Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 162027

Area Forecast Discussion
National Weather Service Paducah KY
227 PM CST Tue Jan 16 2018

.SHORT TERM...(Tonight through Thursday night)
Issued at 228 PM CST Tue Jan 16 2018

Finally, a quiet weather pattern with a warming trend. A few
flurries will linger north of Interstate 64 late this afternoon,
otherwise, clearing skies and snow pack tonight will help
temperatures drop into the 0 to 5 degree range. With winds at 5
kts or less, wind chills will generally be in the 0 to
-8 range. This is above advisory criteria, so we will do another
SPS highlighting the chilly conditions overnight.

Models show surface high pressure sliding south of the PAH
forecast area by Wednesday night into Thursday. Winds will
gradually shift from northwest to south by late Wednesday into
Wednesday evening. Temperatures will already be moderating
Wednesday into Wednesday night, with highs reaching the lower to
middle 20s, and lows in the 10 to 15 degree range.

High pressure will remain to our south through Thursday night,
keeping us high and dry. We will see temperatures climb up to and
above freezing on Thursday, though we will have to see if our
areas with significant snow cover slows our warm up a little.
South winds will stay up Thursday night, and this will help give
us lows in the lower 20s, which is actually getting close to
seasonal normals.

.LONG TERM...(Friday through Tuesday)
Issued at 228 PM CST Tue Jan 16 2018

There remains some slight disparity on the depth, location,
orientation of the closed low over Texas prior to the extended
forecast period and the amount of shearing and weakening of the low
as moves across the southeast U.S.

The 00z and 12z Tuesday deterministic model runs, as well as the
ensembles continue to be clustered along a solution bringing
significant warm air advection into WFO PAH area through the lower
Mississippi valley on Friday.

Given the saturated boundary layer expected over the area due to the
melting and evaporation of snow cover, cannot rule out enough lift
for a few sprinkles of rain late Friday into Saturday.  However,
there is not sufficient accuracy on the coverage area to warrant a
mention of sprinkles (trace precipitation event) leading up to
Saturday night.

The signal is fairly consistent from the suite of numerical models
for some warm advection showers Saturday night into Sunday morning.
There has also been an increasing signal in the low level (surface
to 3km AGL) CAPE and Lifted Index values for a slight chance of
thunderstorms moving into the southeast Missouri counties later
Sunday afternoon and into the evening hours. From a pattern
perspective, the potential for either a singular or multi-banded
(south to north) oriented lines of convective activity through
midnight next Sunday evening. The signal with the departure of the
convective line remains consistent for early Monday as well.

At this point, the only concern for heavy rain/overland flooding
would be Sunday evening, depending on the degree of
antecedent snowmelt late this week.

With regard to temperatures, kept close to the blended guidance for
max/min values, which mirrors the cluster guidance values for a
majority of the guidance, as well as the expectation of suppressed
ground temperature profiles under the current snow cover.


Issued at 1114 AM CST Tue Jan 16 2018

Cold air stratocumulus rotating around the upper trough axis as
it swings through the WFO PAH TAF sites will generate periodic
MVFR ceilings with intermittent snow showers. With the 18z Tuesday
WFO PAH TAF issuance, there was a strong consideration to use
TEMPO groups for the MVFR visibility restrictions due to snow, but
given the chaotic banding nature of the Stratocumulus, decided to
place 4-5 statute miles visibilities in prevailing forecasts for
this afternoon and evening. The visibilities and ceilings should
improve markedly after 06z Wednesday as trough axis moves through
the WFO PAH TAF sites.

As warm air advection moves in from the west, brought in a lower
MVFR ceiling to address stratocumulus/stratus developing as
insolation enhances the mixing for additional cloud development.




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