Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 271343
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
943 AM EDT FRI MAY 27 2016

.UPDATE...
Near term for the rest of today has been updated below.

&&

.SYNOPSIS...
Issued at 342 AM EDT Fri May 27 2016

Summer conditions will persist across central Indiana through the
holiday weekend and into next week with highs mainly in the 80s and
a humid airmass. Daily chances for storms will exist through the
weekend as weak upper level waves track through the Ohio Valley.
After a period with drier conditions for Monday and Tuesday...
chances for storms will return by midweek as a storms system tracks
through the Upper Midwest.

&&

.NEAR TERM /Rest of Today/...
Issued at 943 AM EDT Fri May 27 2016

.UPDATE...Only minor tweaks made to previous grids.  Area of showers and
thunderstorms over southern Illinois should move north northeast and possibly
brushing the far northwest part of our region later today.  Otherwise...
only expect isolated thunderstorms.  Lowered POPS slightly some areas.
But overall previous forecast is on track.

Portion of previous near term discussion follows...
Warm front moving north through the region combining with weak mid
level perturbations in the southwest flow will serve as primary
catalysts in potential for isolated to scattered convection
developing in the moist and unstable airmass. Lack of more
substantial forcing aloft and presence of a mid level cap will be
limiting factors in convective coverage...with model soundings and
RH progs both hinting at mid level drying advecting north into the
region by this afternoon.

Primary focus for scattered storms setting up over western counties
in closer proximity to deeper moisture plume and the enhanced 850mb
flow aligning across the lower Mississippi and Ohio Valleys. Will
carry highest pops here this morning as the warm front lifts north
and again this afternoon as scattered convection develops in the
unstable airmass. Further east...the limiting factors mentioned
above support only low chance pops with any convection remaining
isolated.

Temps...Despite the convective cloud debris slowing warming early in
the day...should see some sun through the course of the day with
warmer METMOS guidance being supported by low level thermals. Expect
a muggy day with highs rising into the 80s.

&&

.SHORT TERM /Tonight through Sunday Night/...
Issued at 342 AM EDT Fri May 27 2016

Forecast challenges focus on continued convective chances throughout
much of the period as waves aloft interact with a moist and unstable
airmass across central Indiana.

Upper low centered over the High Plains will wobble northeast into
the Upper Midwest and then into western Ontario by late weekend.
Dirty southwest flow pattern aloft as multiple weak waves will
continue to eject out from the upper low and lift northeast across
the Ohio Valley and lower Great Lakes. As these waves interact with
the unstable air across the region...opportunities will exist for
isolated to scattered convection through Sunday.

As is often the case in these setups...models having all sorts
of difficulty timing the individual waves aloft creating a low
confidence forecast in timing convective impacts for the forecast
area. At this point...best chances for storms appear for Saturday
and Sunday afternoons during peak heating. Bulk of the stronger
forcing aloft remains to the west of the forecast area on
Saturday...but presence of deeper moisture and surge of slightly
better mid level lapse rates supports chance pops across the
forecast area.

Strongest wave aloft impacts the region on Sunday as a more
pronounced upper trough swings through the lower Great Lakes with a
weakening cold front tracking east. Cooler and drier air in the mid
levels associated with the upper wave will support steepening lapse
rates over the area which should present a better and slightly more
organized convective potential during the afternoon and early
evening in vicinity of the cold front. With that being said...
weaker low level flow will limit coverage to storms. Still plenty of
details to work out but higher chance pops certainly appear
warranted for the afternoon and evening Sunday. Drier air will
overspread the region Sunday night as weak high pressure builds in.

Temps...Low level thermals generally supported MOS guidance for
highs Saturday and Sunday. More clouds should keep temps down
slightly on Saturday with Sunday being the warmer day ahead of the
weak cold front. Overall...expect a muggy summer-like holiday
weekend with highs mainly in the 80s and lows in the 60s.

&&

.LONG TERM /Monday Through Thursday/...
Issued at 239 AM EDT FRI MAY 27 2016

Models are close enough that the SuperBlend initialization was
accepted for most items.

High pressure should keep the area dry on Memorial Day and most of
the area dry on Tuesday. However, a surface system and an
approaching upper trough will bring a return of shower and
thunderstorm chances Tuesday night through Thursday.

Temperatures will continue to be above average through the period.

&&


.AVIATION (Discussion for the 271200Z TAF Issuance)...
Issued at 633 AM EDT FRI MAY 27 2016

Outside of convection, VFR conditions expected through the period.

Area of scattered showers should be just north of the TAF sites by
valid time.

Additional scattered convection is possible anytime today, but
especially in the afternoon. (Widespread convection should remain
west of the area.) Feel that expected coverage will be low enough to
leave out mention in the TAFs.

So far MVFR fog has not materialized, so unless it does soon, will
leave out of TAFs this morning. Otherwise expect mainly mid and high
level clouds this period. Winds will gust over 15kt this afternoon.

&&

.IND Watches/Warnings/Advisories...NONE.

&&

$$

SYNOPSIS...RYAN
NEAR TERM...RYAN/JH
SHORT TERM...RYAN
LONG TERM...50
AVIATION...50



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