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Area forecast discussion 
National Weather Service northern Indiana
138 am EDT Tuesday Jul 22 2014

Synopsis...
issued at 344 PM EDT Monday Jul 21 2014

Hot and humid conditions will move into the area over the next 24
hours ahead of a cold front. This front will bring a chance for
showers and thunderstorms late Tuesday night into Wednesday
followed by cooler and less humid air. Lows tonight will fall
into the middle to upper 60s. Highs will climb to around 90 on
Tuesday.

&&

Short term...(this evening through tuesday)
issued at 344 PM EDT Monday Jul 21 2014

Yet another short term period with no significant weather concerns
as general East Coast ridge gives only slightly through the period.
A trough will move out of the plains towards the northern parts of
the Great Lakes and attempt to amplify some as it approaches. A cold
front will work towards the region...however any impacts will hold
off until outside this forecast period.

Much more Summer like temperatures and humidity will be in store tonight
into Tuesday as nose of 850 mb temperatures over 20 c will edge in during
the day Tuesday yielding highs around 90. While unstable conditions
will exist...strong capping will exist at 700 mb with temperatures climbing
to 12 to 14 c especially in western areas keeping any convection
away and limiting cumulus development. Heat indicies will climb into the
middle and possibly upper 90s...making it feel quite uncomfortable
but not worthy of any headlines.

&&

Long term...(tuesday night through monday)
issued at 344 PM EDT Monday Jul 21 2014

Chances of showers and thunderstorms Tuesday night into early
Wednesday...followed by period of cooler temperatures once again
will continue to be the main items of interest for the long term.

Fast moving eastern Pacific vorticity maximum is expected to progress through
mean western Continental U.S. Ridging Tuesday night...and eventually phase with
broader Hudson Bay negative upper height anomaly. Lack of impressive
deep moisture profiles initially on Tuesday evening should keep cin
in place for bulk of County Warning Area given warm middle level profiles associated
with plume of steeper middle level lapse rates. By later Tuesday
evening into Tuesday night...veering low level flow should finally
begin to advect axis of Richer low level moisture eastward across
the western Great Lakes region. This could be sufficient to overcome
capping concerns for 900-800 hpa based parcels. Axis of greatest
instability should still lag to the southwest across the middle MS
River Valley and with westerly low level jet ramping up somewhat
overnight...any upstream convection should tend to exhibit some
upwind propagation characteristics. Given above...greater
probability of showers and storms should remain west and north of
local area Tuesday night. Will keep low to middle chance going mainly
across the northwest half with some potential of upstream convection
propagating south/southeast into local area.

Dprog/dt over past few days continues to depict a faster cold
frontal progression into local area Wednesday. Forecasted frontal
timing still suggests best diurnally enhanced rain showers/thunderstorms and rain chances
especially across southeast half or third of the area Wednesday
afternoon. Limiting factors to coverage will be increasingly sheared
nature to middle level forcing across the Great Lakes...and relatively
narrow/progressive axis of deeper moisture. Have maintained just a
slight chance of showers across the far southeast into Wednesday
evening...but bulk of precipitation should be southeast of area by 00z
Thursday.

Low level anticyclone to build back into the area Wednesday night
into Thursday to provide dry conditions through Friday along with a
return of slightly below normal temperatures. Not much change to the
remainder of forecast with more amplified eastern Pacific trough
dampening western Continental U.S. Upper ridge by Saturday. This will make
local area prone to series of small scale waves riding over this
ridge with periodic warm/moist advection forcing. Some indications
in Gem of precipitation chances starting as early as later Friday night in
this pattern...but given lingering dry low level air mass will
continue to hold off probability of precipitation until Saturday. Magnitude of instability
also somewhat in question...but will keep broadbrush chance
rain showers/thunderstorms and rain probability of precipitation going for the Saturday through Monday period. After
some moderation to lower 80s possible for the weekend...medium range
models continue to hint at cooler conditions toward end of period as
aforementioned more amplified upper trough digs into the Great Lakes
region.

&&

Aviation...(for the 06z tafs through 06z Tuesday night)
issued at 135 am EDT Tuesday Jul 22 2014

Generally VFR conditions expected at the terminals through the
period. Light winds/clear skies should lead to some radiational
cooling br by morning... but visibilities expected to only briefly fall to
MVFR at worst at the terminals. S-SW flow will increase during the
day as a cold front currently over Minnesota-South Dakota moves E-se. Middle-upper level ridge
will move across northern Indiana in advance of the cold front today resulting
in mainly clear skies. The cold front is expected to move across the
area tonight. Residual warm middle-upper level temperatures associated with
the ridge should limit deep convection along the front despite
decent low level convergence as it moves through our area... so
opted to hold off adding thunderstorms and rain to tafs at this time for this evening... though
some potential exists.

&&

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

$$

Synopsis...Fisher
short term...Fisher
long term...marsili
aviation...jt



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