JKL issues Area Forecast Discussion (AFD) at Oct 12, 8:25 AM EDT335
FXUS63 KJKL 121225 AAA
AFDJKL
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
825 AM EDT Sat Oct 12 2024
.KEY MESSAGES...
- Mainly rain free weather is expected through Wednesday with only
a 20-50% chance of showers Sun afternoon into Sun night.
- Patchy to widespread frost is forecast each night from Mon night
through early Thu.
- A freeze is possible in some spots Mon night to early Tue, with
a more widespread freeze possible Tue night to early Wed and Wed
night to early Thu.
&&
.UPDATE...
Issued at 815 AM EDT SAT OCT 12 2024
Hourly grids were freshened up based on recent observations and
trends. This led to no substantial changes at this point. A milder
day is in store as return flow begins to take shape.
&&
.SHORT TERM...(Today through Sunday)
Issued at 505 AM EDT SAT OCT 12 2024
Early this morning, an upper level ridge was centered over the
southwest Conus and extended north across portions of the western
Conus/Great Basin to BC as well as east and northeast across
portions of the Southern and Central Plains to the mid MS Valley.
An upper trough was over the Southeast Conus while broad
troughing extended from Central and eastern Canada into the Upper
MS Valley to Great Lakes and Northeast Conus. A couple of
shortwaves moving around the ridge over the western Conus to
western Canada and into the trough were working from Saskatchewan
and into Manitoba with another upstream over the northeast
Alberta/northwest Saskatchewan area. At the sfc, a ridge of high
pressure was in place from the Southern Appalachians and across
the Southeast Conus while another area of high pressure was
centered from the upper MS Valley to the western Great Lakes with
a frontal zone in between that extended from a sfc low over the
lower St Lawrence Valley to just south of the Great Lakes to the
mid MS valley before becoming wavy and eventually extending north
to the lee of the Rockies into SD and MT and then west. Valley fog
has formed overnight in eastern KY in portions of the Big Sandy,
Kentucky, and Cumberland basins, though per satellite imagery,
areal coverage appears lower than last night. Temperatures range
widely from upper 30s to around 40 in sheltered valleys to the
upper 40s to around 50 for most ridgetops. The Pike County mesonet
station at 2770 was sitting in the inversion/thermal belt.
Today and tonight, the upper ridge over the Southeast Conus is
expected to build a bit further east into the Southern Plains
while the axis of the ridge should shift east over the western
Conus and extend through the Rockies late tonight as the pattern
tends to amplify over the Conus. Downstream of the ridging upper
level troughing is expected to evolve from Central and eastern
Canada into the Great Lakes and eastern Conus. The initial
shortwave over Canada should move east across Ontario and Quebec
to the St Lawrence Valley while the next one upstream should
sharpen as it reaches Manitoba to western Ontario to the upper MS
Valley late today into this evening and then works into the
western Great Lakes tonight. As this occurs, a sfc wave is
expected to track along the boundary located south of the Great
Lakes reaching IL this evening and the treks across IN and near OH
late tonight. The trailing cold front should begin to sag south
and southeast into the Mid MS Valley to Southern Plains and
approach the OH Valley late tonight as sfc high pressure slides to
the south and southeast of eastern KY. The shortwave trough
should continue east and southeast to the central Great Lakes on
Sunday and possibly close off to an upper low. The associated sfc
low should track into the mid Atlantic by Sunday evening while
the trialing cold front begins to sweep southeast across the
Commonwealth reaching eastern KY by Sunday evening.
Valley fog should lift and dissipate early this morning, and give
way to sunny or mostly sunny skies today. Moisture will begin to
increase today in the lower levels as well as in the upper levels.
Further moistening/moist advection will occur tonight and Sunday
on increasingly strong southwest to west winds aloft. The
approaching cold front should combine with daytime heating for
some of this higher momentum to reach the ground on Sunday once
the nocturnal inversion mixes out. Gusts in excess of 20KT or
generally 20 to 30 mph are currently forecast with wind gusts
having been trended above the low biased NBM values when stronger
systems are crossing our region. Bufkit momentum transfer from the
00Z GFS and 00Z HREF mean sfc wind gusts suggest that the current
forecast has trended in the right direction, upward, but may be
as much as 5 KT or more too low that is as much as 5 to 10 mph too
low at least for gusts during peak mixing. Moisture ahead of the
boundary will be limited with dewpoints reaching the mid to upper
50s and may result in a few hundred J/kg of CAPE while bulk shear
may be as high as 25 to 35KT. Rather weak convection may be able
to develop by early evening and might be capable of producing a
couple of wind gusts stronger than what may be mixed down outside
of convection. Coverage should be meager per CAMS and with limited
moisture and movement rather swift, any rainfall will also be
meager, a few hundredths of an inch at best where rain actually
falls.
As high pressure works east and southeast of the area and more
south to westerly flow ushers in a warmer airmass and eventually a
more moist airmass, temperatures will moderate to about 5 to 7
degrees above normal for highs today with highs nearly 10 degrees
above normal in the upper 70s and low 80s anticipated for Sunday.
In between, lows tonight will be milder than the past couple of
nights.
.LONG TERM...(Sunday night through Friday)
Issued at 413 AM EDT SAT OCT 12 2024
Monday, a Canadian upper low, centered over southern Quebec, will
bring much cooler conditions to eastern Kentucky. In fact,
temperatures will be 10-15 degrees colder than normal, in the upper
50s to lower 60s each day through Wednesday. Breezy conditions can
be expected Monday and Tuesday afternoons, with west to
northwesterly winds 5-10 mph gusting up to 20 mph. Lows Monday night
will drop into the low to mid 30s in the valleys, with ridgetops in
the upper 30s to lower 40s. Patchy fog may develop in valley
locations Tuesday morning and patchy to areas of frost is expected
across the area.
Tuesday, an embedded shortwave within the Canadian low moves through
the area leading to isolated to scattered showers across portions of
eastern Kentucky. Highs will continue to be in the 50s, with lows in
the low 30s and ridgetops in the mid 30s. Areas to widespread frost
is expected to develop overnight.
Wednesday through the end of the week, a ridge of high pressure
starts to build into the area from the Central Plains. This will
result in a warming trend but wont be reflected in the forecast
until Thursday. Highs Wednesday will still be in the 50s, nearing 60
in spots. High pressure with southerly winds is also favorable for
big ridge/valley splits in regard to temperatures at night.
Wednesday night lows will still be in the lower 30s in the valleys,
but upper 30s to near 40 along ridgetops. Conditions continue to warm
heading into the end of the work week, with High temperatures getting
back into the 60s and low 70s by Friday.
&&
.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
ISSUED AT 822 AM EDT SAT OCT 12 2024
Lingering valley fog with some IFR or MVFR conditions in the
deeper valleys will lift and dissipate through 14Z. This was not
affecting the TAF sites. Some additional deeper valley fog may
again form during the 04Z to 08Z timeframe with MVFR or lower
reductions and linger to end the period. Otherwise, VFR conditions
and winds less than 10 KT will prevail as high pressure begins to
depart and a cold front begins to approach. Later tonight as the
cold front begins to approach winds aloft will increase and bring
a LLWS threat to end the period.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JP
SHORT TERM...JP
LONG TERM...GINNICK
AVIATION...JP
Source:
JKL issues Area Forecast Discussion (AFD) at Oct 12, 8:25 AM EDT---------------
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