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Area Forecast Discussion (AFD)

Issued by Jackson, KY (JKL)

FXUS63 KJKL 252016

National Weather Service Jackson KY
316 PM EST Sun Feb 25 2018

.SHORT TERM...(This evening through Monday night)
Issued at 240 PM EST SUN FEB 25 2018

19z sfc analysis shows just about all of eastern Kentucky now in 
the wake of a departing cold front. This front is taking the lower
clouds east along with it as high pressure bubbles in from the 
west. The relaxing of the pressure gradient from this high's 
approach has lightened the winds, though they are still cold 
advecting - generally from the northwest. Temperatures currently 
vary from the low 50s northwest to the upper 50s southeast while 
dewpoints range from low 40s west to the lower 50s in the east. 

The models are in good agreement aloft through the short term
portion of the forecast. They all depict broad southwest flow
continuing over the area between strong ridging above Florida and
troughing north of the Great Lakes down to the Southern Rockies. 
The tail of the northern trough will weaken and head into the Ohio
Valley later tonight into Monday morning. From this, a weakening 
batch of energy and slight height falls pass through eastern 
Kentucky during the day Monday. Following this, ridging and gently
rising heights will move over the area into Tuesday morning. 
Given the model similarities will favor a blended solution with 
an emphasis on the details from the higher resolution NAM12 and 
HRRR in the near term. 

Sensible weather will feature mainly just high clouds around this
evening and overnight as high pressure builds into the area. 
However, one last wave along the past frontal boundary will move
through the Southern Appalachians tonight brushing far
southeastern parts of the CWA with a decent chance of rain
showers. Otherwise, all will be quiet through eastern Kentucky
with relatively mild overnight lows on tap in the upper 30s north
to mid 40s south. Monday will be a nice day under high pressure 
with plenty of sunshine and temperatures climbing into the mid to 
upper 50s. As the high pressure area moves east Monday night, a 
night of good radiation cooling will likely set up a moderately 
large ridge to valley temperature split with the hilltops in the 
mid 30s and most sheltered valleys falling into the upper 20s. 
Also, look for valley fog to develop late at night and possibly 
be thick near the rivers and larger bodies of water. 

Used the CONSShort and ShortBlend as the starting point for all
the grids through Tuesday morning. Did make some significant
changes to the valley locations for lows on Tuesday and also some
point specific temps tonight and Monday. As for PoPs, limited the
measurable rainfall to just the far southeast tonight and only for
a window of time from 06 to 12z - narrower in areal and temporal
extent than the blends. 

.LONG TERM...(Tuesday through Sunday)
Issued at 316 PM EST SUN FEB 25 2018

There is good model agreement with the evolution of the mean flow
during the upcoming week and fairly good agreement with the main
weather makers for our area.

With surface high pressure slipping to our east at the start of
the forecast period, and weak upper ridging over the area, we'll 
have a warm dry day on Tuesday. On Wednesday an upper level trough
will be moving out of the southwest U.S. as a surface low develops
in the southern plains. A leading short wave trough will bring
showers to the area on Wednesday. A more significant round of 
showers will occur Wednesday night into Thursday as the southern 
stream trough begins interacting with some northern stream energy
and develops into a closed upper low. The associated surface low
will deepen from Wednesday into Thursday as it moves into the
northern OH Valley-southern Great Lakes area. 

There is model agreement that the axis of heaviest rains from
Wednesday into Thursday will fall south of Kentucky, but the
southern part of the forecast area could still see significant
rains, especially Wednesday night into Thursday. The current
forecast calls for 1.5 to 2 inches in the southern part of the
forecast area from Wednesday into Thursday, so this will need to
be watched. It is possible some local high water issues could
develop by Thursday. 

Temperatures will be well above normal for the first part of the
forecast period, but colder air will spill into the area by Friday
with more normal temperatures for the start of next weekend.


.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)

A cold front is exiting southeast Kentucky and it no longer has 
much of a pcpn trace on the radar - look for just the last of the 
MVFR ceilings to follow it out of the state over the next couple
of hours. VFR conditions will prevail through the period for all
the TAF sites, though some MVFR cigs and lower vis will be 
possible in the far southeast parts late tonight as a wave brushes
by through eastern Tennessee in the pre-dawn hours. West winds 
will diminish into this evening, with mainly just some higher 
clouds sticking around. Winds will stay light and variable on 
Monday as high pressure settles over the area.