Area Forecast Discussion
Issued by NWS Paducah, KY
FXUS63 KPAH 291146
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
645 AM CDT Fri Aug 29 2014
Issued at 645 AM CDT FRI AUG 29 2014
Revised aviation discussion for 12Z TAFs.
.SHORT TERM...(Today through Sunday)
Issued at 330 AM CDT FRI AUG 29 2014
Main forecast concern is the potential for showers and thunderstorms
over the Labor Day holiday weekend.
The weak frontal boundary that provided the needed convergence for
scattered thunderstorm development Thursday afternoon is forecast to
shift north of the region today. In its wake, a drier atmospheric
profile and weak capping aloft should reduce the probability and
coverage of precipitation today. However, with multiple models
indicating the approach of weak upper level energy and a still
relatively moist atmosphere, will maintain a slight chance mention
this afternoon in northern and western portions of the area where
convective inhibition is the weakest. Temperatures should reach or
just exceed 90 in most spots. However, drier dew points should keep
heat index readings below the century mark in most areas.
An upper level trough over the Central Plains will shift east into
the Mississippi Valley by Saturday. Its approach will heighten the
influx of Gulf moisture on increasing southerly flow. As a result,
the potential for showers and thunderstorms will be on the increase
from the west tonight and Saturday. Additional energy will arrive
from the south Saturday night, which will bring better chances of
showers and thunderstorms to southern and eastern portions of the
area through Sunday.
All in all, models remain in general agreement, but there are
subtle differences. For instance, the ECMWF remains stubbornly slow
in its onset of precipitation tonight and Saturday. This is contrary
to the preferred NAM/GFS. In contrast, the NAM seems too slow in
tapering precipitation off from the west on Sunday, so a GFS/ECMWF
blend is preferred here.
While a few strong storms cannot be ruled out, the main concern
during this time will be locally heavy rain--particularly Saturday
night and Sunday over the southern and eastern 2/3 of the area.
Copious moisture will stream into the region with deep southwest
flow and precipitable water values in the vicinity of 2 inches.
Basin average QPF is currently forecast between one half and one
inch areawide. However, the pattern is conducive to training storms,
which could produce multiple inches in one spot if the right
conditions come together. Something to keep in mind if you will be
camping or enjoying the outdoors this holiday weekend.
.LONG TERM...(Sunday Night through Thursday)
Issued at 135 AM CDT FRI AUG 29 2014
The first half of the long term forecast period looks much the
same, wet/active with daily Pops. This occurs as the flow
transitions from the mean ridge, to a more zonal flow pattern, as
a long wave trof/associated boundary lay out somewhere across the
mid MS/lower OH river valley.
Toward the back half of the long term forecast period, upper level
heights rise in response to broader ridging across the southern
U.S., and the net effect is to shunt pcpn chances out of our area.
We`ll thus taper from mid to high chance cat pops early in the
week, to slgt chance mentions or negligible pops by the end of the
Temps won`t deviate much thru the period, averaging highs in the
upper 80s/around 90, and lows around 70/lower 70s, through the
Issued at 645 AM CDT FRI AUG 29 2014
Once MVFR/IFR fog burns off early this morning, VFR conditions are
expected through the forecast period. Winds will become southerly at
5 to 10 knots after 15Z. Showers and thunderstorms may begin to
impact western terminals after midnight. Added PROB30 mention at
KCGI and KPAH as a result.