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Area forecast discussion 
National Weather Service Jackson Kentucky
401 am EDT Friday Aug 22 2014

Short term...(today through saturday)
issued at 400 am EDT Friday Aug 22 2014

The latest surface map features surface high pressure across the Gulf
Coast states...with broadening low pressure across the plains. A
stationary frontal boundary extends east from the plains into the
Great Lakes/Ohio Valley. Aloft...an upper level ridge is currently
centered near Louisiana with its influence extending further north
into the Mississippi Valley. Troughing remains poised across the
western Continental U.S..

Thunderstorm complexes continue to general up on the northern periphery
of the ridge axis and then proceed to advance east-southeast across the Ohio
Valley. Currently...a weakening complex is skirting northeastern
Kentucky...likely clearing our forecast area in the next 2 to 3
hours.

The models remain in good agreement through the short term...with the
upper level ridge gradually amplifying across the Mississippi Valley.
Details associated with convective initiation continue to be
problematic however...and have stuck with a general model
blend...which favors more vigorous convection during the warmer part
of the day. Today looks to be somewhat of a repeat of
yesterday...with Stout instability building by early this afternoon.
While the mesoscale convective system track has shifted a bit further northeast today
compared to yesterday...outflow boundaries continue to be the main
player...leaving most locations in the line of fire at some point.
Some severe thunderstorms can not be ruled out once again
today...along with isolated flash flooding...where storms can align
along outflow boundaries parallel to the steering flow. Another hot
and humid day looks to be on tap...with a few spots nearing the 100
degree mark in heat indices.

Storms will gradually weaken into the evening hours...although some
nocturnal activity remains at least somewhat of a possibility. Lows
will be muggy once again around the 70 degree mark. Saturday will
feature another warm and humid day...along with the threat of more
scattered convection across the area. There will be less instability
available as middle-level warming takes place from the influence of the
upper ridge. This will keep the severe and flash flood threat lower.

Long term...(saturday night through thursday)
issued at 400 am EDT Friday Aug 22 2014

Upper level ridging will remain in play during the duration of the
extended...with heights expected to build as the high shifts neward
across the Ohio River valley. Building heights will then translate
to rising temperatures. However...middle and upper level winds will
generally remain out of the north during the first few days of the
extended. This...coupled with cloud cover that will hamper maximum
solar radiation...will keep highs in the middle and upper 80s through
Tuesday. Temperatures may then cool down a couple degrees after Tuesday as
high pressure sits overhead and upper level heights associated with
the ridge become more static.

Based on the latest forecast soundings...will agree with previous
forecast that each day should pose a shower/thunderstorm threat
mainly in the afternoon and evening. Given the middle level drying from
Monday on...wouldn/T be surprised if some of these storms produce
some potential hail. In promising news...with the ridging pattern in
place...we will experience no boundary forcing until very late in the
forecast...so this will hamper some of the best instability and
widespread initiation. Winds will be light at the surface...and
remain so as we head up higher into the atmosphere. That being
said...afternoon cape values will be above the 2k j/kg range through
much of the extended...and lapse rates will rise slightly by Tuesday/Wednesday
to 6 to 6.5 c/km...so afternoon heating and instability may be all
that is necessary for scattered cell development each day. A boundary
will finally push into the area by Thursday/Friday day 7/8 /per the latest
GFS model run/. This will bring a more widespread chance for rain and
thunderstorms across the area. However...there is quite a bit of
disagreement in the extended models this far out...so decided to lean
on the allblend for probability of precipitation at this time.

&&

Aviation...(for the 06z tafs through 06z Friday night)
issued at 159 am EDT Friday Aug 22 2014

A complex of thunderstorms will weaken as it skirts by across
northeastern Kentucky between 06 and 10z. This will likely affect a
line from ksym to ksjs between 07 and 09z. MVFR visibilities along
with some gusty northwesterly winds up to around 20 kts will
accompany the leading edge of the showers and storms. Expect MVFR or
worse fog will set in across the rest of the area through dawn...with
IFR or worse fog restricted to the deeper valleys...particularly
those that saw recent heavy rainfall. Once the fog Burns off through
around 13z...a renewed threat of convection will return...mainly
during the afternoon hours.



&&

Jkl watches/warnings/advisories...
none.
&&

$$

Short term...geogerian
long term...jmw
aviation...geogerian

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