JKL issues Area Forecast Discussion (AFD) at Oct 7, 3:45 PM EDT779
FXUS63 KJKL 071945
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
345 PM EDT Mon Oct 7 2024
.KEY MESSAGES...
- Noticeably cooler and drier air is moving into the area today
and this will make for rain free and comfortable early autumn
conditions for much of this week.
- Patchy frost is possible Thursday night and early Friday
morning, primarily in the sheltered hollows away from larger
bodies of water.
&&
.SHORT TERM...(This evening through Tuesday night)
Issued at 335 PM EDT MON OCT 7 2024
A tinge of autumn is in the air this afternoon as thermometers
range from the mid 60s north of I-64 up to the lower 70s in the
Middlesboro Basin/Upper Cumberland River Valley. The surface
analysis shows ~1023 mb high pressure centered over the
Missouri/Iowa border though its influence extends across the Ohio
Valley and beyond. Looking aloft, an ~535 dam low is found over
James Bay while longwave 500H ridging extends from the Desert
Southwest northward into the Canadian Arctic. Hurricane Milton
spins furiously just northwest of the Yucatan Peninsula.
The quiescent weather pattern over the Ohio Valley will persist
through the short-term. The upper level ridging to our west will
become more positively-tilted with its axis stretching from the
Desert Southwest northeastward to over the Northern Hudson Bay by
late Tuesday night while the upper low, initially over James Bay,
drifts very slowly to over Southern Quebec while filling slightly.
At the surface, the high pressure creeps southeastward very
slowly, centering itself over the mid-Mississippi Valley by early
Wednesday morning. This setup will keep a northerly low-level
flow feeding dry and cool air across eastern Kentucky through the
forecast period.
In sensible terms, fair skies prevail through the period (except for
late night/early morning fog in typically-prone river valleys). Look
for temperatures to drop quickly around and after sunset as winds
become light and variable. A radiative inversion can be expected
to develop in valleys both tonight and Tuesday night, leading to a
moderate (5 to 8 degree) ridge-valley temperature splits. Lows
are forecast to range from the upper 30s to the mid 40s. Tuesday's
maximum temperatures are forecast to be similar to today -- highs
in the upper 60s northern hills to lower/middle 70s in the
Middlesboro Basin/Upper Cumberland River Valley.
.LONG TERM...(Wednesday through Monday)
Issued at 335 PM EDT MON OCT 7 2024
The 07/12z model suite analysis beginning Wednesday morning shows an
broad ~540 dam low over Southern Quebec. 500H ridging extends from
the Desert Southwest northeastward to over the northern Hudson
Bay. Finally, Hurricane Milton is swirling over the Gulf of
Mexico just west of the Florida Peninsula. At the surface, high
pressure is centered over the mid-Mississippi/Lower Mississippi
valleys.
Hurricane Milton passes over the Florida Peninsula Wednesday night
and early Thursday and then moves off into the Western Atlantic.
Colder air is pulled equatorward on the western side of the
hurricane, causing a new moisture-starved cold front to develop
over the Upper Ohio Valley and then drop southwestward through
eastern Kentucky Wednesday night and early Thursday. Behind that
dry cool front, another surface high pressure will drop south from
Northern Ontario on Thursday and crest over the Lower Ohio Valley
on Friday. While the incoming air mass won't be all that
different temperature-wise at 850 mb compared to our current air
mass, it will be drier, which will support greater radiative loss
and cooler nighttime temperatures, especially on Thursday night.
Ridging aloft and at the surface then breaks down this weekend as
multiple shortwave troughs carve out a deepening trough which will
extend from northern Nunavut/Baffin Island south the
Ohio/Tennessee valleys by Sunday night. West to southwest low-
level return flow develops Friday night and Saturday ahead of the
trough, boosting 850 mb temperatures across eastern Kentucky back
to around 15C by Sunday. That warm air mass will be fleeting
however, as the incoming trough drops a sharp moisture-starved
surface cold front through the Commonwealth Sunday evening and/or
Sunday night. High pressure then dives south from northern Canada
in the wake of the cold front early next week along with 850mb
temperatures sinking into the single digits (Celsius). Forecaster
confidence in predicted surface temperature diminishes by Monday
as models show substantial spread in how quickly the cooler air
mass filters in behind the boundary. Regardless, deterministic
GFS/ECMWF low-level moisture fields are supportive of dew points
nearing or falling below 32F behind the front which, combined with
the incoming surface high pressure, could set the stage for the
first notable frost of the autumn season.
In sensible terms, look for fair and cool weather to persist
through Friday night. Temperatures peak mainly in the lower to
middle 70s on Wednesday before retreating back into the upper 60s
to lower 70s on Thursday and Friday. Ridge-valley temperature
splits can be expected each night as well as forecast temperatures
bottom out in the lower to upper 40s on Wednesday night, mid 30s
to lower 40s on Thursday night, and upper 30s to mid 40s on Friday
night. At this point, Thursday night is likely the coldest night
with patchy frost a possibility in coldest sheltered hollows
(e.g. Sandy Hook, Moon, Hazel Green, etc.). A quick warming trend
then takes hold for the upcoming weekend as high temperatures
rebound into the mid 70s on Saturday and upper 70s to around 80
for Sunday. Overnight lows moderate into the 40s to mid 50s for
the weekend. There is a low end rain chance (25% or less) on
Sunday night into early Monday with the passage of a cold front,
though there is a good chance that this boundary could pass with
no rain at all. Monday's high temperatures will depend upon how
quickly the front passes -- a quicker passage could result in
high temperatures only in the 50s to near 60, whereas a slower
passage would allow temperatures to still reach into the 60s for
most locations.
&&
.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
ISSUED AT 137 PM EDT MON OCT 7 2024
VFR conditions were reported at the 18Z TAF issuance and will
remain so through the period. High pressure building into eastern
Kentucky will mean unrestricted conditions through Tuesday. There
will likely be some locally dense fog in the valleys late tonight
but it is not expected to reach any of the TAF sites. Winds will
be variable to northerly around 5kts or less through the period.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...GEERTSON
LONG TERM...GEERTSON
AVIATION...GEERTSON/GREIF
Source:
JKL issues Area Forecast Discussion (AFD) at Oct 7, 3:45 PM EDT---------------
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