JKL issues Area Forecast Discussion (AFD) at Nov 3, 4:11 AM EST662
FXUS63 KJKL 030911 CCA
AFDJKL
AREA FORECAST DISCUSSION...CORRECTED
National Weather Service Jackson KY
411 AM EST Sun Nov 3 2024
.KEY MESSAGES...
- Above normal temperatures are expected this week, with record
or near-record temperatures forecast for Tuesday.
- The next chance for widespread measurable rainfall arrives
Tuesday evening into Wednesday.
&&
.SHORT TERM...(Today through Monday)
Issued at 314 AM EST SUN NOV 3 2024
Early this morning, the axis of an upper level ridge extended from
the eastern Gulf of Mexico across the southeast to the Lower OH
Valley to the western Great Lakes. Further west, a trough extended
from western Canada south into the western Conus. At the surface,
a ridge of high pressure was centered in the vicinity of the St
Lawrence Valley and extended into the eastern Great Lakes and also
south to the mid Atlantic and the Carolinas. Meanwhile, a low
pressure system was starting to evolve over portions of the Plains
downstream of the trough that encompassed most of the western
Conus. A warm front east of the low extended across the mid south
to the Southeastern Conus. Locally some valley fog has developed
along the rivers and some of the deeper valleys, with several
valley locations in the north and east in the mid to upper 30s
with 40s to near 50 observed elsewhere. Dewpoints were largely in
the 30s to low 40s. However, return flow has led to dewpoints in
the upper 40s at the KY Mesonet stations in Pike County at around
2770 feet and Harlan County at 4031 feet.
Today and tonight, upper level ridging is expected to remain in
place from the eastern Gulf of Mexico across the FL peninsula to
the Bahamas with guidance suggesting the ridge strengthening with
rising heights into the Southeast Conus to mid Atlantic states to
eastern Great Lakes. At the same time, the axis of the trough over
the western Conus will work to the Four Corners region and
central to southern Rockies region as it approaches the Plains.
This trough axis should work into the Plains on Monday as the axis
of the upper level ridge to the east moves east of the Southeast
and mid Atlantic coast to Quebec line. The warm front is expected
to lift into eastern KY by this afternoon and then gradually
north of the area tonight into Monday morning as the boundary and
sfc waves along it evolve downstream of the upper trough moving
from the western Conus and into the central Conus by the end of
the period.
As the warm front lifts north and into eastern KY today, an
increase in moisture near 850 mb or roughly in the 4 to 7kft agl
range is progged by the 0Z GFS and 0Z NAM and is consistent with
0Z HREF forecast soundings. Some of this increase is already
evident in the higher elevation KY Mesonet observations. This
increase in moisture and the approach of the warm front should
lead to some clouds at times at roughly 4 to 7kft agl during the
day today. Sfc dewpoints will also gradually increase as well. In
addition to the increase in moisture, the southerly flow will
result in highs today about 7 degrees or so on average above
Saturdays readings.
In the warm sector tonight, moisture near 850 mb is progged to
decrease and this should lead to at least times of sky devoid of
low clouds with mainly high and some mid clouds passing. Another
ridge/valley temperature split is favored, especially across the
north and east. Some valley fog may also form, but coverages is
expected to be less than recent nights. Lows in the 50s should be
common outside of the deeper valleys where mid to upper 40s are
anticipated. Another mild day will follow for Monday with
continued southerly flow between sfc and upper level ridging to
the east of the region and the upper level trough and associated
sfc front/system moving into the Central Conus.
.LONG TERM...(Monday night through Saturday)
Issued at 410 AM EST SUN NOV 3 2024
The 03/0Z model suite is in better agreement than usual through
the extended with respect to the main synoptic features. A strong
upper level ridge resides over the southeastern CONUS at the start
of the period, while a potent trough extends from the Northern
Plains of Canada southward into upper Rio Grande Valley. Further
upstream, a second potent northern Pacific 500H shortwave trough
dives into Four Corners region, effectively kicking the original
trough out through the Plains and into the Midwest by late
Tuesday. As it lifts northeast, this original trough dampens
considerably as it attempts to push the east coast ridge further
out into the Atlantic, but instead only managing to flatten it a
bit. The passage of this trough further east of the axis of the
ridge combined with the digging actions of the second upstream
trough into the Four Corners, the ridge over the southeast
reamplifies and/or reestablishes its influence across the eastern
CONUS by Friday, though in a weakened state. The re-amplification
of this eastern ridge is short-lived however, as the low over the
Four Corners then begins to push eastward into the Central Plains
by the end of the period, forcing the ridge to finally succumb. At
the surface, high pressure over New England shift out into the
Atlantic as a surface cold front slides eastward into the Midwest
by mid-week (Wed-Thu). This boundary becomes quasi-stationary and
barely manages to drift southward into eastern Kentucky by the end
of the period.
Sensible weather, features unseasonably mild weather for early
November, with near record afternoon high temperatures, upper 70s
to lower 80s, expected on Tuesday. Thereafter, temperatures
average about 5-10 degrees above normal. The potential for rain
increases by mid-week, with highest PoPs forecast during the
Wednesday through Wednesday night time frame for the first round
of precipitation. PoPs increase again at the end of the forecast
window (second round) as the second storm system moves out of the
Great Plains towards the lower and mid Ohio Valley region.
Ensemble solutions suggest a 40- 80% chance of a tenth of an inch
with the mid-week system. Highest probabilities are found over our
northwest, especially our Bluegrass counties while our lowest
probabilities are advertised across our far southeast, along the
KY/VA state line. Probabilities for higher QPF drop off very
rapidly from there. So this first round of rainfall could wind up
being a relative high PoP, low QPF scenario as the first system
struggles to produce with such a strong ridge in place over the
southeastern CONUS.
Thereafter, confidence is not high with respect to the timing and
strength of the second storm system approaching the Ohio Valley
at the end of the period. Strongly suspect the best, or highest
PoPs will trend further out in time with future cycles, just
beyond the end of the current forecast window. One positive...if
trends in solutions are correct, the stubborn eastern CONUS ridge
could begin to finally break down in ernst, making it possible for
subsequent storms systems to bring more meaningful rainfall
totals to the area.
&&
.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
ISSUED AT 150 AM EDT SUN NOV 3 2024
High pressure at the surface and upper level ridging aloft will
gradually shift to the east and northeast. However, the
combination should lead to VFR conditions throughout the TAF
period with one exception. Deeper valley fog mainly near rivers,
the larger creeks and area rives should develop prior to dawn and
linger as late as 14Z to 15Z and could result in some MVFR to IFR
reductions if not locally lower. However, these is not expected
to affect the TAF sites. Outside of this, passing high clouds are
expected through the period and some clouds in the 4 to 6kft agl
range are anticipated due to an increase in moisture in that
layer between about 12Z and 02Z as a warm front lifts into the
Commonwealth. The winds will be light and variable through around
14Z, before becoming around 5KT or less between east and south
though averaging from the southeast.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...JP
LONG TERM...GEERTSON/RAY
AVIATION...JP
Source:
JKL issues Area Forecast Discussion (AFD) at Nov 3, 4:11 AM EST---------------
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