Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 170806
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
306 AM CDT Tue Apr 17 2018

.SHORT TERM...(Today through Thursday night)
Issued at 306 AM CDT Tue Apr 17 2018

Clear skies, mostly light winds and dry air have allowed freezing
air to develop over the entire Freeze Warning area as of 07Z.
Temperatures over the Frost Advisory area are still in the middle
to upper 30s, with frost development here at WFO Paducah with 35
degrees. Temperatures are being stubborn in the upper 30s over
the Bootheel and adjacent flat lands of southeast Missouri despite
calm winds reported at KPOF and KMAW. Obviously no changes will
be made to the existing headlines, but for the most part they
appear to be working out pretty well.

A rather vigorous storm system will emerge from the Rockies into
the central and northern Plains by this evening. This will result
in upper ridging building overhead and a warm front developing
over southern portions of our region today. The result will be a
nice warm up, but the boundary will create a fairly sharp gradient
in temperatures from upper 50s north to lower 70s south. At KEVV
this will result in 20 degrees of warming compared to yesterday
even though they will still be about 10 degrees below normal.

As the upper storm system moves across Iowa tonight and near Lake
Michigan by Wednesday evening, the main story here will be winds.
Gusty southwest winds will develop over much of the area before
sunrise Wednesday morning, as the warm front briefly lifts north
of the area. The winds will veer to west as the cold front moves
quickly eastward across the area through the day. Gusts 30-35 mph
will be possible by afternoon.

Surface high pressure over the Gulf of Mexico Wednesday will
effectively rob this storm system of low-level moisture and
we will be mostly dry. The models bring a nice elevated mixed
layer overhead south of the upper system which will cap any hope
of deep convection, and it will also allow temperatures to warm up
quickly into the 70s. 00Z NAM soundings near KOWB indicate that
the capping inversion may be lifted enough to squeeze out a
shallow layer of instability beneath it in the late afternoon.
We`ll have a small area of a very slight chance of showers just in
case, but thunder is not a possibility.

Behind the system, northwest winds and cold advection will be the
rule Wednesday night and Thursday. Temperatures will drop around 5
degrees below normal for lows Wednesday night and 10-15 degrees
below normal for highs Thursday. Thursday night frost will return
to much of the area as temperatures drop into the middle 30s and
winds diminish to 5kts or less. Areas of frost are forecast for
all but the Purchase Area and southern portions of southeast
Missouri.

.LONG TERM...(Friday through Monday)
Issued at 306 AM CDT Tue Apr 17 2018

Average confidence on timing of precipitation in this forecast
package, but above average confidence in spatial coverage of
PoP/Weather in the extended forecast period.

The ECMWF and the 4km NAM-WRF ARW/NMM families initialized fairly
well in the 00z Tuesday model cycle. The regionally blended model
initialization remained close the ECMWF solution with respect to the
areal placement of PoPs and weather, but the influence of the rest
of the model suite expanded the chances for rain a little larger
than what is likely to occur this weekend and into early next week.

Ridging dominates through Saturday with still below seasonal norms
for temperatures going into Saturday.

The ECMWF moves and upper closed low from central California and
eastward through the northern limit of the southern Plains and Lower
Mississippi valley through Arkansas, between Friday and Sunday
night. The best dynamic support in the northeast Quadrant of the low
will occur while the low is vertically stacked and cold core over
the weekend. Added a small chance of thunderstorms near the Purchase
area of west Kentucky Sunday afternoon. Given the nature of the
system, any weather will most likely be elevated. An isolated
hailstorm or two cannot be ruled out along the southern WFO PAH
border from southeast Missouri through west Kentucky that day. As
the upper low becomes more disorganized through next Tuesday, rain
chances will diminish, with low probabilities for any thunderstorm
event.

The upper low eventually moves along the eastern half of the WFO PAH
forecast area by Tuesday, limiting the coverage and intensity of the
rain. With the influence of the upper low over the area,
temperatures will remain five to, in some cases ten degrees below
normal for this time of year.

&&

.AVIATION...
Issued at 620 PM CDT Mon Apr 16 2018

VFR conditions through Tuesday. WNW winds up around 10 kts will
subside early this evening, then become light S/SW Tuesday.


&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...Freeze Warning until 9 AM CDT this morning for ILZ075>078-
     080>091.

     Frost Advisory until 9 AM CDT this morning for ILZ092>094.

MO...Freeze Warning until 9 AM CDT this morning for MOZ076.

     Frost Advisory until 9 AM CDT this morning for MOZ086-087-100-
     107>112-114.

IN...Freeze Warning until 9 AM CDT this morning for INZ081-082-
     085>088.

KY...Freeze Warning until 9 AM CDT this morning for KYZ007-010>022.

     Frost Advisory until 9 AM CDT this morning for KYZ001>006-008-
     009.

&&

$$

SHORT TERM...DRS
LONG TERM...Smith



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