Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 241654
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1254 PM EDT TUE MAY 24 2016

.UPDATE...
The AVIATION Section has been updated below.

&&

.SYNOPSIS...
Issued at 236 AM EDT Tue May 24 2016

High pressure will allow for one more dry day before thunderstorm
chances return Tuesday night and continue through the Holiday
weekend as upper waves interact with an increasingly moist and
unstable atmosphere.

The southerly flow off the Gulf of Mexico will allow for slightly
above normal temperatures with highs in the upper 70s and lower 80s.

&&

.NEAR TERM.../Rest of Today/
Issued at 951 AM EDT Tue May 24 2016

Upped sky cover some all areas with cirrus moving across, but upped
the highest in the far southwest where an area of mid cloud is
approaching from southern Illinois. That area of cloud is producing
some sprinkles/light showers there, but don`t expect these to make
it into the area with a drier atmosphere in place here.

Otherwise adjusted high temperatures down just a bit with more cloud
cover expected.

Previous discussion follows...

One more dry day is expected today as surface high pressure shifts
to the southeastern states. Should only see an increase in late day
high clouds from northwest to southeast.

South and southwest winds to around 10 mph should allow temperatures
to top out at or slightly above 00z MOS...in the lower to mid 80s.

&&

.SHORT TERM.../Tonight through Thursday night/
Issued at 236 AM EDT Tue May 24 2016

Short term focus will be on thunderstorm chances through the
period...as models are very close in the overall synoptic pattern
through the late week and beyond.

Models have been very consistent in showing numerous impulses being
ejected northeastward across the Ohio Valley and lower Great Lakes
courtesy of a southwestern upper low. The southwestern low is
currently near the San Francisco Bay and will gradually curl across
the dessert southwest before moving to the Rockies by 12z Friday.
Meanwhile...at the surface...southerly flow on the backside of a
southeastern high and ahead of a slow moving Plains frontal
system...will result in an increasingly moist and unstable
atmosphere over the area. The result will be off and on
thunderstorms starting tonight as the first upper wave moves through
the southwest upper flow. Will start with evening chances across the
western counties and then spread pops east through the night with
the wave.

Models agree that the next distinguishable short wave will move
across central Indiana Wednesday evening and early overnight. This
wave will have even more instability to work with with mixed layer
CAPES 1000 j/kg or more. In addition...a 30 knot low level jet will
nose in from the west and add fuel to the storms. This could be
enough for an isolated severe storm...mainly near and west of a
Covington to Rockville to Clay City to Odon line during the late
afternoon and evening per the Marginal Risk of the SPC Day2 Severe
Outlook. In addition...with the best combo of dynamics and
thermodynamics...Wednesday afternoon and evening should see the most
coverage of thunderstorms and so went with the highest pops then
with likely over the southern two thirds of the area Wednesday night.
With deep shear lacking...damaging winds and large hail would be the
main severe threats.

Although model CAPES are progged to 2000 j/kg or higher Thursday
afternoon...there is no discernible upper wave...so went with
smaller chance pops. Another wave will move through Thursday
night...so kept chance pops going.

Coverage of convective elements will have a lot to do with
temperatures. Prefer near or slightly above MOS temperatures...which
have verified better lately. This translates to highs in the lower
to mid 80s and lows in the 60s.

&&

.LONG TERM /Friday through next Monday/...
Issued at 227 AM EDT Tue May 24 2016

Ensembles in good agreement with respect to the overall pattern
during the extended. Mean ridging expected along the east coast
with troughing over the western parts of the country.

An upper disturbance is expected to eject into the northern Midwest
or western Great Lakes over the weekend. In the wake of this
system, heights are progged to rise a bit, however ensembles
suggest a weakness in the upper ridge may linger over the Ohio
Valley into early next week.

Ensembles continue to suggest daily chances for convection
throughout the extended. However, convection may become more
diurnal in nature by early next week as the Plains disturbance
moves away, and the local area becomes more influenced by the
weakness in the upper ridge.

&&

.AVIATION /Discussion for the 241800z tafs/...

Issued at 1247 PM EDT Tue May 24 2016

VFR conditions will continue.

Strong ridging will remain in place east of Indiana...allowing a
warm southerly flow of air into the Ohio valley. Weak short wave
over the central Plains will slowly pushing toward Indiana
tonight...however lower level features and forcing remain
weak...thus have trended toward VFR CIGS as time heights continue
to suggest some lower level saturation through the night.

Forecast soundings show steep lapse rates on Wednesday with CAPE
in excess of 2000. Convective temperatures will be reached.
However models suggest well-organized forcing mechanisms fail to
exist. Thus for now...will trend toward vcsh/vcts during the
daytime heating hours to account for pop up diurnal
showers/storms.

&&

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

$$

SYNOPSIS...MK
NEAR TERM...MK/50
SHORT TERM...MK
LONG TERM....JAS
AVIATION...JP



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