JKL issues Area Forecast Discussion (AFD) at Dec 18, 12:58 AM EST755
FXUS63 KJKL 180558
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1258 AM EST Wed Dec 18 2024
.KEY MESSAGES...
- An area of showers and possible thunderstorms will make its way
east and southeast over the area from the predawn hours
Wednesday into Wednesday evening.
- Much colder air will arrive as rain departs late Wednesday and
Wednesday night. It will become cold enough for a possibility
of some light snow as the next weather system passes through
Friday into Friday night.
&&
.UPDATE...
Issued at 1037 PM EST TUE DEC 17 2024
Areas continue to decouple, resulting in rapid temperature drops.
Have adjusted the diurnal curve and lowered low temperatures to
reflect current trends.
UPDATE Issued at 710 PM EST TUE DEC 17 2024
Some valleys have started to decouple ahead of incoming cloud
cover and rain. Present temperatures were dropping faster than
anticipated as a result. Adjustments were made to the overnight
lows in valley locations to account for the rapid cool off. Valley
fog was also added to the grids earlier than previous forecast to
account for present conditions and observations.
&&
.SHORT TERM...(This evening through Wednesday night)
Issued at 453 PM EST TUE DEC 17 2024
A frontal boundary is stalled to our south and southeast late this
afternoon. Surface high pressure behind the front is over the
central Appalachians and has brought clearing skies to most of the
area. With light winds and mainly clear skies expected to start
the night, radiational cooling should allow for cold air to start
pooling in valleys, with ridge/valley temperature differences
showing up.
However, a modest mid/upper level wave will support low pressure
development along the front to our southwest, with the low
tracking east northeast through eastern KY on Wednesday. As it
approaches, our pressure gradient will tighten and low level flow
will increase overnight. Clouds will also begin to make a comeback
overnight. The combination should result in low temperatures being
reached before the normal time around dawn, with readings probably
starting to climb overnight. The surface low will temporarily
pull the front back north, giving mild temperatures for all but
perhaps the northern edge of the forecast area through mid day
Wednesday. The low will also briefly pull considerable moisture
north into the state, and with support from the advancing wave
aloft, showers will occur. Forecast soundings also show weak
elevated instability, and some rumbles of thunder can't be ruled
out.
The low will depart to the east northeast late in the day, with
the trailing cold front pushing through and departing to the
southeast. Much colder air will arrive behind the front, but this
time around it looks like moisture will also dwindle fast enough
to avoid any change to snow. Low clouds are still expected to
linger in the shallow moisture Wednesday night.
.LONG TERM...(Thursday through Tuesday)
Issued at 329 PM EST TUE DEC 17 2024
The large scale flow pattern aloft in the extended will start off
with a trough of low pressure exiting southeastern Canada and
northern New England, with some precipitation lingering behind the
trough as it moves away from land. Another trough of low pressure
will be moving through the northern Plains and into the Great Lakes
Thursday and Thursday night. As this shortwave digs southeastward,
it will move through the central Ohio Valley and eventually into the
mid-Atlantic region, Friday night into Saturday. This feature will
bring rain and snow showers to eastern Kentucky as it moves through
our area, and temperatures fall to near and eventually below
freezing. The precip will start out as rain early Friday morning,
but will quickly mix with snow during the afternoon. By early Friday
evening, enough cold air should have advected into the region behind
a departing trough, to allow precip to change over to all snow. Due
to the fast movement of the the system and ambient ground
temperatures above freezing, little if any snow accumulation is
expected. The last bit of snow be out of our area by early Saturday
morning.
A ridge of high pressure will settle over the region to start the
weekend, and will remain in place into the first of the new work
week. Temperatures will continue to be quite cold Saturday and
Sunday, as an arctic air mass invades the region. Highs on Saturday
and Sunday will likely not make it out of the 30s across our area.
By Monday, we should see a slow warm up begin, as winds shift around
to the south and ample sunshine continues across the area. The
warming should continue on Tuesday, as winds remain out of the
south. However, another area of low pressure might be moving into
the area on Tuesday as well, bringing yet more rain to the area, as
temperatures should be in the low to mid 40s by the time precip
begins. Nightly lows will be in the upper teens and lower 20s on the
coldest nights, and mainly in the upper 20s to lower 30s on the not
so cold nights. No weather hazards are expected at this time in the
extended portion of the forecast.
&&
.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
ISSUED AT 1258 AM EST WED DEC 18 2024
All terminals minus, KSYM and KJKL have fallen out of VFR and into
either MVFR or IFR. Terminals KSME and KLOZ are currently in IFR
as lowering CIGS, ahead of an approaching system are over those
sites. KSJS is MVFR due to valley fog moving into that site. Over
the next few hours, all terminals will fall into MVFR/IFR as the
aforementioned system moves into the region. Showers associated
with the system will begin to move northeast into the area after
08Z and showers are forecast to continue through roughly
00Z/Thursday. Isolated to scattered thunderstorms will be possible
but due to lack of confidence in the locations of those storms,
they've been left out the TAF. Also with this system, LLWS will be
possible from 12Z to 18Z before surface winds increase and negate
LLWS. Sustained south-southwesterly winds from 10 to 12 knots and
gusts to 20 knots will be possible after 18Z through frontal
passage later in the forecast period. Lastly with frontal passage,
winds will begin to shift from the south-southwest to the
northwest. Terminals will begin to see some improvement in CIGS
toward the end of the TAF period as surface high pressure builds
back into the area.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GINNICK
SHORT TERM...HAL
LONG TERM...AR
AVIATION...VORST
Source:
JKL issues Area Forecast Discussion (AFD) at Dec 18, 12:58 AM EST---------------
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