Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 260454

Area Forecast Discussion
National Weather Service Paducah KY
1154 PM CDT THU AUG 25 2016

Issued at 1153 PM CDT Thu Aug 25 2016

The AVIATION section has been updated for the 06Z TAF issuance.

UPDATE Issued at 838 PM CDT Thu Aug 25 2016

The dominance of the ridge is showing up as convective elements
over the WFO PAH CWA and southward are decaying rapidly this
evening in the presence of drier air is advected into the area at
low to middle levels from the southwest. Higher level moisture is
still being advected northward from NW Louisiana and Arkansas from
convection in that area. The NAM-WRF (NMM version) and the ESRL
HRRR high resolution model guidance appear to be initializing the
best with the evolution of convection for the remainder of
tonight. This effectively shifts any chances for thunderstorms
away from Southeast Missouri until daybreak. Ripples of vorticity
and long with deeper columnar moisture will work into Southeast
Missouri, Southern Illinois, and the Purchase area of West
Kentucky by Friday afternoon. However, the best lift will remain
over Southeast Missouri and Southern Illinois late Friday morning.
The best chances of rain should persist there as well.


.SHORT TERM...(Tonight through Saturday night)
Issued at 218 PM CDT Thu Aug 25 2016

Dry across the CWFA, hot and humid this p.m. with convection along
our southern CWFA boundary into MO bootheel, NE AR and NW TN.
Expect a mainly dry evening overall. After midnight, as moisture
comes around the west side of a mid level high over the SE U.S. we
have a slight chance of convection into our western counties
(SEMO, SRN IL). This in conjunction with a weakening boundary
moving SSE into the area.

The boundary will essentially wash out across the region, with a
subtle uptick in overall moisture on the west side of the
aforementioned high. Therefore some chance PoPs in the forecast
Friday through Saturday night, slightly higher during the
afternoon and early evening. Spatially, slightly higher PoPs NW of
the Ohio vs. west KY. Models still struggling somewhat with the
fine scale details. So am playing the PoPs more in line with
synoptics and best placement of moisture. Temps will be a
persistence forecast blended with MOS.

.LONG TERM...(Sunday through Thursday)
Issued at 218 PM CDT Thu Aug 25 2016

Confidence remains on the low side with the extended due to model

In contrast models do agree on upper level ridging dominating the
extended. The GFS indicates a very dirty 500mb ridge...while the
ECMWF has much cleaner and climatological scenario. Not necessarily
the correct one but neater just the same. Will definitely focus
storm chances in a diurnal or maximum heating the ECMWF
would suggest. This will depend heavily on collaboration and the
extended init of course. Sunday appears to be the best chance for
diurnal storms as the upper level ridge drifts eastward to the
Atlantic coast before retrograding back west through the week.
In the afternoon hours will be our best chances as surface
instability is favorable for storm development. surface based
CAPE`s are topping out around 2k j/kg/2 and surface based LI` well
into the negatives. Elevated index values are border line but
favorable for mainly afternoon storms. Finally toward the end of
next week...if the ridging truly moves west it will force the
tropical disturbance to take a more easterly route as the ECMWF is
currently advertising.

As for temperatures highs will be slightly above normal or around 90
with lows about nearly 10 degrees above normal or around 70. Dew
points will average 70 to 75. So the muggy conditions are expected
to prevail.


Issued at 1153 PM CDT Thu Aug 25 2016

The 00Z guidance has trended drier for the early morning period,
so confidence is increasing in at least IFR fog at KCGI and KPAH.
Just to muddy the works a bit, there is some signal for a LIFR
ceiling at both of these sites. The 00Z guidance supports more of
a diurnal convective threat, but continues to keep it southwest of
KEVV and KOWB. Winds will be light and generally from the
southeast through the period.


.PAH Watches/Warnings/Advisories...


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