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Area forecast discussion
National Weather Service Jackson Kentucky
651 am EST sun Feb 19 2017

issued at 651 am EST sun Feb 19 2017

Patchy drizzle making headway toward the Virginia state line, in
accordance with eastward progression of a weakening upper low. Low
stratus will hold in place much of the morning as patchy fog
mixes out. Warmer air moving in aloft and gradual clearing this
afternoon should still allow for temperatures to top out in the
low-mid 60s.


Short term...(today through monday)
issued at 347 am EST sun Feb 19 2017

Areas of drizzle will continue to move across eastern Kentucky early
this morning as the deformation zone of a filling upper low pushes
across the Appalachians into the Atlantic. Portions of the Big Sandy
region into northeastern Kentucky could squeak out a hundredth of an
inch nearer the greater upper lift, but not expecting much more than
some morning dampness underneath abundant stratus cloud cover.
Patchy fog should also hang around until early-mid morning as mixing
ensues, thus allowing surface visibilities to improve.

Deep layer subsidence will move overhead later this morning through
this afternoon, bringing gradually clearing skies and an end to any
lingering drizzle. Warmer temperatures will advect in aloft with
850 mb temperatures rebounding into the 7-9c range, but a strong
and lowering subsidence inversion may hinder boundary layer mixing
into this. Nonetheless, above average temperatures will once
again be in place with highs climbing into the low-mid 60s.

High pressure, leading to light winds and clearing skies this
evening/tonight, and the lack of any appreciable dry air advection
will lead to fog development later this evening through tonight.
Crossover temperatures in the mid 40s will easily be reached tonight
as Ridgetop low temperatures fall into the low-mid 40s with
valleys cooling into the mid-upper 30s. Have thus made mention of
patchy fog across much of eastern Kentucky with areas of dense fog
in the valleys. High clouds will be on the approach downstream of
a trough moving into the Great Plains, but this does not look to
have a large impact on near-surface cooling. Further warming is in
store for Monday as a low-level thermal ridge slides overhead,
promoting high temperatures in the upper 60s to low 70s.

Long term...(monday night through saturday)
issued at 347 am EST sun Feb 19 2017

The extended period will feature well above normal temperatures and
alternating periods of dry and wet weather. The period will start
off dry, as a ridge of high pressure slowly moves off to our
east. The dry weather will likely come to an end on Tuesday, as a
slow moving frontal boundary moves toward the area. The front
should move across the area very slowly Tuesday and Tuesday night.
The problem with this initial boundary will be a lack of good
upper level support and a poor temperature contrast across it.
This will make for a relatively weak and diffuse front that will
have little lift and instability associated with it. This will
mean scattered light rain showers will most likely move through
eastern Kentucky Tuesday and Tuesday night, as the front passes
through. The rain should be out of the area by Wednesday
afternoon. The next round of rain currently being forecast is for
the period Wednesday night through Saturday, as a series of
weather systems are progged to move across this part of the
country. The models are currently showing differences in timing of
the passage of the weather systems, and the areal extent and
amounts of precipitation associated with them. That being said, it
does appear that a couple of frontal boundaries may move across
the Ohio and Tennessee Valley regions from mid week Onward,
bringing multiple rounds of precipitation to eastern Kentucky. The
question will be exactly when this happens and how much rain we
end up with. Decided to make slight modifications to the blended
model data from Wednesday night Onward, going with lower
precipitation chances overall than the model blend gave. Also did
not see enough evidence in the model data to warrant including
thunder in the forecast at this time.

Temperatures the first several days of the extended will feel much
more like late Spring than late winter, with highs in the upper 60s
and lower 70s expected Tuesday through Friday across the area. A
cool down is then expected for the upcoming weekend, as a cold front
moves through and eventually allows cooler air to invade the area.
Even though it will be much cooler next Saturday than during the
rest of the week, saturdays highs are still forecast to be in the
50s, which is still well above normal for this time of year. Nightly
lows are forecast to be in the 40s and 50s.


Aviation...(for the 12z tafs through 12z Monday morning)
issued at 651 am EST sun Feb 19 2017

IFR/MVFR ceilings will remain in place this morning as high
pressure builds east toward eastern Kentucky. Patchy fog will lead
to scattered IFR/MVFR visibilities this morning, before mixing out
later this morning through this afternoon. VFR conditions should
return by mid afternoon as winds remain light out of the
west/southwest near or below 5 knots through the period. Fog
development late this evening and tonight currently looks
widespread enough to impact all area terminals at some point prior
to 12z Monday. More sheltered valleys will likely see areas of
dense fog while higher ridgetops may only see slight visibility


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