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Area forecast discussion 
National Weather Service Indianapolis in
1025 am EDT Wednesday Aug 20 2014


The aviation section has been updated below.


issued at 335 am EDT Wednesday Aug 20 2014

A frontal system will stall out over the area for most of this week.
This will serve to keep the weather unsettled overall into the
weekend. This front may dissipate by early next week.


Near term /today/...
issued at 335 am EDT Wednesday Aug 20 2014

A wave aloft and frontal boundary which contributed to the severe or
near severe line of storms last night has since exited to the
southeast of the forecast area. Conditions should remain dry through
this morning...but expect fog to develop later this morning...and
possibly dense fog in some locations. Will need to monitor trends to
see if a Special Weather Statement or more is required.

As for the rest of today conditions look dry until later this
evening when another wave aloft moves across the area along the
meandering frontal boundary. Convection does not appear to get very
organized so will stick with chance/scattered probability of precipitation from after 18z
until midnight.

MOS has been overdoing temperatures past few days so went slightly
lower for highs in the middle to upper 80s. With dew points in the
upper 60s to low 70s conditions will still feel humid.


Short term /tonight through Friday night/...
issued at 335 am EDT Wednesday Aug 20 2014

As mentioned above...scattered chances for thunderstorms will be in
the forecast through his evening as the frontal zone lingers over
the area. Late tonight into early Thursday morning the warm
advection pattern gets better chances of convection
are probable during this time. In addition...models hinting at a
possible mesoscale convective system moving southeast into central Indiana from Wisconsin
after 06z Thursday morning. All of the short term guidance is keying
in on this feature so increased probability of precipitation across counties north of
Interstate 70 to likely from late tonight through early Thursday
morning. Storm Prediction Center does not have central Indiana in a slight risk anymore
at this time...however some of these storms could have the potential
to be strong as lapse rates/deep shear continue to look favorable
for storm organization. Will continue to monitor trends and
developments as there are still many questions as to exact location
and timing of this possible convection.

For the rest of the period...the deep shear diminishes with time
however the local area continues to be on the edge of a middle level
cap. As a result...additional convective clusters may be possible
into Friday with any possible disturbances that may ripple through
the flow. Will continue with chance probability of precipitation going into Friday.

Went slightly lower than MOS for highs based on persistence and at
or above MOS for lows based on clouds/precipitation chances.


Long term /Saturday through Wednesday/...
issued at 335 am EDT Wednesday Aug 20 2014

Models continue to depict perhaps the warmest stretch of the season
thus far for the coming weekend as an upper level ridge strengthens
over the lower Mississippi and Ohio valleys. This may be the closest
call yet this Summer for the elusive 90 degree mark at Indianapolis.
That said...several factors will have a hand in determining whether
or not we get there. While Summer began on quite a wet note with one
of the top 15 wettest junes...which has likely contributed at least
in some small part to the lack of heat thus far...the atmosphere has
reversed itself somewhat since the start of July...and Indianapolis
is roughly two to two and a half inches below normal on precipitation since
then...or around the same amount that June was above normal.
However...the guidance depicts a moist airmass with dewpoints
pushing the low to middle 70s at times. Additionally...while the
forecast will only carry probability of precipitation into Saturday night.../and again late
in the period as the ridge breaks down and temperatures
moderate/...the periphery of the ridge...where convection may occur
in a ring of fire style...and the corridor where any organized
convective complexes may track...will not be that far north of the
area...and this could complicate matters as well. If some diurnal
convection manages to occur despite the quite warm midlevel
temperatures pushing 10 to 12c...that would also potentially work
against the heat. Will be interesting to see how close we get to 90
or if we manage to finally breach the mark. If it occurs this will be the latest first 90 degree day since
1960...when 90 was not reached until September first. This is of
course excluding 2004...the only year on record thus far without a
90 degree reading.

It is Worth noting that the European model (ecmwf) ensemble MOS is quite warm...a few
degrees above what will be the official forecast numbers. GFS
ensemble MOS means are much cooler and with much lower Standard
deviation. Will be curious to see how each performs...but the
significant spread in the European model (ecmwf) MOS does not inspire confidence at
this time.


Aviation /discussion for the 20/15z kind taf update/...
issued at 1025 am EDT Wednesday Aug 20 2014

Fog has just about cleared out at kind taf. Otherwise...made minor
tweaks to kind taf.

Portion of previous aviation discussion follows...
expect little beyond some scattered fair weather cumulus today and
the early part of the evening. Thunderstorm activity may impact the
sites from late evening on...but for now will only include a thunderstorms in the vicinity
mention as timing and impacts at any one site are extremely
uncertain for now.

Winds will be out of the west around 10 to 12kt today...becoming
south/southwesterly tonight.


Ind watches/warnings/advisories...none.



near term...smf
short term...smf
long term...nield

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