Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 251135
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
735 AM EDT Mon Mar 25 2024

.KEY MESSAGES...

- A critically dry air mass and an increase in southeast downslope
  winds will result in increased fire danger through late this
  evening.

- Above normal temperatures return today before another round of
  rainfall late tonight and Tuesday. A few thunderstorms will be
  possible across the area late tonight and Tuesday morning.

- Temperatures cool to within a few degrees of normal from Tuesday
  through Friday, with the threat for sub-freezing temperatures
  returning for many valley locations on Wednesday and Thursday
  nights.

&&

.UPDATE...
Issued at 735 AM EDT MON MAR 25 2024

The only somewhat significant change to the grids is to update sky
cover based on current satellite trends through early this evening.
Also blended in latest hourly temperature and wind grids into the
NDFD forecast.

&&

.SHORT TERM...(Today through Tuesday)
Issued at 452 AM EDT MON MAR 25 2024

A pronounced surface high pressure continues to wedge down the east
side of the Appalachians while a strong cyclone continues over the
Central Plains. This is causing an increased pressure gradient over
the western slopes of the Appalachians and a modest increase in
downslope southeasterly winds. This combined with an already
exceptionally dry air mass in the lowest 10,000-ft of the atmosphere
will produce very low humidity today bottoming out as low as the
upper single digits to mid-teens across much of eastern Kentucky and
greatly increase the risk of wildfires through this evening.
Already, humidity values across parts of eastern Kentucky,
especially over the higher terrain along the Virginia border and
adjacent ridges to the northwest are below 30 percent RH, which is
an unusually poor humidity recovery. Given the warm downslope drying
conditions with gusts approaching 20 mph or higher at times, the
forecast high temperatures for this afternoon remain well above
deterministic NBM guidance in the lower to mid 70s.

The air mass moistens overnight from southwest to northeast and from
the mid-levels to the lower levels of the atmosphere as the
aforementioned low pressure system begins to push a cold front
across the Mississippi River Valley toward our forecast area. Drier
air impinging on the moisture aloft will provide enough instability
to warrant mention of showers with a slight chance of thunderstorms
after midnight and lasting through Tuesday morning, and given the
very dry low-levels gusty winds will be a threat with heavier
showers and elevated storms initially. Increased cloud cover will
likely keep temperatures well into the 40s to near 50 degrees, but
lower 40s are possible in the far eastern sheltered valleys where
dry air will linger through much of the night. Southeast winds will
also increase this evening into the overnight, especially in our far
southwest corner of the CWA, such as Wayne County, and may also
increase to Wind Advisory criteria tonight over and just downstream
of the high terrain of southeastern Kentucky. A Wind Advisory may be
needed for all or parts of these areas for later today into Tuesday
morning.

The cold front will continue to slowly march east across the
Bluegrass State, and will likely remain west of the forecast area at
the end of the short term period early Tuesday evening. QPF looks to
be primarily one-quarter to one-half inch, with some areas less,
with many models depicting a dry slot causing shower chances to
diminish from west to east as the afternoon progresses. Given
expected breaks in rainfall during the day Tuesday and with
continued southerly flow ahead of the front, highs will still reach
into the 60s for most locations.

.LONG TERM...(Tuesday night through Sunday)
Issued at 452 AM EDT MON MAR 25 2024

The 25/00z model suite is initially in good agreement on Tuesday
evening showing a broad upper level trough extending from an ~527
dam low over southern Manitoba down into northern Mexico. At the
surface, an ~994mb low is passing over the Upper Great Lakes while
an associated cold front sweeps out an arc through the Ohio Valley,
across Central Kentucky and extends into the Lower Mississippi
Valley.

The trough will translate eastward across the Mississippi Valley on
Wednesday pass across the Ohio Valley/Southern Appalachians on
Thursday and depart off the Mid-Atlantic Coast on Friday. A low-
amplitude upper level ridge will build across the Central CONUS
behind the departing trough and remain in place through the
remainder of the forecast period. At the surface, the cold front
will precede the trough, crossing eastern Kentucky Tuesday night.
Thereafter, high pressure will build eastward from the Plains as it
drift toward Florida by the weekend. The initially chilly northerly
winds behind the cold front will turn back to southerly on the
backside of the high by Friday night. Theta-e gradient analysis
shows frontal boundary formation from the Chesapeake Bay to the
southern shores of Lake Michigan Friday and Friday night. That front
may sag south somewhat during the latter part of the weekend and
potentially spark convection but there is still uncertainty with
regard to available instability.

The sensible weather will feature any showers diminishing from west
to east on Tuesday night and Wednesday as the cold front plods
through the area. A stray shower could linger into Wednesday night
adjacent to the Virginia border. Clouds will likewise breakup
gradually from west to east. Look for a mild Wednesday morning with
low temperatures in the mid 40s to lower 50s and highs in the upper
50s to near 70, west to east. Cooler air will continue to move in
Wednesday night as high pressure builds east bringing widespread
lows in the 30s. The greatest chance for frost and freezing
temperatures on Wednesday night will be in valleys and low-lying
areas along and west of the Pottsville Escarpment. The cooler, drier
airmass will continue to infiltrate on Thursday with highs only
achieving the 50s while dew points retreat back into the 20s
under mostly sunny skies. This will set the stage for the coldest
temperatures of the forecast period on Thursday night when clear
skies and light winds will permit temperatures to drop back into
the upper 20s in cooler valleys and lower to middle 30s elsewhere.
Frost is likely for many. Looking ahead to Friday, temperatures
will moderate back into the 60s for most locations under ample
sunshine. Continued moderation of daily maximum temperatures to
near 70 can be expected for both weekend days. The next chances
for precipitation will also come next weekend.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
ISSUED AT 713 AM EDT MON MAR 25 2024

VFR conditions are expected through the TAF period, with
decreasing confidence at the end of the TAF period as high-based
showers and storms begin to move into the forecast area. Light
southeast winds will gradually increase in strength through the
day, then become stronger and gusty through the overnight hours
while gradually veering to a southerly direction at times. Despite
the increasing winds, even stronger winds just above the surface
overnight tonight warrant a mention of LLWS.

&&

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

$$

UPDATE...CMC
SHORT TERM...CMC
LONG TERM...GEERTSON
AVIATION...CMC


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