Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 250416
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1216 AM EDT SAT JUN 25 2016

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

&&

.SYNOPSIS...
Issued at 246 PM EDT Fri Jun 24 2016

High pressure will bring dry and less humid weather to central
Indiana through Saturday. Heat and humidity will briefly return for
Sunday ahead of a cold front that will bring scattered thunderstorms
Sunday and Sunday night. Cooler and drier weather is expected for
most of the first half of next week...followed by a stormy and more
unsettled regime for late week as low pressure and an upper
level wave track through the Ohio Valley.

&&

.NEAR TERM /Rest of Tonight/...
Issued at 940 PM EDT Fri Jun 24 2016

.Update...Drier air was slowly spreading south across our forecast area.
However a few sites in our far south still had dewpoints in the 70s and
have added patchy fog late tonight from Lawrence county to southern
Jennings county.  Otherwise...the current forecast is on track and no
other changes are needed with mostly clear skies overnight.

Portion of previous near term discussion follows...Skies are expected to
be mainly clear overnight with perhaps just some passing cirrus.
Surface flow will gradually veer to light easterly towards daybreak
as the surface ridge shifts into the eastern Great Lakes.

Temps...Largely trended towards the cool end of guidance for lows as
the combination of light winds and clear skies should support near
ideal radiational cooling conditions for most. The predominant E/NE
flow overnight will likely keep KIND warmer as modified air off of
the urban heat island drifts over the airport.

&&

.SHORT TERM /Saturday through Monday/...
Issued at 246 PM EDT Fri Jun 24 2016

Forecast challenges focus on convective chances for Sunday and the
first part of Monday as a cold front tracks across the Ohio Valley.

The surface ridge will remain a dominant influence as it shifts to
the East Coast for Saturday and Saturday night...maintaining a dry
easterly component to the low level flow. Cu will largely be limited
with convective temps near 100 and unreachable. Expect abundant
sunshine with warm temperatures and continued lower humidity as
dewpoints bottom out in the upper 50s and lower 60s over all but the
lower Wabash Valley.

The front that tracked through the region Wednesday and Thursday and
now currently resides over the Tennessee Valley will become a factor
once again for late weekend as it is drawn back north late Saturday
and early Sunday in response to strengthening low pressure over the
northern Plains. The warm front will lift back into the region
Sunday morning but in the absence of more substantial lift...hard to
justify more than just low chance pops as it tracks north through
the region.

The bigger impact from the passage of the warm front will be to
bring a resumption of the very warm and muggy conditions of the last
few days for much of Sunday. This will certainly be a factor as the
cold front associated with the aforementioned low approaches central
Indiana late Sunday. Modest instability with MLCAPEs in excess of
3000 J/KG will be present as dewpoints surge back into the 70s with
precip water values recovering to back above 2 inches. The threat
for strong to severe storms Sunday afternoon and evening is
present...but the threat will largely hinge on the moist unstable
airmass...outflow boundary interactions and available forcing via
the cold front. With the low displaced well to the north...forcing
aloft and BL shear are overall weaker than desired for a more
substantial severe threat. More than likely...expect more of a pulse
intensity to convection with a lack of organization due to the
limiting factors mentioned above. Locally damaging winds from
collapsing downdrafts...frequent lightning and torrential rainfall
may serve as the primary impacts from storms. Will carry highest
pops Sunday afternoon and evening...gradually ending rain from the
northwest overnight as the front shifts east.

High pressure will quickly build into the area behind the front for
Monday. Held onto low chance pops Monday morning in southern
counties to account for any lingering convection. May need to insert
pops again by late day Monday as a secondary front approaches with a
more amplified upper trough. This front will usher in a cooler and
much drier airmass in the days that follow. Despite a lack of low
level moisture...the front may produce just enough lift to generate
isolated convection during the late afternoon and evening. Will
continue to monitor.

Temps...trended at or just above MOS for highs Saturday and Sunday.
Should see highs into the upper 80s to low 90s Saturday with lower
90s for most on Sunday. Max heat indices will once again rise into
the upper 90s to around 100 Sunday afternoon with the return of the
deeper moisture. Highs will cool slightly into the mid and upper 80s
Monday with more pronounced cooling thereafter. Took a MOS blend for
lows through the period.

&&

.LONG TERM /Monday night through next Friday/...
Issued at 215 PM EDT Fri Jun 24 2016

Ensembles in good agreement in retrogression of the heat ridge
back into the southern rockies next week as upper troughing
develops over the eastern parts of the country.

Ensembles continue to suggest an upper wave may drop southeast
into the local area from the northern Plains around next Thursday.
Will keep some PoPs in the forecast from Wednesday night through
next Friday to cover this feature. Prior to the arrival of this
feature, ensembles suggest little threat for precipitation before
Wednesday night.

&&



.AVIATION (Discussion for the 250600Z TAF Issuance)...
Issued at 1216 AM EDT Sat Jun 25 2016

MVFR conditions expected at some outlier sites around
sunrise...otherwise VFR.

Drier air is slowly making its way southwest. Still looks like it
will make it into KLAF in time to prevent fog formation, but
confidence is lower. Easterly flow from the city should keep KIND
fog free. The other sites will have enough moisture for MVFR fog
around sunrise.

Any fog will burn off quickly leaving VFR conditions for Saturday.

&&

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

&&

$$

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



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