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Area forecast discussion 
National Weather Service northern Indiana
204 am EDT Thursday Sep 3 2015

issued at 155 am EDT Thursday Sep 2 2015

A series of upper level disturbances will track across the Great
Lakes and Ohio Valley regions today and tonight resulting in
isolated to scattered showers and thunderstorms...especially this
afternoon into this evening. Otherwise...very warm and humid
conditions will persist through the rest of the week. Highs will
be in the middle to upper 80s. Lows will be in the middle to upper 60s.


Short term...(this evening through thursday)
issued at 413 PM EDT Wednesday Sep 2 2015

A weak upper level system moved through earlier this morning and
deposited some outflow boundaries from earlier convection.
Afternoon heating had allowed convective available potential energy to rise to between 3000 and
3500 j/kg according to storm prediction mesoscale analysis of cape
values. Middle level lapse rates between 5.0 and 5.5 c/km were very
stable...and low level wind shear was very limited. Expect storms
late today and early tonight to be of the pulse type and highly
diurnal with this environment. Wind gusts around 45 miles per hour over
Northwest Ohio were reported from earlier convection. Given the
latest Storm Prediction Center downdraft cape values between 1100 and 1400 j/kg...wind
gusts to 50 miles per hour are possible through early tonight. Otherwise...
storms should dissipate tonight...and then redevelop Thursday as
an upper level system moves into the area. The best chance for
rain will be late in the afternoon with daytime heating.
Temperatures will rise into the 80s again Thursday.


Long term...(thursday night through wednesday)
issued at 413 PM EDT Wednesday Sep 2 2015

No major shifts in the weather pattern into the weekend as strong
high pressure will control the region. Afternoon highs well into
the 80s combined with dewpoints in the middle 60s to near 70 will
set the stage for unstable conditions with little in the way to
prevent convection from firing Friday into Saturday. Although
there won't be any clear forcing mechanism...the risk will
nonetheless be there for hit and miss showers or storms. Will
maintain the afternoon/evening mention for this period.

Models are trending towards a slower arrival to the cooler and less
humid air into the region as the first wave set to approach Monday
essentially hits a brick wall and moves northwest of the region.
Showers and storms will likely accompany this feature but how far
into the area they will make it seems more in question. For
continuity sake will keep chance probability of precipitation going with trends potentially
dictating lowering/removal in later forecasts. More Stout system set
to move in by Wednesday with a deeper trough and better chance to at
least dampen the ridge and bring somewhat better chances for showers
and storms. Will go with chance probability of precipitation for now. As noted...cooler weather
will hold off till at the end of the period with continuation of
above normal temperatures and muggy conditions.


Aviation...(for the 06z tafs through 06z Thursday night)
issued at 155 am EDT Thursday Sep 3 2015

A series of upper level short waves progressing through the upper
ridge across the area will result in scattered thunderstorms
across the area later today...particularly in the 18z-03z
timeframe. Greatest coverage this afternoon is expected across far
northern Indiana/Southern Lower Michigan...with better chances of
storms gradually shifting across remainder of northern Indiana
late afternoon/early evening. At this time have not made any
changes to prob30 thunderstorms and rain groups for both terminals...and will need
to assess the need for the 12z tafs of possibly including tempo
thunderstorms and rain this afternoon. More spotty showers/storms are possible this
morning as large scale forcing continues to slowly increase along
with weak low level thetae ridge nosing back into the area. In
addition...patchy fog continues to develop early this morning and
have made no changes to MVFR ceilings at terminals in the 08z-12z


Iwx watches/warnings/advisories...


short term...skipper
long term...Fisher

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