JKL issues Area Forecast Discussion (AFD) at Aug 3, 10:06 PM EDT884
FXUS63 KJKL 040206
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1006 PM EDT Sat Aug 3 2024
.KEY MESSAGES...
- Shower and isolated thunderstorm activity winds down through
early this evening.
- Areas of dense fog will form through the night into Sunday
morning.
- Heat and humidity will be in place on Tuesday, with afternoon
heat indices near 100 degrees in a few locations.
&&
.UPDATE...
Issued at 1006 PM EDT SAT AUG 3 2024
We are watching an area of showers and thunderstorms track
southward out of the Bluegrass region this evening. This will end
up pushing toward the Lake Cumberland region tonight and
therefore opted to add in some PoPs for this area. The CAMs have
struggled to keep up with this convection and therefore leaned
more toward the blend of the shorter range guidance with
modifications. The NBM is killing this activity off too fast
(likely a result of the CAMs issues mentioned above) making it
difficult to use for this update. Outside this only minor changes
made for this update.
UPDATE Issued at 830 PM EDT SAT AUG 3 2024
We will see mid-level heights on the rise as upper level trough
exits to the east tonight. This coupled with near by surface high
pressure will lead to the potential for areas of dense fog
overnight and for now in coordination with surrounding offices
have opted to issue a SPS to highlight this risk tonight into
Sunday morning. Outside of this, only minor updates were made to
the overall forecast, with ample fog already added to the grids.
UPDATE Issued at 701 PM EDT SAT AUG 3 2024
More concentrated convection is winding down across the area,
with some isolated to widely scattered activity still hanging on,
in response to lingering backside vorticity associated with the
departing trough, along the aid of some late day heating. Expect
this activity to gradually die off as we lose instability. Have
freshened up the PoP grids to account for the latest trends in
radar.
&&
.SHORT TERM...(This evening through Sunday night)
Issued at 356 PM EDT SAT AUG 3 2024
The latest upper level map features a closed low spiraling over
the eastern portion of Hudson Bay, with cyclonic flow fanned south
to the U.S. border. Further south, a trough is aligned from the
eastern Great Lakes down through eastern Kentucky and portions of
the Deep South. Meanwhile, the heart of a stagnant ridge remains
anchored over the Four Corners region. At the surface, a cold
front is positioned from the central Appalachians down through the
Deep South. Shower activity has been prevalent across eastern
Kentucky through this afternoon, thanks to the upper level trough
directly overhead. Thunderstorms have been more isolated in
nature, with temperatures ranging from the mid 70s, where rain-
cooled air recently occurred, to the lower 80s, where some breaks
in the clouds have allowed for a quick warm up.
The models are in very good agreement aloft through the period.
Troughing aligned over the Appalachians will nudge east and
dampen, as ridging builds east from the middle Mississippi
Valley. At the surface, modest high pressure will gradually take
hold across the Commonwealth, ushering in the start of a period of
dry weather. Scattered to numerous showers and isolated
thunderstorms will diminish through early this evening. Rising 500
mb heights, clearing skies, recent rainfall, and lower dew point
depressions starting out in the evening, should yield a night for
areas of dense fog. Will play this up in the HWO. Temperatures
will cool off to the mid to upper 60s. Once the fog burns off
through the mid-morning hours on Sunday, skies will turn mostly
clear. Temperatures will return to the upper 80s for most
locations, with a few sites perhaps reaching the 90 degree mark.
Afternoon dew points should be a bit drier, with mid 60s achieved
during peak mixing. Mostly clear skies and calm winds will yield
another late night of fog, but this should be a bit more confined
to the valleys. Temperatures will dip into the mid 60s, with a
few of the particularly sheltered valleys cooling to the lower
60s.
.LONG TERM...(Monday through Saturday)
Issued at 356 PM EDT SAT AUG 3 2024
This particular long term forecast package is characterized by two
dominating synoptic features. The first is a building ridge and its
correspondent surface high pressure system in the first half of the
week. The second is a tropical low pressure system that will loiter
around the Florida/Georgia/Carolinas region for a few days before
drifting inland later in the week. As such, expect generally drier
weather in Eastern Kentucky this upcoming week, but low rain chances
will creep back into the forecast from the east during the second
half.
On Monday and Tuesday, the area is on the eastern periphery of a
strong (recent guidance has strengthened it up to 598 dam) 500mb
ridge. Skies will remain mostly clear on these days, allowing
temperatures to follow a strong diurnal curve. These two days will
be marked by afternoon highs in the low to mid 90s and morning lows
in the 60s. It should be noted that these clear sky conditions will
also foster terrain-enhanced differences in temperatures. Low-
lying areas such as valleys will thus be cooler in the mornings
and warmer in the afternoons under this weather pattern. Heat
indices across the area should remain below the 100 degree
threshold on both days, as these temperatures have less moisture
to work with to create heat stress amidst this drier pattern. On
Tuesday afternoon, upper level troughing should begin to dig into
Virginia from the Mid Atlantic States, yielding minimal (15%)
PoPs in our far eastern counties alongside peak diurnal heating in
the afternoon hours. This reintroduction of (minimal) PoPs into
the forecast signals the beginning of an interesting interaction
between a frontal boundary and the tropical system in the latter
half of the extended forecast.
On Wednesday, a weak frontal boundary should move through the area,
supported aloft by fairly deamplified troughing. As such, the
precipitation chances associated with this moisture-starved front on
Wednesday appear meager at only 10-25%. At the same time, the
tropical system at play will have traversed through Florida's Big
Bend Region and re-emerged over the Atlantic Ocean near Savannah,
Georgia. It is expected to come to a crawl off the coast there, and
the aforementioned front should simultaneously stall over the
eastern Appalachians. Models have come to a greater consensus that
this stall will end on Friday, with the system slowly pushing
notably further inland into the Carolinas than it did in previous
guidance. The increased proximity of this system and thus its
interaction with the stalled boundary yielded in slight to low
chance PoPs across the eastern half of the forecast area on Thursday
and Friday in the latest NBM run. Given the great deal of
uncertainty surrounding the evolution of this tropical system, no
significant deviations from these PoPs were made at this time. Rain
chances from this system are thus the greatest (albeit maxing out
at 30%) and most widespread on Friday afternoon and evening in
Eastern Kentucky. Regardless of precipitation, expect high cloud
coverage to increase from east to west if this tropical system
creeps into the Carolina late next week. The combination of the
predecessor cold front and these clouds will keep temperatures
slightly cooler late next week, with highs in the mid 80s and lows
in the low to mid 60s.
Interested parties should continue to monitor the forecast in the
coming days as the details regarding the complex evolution of this
tropical system resolve in higher resolution models. At this moment
in time, however, it appears that impacts in Eastern Kentucky from
this system will be minimal to none, especially after the sunny and
warm days early in the week help to dry things out antecedently.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
ISSUED AT 701 PM EDT SAT AUG 3 2024
Scattered convection will diminish across the area through 03z.
Will continue to hold onto VCSH at all terminals for a few more
hours, but any direct impacts look unlikely at this point. Fog
will be the next concern, as skies clear and winds go calm
overnight. Will continue to forecast LIFR at the terminals
between 08 and 13z, before this lifts and dissipates by 14z, with
a return to VFR conditions. Winds will average around 5 kts or
less through the period.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...DJ
SHORT TERM...GEOGERIAN
LONG TERM...MARCUS
AVIATION...GEOGERIAN
Source:
JKL issues Area Forecast Discussion (AFD) at Aug 3, 10:06 PM EDT---------------
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