Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 021200 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
800 AM EDT Tue Jun 2 2020

.UPDATE...
Issued at 750 AM EDT TUE JUN 2 2020

The forecast is on track this morning so have mainly just added in
the latest obs and trends - as the ridge to valley differences
have shrunk following sunup and the fog is not too bad in the
valleys, at all. These updates have been sent to the NDFD and web
servers.

&&

.SHORT TERM...(Today through Wednesday)
Issued at 410 AM EDT TUE JUN 2 2020

07z sfc analysis shows high pressure pulling away from the state
to the east with low pressure back to the northwest. This has
allowed some mid and high level clouds to pass over eastern
Kentucky this night with even some sprinkles falling in the past
evening. These clouds have been variable through the night and
likely hindered the radiation cooling keeping the ridge to valley
temperature difference from getting too large or supporting much
more than some fog in the river valleys. Temperatures currently
range from the low and mid 60s on the ridges to some low 50s in a
few of the more sheltered valleys in the east. Dewpoints,
meanwhile, vary by elevation from the low 50s in the low spots to
the mid 40s on the ridges.

The models are in fairly good agreement aloft through the short
term portion of the forecast as the ridge nosing into Kentucky
gives way to a weak trough and its mid level energy spreading
into the area from the west. This is best depicted by the NAM and
GFS whereas the ECMWF is even weaker with this feature. As a
result, heights will slowly fall over the area through Wednesday
evening as northwest flow becomes more zonal. This has added a
larger amount of spread to the models than recent runs - lowering
confidence in any specific solution. Given these circumstances
have favored the blended model solution from the NBM with a lean
on the NAM12 and CAMs for specifics.

Sensible weather will feature more moist and cloudy conditions
through Wednesday between sfc systems. The now moderating airmass
will also end up warmer during the days and milder at nights than
the past few. In addition, a stray shower or thunderstorm cannot
be ruled out either afternoon and evening, though given the weak
pressure pattern and limited upper level support anticipate the
CWA staying dry. Early this morning, and again tonight, we will
see some limited patchy valley fog and a small to moderate ridge
to valley temperature difference. The main concern for weather
will be later Wednesday night when there will be a small chance
that activity to the north could dive south enough to affect
parts of our area with showers or even a thunderstorm - though at
this time the best forecast looks to be quiet weather into
Thursday.

The NBM guidance was adjusted for temperatures this morning and
tonight adding in more terrain detail as well as to dry out the
afternoon dewpoints a bit extra during each day. Did not see the
need to adjust the PoPs from the NBM much except perhaps raise
them a tad after peak heating both afternoons.

.LONG TERM...(Wednesday night through Monday)
Issued at 335 AM EDT TUE JUN 2 2020

A frontal boundary will stall across Ohio/Indiana Wednesday
night. While there is a small chance a few showers could work
south overnight, given the front should stay well north of the
area, there is a good chance the dry weather could hold through
Wednesday night. By Thursday, a shortwave trough will push east
across the area. The combination of increased moisture and lift
from the wave will lead to better coverage of showers and storms
by Thursday afternoon. As the wave departs Thursday night, we
should see some subsidence in its wake, limiting shower coverage
for the night. However, instability will increase again on Friday,
leading to another threat for afternoon showers and storms. A
stronger shortwave crossing the great lakes will eventually send a
stout cold front south across the area Friday night into
Saturday. There is still some uncertainty on the timing of this
front with the spread actually increasing with the 00z model run.
Thus, confidence is low on when the front will actually push
through, but it does look like it should be out of here Saturday
evening, with dry weather expected for at least the second half of
the weekend. Cooler and drier air will filter into the area for
Sunday as high pressure builds south into the region. High
pressure will remain in control through the early half of the
week, but as the high shifts east, warm weather should quickly
build back into the region. We will be watching a potential
tropical system that will move onshore along the Gulf coast states
and could threaten the area by mid to late next week. However,
the exact track of this system remains very unclear at this time.

&&

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
ISSUED AT 800 AM EDT TUE JUN 2 2020

VFR conditions will be found at all TAF sites through the end of
the period. Variable mid and high level clouds early this morning
will diminish by afternoon. Winds will be light and variable
first thing this morning, but begin to increase again by mid
morning from the southwest. We may see a few gusts of up to 15
mph during the afternoon before the winds diminish toward sunset.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...GREIF
SHORT TERM...GREIF
LONG TERM...KAS
AVIATION...GREIF


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