Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 270845

National Weather Service Jackson KY
445 AM EDT Tue Jul 27 2021

.SHORT TERM...(Today through Wednesday)
Issued at 445 AM EDT TUE JUL 27 2021

08Z sfc analysis shows that the cold front has nearly cleared
eastern Kentucky to the south and, with this, clearing skies
have worked in from north to south during the night. As a result
of the decreasing clouds, good radiational cooling commenced and
have led to a small ridge to valley temperature split developing
along with dense fog in the river valleys. Readings are currently
ranging from the low 60s northwest - in the drier air - to the low
70s in much of the Cumberland Valley with some mid 60s found in
the northeast valleys. Dewpoints, meanwhile, are near temperatures
at most sites ranging from the low 60s north to the low 70s
south, amid light winds. The fog set in early and thickened
through the night - affecting the valleys the worst. With plenty
of locations likely seeing visibilities below 1/4 mile have issued
an SPS for it through 13Z when it should start breaking up.

The models remain in near lock-step agreement aloft through the
short term portion of the forecast. They all depict ridging
dominating the bulk of the country - aside from the troughing in
the Northeast - through the middle of the week. For eastern
Kentucky this will mean mostly rising heights through the short
term with a brief drop later tonight as a wave passes by to the
northeast. Strong ridging then builds further into the area
through 00Z Thursday. A tight model spread supported using the
blended NBM for the short term forecast grids with little
adjustment needed.

Sensible weather will feature a foggy start to the day -
especially in the valleys - followed by a warm and mostly sunny
afternoon. While the NBM does kick off some convection in the
far south later in the afternoon, the CAMs and NAM12 are mainly
dry so have followed suit. Mostly clear skies will set the stage
for a typical ridge to valley temperature split tonight as high
pressure settles over the area. In addition, we can expect river
valley fog to be rather thick into Wednesday morning. An even
warmer day will then be on tap for Wednesday with the low 90s
plentiful for highs across the CWA.

Made the most adjustments to the NBM temperatures for terrain
distinctions tonight. As for PoPs, did nudge the NBM numbers down
in the afternoon in the far south, using the CAM consensus to
support a mainly dry and thunderstorm free forecast.

.LONG TERM...(Wednesday night through Monday)
Issued at 400 AM EDT TUE JUL 27 2021

Strong and extensive riding aloft in the western CONUS will keep
hot and dry weather in place out there, which will contribute to
high fire danger that has been going on for weeks now. Extensive
troughing in the east will contribute to a steady cooling trend in
the extended and occasional periods of precipitation for eastern
Kentucky. After seeing one more hot day on Thursday, when highs
are expected to max out in the lower 90s for most locations, a
passing cold front will usher cooler than normal air into the
region from Friday into the first of next week. Highs from Friday
onward should only rise into the low to mid 80s around the area.

A couple of passing weather systems/fronts will bring chances for
showers and storms to eastern Kentucky Thursday through Monday. A
cold front will pass through initially, before stalling out just
to our south and then will move back northward as a warm front.
The cool air mass north of this boundary will keep our
temperatures below normal for several days. Nightly lows will will
also be fairly cool, with min readings in the upper 50s to lower
60s from Friday night onward. Lows will be warmer early Thursday
and Thursday night, with readings those two periods only falling
into the upper 60s to lower 70s.


.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)

The last of the showers in the south have faded out leaving behind
mostly clear skies and plenty of valley fog. As a front settles
through the area slightly drier air will try to make its way
south into the JKL forecast area during the night, but will have
trouble scouring out our moist surface air mass. As it is much
drier aloft in the mid/upper levels, good radiating conditions are
underway and with light winds, this should lead to extensive fog
in valleys, likely eventually affecting at least some of the TAF
sites south and east of KJKL. The fog will be dense in some
locations, with VLIFR conditions at times. All the fog then
dissipates later this morning, leaving VFR conditions to carry
into the night. Winds will remain generally from the northeast at
5 kts or less through the period.




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