Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 020836
AFDPAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
336 AM CDT Tue Sep 2 2014

.SHORT TERM...(Today through Thursday)
Issued at 336 AM CDT TUE SEP 2 2014

A frontal boundary approaching the region from the plains this
morning is forecast to drop into our CWA today, become
quasi-stationary from E-W across the CWA tonight, then lift back to
the northeast as a warm front on Wednesday.

As a result, shower and thunderstorm coverage will increase from the
west this morning, then taper off from the west this afternoon as
the deeper moisture shifts to the east. In the meantime, with
precipitable water values remaining high (>=2 inches), locally heavy
rainfall is expected with the stronger storms today. Per soundings not
much directional shear available, but there is decent speed shear,
so a few storms may become near severe, but no widespread severe
weather is expected.

Late tonight there may be overrunning/warm air advection
precipitation over the southwest sections of our CWA. Wednesday as
the boundary lifts back across the area, precipitation chances
should spread northeast across the entire CWA.

Wednesday night into Thursday our CWA will be in the warm sector
with models showing weak ridging aloft. Feel leaving precipitation
out Wednesday night is a safe bet, but on Thursday with lack of
deep moisture combined with the ridging aloft, an isolated storm
or two could pop up just about anywhere in the heat of the day,
but at this point it is too difficult to pinpoint where, so
decided to leave precipitation out at this time.

Temperatures starting out near normal (low to mid 80s) at the
beginning of the period will warm into the lower 90s by the end of
the period. Unfortunately dew points will remain in the mid 60s to
lower 70s through the period, so no relief in sight from the high
humidity of summer.

.LONG TERM...(Thursday night through Monday)
Issued at 336 AM CDT TUE SEP 2 2014

The PAH forecast area will be under the influence of the weak
anti-cyclonic flow of a mid/upper ridge late in the week. However,
plenty of moisture and instability in the lower trop will make isold
to scattered showers and tstms possible Fri as the ridge aloft
begins to be suppressed by a longwave nrn stream trof sinking into
the central/ern CONUS. As a cold front approaches the region from
the north, pcpn chances will continue to increase Fri night.

In fact, the cold front is progged to enter the nrn half of the
region by then. Highest PoPs will be after 12Z Sat for most of the
region as it appears that most pcpn will be post-frontal. The
GFS/ECMWF ensemble means now seem in better agreement with the
strength and ewd movement of the sfc high sinking swd into the
central CONUS behind the cold front. The operational GEM does not
show the high being as strong, and therefore continues to lag the
cessation of pcpn through Sat night compared to the GFS and ECMWF.
We will leave PoPs in primarily the srn half of the region for now.

Sunday and Mon are expected to be dry and noticeably cooler...with a
drop of around ten degrees compared to Fri, and a nrly to nerly
breeze. Say goodbye to 70s dewpoints for a little while.

&&

.AVIATION...
Issued at 336 AM CDT TUE SEP 2 2014

Main aviation concern is the complex of thunderstorms entering
southern IL and southeast MO as of midnight. These storms are
associated with an upper level disturbance that will move east
overnight. The storms should hold together overnight as they feed on
a moist southwest low level jet from 35 to 45 knots at 850 mb. The
time frame for their passage at the taf sites is mainly 08z to 13z.
Some storms could develop over the kevv/kowb area even earlier than
that.

Once the storms exit the region...broken cumulus clouds will bubble
up with daytime heating. Bases should rise from mvfr to vfr levels
by noon or so. Skies will then become mostly clear with loss of
daytime heating around sunset.

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
MO...NONE.
IN...NONE.
KY...NONE.
&&

$$

SHORT TERM/AVIATION...JP
LONG TERM/FIRE WX...DB







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