Area Forecast Discussion
Issued by NWS Paducah, KY

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
FXUS63 KPAH 170034

Area Forecast Discussion
National Weather Service Paducah KY
734 PM CDT Tue Jul 16 2019

Issued at 733 PM CDT Tue Jul 16 2019

A quick early evening forecast update to reflect the expiration
of the Flash Flood Watch and the refinement of weather and PoP
grids for the rest of the first period (tonight).

Any additional heavy rain potential this evening will be limited
to isolated cells and should not be a concern for any widespread
flash flood potential. Therefore, the Flash Flood Watch was
allowed to expire.

Anticipate a broken linear band of showers and thunderstorms to
slowly advance southeast through the WFO PAH forecast area this
evening, along and in advance of the shear axis/trough south of
the low (formerly the remnants of Barry). Given the a mean forward
speed around 12k knots (15 mph) of the trough axis through the WFO
PAH forecast area it will take at least through 13z Wednesday (8am
CDT) to exit the area. May attempt to refine the timing and
coverage with a mid-evening update.

The focus and messaging tonight and beyond will shift to the
combination of excessive heat and humidity left in the wake of the
remnants of Barry, as high pressure builds into the region for the
latter half of the week.


.SHORT TERM...(Tonight through Thursday night)
Issued at 330 PM CDT Tue Jul 16 2019

Remnants of Barry continue to churn over the mid MS Valley this
afternoon. Ahead of the main mid level trof, sct bands of showers
and thunderstorms will continue into the evening, though many
places will stay rainfree a vast majority of the time. However,
due to the tropical nature of the system, where storms do occur,
they will tend to try and rotate. Thus, a brief weak tornado spin-
up cannot be ruled out. Other than that, torrential downpours
will accompany the storms. Due to the scattered nature of the
convection this evening. plan to allow the flash flood watch to
expire at 7 PM CDT.

Trof axis will be east of the region by Wednesday morning,
bringing a gradual end to the higher rain chances. In fact,
Wednesday will serve as more of a transition day, as a massive
heat dome of high pressure aloft begins to build from the Plains
into the MS/Lower OH River Valleys. As rain chances begin to
dwindle Wednesday, temps will begin an upswing. Most locations
will challenge or even top 90 tomorrow afternoon. Places
along/west of the MS River will even see heat indices from 100 to
105 degrees, with readings up close to 100 elsewhere.

As the large dome of high pressure moves east closer to the region
Thursday, the heat wave will also shift eastward. In fact, with
the potential to see heat indices near or above 105 for several
afternoons in a row leading into the weekend, decided at this
point to initiate an excessive heat watch for the entire forecast
area beginning Thursday afternoon. I also weighed in the fact
that the heat will be lasting into weekend activities. Definitely
looks to be a very hot and steamy stretch of days.

.LONG TERM...(Friday through Tuesday)
Issued at 330 PM CDT Tue Jul 16 2019

An expansive ridge aloft will be in place over the southern
states at the beginning of the extended forecast period. This will
have a capping effect, precluding pcpn through at least the first
half of the weekend for the PAH forecast area. Meanwhile,
southwesterly low level flow will tend to maintain the oppressive
conditions (mid 70s surface dewpoints and low temps, highs in the
lower half of the 90s) through the weekend. Heat headlines are
planned through the weekend.

Among the medium range model solutions, and the GEFS/ECENS, finer
details are not all that clear as to timing and amplification of the
longwave pattern aloft by early Mon, but mid level shortwave energy
in the northern Plains is progged to move eastward and eventually
phase with a low near Hudson Bay. This should result in
amplification of the northern stream flow, allowing building of the
ridge in the southwestern CONUS and suppressing the ridge over our
region. This pattern should enable an airmass change behind a
surface wind shift to the north early Mon, which the initialization
blend supports.

As heights fall, and the surface boundary approaches, some isolated
shower and tstm activity is possible in the easternmost counties
late in the weekend and more so on Mon across a larger sector of the
PAH forecast area. It may take a while for the deeper moisture to be
swept out of our region (according to the ECMWF), so a small
probability of activity was maintained in the forecast mainly for
parts of southeastern MO and western KY Tue (Day 7). At this time,
it appears Mon and especially Tue will have noticeably more
comfortable conditions under northwesterly flow aloft and increasing
surface pressure.


Issued at 617 PM CDT Tue Jul 16 2019

For the 00z Wednesday WFO PAH TAF issuance, left an intermittent
mention (via TEMPO group) of VFR/MVFR ceilings and visibilities
for KCGI/KPAH through 02z Wednesday and for KEVV/KOWB through 04z
Wednesday to handle the bands of convection associated with the
remnants of the tropical system Barry. Most of this activity
should be diurnal in nature and dissipate quickly. Kept a longer
mention of VFR showers at KVMN given its proximity to the center
of the low circulation.

Although there is somewhat lower confidence at this time, kept a
mention of MVFR (and briefly IFR) ceilings overnight at KPAH and
KEVV. These lower ceilings may need to be revisited with the 06z
Wednesday TAF issuance.

Otherwise, VFR conditions should dominate the WFO PAH TAF sites
after 12z Wednesday


IL...Excessive Heat Watch from Thursday afternoon through Sunday
     evening for ILZ075>078-080>094.

MO...Excessive Heat Watch from Thursday afternoon through Sunday
     evening for MOZ076-086-087-100-107>112-114.

IN...Excessive Heat Watch from Thursday afternoon through Sunday
     evening for INZ081-082-085>088.

KY...Excessive Heat Watch from Thursday afternoon through Sunday
     evening for KYZ001>022.



AVIATION...Smith is the U.S. government's official web portal to all federal, state and local government web resources and services.