Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 212328

Area Forecast Discussion
National Weather Service Paducah KY
527 PM CST Tue Feb 21 2017

Updated aviation section for 00z taf issuance


.SHORT TERM...(Tonight through Thursday night)
Issued at 247 PM CST Tue Feb 21 2017

Look for isolated and banded segments of light precipitation to
continue to drift northeast to east through the evening hours,
generally east of the Mississippi River. The NAM-WRF (ARW/NMM
versions), as well as the RAP guidance, seem to have a fair
handle on the precipitation field.

Cloud cover will be some what problematic overnight, as parts of
Southern Illinois, Southeast Missouri, and the Purchase area of
West Kentucky will be under a col, limiting efficient scouring of
moisture across the area. There will be some variable clearing
across the aforementioned area as the lower clouds and cirrus
erode slowly from the northwest into the WFO PAH forecast area.
Given the variability in cloud cover and radiational loss
(inducing thermal gradients), there will be some potential for
locally dense fog between 2 am and 9 am CST. For now, plan to
issue a general special weather statement alluding to the
potential overnight, but will leave any final go/no go decision
for a dense fog advisory to the evening forecast crew.

With low to middle level shortwave ridging in place, could see a
slower evolution of clearing and/or development of partly to
mostly cloudy skies across the WFO PAH forecast area during the
day on Wednesday due to weak mixing under the capping layer aloft.
Even with this cloud cover, the WFO PAH forecast area could still
see high temperature records tied or broken.

Stronger warm air advection will take place on Thursday, with some
slight erosion of the cap (south of the warm front) over
Southeast Missouri and Southern Illinois late Thursday night. With
the exception of Friday (in the extended forecast period), there
could be near record setting high temperatures again on Thursday.
At this point, current forecast temperatures may still be underdone
by 1-3 degrees. Still holding out that some location in the WFO
PAH forecast area will flirt with temperatures near 80 by the end
of the workweek.

.LONG TERM...(Friday through Tuesday)
Issued at 247 PM CST Tue Feb 21 2017

Models remain in good agreement, and they have been for quite a
while, showing a cold front moving across the PAH forecast area on
Friday. Models indicate pretty good instability along and ahead
of the front, and SPC has outlooked eastern portions of our
region. So thunderstorms seem a good bet on Friday, especially in
the afternoon hours. We may see some sunshine in the morning
hours, and with some gusty south winds, high temperatures will
reach the upper 60s to middle 70s.

The front will push east of our region by 06z Saturday, and showers
and storms will quickly end by late Friday evening.  Colder air will
filter in behind the front, with low temperatures dropping into the
middle 30s to lower 40s.  High pressure will briefly take hold
across our region for the weekend, with the center of the high
moving over our area Saturday night.  With mostly clear skies and
northwest winds, temperatures will actually be near to even a few
degrees below seasonal normals Saturday through Sunday.

By late Sunday into Sunday night, the ECMWF shows a warm front
lifting across the middle Mississippi valley.  The GFS and Canadian
are a bit slower with this feature, and just went with slight to low
chances for light showers across much of our area Sunday evening. We
should be dry late Sunday night, then both ECMWF and GFS show
widespread precipitation developing and spreading east by Monday
evening due to an approaching low pressure system and cold front.
Instability increases by Monday night, so went with slight to low
chances for showers on Monday, with increasing chances for showers
and slight chances for thunderstorms Monday night into Tuesday.
Southerly flow will lead to a significant warming trend for the
beginning of the work week, with readings again well above seasonal
normals Monday and especially Tuesday.


Issued at 527 PM CST Tue Feb 21 2017

Main concern for tonight is the potential for fog and low stratus.
Cigs early this evening will remain primarily vfr, though areas of
mvfr are likely in light rain across western KY and extreme se
Missouri. Later on tonight, the thick overcast is forecast to become
thinner or possibly scatter out. If this occurs, conditions would be
highly conducive for dense fog with light winds and rain-moistened
ground. The most likely area for this to occur is north and west of
kpah, and dense fog will be forecast at kcgi. Fog and stratus will
likely increase at all sites right before sunrise, when radiational
cooling will be strongest. It will take some time for the low clouds
and fog to burn off Wed morning, and even in the afternoon cigs will
only improve to mvfr.




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