JKL issues Area Forecast Discussion (AFD) at Mar 21, 1:36 AM EDT227
FXUS63 KJKL 210536
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
136 AM EDT Fri Mar 21 2025
.KEY MESSAGES...
- Scattered to numerous rain showers and sprinkles may mix with or
change to snow showers or flurries before ending overnight. The
best chance of snow is mainly at higher elevations near the VA
border.
- A couple of dry cold fronts cross the area Friday night and
again late Saturday.
- Another system crosses the area to end the weekend and should
bring another round of showers and possibly thunderstorms.
&&
.UPDATE...
Issued at 135 AM EDT FRI MAR 21 2025
Ingested latest observational temperature, wind and PoP grids and
tweaked based on recent trends. No major changes were made to the
forecast.
UPDATE Issued at 1026 PM EDT THU MAR 20 2025
Made additional updates to PoPs, Sky, and Frost grids, with PoPs
updated utilizing the 00z CAMS which arrived in the last half-
hour or so.
UPDATE Issued at 730 PM EDT THU MAR 20 2025
Updated PoPs and Sky grids through the overnight based on latest
observed and model trends.
&&
.SHORT TERM...(This evening through Friday night)
Issued at 430 PM EDT THU MAR 20 2025
Late this afternoon, an upper level ridge extended north between
Bermuda and the southeast U.S. coast while a shortwave ridge
extended from the Southern Plains toward the Upper MS Valley. In
between, a shortwave trough extended from Ontario to the eastern
Great Lakes to the OH and TN Valleys to the Southeast. Further
west, a shortwave trough extended from the Northern Rockies to the
Four Corners vicinity. One shortwave trough axis within the
eastern Conus trough extended across eastern KY and into the
Southern Appalachians while another was entering the Lower OH
Valley/western Ky area this time. Stratocumulus and cumulus was
extensive from the Great Lakes to Central and eastern KY south
into the southeastern states. Showers, in some cases mixed with
snow grains where rates are heaviest, were moving across much of
eastern KY with snow falling at the highest elevations above 3000
feet. Temperatures have slid through the day to around 40 or the
upper 30s for most locations and some mid 40s for valleys in the
Big Sandy region. The highest elevations above 3500 feet were at
or below freezing at this time. Winds in the lowest levels have
become more west to northwest or usplope as temperatures aloft
cool ahead of the 500 mb trough axis.
This evening and tonight, the initial shortwave trough will move
east of eastern KY this evening while the second shortwave
reaches eastern KY this evening and shifts to the east and
southeast by around midnight or so. Cold air advection will
continue at 850 mb through the evening, before warm air advection
ensues later tonight when 500 mb heights rise/shortwave upper
ridging as well as surface high pressure build in late at night.
Showers will continue into the evening and as colder air arrives
mix with or change to some snow briefly, especially over the
higher elevations above 2000 feet. However, with the loss of
daytime heating and moisture becoming more shallow with the
arrival of the second shortwave followed by the warm advection
aloft these should taper to flurries and sprinkles and then end.
Low clouds should also decrease from west and northwest to east
and southeast through the night as mixiness also decreases. This
could allow for some decoupling of valleys later in the night and
some patchy frost or areas of frost in some areas. However,
temperatures should bottom out below freezing areawide.
For Friday, the surface and upper level ridging will shift east
across eastern KY as a trough that is currently over portions of
the Rockies/Four Corners area reaches the Plains and approaches
the MS Valley toward evening. At the surface, high pressure will
build east over the eastern Gulf or along the Gulf coast and into
the Southeast. The airmass in the Southeast and Southern
Appalachians into eastern KY will be very dry, with PW forecast
in the 0.1 to 0.2 inch range per 12Z HREF. Climatologically, these
values are below the 10th percentile. Mixing should promote
dewpoints dropping into the teens to low 20s, perhaps mid 20s
along the western fringes of the area. This dry airmass should
warm readily as the sfc high moves east with southwest flow
allowing temperatures to climb to nearly normal for this time of
year. The result will be RH values falling off below 25 percent
in many areas near or south of I-64 and east of Lake Cumberland
and some locations should drop below 20 percent.
Friday night, the shortwave trough that will have neared the MS
Valley Friday afternoon and evening will progress east to Ontario
to the eastern Great Lakes to eastern KY and the southern
Appalachians. A dry, moisture-starved cold front will precede
this shortwave trough across the Commonwealth and should arrive in
eastern KY during the overnight hours. However, the pressure
gradient may be sufficiently weak enough to allow for
southeastern and eastern valleys to decouple during the evening
and allow temperatures to drop into the 30s before the front,
followed by a potential rise in temperatures toward dawn, or a
rise and then a fall again near dawn with some relaxation in the
pressure gradient.
.LONG TERM...(Saturday through Thursday)
Issued at 312 PM EDT THU MAR 20 2025
The forecast period begins with a passing dry cold front. The system
responsible will be well to the north of the CWA in central and
south Canada; however, the cold front will extend through the Great
Lakes and into the Ohio Valley. Moisture will be lacking with the
boundary and PoP chances will be zero but increased southerly winds
ahead of the front are expected through the day. A major temperature
fluctuation isn't expected with this boundary as highs Saturday will
be in the upper-50s to lower-60s. Sunday's highs will climb even
higher into the mid to upper-60s and lower-70s.
Quickly following on the heels of the early Saturday dry system,
another surface low will track along the U.S./Canada border with the
trailing cold front tracking eastward toward the Commonwealth/CWA.
Through the day Sunday, increasing PoP chances are expected with
thunderstorms developing late Sunday afternoon and continuing
through very early Monday morning. The SPC has southwestern portions
of the CWA under a Day 4 15% Severe Weather Risk for this cold front
and severe weather potential should be watched as there could be a
strong to severe storm with this front. Once the front crosses
through the region early Monday afternoon, showers will taper off
from west to east as surface high pressure builds in from the west.
More seasonal temperatures will build back into the region beginning
Monday and continuing through the end of the forecast period.
Model confidence continues to lack after Monday's system and the
approach of another system for Tuesday afternoon. The ECMWF tries to
bring a weak Clipper system on the heels of the exiting
Sunday/Monday system before building high pressure back into the
region for Wednesday. The GFS keeps surface high pressure through
the end of the period. Again, didn't deviate from the NBM which has
a system moving into the region bringing 20%-30% PoP for Tuesday
afternoon, 30%-40% overnight Tuesday and decreasing PoP for
Wednesday as high pressure returns to the forecast area.
Overall the period will be highlighted by several passing systems
that'll bring chances of rain and thunderstorms and a return to more
seasonal temperatures. Also, we'll begin to see a return of frost to
the area beginning early Saturday with chances for frost again
Tuesday morning and Thursday morning.
&&
.AVIATION...(For the 06Z TAFS through 06Z Friday night)
ISSUED AT 135 AM EDT FRI MAR 21 2025
Skies begin to clear from west to east as any remnant rain/snow
showers continue to taper off across the high SE terrain
bordering VA. In general a mix or MVFR and VFR conditions will
transition to prevailing VFR conditions. Mid to high level clouds
do return to the area around 20Z. Winds should be light and
variable through 12Z-13Z before backing to a southwest direction
through the remainder of the TAF period. Winds remain under 10
kts.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GINNICK
SHORT TERM...JP
LONG TERM...VORST
AVIATION...GINNICK
Source:
JKL issues Area Forecast Discussion (AFD) at Mar 21, 1:36 AM EDT---------------
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