Area Forecast Discussion
Issued by NWS Paducah, KY

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000
FXUS63 KPAH 230752
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
252 AM CDT FRI SEP 23 2016

.SHORT TERM...(Today through Sunday)
Issued at 252 AM CDT Fri Sep 23 2016

Weak high pressure and mid level ridging will keep our forecast
dry through Saturday night. By Sunday afternoon and approaching
front and a greater presence of moisture means we will carry a
chance PoP for convection over the west 1/3 of the area. A
persistence MOS forecast will continue to be used for most wx
elements, including temps. Will have our early morning fog this
a.m. Expect the same again tonight.

.LONG TERM...(Sunday night through Thursday)
Issued at 252 AM CDT Fri Sep 23 2016

The past several days have been interesting in watching the
evolution of the western U.S. trough axis and how the medium range
model guidance has been attempting to resolve the intensity of flow
within the trough as it moves into the Central Plains.

Preferred guidance suggested a mix of the ECMWF and Canadian (CMCnh)
had greater value over the regionally initialized model blend. Both
the deterministic and ensemble solutions varied from day to day,
suggesting a large spread in the way the guidance was adjusting the
Western U.S. trough.

Each of the latest runs of the ECMWF, GFS, and CMCnh had some
characteristics that verified well.  Ironically, now that the
western U.S. trough has been within a denser observational network
in the last day or two, all of the medium range guidance appear to
be synchronizing into a solution with the progression of the trough
axis through the WFO PAH forecast area. With this forecast package,
mixed the regionally initialized blended guidance with a 30%
weighting of the 00z Friday ECMWF, GFS, and CMCnh medium range
numerical model guidance.

The net effect is still the same for the onset of convective
activity into the western sections (Southeast Missouri/Southwest
Illinois) of the WFO PAH forecast area late Sunday night, but the
progression of the trough is now much faster, pushing the baroclinic
zone through the WFO PAH forecast area as early as late Monday
night/early Tuesday morning of next week.  This is almost 24 hours
faster than model runs earlier in the week. In addition, the cold
air advection is much more persistent and prolonged following the
frontal passage on Tuesday, yielding much cooler temperatures and
drier air than previous forecast.

Finally, the spurious convection associated with the movement of the
closed circulation embedded in the trough through the Great Lakes
has shifted away from the WFO PAH forecast area during the middle
and latter part of next week.  There was already low confidence in
this solution the past couple of days, so it was nice to be able to
remove rain chances without any collaborative headaches associated
with previous regionally blended guidance solutions.

Fall-like temperatures will be here...it will just take a few more
days!

&&

.AVIATION...
Issued at 252 AM CDT Fri Sep 23 2016

Mainly VFR conditions again with light winds. Variable MVFR-LIFR
visibilities due to shallow fog this a.m. and again tonight.

&&

.PAH Watches/Warnings/Advisories...
IL...None.
MO...None.
IN...None.
KY...None.
&&

$$


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