Issued at 111 PM EDT Wed May 25 2016

A weak trough moving through an unstable airmass over our area
tonight is expected to cause scattered showers and thunderstorms.
An upper level ridge will move into the area Thursday providing
fair weather. Lows tonight will be in the mid 60s with highs
Thursday in the lower and middle 80s. It will remain warm and
humid through the Memorial Day weekend with chances for showers
and thunderstorms continuing... though most of the weekend should
be dry.


.SHORT TERM...(Today and Tonight)
Issued at 350 AM EDT Wed May 25 2016

Convective season begins this week with several chances for
thunderstorms. No strong forcing to really drive convection so
models struggling with evolution and showing various outputs based
on convective parameterization schemes of each model. Satellite and
radar composite showing widespread convective complexes upstream
over the plains early this morning. Individual MCVs can be seen in
radar mosaic loops and these remnant circulations expected to
progress eastward today and likely generate our convection late this
afternoon into the overnight hours.

Hires guidance has been indicating expansion/development of pcpn
over nrn kentucky and southern Indiana early this morning with
propagation northeastward today. This pcpn has struggled to
materialize and develop per latest radar mosaics so question how
much if any pcpn will make it into the east this morning into
early afternoon. Heating today will produce 1000-2000 J/KG CAPEs
per tempered model output. Models and official forecast have shown
a rather high moisture bias in the low levels...especially Tuesday
where sfc dewpoints verified 6-10 degrees too high due to
afternoon mixing. Used mixing tool to lower afternoon dewpoints
today by 2 to 5 degrees keeping afternoon readings lower than
general blends. Any weak short wave may still be able to initiate
isolated convection with afternoon heating and increasing theta E so
allowed for at least slight chance pops mid to late afternoon.

Better but still conditional chances for thunderstorms arrive
tonight provided MCV continues to move northeast. Highest PoPs in
the west tonight with decaying pcpn likely lifting northeast and
possibly missing southeast areas. Low confidence in actual
evolution given various model solutions so maintained chance pops
in the southeast overnight.

High temperatures today should be in the lower to middle 80s. It
will feel a bit more humid but expected afternoon mixing to help
limit dew point rise and should keep afternoon apparent temps in
the lower to middle 80s...but still warmest of the season so far.
Lows tonight will remain in the 60s with dew points creeping up
making for a muggy night.


.LONG TERM...(Thursday through Tuesday)
Issued at 350 AM EDT Wed May 25 2016

Confidence remains low with respect to any forecast details and
timing of convection in the long term period. Ongoing short term
convection and resultant MCVs to drive convection in the early
portion of the long term. Later periods still characterized by low
to mid chance pops through most of the long term forecast with
meandering frontal boundary and weak short waves providing the
means for development in a rather moist and unstable low level
environment. A marginal risk for severe weather exists Thursday
afternoon and evening but really dependent on Wednesday night MCV
and convection and what is left behind. 0-3km bulk shear looks to
be 20-30 knots with possible CAPE values in the 2-4k J/KG range.
This would be sufficient for some strong to severe storms with
winds and hail primary hazards.


.AVIATION...(For the 18Z TAFS through 18Z Thursday Afternoon)
Issued at 111 PM EDT Wed May 25 2016

Moderate instability has developed over nrn IL this aftn along/ahead
of a wk shrtwv/sfc trof. This system expected to move across nrn
IN tonight. With just wk instability fcst across ne IN when the
shrtwv moves through, just mentioned showers at FWA tonight, with
contd mention of tstms at SBN where instability expected to be
greater. Low level moistening overnight expected to result in
brief mvfr cigs across the area Wed morning... mixing out by


.IWX Watches/Warnings/Advisories...


SHORT TERM...Lashley
LONG TERM...Lashley

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