Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 220812

Area Forecast Discussion
National Weather Service Indianapolis IN
412 AM EDT Tue May 22 2018

Aviation section updated


Issued at 254 AM EDT Tue May 22 2018

A cold front will move through the area today, bringing another
chance for showers and thunderstorms. High pressure will then
provide dry conditions through early Saturday. Another front and
upper system will bring rain chances Sunday into early next week.
Temperatures will remain above normal.


.NEAR TERM.../Today/
Issued at 254 AM EDT Tue May 22 2018

Early this morning low pressure was across north central Illinois. A
front stretched east from the low across northern Indiana as well as
southwest from the low through Illinois. Dense fog was north of the
front across northern Indiana and northeast Illinois.

The dense fog should remain north of the forecast area early this
morning with the front remaining north.

The low will work slowly east today and drag the front through the
area. There will be some weak upper support with a weak upper trough
moving through and a weak upper jet.

The Storm Prediction Center`s mesoscale analysis shows some elevated
CAPE available already this morning, and heating today will provide
additional instability.

Thus expect some scattered showers and thunderstorms to develop
along and ahead of the front today. Will go slight chance to chance
category PoPs today, with the highest PoPs across the eastern half
or so of the area this afternoon when the best instability will be
available. Not expecting any severe storms though.

Went a little above the model blend for highs, closer to the MAV
MOS. The warmer MAV MOS has been doing better with temperatures


.SHORT TERM.../Tonight through Thursday night/
Issued at 254 AM EDT Tue May 22 2018

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

The short term will be quiet with surface high pressure building in
and upper ridging developing aloft.

Thus expect mostly clear skies most areas. Went a little above the
model blend for highs Wednesday based on recent trends. Otherwise
the initialization`s numbers are decent.


.LONG TERM /Friday through Monday/...

Issued at 224 AM EDT Tue May 22 2018

Confidence is low in this forecast period.

The ECMWF suggests ridging aloft on Friday deteriorating to a
weak trough by Saturday and Sunday. However...little to no upper
support appears to push across Indiana. Best forcing remains
across the northern Great Lakes and Ontario. Meanwhile...the ECMWF
suggests a tropical upper low moving onshore into the lower
Mississippi valley by Saturday before moving to Western Tennessee
by Monday. For the most part...Indiana remains caught between
these two systems until Monday when the upper low to the south
begins to arrive.

Given the lack of support on Friday through Sunday...only triggers
at this point appear to be diurnal convection due to daytime
heating. Best chances here appear to be Sunday afternoon and there
after as models suggest a return of moisture as dew points surge
into the 60s. Thus removed many 20% pops from the forecast
builder...trending toward dry for Friday-Saturday. Kept 30 pops in
for Sunday afternoon for now...but again...confidence remains low.
best chances remain to be on Monday as the upper low to the south
begins to influence weather across Indiana.


.AVIATION /Discussion for 220900Z IND TAF update/...

Brief MVFR fog will be possible this morning as dew points
depressions have approached zero. When Heating and mixing
resume...a quick return to VFR is expected. Again as showers may
develop along ands ahead of the front...thus VCTS and MVFR with
any TSRA that strikes a TAF site after 15Z.

Previous Discussion Below

/Discussion for the 22/06Z TAF Issuance/...

Issued at 1152 PM EDT Mon May 21 2018

VFR conditions will prevail early tonight. However, MVFR (or
worse) conditions are expected in the predawn hours along with
possible redevelopment of showers and thunderstorms with frontal
boundary. MVFR category will then persist through the morning
hours before VFR returns for the remainder of the TAF period.
Meanwhile, winds will start out southerly, gradually veering to
the northwest with sustained speeds of 4 to 8 kts.




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