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Area forecast discussion 
National Weather Service northern Indiana
741 PM EDT Tuesday Sep 1 2015

Synopsis...
issued at 345 PM EDT Tuesday Sep 1 2015

Scattered showers and thunderstorms are possible through the
evening and overnight as an upper level disturbance moves through
the area. Isolated afternoon showers and thunderstorms will then
be possible through the end of the week with hot and humid
conditions in place. Highs will be middle to upper 80s with lows in
the middle to upper 60s.

&&

Short term...(this evening through wednesday)
issued at 345 PM EDT Tuesday Sep 1 2015

Pesky compact midlevel vorticity maximum continues to swirl across central
Indiana this afternoon with little forward momentum. Dewpoints in
the low 70s supporting some decent SBCAPE per Storm Prediction Center/rap mesoanalysis
despite very poor lapse rates aloft. DPVA in the presence of this
instability is generating some scattered convection...with the highest
coverage in our south closer to the height anomaly and along remnant
outflow from morning convection. Expect this activity to continue
through the evening but should wane with the loss of daytime
heating.

Main line of convection to our west/SW this morning was actually being
driven by focused 305k isentropic upglide on the backside of
midlevel circulation. Some of the latest models (both hi-res and
otherwise) show this area of enhanced ascent and moisture
convergence with 20-25 knots low level jet setting up again over at least our
southeast counties later tonight...prompting continued low chance
probability of precipitation in our east through tomorrow. Coverage highly questionable
given weak forcing and instability so will maintain just slight
chance probability of precipitation for now. No severe weather expected with any of this
activity given limited updraft potential and virtually no flow
aloft. Corollary to this is that any convection that does manage to
develop and persist will move very slow and could lead to locally
heavy rainfall.

Other main story will be the heat and humidity. Highs tomorrow
expected to be a few degrees warmer than today...approaching 90f.
With dewpoints in the low 70s once again...heat indices will likely
approach the middle 90s.

&&

Long term...(wednesday night through tuesday)
issued at 345 PM EDT Tuesday Sep 1 2015

Hot and humid conditions to dominate the region through the upcoming
Holiday weekend and beyond with only minimal chances for needed
rainfall.

Upper level ridging will continue to influence the region into
Friday with a series of weak disturbances riding its periphery. One
of these is poised to move NE out of plains and then drop southeast into
the western Great Lakes Thursday and lingering into Friday. NAM/GFS
soundings suggest we should be uncapped with at least low to
moderate instability around. Wild card will be amount of surface
convergence associated with this feature and its ability to spark
isolate to maybe scattered convection. Will be keeping probability of precipitation subdued for the
time being in the slight chance to low chance category during the
afternoon/evening hours.

By Saturday...medium range models all agree on 588 dm or higher upper
level heights nudging into the region and holding tight into Monday.
This will result in highs well into the 80s and possibly around 90
with heat indicies into the 90s. Deep low pressure will move into
the western states Saturday and make an attempt to break down the
ridge for the start of next week. European model (ecmwf) does suggest a weak
disturbance well south of the main upper low that could bring an
outside chance of a afternoon/evening shower or storm to the area
Tuesday.

&&

Aviation...(for the 00z tafs through 00z Wednesday evening)
issued at 735 PM EDT Tuesday Sep 1 2015

Isolated thunderstorms have avoided both terminals this evening
and that trend appears to continue overnight. Dewpoints in the low
70s lends some concern for fog potential overnight...but it
appears SW winds will be just strong enough to keep fog
development at Bay. This is supported by latest rap and hrrr which
keep visibilities p6sm all night. Decided to keep tempo 4sm br
mention in the taf given the aforementioned moist low level
dewpoints. Otherwise...a few showers and thunderstorms are
possible later tonight across central Indiana as the low level jet
strengthens...but these should stay south of kfwa. Showers and
thunderstorms on Wednesday will likely be even more widespread
than today...so have not included any mention in this taf
issuance.




&&

Iwx watches/warnings/advisories...
in...none.
Michigan...none.
Ohio...none.
Lm...none.
&&

$$

Synopsis...agd
short term...agd
long term...Fisher
aviation...Bentley



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