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Area forecast discussion 
National Weather Service northern Indiana
746 PM EDT Thursday Jul 24 2014

issued at 745 PM EDT Thursday Jul 24 2014

High pressure and northerly winds will bring cooler and drier
conditions to the area through Friday. Lows tonight will drop into
the lower and middle 50s. Highs on Friday will be in the upper
70s. There is a chance for showers and thunderstorms from Friday
night through the weekend.


Short term...(this evening through friday)
issued at 305 PM EDT Thursday Jul 24 2014

Fair/low humidity weather will persist into tonight-Friday morning as a
1022 mb surface high folds southeast over the area tonight and toward
the middle Atlantic on Friday. Surface dewpoints already mixing out into
the upper 40s/low 50s this afternoon...and ideal radiational cooling
tonight...will support relatively cool min temperatures for late July.

Northwest flow aloft will dampen into Friday as a ridge flattening negative
height anomaly translates east into southern Saskatchewan by 18-00z.
A weak lead perturbation in semi-zonal flow downstream and ramp up
in low level jet in advance of Lee side trough should trigger convection
across the upper Midwest/Iowa later tonight-Friday morning...likely
drying up with southeastward progression thereafter into dry/stable air.
Still could see a shrinking area of high based showers survive into
our far western zones by late Friday afternoon given developing
return flow/7h Theta-E advection on backside of high.
Otherwise...expect an increase in middle-high level clouds tomorrow
with highs into the upper 70s.


Long term...(friday night through thursday)
issued at 305 PM EDT Thursday Jul 24 2014

Potent SW over southern British Columbia this afternoon will pinwheel eastward into Sat before
merging west/deep upper trough developing eastward of James Bay in response to
dramatic upstream blocking developing through western Canada thanks in part
to typhoon matma.

As this evolution takes air of late will erode rapidly
as SW follow deepens ahead of a developing frontal boundary from the upper Midwest southwestward
through the plains. Eastward fold of sig ll Theta-E ridge and eastward advection
of Stout eml point to potential for severe weather later Sat and again on
sun. But as yet still very uncertain tied to timing of southeastward
dig of absorbing southern Canada disturbance...positioning of surface frontal
boundary and northeastward extent of ll moisture rtn. Will continue west/general Middle Range
chance probability of precipitation Sat afternoon through sun.

Otrws another unseasonably cool airmass to again overspread the
lakes/Ohio Valley early next week as amplified blocking pattn more Akin
to middle winter takes shape across noam. Temperatures much below normal expected
Monday-Tuesday before moderating thereafter.


Aviation...(for the 00z tafs through 00z Friday evening) issued
at 745 PM EDT Thursday Jul 24 2014

VFR conditions expected through the period as high pressure slowly
moves east. Light or calm winds tonight will become southwest
around 10 knots Friday.


Iwx watches/warnings/advisories...


short term...steinwedel
long term...T

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