Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service northern Indiana
305 PM EDT Wednesday Jul 23 2014

Synopsis...
issued at 1200 PM EDT Wednesday Jul 23 2014

High pressure and northerly winds behind an exiting cold front will
bring cooler and drier conditions to the area through Friday. Lows
tonight will be in the middle 50s with highs tomorrow in the middle to
upper 70s.

&&

Short term...(this evening through thursday)
issued at 305 PM EDT Wednesday Jul 23 2014

Deepening cold/dry advection late this afternoon will bring any Post
frontal low stratus/patchy drizzle across southeastern zones to an
end by early this evening. Elsewhere into this evening...dry with
broken strato cumulus deck possibly slower to clear under subsidence
inversion given some added moisture flux off the lakes in
diminishing northerly flow.

40-50 meter 500 mb height falls expected locally tonight as
shortwave nearing the Ontario/Minnesota border drops southeast through the
lower lakes. This wave may spread some middle-high clouds into the
area...with strong middle-upper level subsidence in wake of this
feature allowing stable Canadian high pressure to build overhead
on Thursday. Low humidity, clearing skies, and below normal temperatures
will be the result with lows dropping into the 50s tonight...
recovering into the 70s tomorrow.

&&

Long term...(thursday night through wednesday)
issued at 305 PM EDT Wednesday Jul 23 2014

Another in a relentless series of Canadian origin anticyclones will
be sprawled across the Great Lakes/Ohio Valley to start the period Thursday night
west/another well below normal night of min temperatures expected. However again short
lived west/progressive wrly follow pattn maintaining across southern Canada west/next
potent SW trough of noted prognosticated to amplify southeastward over western Continental U.S.
Ridge Sat.

Expect building ll Theta-E ridge ahead of upper trough across the plains on Friday
to fold over into the western lakes Friday night in association/west Leading Ridge
rider shearing eastward. Given timing of middle level trough passage and eastward
arrival of sufficiently moist Theta-E plume have many doubts with respect to
precipitation chances and have cut prior grids substantially especially in light of
dry looking 12z consensus. Prospects appear better Sat night/sun
inadv of primary SW impulse digging sharply southeastward out of southern Canada.

Regardless another cool Canadian airmass expected to funnel south Sun
night through Tuesday west/well below normal temperatures rtng.

&&

Aviation...(for the 18z tafs through 18z Thursday afternoon)
issued at 1236 PM EDT Wednesday Jul 23 2014

Shallow Post frontal cooling/saturation under a strengthening
subsidence inversion has allowed for a low MVFR stratus deck to
linger over the terminals so far today. Diurnal heating and dry
advection in deepening northerly flow will allow cloud bases to rise
above fuel alt and become more broken shortly after taf issuance.
Moisture flux off the lakes in cool northerly flow may allow
scattered/broken VFR stratocu to linger into this evening and early
overnight. Otherwise...northerly winds 8-15 knots this afternoon
will diminish tonight as surface high pressure begins to build in.

&&

Iwx watches/warnings/advisories...
in...beach hazards statement through Thursday morning for inz003.

Michigan...Beach hazards statement through Thursday morning for miz077.

Ohio...none.
Lm...Small Craft Advisory until 8 am EDT Thursday for lmz043-046.

&&

$$

Synopsis...agd
short term...steinwedel
long term...T
aviation...steinwedel



Visit US at www.Weather.Gov/iwx (all lower case)

Follow US on facebook...twitter...and youtube at:
www.Facebook.Com/nwsnorthernindiana
www.Twitter.Com/nwsiwx
www.Youtube.Com/nwsnorthernindiana

National Weather Service Glossary of Abbreviations