JKL issues Area Forecast Discussion (AFD) at Nov 4, 1:07 PM EST529
FXUS63 KJKL 041807
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
107 PM EST Mon Nov 4 2024
.KEY MESSAGES...
- Above normal temperatures are expected this week, with record
or near-record high temperatures forecast for Tuesday.
- The next chance for widespread measurable rainfall arrives
Tuesday evening/night into Wednesday.
&&
.UPDATE...
Issued at 105 PM EST MON NOV 4 2024
Unseasonably mild temperatures for early November, ranging from
the mid to upper 70s at most locations, are noted around the
forecast area early this afternoon. Thinning in the high clouds
have allowed temperatures to warm more rapidly that previously
forecast, thus warranting an 2-3 degree increase in high
temperatures. A few of the warmest valley locations are now
expected to reach the lower 80s, but a vast majority of locations
should see highs between 75 and 80.
UPDATE Issued at 1002 AM EST MON NOV 4 2024
Valley temperatures were lagging slightly behind forecast values.
Minor adjustments were made to bring hourly temperature and sky
cover forecast into line with the latest observations and model
data. Forecast is still on track for a partly sunny afternoon with
high temperatures warming well into the 70s at most locations.
UPDATE Issued at 655 AM EST MON NOV 4 2024
Hourly grids were freshened up based on recent observations.
Overall, this led to no substantial changes.
&&
.SHORT TERM...(Today through Tuesday)
Issued at 423 AM EST MON NOV 4 2024
Early this morning, an upper level ridge was centered in the
vicinity of FL with the axis of this ridge extending northwest
into the Appalachians to eastern Great Lakes to James Bay and
Hudson Bay. Further west, the axis of an upper level trough
extended from western Canada to MT to portions of the Rockies to
Mexico. This leaves eastern KY in south to southwest flow aloft
between these two systems. At the surface, a ridge of high
pressure was centered over New England with another sfc high
centered in VA. In between these two a warm front was lifting
north toward the Great Lakes downstream of an area of low pressure
in the Upper MS Valley region. A wavy frontal zone extended south
from this low into the central to southern Plains. This leaves
eastern KY in the warm sector. Mainly high clouds have worked
through the region overnight, with at times a few mid or low
clouds as well. With the southerly gradient in place, some deeper
valley locations have decoupled with temperatures there having
dropped off into the upper 40s. Patchy valley fog may also have
developed in some areas, but no current observations indicated it
and the degree of high clouds limited detection from the fog
channel difference or nighttime microphysics RGB.
Today and tonight, the upper level ridge is expected to
strengthen off the southeast U.S coast with the axis of the ridge
working further east of eastern KY to the mid Atlantic coast to
New England to Quebec through dawn on Tuesday. Meanwhile, the
upper level trough axis should progress into the Central
Conus/Plains. As this occurs, sfc low pressure should track
northeast along the frontal zone from the Southern Plains to the
mid MS Valley/eastern IA. The trailing cold front should near the
confluence of the OH and MS Rivers to the TX Gulf coast through
late tonight while sfc high pressure departs into the Atlantic. On
Tuesday, the upper trough will near the western Great Lakes to MS
Valley with the associated sfc low trekking to the upper
peninsula of MI and the trailing cold front reaching the Lower OH
Valley/far western KY to LA through early Tuesday evening.
Southerly flow of milder air ahead of the front will continue into
eastern KY.
Through Tuesday, rain free weather is expected with afternoon
winds the next couple of days both on the breezy side as the
region should reside within a decent gradient between high
pressure to the east and the gradually approaching cold front.
Otherwise, any lingering patchy valley fog this morning should
dissipate by 10 AM EST or earlier and patchy valley fog cannot be
ruled out for tonight as well.
0Z HREF and Bufkit momentum transfer both suggested upward
adjustments to NBM sustained wind speeds and gusts were needed for
the next two days, with this especially the case on Tuesday, when
gusts as high to 20 to 25KT seems plausible. Winds will be out of
the south on both days with a downslope component off of the
higher terrain of eastern TN and southwest VA. This combined with
daytime mixing of some drier air aloft should also result in
dewpoints below NBM deterministic on both afternoons, especially
on Tuesday.
Highs will remain at least 10 to 15 degrees above normal both
today and on Tuesday, with departures on Tuesday reaching the 15
to 20 degrees above normal range. Record or near record highs are
forecast for Tuesday. The record high of 79 at JKL from 1994 and
2015 should be broken, while the cord high at LOZ which is also 79
from 1975 is expected to be tied or broken. Meanwhile, lows for
tonight will also be 15 or more degrees above normal..
.LONG TERM...(Tuesday night through Sunday)
Issued at 442 AM EST MON NOV 4 2024
We begin the extended with a high amplitude but progressive flow
aloft...progressive in the sense of shortwave troughs passing
through a more stationary mean pattern of a deep western CONUS
trough and persistent ridging over the southeast US. Model solutions
in general have been hinting at a pattern change with the core
westerlies dropping southward through time, with upper level flow
becoming more broadly zonal overall, which is typical as we
transition from from Sept/Oct into November. The ensemble of the
LREF suggests this to be the case with much weaker ridging over the
east, though it does keep some troughing over the far southwest. In
comparison, the operational 0Z ECMWF reflects a tendency towards
this more zonal scenario initially, but eventually returns back to
the more persistent mean western trough/southwestern low and
southeast ridge pattern.
Two main features have the greatest impact on our sensible weather
during the extended portion of the forecast, both being shortwave
troughs that are expelled from the western CONUS mean trough. The
first of the two takes aim at our area during the mid-week time
frame. This first system dampens quickly as it lifts northeast into
the Upper midwest, and has been trending weaker with each new model
cycle. As a result, its associated surface frontal boundary only
makes it as far southward as the Ohio River Valley before becoming
quasistationary. As a result, PoPs have trended lower and rainfall
totals have trended lower, which was not totally unexpected. The
strength and persistence of the southeastern ridge has been
remarkable. Similarly, the second trough/low that lifts out of the
deep southwest has trended a bit slower and further northwest in its
path eastward. Impacts from this second system are greatest further
out in the forecast, closer to the end of the forecast window, or
possibly just beyond. As mentioned yesterday, the window of highest
PoPs associated with our second round of weather have as expected,
slid further out in time as well, late Sunday into the following
Monday, at the very end of the forecast window.
Consequently expect the unusually warm weather to continue through
the entire period. One main change to the extended package was the
introduction of thunder during the Wednesday-Thursday time frame.
While overall instability is not that impressive, thunder could not
be totally ruled out based on forecast soundings over our
southwest. The main nudgers to include thunder in this cycle was
one, collaboration with neighbors and two, SPC included a general
thunder in southwestern portions of our forecast area for Dy3.
Overall instability remains marginal at best, with LREF ensemble
probabilities of SBCAPE GTE 100 J/kg only at 30-40%. The NBM has
advertised greater probabilties of thunder, but has been quite
inconsistent from run to run not only with probabilities but with
location of highest probs as well. Thus confidence in thunder is
relatively low overall at this time.
&&
.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
ISSUED AT 1240 PM EST MON NOV 4 2024
VFR conditions prevail through the period at the TAF sites and
any fog tonight will be restricted to the most sheltered of river
valleys. Southerly winds at 6 to 12KT with gusts to around 20KT
are expected through this afternoon before slowing to variable at
around 5KT overnight. Winds increase aloft overnight leading to
LLWS potential late, especially west of I-75 where shear was
mentioned in the SME TAF. A brief period of LLWS exceeding 30KT
in the lowest 2kft AGL is also possible at sites further east
near sunrise on Tuesday but was not included in this TAF issuance.
Any LLWS will give way to gusty southerly winds of 10 to 15KT
with gusts of 20 to 30KT once mixing resumes Tuesday morning.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GEERTSON
SHORT TERM...JP
LONG TERM...RAY
AVIATION...GEERTSON
Source:
JKL issues Area Forecast Discussion (AFD) at Nov 4, 1:07 PM EST---------------
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