Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 222010
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
310 PM CDT Sun Apr 22 2018

.SHORT TERM...(Tonight through Tuesday night)
Issued at 310 PM CDT Sun Apr 22 2018

This afternoon, 500mb low was over NW Arkansas, accompanied by a
broad area of showers and isolated thunder east and north of its
center. Surface low was well south over central Mississippi. The
upper low will end up over east Arkansas by 06z, with showers
continuing to head north and then northwest across our CWFA.
Categorical PoPs most areas, with increasing PoPs across the
Evansville Tri-State. From 06z-12z, best PoPs will shift north
toward I-64, with activity becoming more scattered elsewhere as
slightly drier mid level air works north. There may be isolated
thunder into SEMO late today and this evening per elevated
instability parameters, possibly far west KY. Not much expected.

Monday, shower chances will continue, though more scattered in
coverage. Isolated thunder possible again, especially east of the
MS River. Rain chances will decrease Monday night through Tuesday
evening from west to east with the ENE movement of the SFC/H5 low
systems. Dry overnight Tuesday.

Rainfall totals from just over 1/2 inch along the I-64 corridor,
to near or just above 2 inches far southern sections. Again the
duration aspect and rates will keep us away from flood/impact
concerns. Discontinued the ESF earlier. Overall, used CAM`s output
for short term PoP trends, merging toward a NAM, ECMWF blend
Monday through Tuesday. Favor a blend of the MET and ECS MOS for
temps.

.LONG TERM...(Wednesday through Sunday)
Issued at 310 PM CDT Sun Apr 22 2018

The deterministic models were in decent agreement in the initial
part of the extended forecast, however, chaos increased in those
solutions and the ensemble members beyond midweek. The GEFS/ECENES
means were in reasonable agreement through the extended period,
though.

On Wed, as a departing low pressure system departs the PAH forecast
area to the east and phases with a northern stream shortwave, we
will be essentially between systems under northerly low level flow.
However, another mid level shortwave trof will move out of the
central Plains toward AR late Wed, possibly resulting in some
isolated light shower activity primarily in the southwestern half of
the region during the daylight hours. There will certainly be an
increase in cloud cover.

Drier, higher pressure air near the surface, driven by northerly low
level winds for most of the Wed night/Thu period, should help
preclude measurable pcpn for us as cloudiness gradually decreases.

The mid level pattern across the CONUS is generally progged to
become highly amplified later in the week, with shortwave energy
digging into an evolving longwave trof over the eastern CONUS. The
ensemble means suggested the presence of this shortwave. The
deterministic model solutions varied in the evolution, strength, and
path of this system, with non-EC models showing it as more of a
closed or closing, nearly stacked low. The ECMWF continued to show
the system as more of a meridional mid level trof, accompanied by a
surface cold front, arriving at least 12 hours later than in the GFS
solution, which was the fastest. As a result, a broad-brush approach
of limited PoPs was taken for the Thu night/Fri time frame. Thus, as
early as Thu evening, shower activity could occur mainly in the
western half of our region. The limited forecast PoPs expand to the
entire region Fri.

From Fri night through next weekend, our region should be under
general high pressure and slackening northerly or northwesterly flow
aloft, meaning rain-free conditions with moderating temps. Overall,
the temps during the extended are forecast to be relatively mild,
with no wild swings.

&&

.AVIATION...
Issued at 310 PM CDT Sun Apr 22 2018

Will continue to trend toward MVFR and IFR cig conditions late
today through tonight working north from southeast MO and west KY,
into southern IL and southwest IN, with occasional MVFR to local
IFR vsbys in areas of showers as well. East winds will continue,
breezy at times with gusts just above 20 kts or so. Could be LLWS
across west KY around 06z, as winds up around 2k/ft increase to 40
to 50 kts from the east. Should last just a few hours.

&&

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

$$


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