Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 291843 AAC
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
243 PM EDT Wed Mar 29 2017

.UPDATE...
Issued at 230 PM EDT WED MAR 29 2017

Hourly temperatures and sky cover have been updated based on
recent satellite and observation trends. This led to no
significant changes at this time.

UPDATE Issued at 1155 AM EDT WED MAR 29 2017

Surface high pressure extends from the Hudson Bay region south
across the Great Lakes and into the OH Valley. Meanwhile, a mid
level ridge extends from the Caribbean and Florid north into the
OH Valley and southern Great Lakes. Low level moisture trapped
below a subsidence inversion remains across the region behind the
low pressure system that moved across the area Monday night and
early Tuesday morning. The stratus and stratocu are gradually
thinning and eroding from the TN Cumberland Plateau and high
terrain of SW VA north and northwest. Some CU has developed in its
wake however in portions of the Cumberland Plateau. This clearing
or scattering of the low clouds should continue to gradually move
from south to north with high pressure in control. This pattern
should lead to the highest max T near the TN border where low to
mid 70s are anticipated with near 60 in the north. Hourly grids
have been updated for temperature and sky trends.

UPDATE Issued at 755 AM EDT WED MAR 29 2017

Updated the grids to take out the morning patchy valley fog and
also to fine tune the cloud cover through midday. Also tweaked the
near term T and Td grids per the latest obs and trends. These
have been sent to the NDFD and web servers - along with a
freshened set of zones.

&&

.SHORT TERM...(Today through Thursday)
Issued at 455 AM EDT WED MAR 29 2017

08z sfc analysis shows high pressure building south into
Kentucky. This has brought just slightly drier and cooler air to
the region with plenty of low level moisture remaining. As a
result, low clouds still plague our night sky with some earlier
clearing in the Cumberland Valley and north of Interstate 64 now
filling back in. Temperatures are running just a tad cooler than
last night with most places in the upper 40s to lower 50s while
dewpoints are holding within a couple of degrees of the dry bulb
values. The amount of clouds and light north to northeast winds
have prevented the fog from getting much of a foothold so far
across eastern Kentucky - but do expected a few patches in the
valleys toward dawn particularly in places that manage to get some
clearing.

The models are in much better agreement aloft through the short
term portion of the forecast when compares to yesterday at this
time. They all depict a decent mid level ridge through Kentucky
and the Ohio Valley today as a deep southern stream low rolls into
the Southern Plains. This trough then will progress northeast to
the Central Plains tonight further bolstering the ridge over our
area. Energy from the trough will approach Kentucky Thursday
morning as the main portion lifts further into the middle of the
country. This continues to be the case through Thursday with the
trough holding strong while crossing Missouri with the GFS and
ECMWF nearly identical at mid levels - heightening confidence in
the blended solution. This will also place eastern Kentucky in
southwest flow for that afternoon and evening as heights start to
fall. Given the strong model agreement have favored a blended
solution with a lean toward the higher resolution ones for wx
details, especially on Thursday.

Sensible weather will feature a return of sunshine later today
with temperatures climbing into the mid to upper 60s most places.
However, there will be a significant difference in warmth north
to south across the area with low 70s found near the Tennessee
border and cooler lower 60s to the far north closer to the center
of the departing high pressure. A large ridge to valley
temperature difference is anticipated tonight in the course of WAA
and southerly sfc winds kicking in through the night keeping the
ridges better mixed while radiational cooling chills the sheltered
valleys. Patchy valley fog can be expected, as well, into
Thursday morning. For Thursday proper, warm temperatures will be
the rule with southerly winds and some sunshine helping readings
soar into the mid and upper 70s. This will also raise instability
throughout the area later in the day and should triggers arrive
showers and storms will be possible - along with a potential for
severe weather late depending on upstream development and
evolution. The better chances for severe activity for eastern
Kentucky will occur later in the night and not match up all that
well with the best diurnally driven instability.

Again used the ShortBlend and CONSShort as a starting point for
the grids with some rather large, terrain based adjustments made
to temperatures tonight. As for PoPs, made some minor adjustments
to better target the still generally low chance PoPs later in the
day Thursday.

.LONG TERM...(Thursday night through Tuesday)
Issued at 308 AM EDT WED MAR 29 2017

A shortwave trough will advance east across the region Thursday
night into early Friday morning sending widespread showers and a
few thunderstorms across the region. Given good moisture and lift,
will maintain the categorical pops through this period. The mid
level low will cross northern Kentucky Friday afternoon with
numerous showers likely well into the afternoon, making for
another cloudy, cool, and damp day. Rain showers will wind down
into Friday night, but may transition to some patchy drizzle as
some low level moisture will remain left behind. Any drizzle will
come to an end by midday Saturday with the rest of the weekend
featuring a return to dry weather as a surface ridge spreads
eastward across the region.

Our next storm system looks to arrive on Monday and Monday night
sending another round of rain showers into eastern Kentucky. Looks
like pretty strong southeast winds with this system through
Monday, so we`ll have to see how much that eats away at potential
rainfall given the downsloping conditions. In fact, some areas may
struggle to measure with the kind of solution models are currently
centering around. Eventually forcing will win out and we should
see some showers or storms over most of the area, certainly by
Monday night. Wrap around moisture may keep a chance of showers
going into mid week with another system following on the heels of
this system yet again. The active and wet weather looks to
continue. Models also support a continuation of the mild weather
outside of a cooler day on Saturday with the clouds.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
ISSUED AT 215 PM EDT WED MAR 29 2017

Low level moisture continues to mix out with high pressure in
place. This is leading to improvement from MVFR to VFR from south
to north. SME and LOZ are already VFR and JKL, SJS, and SYM
should improve to VFR during the first 2 to 3 hours of the period.
VFR should then persist through the end of the period. An
increase in high and then mid level clouds should occur 0Z to 12Z,
with some low clouds and cumulus development possible late in the
period. A stray shower or even a thunderstorm cannot be
completely ruled out late, but better chances will come after the
period.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...JP
SHORT TERM...GREIF
LONG TERM...KAS
AVIATION...JP


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