Area Forecast Discussion
Issued by NWS Paducah, KY

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000
FXUS63 KPAH 012341
AFDPAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
640 PM CDT Fri Aug 1 2014

.UPDATE...
Issued at 640 PM CDT FRI AUG 1 2014

Revised aviation discussion for 00Z TAFs.

&&

.SHORT TERM.../Tonight through Sunday night/
Issued at 258 PM CDT FRI AUG 1 2014

In terms of sensible weather...not a whole lot of change is expected
in the short term. Weak high pressure will remain quasi stationary
just to our north...keeping a light northeasterly wind flow of
unseasonably dry air both at the surface and aloft. 850 mb temps
will change very little through Sunday...averaging around 15 c. Day
to day variations in our high and low temps over the next few days
will be small...determined mainly by variations in cloud coverage.

Despite the passage of a couple of 500 mb shortwave troughs...precip
chances will remain quite low in this dry air mass. A moderately
strong 500 mb trough will move southeast across the Mid Mississippi
Valley tonight. Latest radar and lightning data at 1930z shows a
band of showers and storms ahead of this trough from central IL to
east central MO. Based on radar and lightning trends...the hrrr
looks reasonable with a movement more east than southeast this
evening. Will raise pops a little higher into the chance category
from kmdh north and west this evening. The activity is forecast by
nearly all numerical guidance to weaken or dissipate around 06z.

With the mid level trough to our east on Saturday...the lift needed
for diurnal convection is tough to locate. Will maintain slight
chance pops over sw Indiana and the Pennyrile region of west
Kentucky...closer to the trough axis. Could not rule out a few small
cells west of there...similar to what is occurring this afternoon.
Will keep the forecast dry for Sunday in all areas...though a few
pinprick showers may again form with diurnal heating.

.LONG TERM.../Monday through Friday/
Issued at 258 PM CDT FRI AUG 1 2014

The PAH forecast area will initially be under the influence of weak
flow at the sfc and aloft, associated with an expansive swrn CONUS/
central Plains mid/upper ridge, which we are on the edge of. As
early as Tue, it is possible that a dying MCS or two moving through
the nwrly flow aloft may flirt with the nwrn counties, but the
relatively dry air in place should help reduce the likelihood of
them surviving in the PAH forecast area.

However...some of the latest deterministic guidance, which has
tended to flip-flop a bit, seemed to hint that some pcpn is possible
in the nrn and far ern counties by Wed. By that time, the ECMWF/GEM
showed a fairly well-defined baroclinic zone forming across the
upper Midwest and parts of the OH river valley, with the mid/upper
ridge holding over the PAH forecast area, and therefore dry. The 12Z
GFS indicated a more prominent longwave trof in the ern CONUS, with
lower heights over our region, and a generally wetter picture
overall. This limited chance of deep moist convection for the nrn
half will exist through Wed night. The initialization blend
suggested that pcpn chances should pick up a bit across the rest of
the region by Thu as the baroclinic zone gets closer to our region
and waves of low sfc pressure form along it. The boundary should
stay in our vicinity through at least Fri, with scattered showers
and tstms probable.

Dewpoints should be back to around 70 by Fri, along with near
average temps.

&&

.AVIATION...
Issued at 640 PM CDT FRI AUG 1 2014

The passage of a weak upper level wave will bring an increase in mid
level VFR cloudiness tonight. Will monitor scattered showers and
thunderstorms over southern Illinois and southeast Missouri through
the evening for any impact at local forecast terminals. However,
general thinking is that much of this activity should diminish
before reaching the terminals. Patchy fog may briefly restrict
visibilities at KCGI and KPAH late tonight. Otherwise, nearly calm
winds tonight will become northeast around 5 knots on Saturday.

&&

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

$$

SHORT TERM...MY
LONG TERM...DB
AVIATION...RJP





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