Area Forecast Discussion
Issued by NWS Paducah, KY

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000
FXUS63 KPAH 252327
AFDPAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
627 PM CDT Sat Oct 25 2014

.UPDATE...
Issued at 627 PM CDT SAT OCT 25 2014

Updated Aviation section for 00Z TAF Issuance.

&&

.DISCUSSION... /ISSUED 314 PM CDT Sat Oct 25 2014/

SHORT TERM...(Tonight through Tuesday)
Issued at 314 PM CDT SAT OCT 25 2014

A weak surface front has pushed through the region today. The main
impacts were northwest winds and some drying across the northern
half of the area. The northwest winds actually brought warmer low-
level air across the region, so would be hesitant to call it a
cold front. Anyway, this boundary will become stationary tonight,
leaving light winds and clear skies across the region.

The statistical guidance is hammering on dense fog development in
the better moisture over southeast Missouri...much of west
Kentucky and adjacent portions of southern Illinois. Am somewhat
concerned for low cloud development in this moist environment, so
will only mention patchy dense fog in the grids and give it a
mention in the HWO for now. If confidence increases this evening,
then a Dense Fog Advisory may be necessary.

Winds will be veering to the southeast Sunday, and there is some
conflict in temperature guidance. The NAM/MET is several degrees
cooler east of the Mississippi than the GFS/MAV. Given today`s
warmth, figure the MAV is the way to go. South winds over 5kts are
expected to persist through Monday night, and that should lead to
a mild night. Generally went a bit above consensus guidance for
lows.

Monday will be breezy and quite warm ahead of our next weather-
maker. Went closer to the warmer GFS/MAV guidance again for highs.
Much of the area will push the middle 80s. Strong south southwest
winds will continue through Monday night, so went above
statistical guidance for lows again.

Our next storm system will push a cold front and area of convection
eastward into the area between 06Z and 12Z Tuesday. The 12Z ECMWF
and GFS are in decent agreement in bringing the convection to near
the Wabash and Ohio rivers by 12Z Tuesday. The front and
convection will then push eastward through the remainder of the
area into Tuesday afternoon. The front will become more aligned
with the upper flow as it gets to the KY/TN border, so it may slow
up and linger a bit in the southeast.

The 12Z models all show a nice area of negative Showalter Indices
and even some negative LI`s at times with the band. Will therefore
mention thunder throughout the event. Precipitable water values
will climb to 1.5"-1.7" range, which is climatologically high for
late October, so would not be surprised to see some locally heavy
rainfall, especially Tuesday afternoon in the southeast.

LONG TERM...(Tuesday Night through Saturday)
Issued at 314 PM CDT SAT OCT 25 2014

At the beginning of the extended period, there may be some rapidly
diminishing convection in the sern half of the PAH forecast area.
Otherwise, a drier air mass will invade the region under wnwrly flow
aloft, providing mostly clear and cooler than average conditions
through Wed night.

There is some question as to whether anything measurable will fall
Thu/Thu night as the overall pattern across the CONUS amplifies, and
a fast-moving mid level shrtwv strengthens and moves into the
Midwest. There have been some hints among the med range models,
including the 12Z ECMWF, that enough lift and moisture convergence
may develop across parts of our area for some light rain to occur
during this period. However, at this time the forecast is held to
"non-measurable" Thu/Thu night, except for nrn Pike County IN Thu
night, due to the sporadic nature of the recent model solutions.

Model consensus seemed to suggest some possibility of measurable
pcpn lingering into Fri due to shrtwv energy passing through. At
this time, this is where showers were included in the forecast for
roughly the ern half of the area. Some of what the initialization
blend suggested today was influenced by the 00Z ECMWF model`s
development of a mid level low (with sfc reflection) over the PAH
forecast area, not repeated in the 12Z version. However, by Fri
evening, the ECMWF and GFS do close a mid level low over the nern
CONUS, with fast nrly mid level flow, and a cold advection pattern,
to its sw. This will provide a noticeable cool-down for next
weekend, with freezing temps possible.

AVIATION...
Issued at 626 PM CDT SAT OCT 25 2014

A weak cold front continues to push slowly south through the
region this evening. It is forecast to stall out just south of
the area tonight, and then come back as a warm front Sunday. The
front will continue to usher drier air into KEVV and KOWB. This
should prevent significant fog formation late tonight at these
sites, despite clear and nearly calm conditions.

Low-level moisture will likely remain over KCGI and KPAH through
the period and thus the potential for MVFR or even IFR ceilings
develop overnight. Guidance strongly indicating IFR or lower fog
formation at both sites. Bottom line is that impacts remain likely
at both locations tonight into early Sunday.

&&

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

$$

SHORT TERM...RS
LONG TERM....RS





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