Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 171118
AFDPAH

Area Forecast Discussion
National Weather Service Paducah KY
518 AM CST Fri Nov 17 2017

.SHORT TERM...(Today through Sunday night)
Issued at 206 AM CST Fri Nov 17 2017

Return southerly flow will develop today, as high pressure moves
away from the region. Should be a mainly dry day. Cannot rule out
a few sprinkles, but overall weak forcing and lack of deep
moisture should limit precip chances today. May keep a 20 slight
chance PoP far west counties in SEMO, southern IL this afternoon
where slightly better chances exist.

Tonight, there should be an uptick on convective chances as a warm
front surges northeast quickly in the evening. Coverage overall
should continue to be scattered as we quickly transition to the
warm sector, and support aloft is modest at best. Elevated
instability parameters support thunder most of the night with any
of the activity, especially from 03z on.

By 12z Saturday, a strong cold front will be just northwest of our
CWFA, ahead of a positive mid level s/wv across the Plains. Around
Noon Saturday the front should be just east of the Ohio River and
into SW Indiana, quickly departing our eastern counties by mid
afternoon. Will continue to monitor the potential for strong to
isolated severe wind gusts with linear low topped convection in
close proximity to the front due to strong frontogenetic forcing.
Unlike the last event on back on 11/5, frontal forcing is much
better as are our upper level jet dynamics. However, one similar
sounding item is, once again, marginal low level lapse rates.
There is also a persistent warm thermal profile in roughly in the
5-9k/ft layer. Using MUCapes, or even MLCapes doesn`t tell the
whole story regarding the potential to mix down with max
efficiency strong winds. The GFS depicts more favorable lapse
rates for wind transfer, in both convection and with gradient
winds. The NAM and ECMWF are more muted. So there are still some
question marks with the overall severe wind gust potential. SPC`s
marginal outlook seems reasonable for now. Also, with respect to
gradient wind Saturday, we may be looking at a Wind Advisory type
event. However there is plenty of lead time available for the day
shift to take another look and issue if they so choose. A last
axis of moisture should move across the northern 1/2 of the area
from 22z to 02z Saturday evening. The NAM is chilly and would
suggest a few snow flakes may mix in (of no consequence). However
the GFS and ECMWF do not. No mention planned.

Sunday through Sunday night, high pressure will be the rule with
cool dry weather still expected.

.LONG TERM...(Monday through Thursday)
Issued at 206 AM CST Fri Nov 17 2017

Confidence in the long term portion of the forecast is higher than
average owing to good overall model agreement and no significant
weather through the period.

A relatively flat upper level flow pattern at the beginning of the
week is forecast to amplify by mid week as a strong ridge becomes
established over the western half of the U.S. with a mean trough
over the eastern half. This will place our region in northwest flow,
which should result in temperatures near or below normal through
much of the period.

Starting with Monday, high pressure will be situated east of the
area. With southerly flow on its western flank, a warming trend is
expected both Monday and Tuesday. The pairing of southerly flow with
ample sunshine should boost temperatures into the 50s for highs,
which is near normal for this time of year.

Recent deterministic models and ensembles have been very consistent
on advertising a dry frontal passage Tuesday afternoon into Tuesday
night. This will be followed by a reduction in temperatures mid
week. The model blend leans more in the direction of the preferred
cooler GFS MOS guidance. In comparison, the 12Z ECMWF seems way too
warm--likely influenced by its development of a closed low over the
southern U.S., which is more of an outlier solution at this time.

Currently, Thanksgiving Day looks dry as high pressure is forecast
to slide east across the area into the Ohio Valley. After morning
readings in the upper 20s to lower 30s, temperatures should make a
run at the 50 degree mark by afternoon.

&&

.AVIATION...
Issued at 518 AM CST Fri Nov 17 2017

Low clouds continue to move WNW across southwest IN and west KY.
Cigs will remain 300-700FT with vsbys 2-5 mi, with improving cigs
after 15-17z KEVV/KOWB. Otherwise continued areas of MVFR fog
through mid morning, with 8-10k/ft clouds moving east across
southeast MO toward southern IL and far west KY. Winds will pick
up considerably later today, and continue overnight. Expect south
winds to gust in the 20-30kt range tonight. Some scattered showers
and isolated thunderstorms will be possible overnight.

&&

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

$$

Short Term...CN
Long Term....RJP
Aviation.....CN



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