Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus63 kind 221052 

Area forecast discussion
National Weather Service Indianapolis in
652 am EDT Tue may 22 2018

the aviation section has been updated below.


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 European model (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 European model (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 the 221200z taf/...

Issued at 651 am EDT Tue may 22 2018

Patchy dense fog this morning has led to some IFR or worse
conditions this morning due to visibility. As daytime heating and
mixing resumes...a quick return to MVFR or better is expected.

A cold front will sweep across the taf sites through 18z. A few
showers along and ahead of the front will be possible and may
impact the taf sites. Radar indicates some of this shower
development already northwest of laf. Due to low confidence of specific
timing...used thunderstorms in the vicinity for a window through approximately 18z at most
locations. Any thunderstorms and rain that strikes a taf site may result in brief
MVFR or worse conditions.

In the wake of the front...a return to VFR conditions is expected
as high pressure builds across the area. Forecast soundings
suggest a dry column at that point and time heights show


Ind watches/warnings/advisories...


National Weather Service Glossary of Abbreviations