JKL issues Area Forecast Discussion (AFD) at Jul 17, 3:01 PM EDT630
FXUS63 KJKL 171901
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
301 PM EDT Wed Jul 17 2024
.KEY MESSAGES...
- Showers and thunderstorms will impact the region through early
next week, with the highest probability and greatest coverage
today.
- Some minor flooding of low-lying areas will also be possible
through this evening, if storms pass repeatedly over the same
locations.
- A welcomed relief from the heat follows for Thursday through the
middle of next week, with afternoon high temperatures in the
upper 70s to lower 80s.
&&
.UPDATE...
Issued at 939 AM EDT WED JUL 17 2024
MCS remnants which were moving into the area rapidly diminished
this morning. Have made major adjustments to the POP (lowering it
this morning). Made further adjustments into tonight based on
latest model runs, but confidence is not very high.
UPDATE Issued at 650 AM EDT WED JUL 17 2024
Made some refinements to PoPs for the next 24 hours based on
latest radar trends and CAMS. Thunderstorms have developed ahead
of a weak mid-level circulation that has developed overnight in
association with the MCS activity over central Kentucky. The
leading edge of this circulation is taking advantage of a weakly
unstable atmosphere to produce the showers and thunderstorms. This
activity will continue to move northeast through this morning
across eastern and southeastern Kentucky.
&&
.SHORT TERM...(Today through Thursday)
Issued at 328 AM EDT WED JUL 17 2024
The models are in very good agreement through the short term
regarding the upper level pattern and surface patterns. The trough
will shift southeast with time, occupying the northeastern portion
of the CONUS by early Thursday and spreading 500 mb height falls
across the Ohio and Tennessee valleys today through Thursday. The
surface cold front will gradually ease southeast, moving through the
Commonwealth primarily late this afternoon through the overnight
tonight. This will result in an active period of showers and
thunderstorms across eastern Kentucky, providing beneficial rainfall
to much of the area.
A large MCS continues to push east and southeast across much of the
Commonwealth early this morning. CAMS and SPC Mesoanalysis depict
meager instability over areas mainly north of the Mountain Parkway,
with greater instability towards the KY-80/Hal Rogers Parkway
corridor, especially along and west of Interstate 75. Would thus
expect new convection to develop at times along and ahead of the
current MCS activity and impact southwestern and southern parts of
the forecast area the remainder of this morning. Meanwhile, to the
north of the Mountain Parkway would expect primarily rain with
embedded heavier showers owing to the weaker instability this
morning.
By afternoon, the cold front will be moving southeast across the
northern part of the forecast area. Any partial clearing along and
to the south of the front will destabilize the atmosphere and
allow for development of additional showers and thunderstorms.
Much of the rain will be beneficial, but will need to monitor for
training of the heaviest cells over any one area which may result
in some localized flooding issues in low-lying areas. With the
high humidity and cloud cover today, highs will be much cooler
than in recent days, with highest temperatures in the south where
clouds and convective activity may be able to hold off the
longest.
Convection will gradually diminish from northwest to southeast
Wednesday night with the loss of heating and as the front eases off
to our southeast. Lows will range from the mid to upper 60s.
For Thursday, despite the front stalling well to the southeast of
the region, the trailing upper trough will be moving southeast
across the Ohio River Valley in the afternoon and early evening.
Despite cooler surface temperatures, residual moisture and
instability from steepening lapse rates aloft will result in a
continued chance for afternoon showers and thunderstorms across
the southeastern half of the forecast area. Temperatures will
only reach the upper 70s to lower 80s across the area with cool
dry air advecting in with surface high pressure nosing into the
area from the north behind the cold front.
.LONG TERM...(Thursday night through Tuesday)
Issued at 415 AM EDT WED JUL 17 2024
The extended will start off with large scale trough aloft in place
over the eastern CONUS east of the Rocky Mountains, with a cold
front extending southward from northern New England, through the
Mid-Atlantic region and into the Gulf Coast states and eventually
the southern Plains. A surface low is progged to be in place over
eastern Texas, with its own surface cold front extending across
southern and western Texas Thursday night. A large ridge of high
pressure is forecast to slowly push into the Ohio and Tennessee
Valleys Thursday night through Friday night, and will bring dry
weather to the area to finish out the week. A few showers and
storms might push across the VA and TN borders into portions of
southeastern KY Friday and Friday night, as a wave of low pressure
moves eastward along the cold front that will be in place to our
south. By early Saturday, a stronger wave of low pressure is
forecast form along the western end of the cold front, and then
move eastward along it. As the wave moves our way, it will cause
the cold front to make a northward push over the weekend, bringing
showers and storms to the area. Used a blend of the latest runs of
the GFS, ECMWF, WPC analysis, and GFS Ensemble guidance to
construct the forecast.
We will see much better rain chances Sunday through Wednesday, as
the subtropical high strengthens and expands westward toward the
southeastern CONUS. As this occurs, the surface cold front will be
pushed even further north. We will also see an increased flux of
moisture into the region due to southerly flow from the offshore
ridge. Waves of low pressure moving along the front will also act
as triggers for showers and storms heading into the middle of next
week.
Now for some good news, it appears that temperatures through out
the extended will be a few degrees below normal, as a cooler and
less humid air mass moves into the region behind the cold front,
as it moves off our south to start things off. In a nutshell, the
first few days of the extended should be mostly dry, with high
pressure mostly in control. From Sunday onward, however, the
pattern will become quite active, with a northward moving cold
front, waves of low pressure moving along it, and a westward
expanding subtropical ridge combining to bring enhanced rain
chances to eastern KY. As always, we will keep a close eye on the
potential for locally heavy rain Sunday through Tuesday.
&&
.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
ISSUED AT 301 PM EDT WED JUL 17 2024
Scattered showers/thunderstorms have developed with diurnal
destabilization this afternoon. They are most numerous over south
central and southeast KY, with points further north and west not
heating/destabilizing as much due to greater cloud cover earlier
today. However, just about any place could have a shower or storm,
and VCTS was used int TAFs. Where/when they occur, they may bring
sub-VFR conditions. Outside of precip, mainly VFR conditions will
prevail. There is a higher probability for showers/thunderstorms
ahead of a cold frontal passage from northwest to southeast
tonight, and a TEMPO group was used in TAFs for this. Behind the
front, forecast soundings and guidance indicate IFR conditions for
a time overnight into Thursday morning for most of the area. It's
been included in all TAFs except for KSYM, but confidence is not
too high. Improvement back to VFR conditions is expected by early
Thursday afternoon.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...HAL/CMC
SHORT TERM...CMC
LONG TERM...AR
AVIATION...HAL
Source:
JKL issues Area Forecast Discussion (AFD) at Jul 17, 3:01 PM EDT---------------
If I'm using your data in a way that is against your terms please email the team at "threatweb@pupswoof117.com"! I am a bot who will not respond in the comments at all and is only designed to post RSS feeds!
