Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 251137

National Weather Service Paducah KY
537 AM CST WED NOV 25 2015

Issued at 537 AM CST WED NOV 25 2015

Revised aviation discussion for 12Z TAFs.


.SHORT TERM...(Today through Friday)
Issued at 330 AM CST WED NOV 25 2015

The near term presents fairly high confidence with good model
agreement. Southerly low level flow will continue to increase
through the period as surface high pressure over the eastern U.S.
slowly shifts east with time. In the upper levels, a closed low
near the Oregon-Nevada border will stall over the Great Basin
through Friday. The resultant transition in the upper level flow
pattern from zonal to southwesterly will result in the advection
of Pacific moisture into the region. A cold front approaching
from the Plains will provide a source of lift and convergence to
produce widespread rain by the end of the week.

But until that happens, the dry weather is forecast to continue
today and across much of the area into Thanksgiving Day. The
increase in moisture will result in more clouds over western
portions of the region today, and over most of the area tomorrow.
Ripples of enhanced isentropic lift may even yield a few very
light showers or sprinkles just west of the region today. This
will likely translate east into portions of southeast Missouri
and southwest Illinois on Thanksgiving Day. But even there, any
shower activity should be very spotty and light.

Precipitation chances increase markedly from the west Thursday
night and Friday with the approach of the cold front and more
substantial upper level energy. Thunder is not anticipated given
the forecast of largely positive showalter indices and a moist
adiabatic thermal profile. Forecast QPF through Friday afternoon
ranges from nearly 2 inches across western portions of southeast
Missouri and southwest Illinois to less than a quarter inch in the
southern Pennyrile region of western Kentucky. Given the ample
recovery time from the last rain event and the anticipated slow
steady nature of this event, we do not expect 2 inches of rain to
cause much in the way of substantial impact--at least through
Friday. As a result, will not issue any headline product at this

A moderating trend will result in unseasonably warm conditions
through the period. Highs through Friday are forecast in the
upper 50s to mid 60s, with Thanksgiving Day the warmest of the
bunch. Lows should moderate from the upper 40s tonight into the
mid 50s by Thursday night.

.LONG TERM...(Friday night through Tuesday)
Issued at 330 AM CST WED NOV 25 2015

A blend of the EC/GFS ops and ECENS/GEFS was used for this forecast.
Relatively good agreement exists for such a complex upper air
pattern. A large closed H5 low over the Intermountain west 00z
Saturday is forecast to slowly move ENE into the middle of the
nation by 12z Monday. A persistent SW/WSW flow aloft will result in
several disturbances passing across the area, coincident with a
persistent 850mb moisture transport into the area from the SSW
despite the passage of a surface front. This will result in a
prolonged period of rain/rain showers that starts prior to our long
term frame of reference (late Thanksgiving through Friday) and lasts
through Sunday before tapering off.

Convective parameters for thunder still weak. However, despite the
lack of deep convection forecast, pwat`s running up toward 1.5
inches is around +2 standard deviations for mid November. High
rainfall totals appears likely. Will advertise this in the HWO along
with the possibility of flooding. Certainly does not look like Flash
Flooding given the prolonged duration, and lack of high rates at any
given time, much like the last rain event we had, that resulted in
hardly any flooding at all. Just a chance of showers Monday through
Tuesday until the parent upper low passes by to our north,
eventually followed by drying from the west.

For the second consecutive night shift we`ve had to raise low temps
and slightly adjust highs upward from inherited forecast, as the
default blend grids seemed to contain a cool bias. Our diurnal swing
should be minimized by the effects of precip, and the lack of a
significant push of cooler air given the close proximity of a
frontal boundary that may hang up across the SE part of our area,
give or take. Our numbers are just a degree or so under coolest MOS
solutions from the ECMWF and GFS, closer to base model output, and
milder than WPC for the most part.


Issued at 537 AM CST WED NOV 25 2015

High pressure will keep dry VFR conditions in place through much of
the forecast period. Southeast to south winds will pick up to around
10 knots this morning with occasional gusts of 15 to 20 knots by
afternoon. A deck of low VFR ceilings will overspread the area
tonight, with MVFR ceilings possible at KCGI by daybreak Thursday.


.PAH Watches/Warnings/Advisories...


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