Area Forecast Discussion
Issued by NWS Paducah, KY

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742
FXUS63 KPAH 281918
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
218 PM CDT Sun May 28 2017

.SHORT TERM...(Today through Tuesday night)
Issued at 218 PM CDT Sun May 28 2017

Any showers or thunderstorms that can form this afternoon will be
short lived and weak. Cloud cover has kept the instability at less
than 1000 J/kg as of this writing. Expect any precipitation to
dissipate shortly after sunset if not before. cold front is just
entering the northwest portion of the CWA but it should pass
through the area this evening.

Monday looks to be dry and warm.

The upper level low currently over southern Canada is forecast to
move south into the Great Lakes area tomorrow. As it does several
small lobes of energy are spinning around it. One can be seen
over Lake Superior this afternoon in the satellite data. One of
the larger pieces of energy will help push another cold front
southward into the Lower Ohio Valley by tomorrow evening. Models
have enough moisture to squeeze out some post-frontal showers and
possibly a thunderstorm during the evening hours on Monday over
the northern sections. These are expected to dissipate around
midnight.

Tuesday looks to be dry with the surface ridge centered over the
region and the upper level low over the Great Lakes lifts back
into Canada.

Moisture returns at 925 and 850 during the night Tuesday and may
allow for a few showers to develop over the area after midnight. A
couple of thunderstorms are possible along the southern border
where some weak instability will be available.

.LONG TERM...(Wednesday through Saturday)
Issued at 218 PM CDT Sun May 28 2017

In the extended period, The WFO PAH forecast area is situated at the
base of a blocking pattern that remains fixed across the U.S. for at
least a week, as advertised by the 12z Sunday deterministic GFS
numerical model. A closed low centered over the Ontario Province
wobbles in place in the east, while an intermountain ridge axis in
the West is oriented from Wyoming into Western Texas through the
week.

The local forecast area remains at the base of faster westerlies
oriented in a zonal pattern through the middle of the week, shifting
to a northwesterly flow late in the week/next weekend, as the ridge
encroaches behind the very slowly departing low in southern Canada.

The proverbial "fly in the ointment" is a forecast cyclonic (mid-
level) developing low circulation (near 33.09N/132.79W on GOES 16
6.93 micron water vapor band) on the east southeast end of the
eastern Pacific trough.

The GFS, best initialized this Sunday morning, attempts to slowly
move, then deepen the aforementioned feature into an open wave over
southern California and the California Baja.  This wave is progged
to have enough energy  to undercut and dampen the center of the
ridge into eastern TX and OK.  Given the uncertainty with 1)
propagation and persistence of this low pressure as it is progged to
move into the South Central Plains/Texas by midweek, and 2) the
amount and speed of return flow from the western Gulf of Mexico,
there is low confidence (less than 40%) when or even if this low
will develop and impact the WFO PAH forecast area during the latter
half of this week. Depending on the influence of the robust
precipitation progged 12z Sunday GFS in the regionally collaborated
model guidance, may need to lower PoPs/Weather for late in the week.
In the meantime, anticipate some waffling of the placement,
intensity and duration of the precipitation chances late this week.

With respect to any severe potential with any thunderstorms forecast
late this week, the WFO PAH forecast area will be well enough
removed from the faster baroclinic zone and main moisture plume in
the upper Midwest to support any widespread severe weather potential.
Cannot completely eliminate any diurnally driven mesoscale
influences, but the probability of any widespread severe weather is
quite low.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z Monday AFTERNOON)
ISSUED AT 1214 PM CDT SUN MAY 28 2017

Plenty of MVFR clouds initially but these will be breaking up
during the afternoon with skies going SKC around 00z or so.
Isolated showers and thunderstorms are expected this afternoon so
kept VCSH at all sites except for KCGI. Winds will continue to
gust to 20-22 kts for most of the afternoon.


&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...Lake Wind Advisory until 8 PM CDT this evening for ILZ075>078-
     080>094.

MO...Lake Wind Advisory until 8 PM CDT this evening for MOZ076-086-
     087-100-107>112-114.

IN...Lake Wind Advisory until 8 PM CDT this evening for INZ081-082-
     085>088.

KY...Lake Wind Advisory until 8 PM CDT this evening for KYZ001>022.

&&

$$

AVIATION...PS
SHORT TERM...PS
LONG TERM...SMITH



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