JKL issues Area Forecast Discussion (AFD) at Aug 14, 1:20 AM EDT719
FXUS63 KJKL 140520
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
120 AM EDT Wed Aug 14 2024
.KEY MESSAGES...
- Temperatures gradually rise to near normal levels by Wednesday and
remain there through Friday.
- Humidity and the possibility of showers and thunderstorms will
increase late in the week.
&&
.UPDATE...
Issued at 1053 PM EDT TUE AUG 13 2024
Hourly grids were updated based on recent observations and trends.
The thin mid level clouds that had been in place across northern
portions of the area have diminished in areal extent, but some
still remain in the vicinity of the Mountain Parkway or in spots
from KIOB toward KSJS and KPBX per recent observations and
satellite imagery. Otherwise, cirrus is streaming overhead with
the thickest of this crossing the southwest at this time. In most
locations where there mid level deck was not present, temperatures
were in the 60s at this time. However, some ridgetop and more open
terrain locations were nearer to the 70 degree mark.
Hourly grids were freshened up based on recent observations and
trends. Overall, min T for valley locations that had experienced
the thin mid level deck was increased a couple of degrees, with
little or no change in min T elsewhere at this point.
UPDATE Issued at 801 PM EDT TUE AUG 13 2024
A rather thin mid level deck has been quite persistent across the
north late this afternoon and evening, with this deck having
drifted to as far south as near a KJKL to KSJS line. Model
guidance such as the RAP keeps the layer between about 850mb and
700mb with higher rh compared to rh above and below those levels
for much of the night. Weak flow in that layer of around 5KT or
so is also forecast. There is uncertainty as to how long this deck
may persist, but it could affect some areas for much of the
night. Other areas would be left with more significant breaks or
just high clouds. This leads to a lower than average confidence in
overnight lows and the areal extent of ridge/valley temperature
splits. At this point, sky cover was increased in the current general
footprint of this cloud deck through near midnight, but trends
will be monitored. Otherwise, hourly grids were freshened up
based on recent observations.
&&
.SHORT TERM...(This evening through Wednesday night)
Issued at 355 PM EDT TUE AUG 13 2024
Seeing a general northwest flow pattern aloft through the period.
Subtle short wave features continue to weaken and drift off to the
east through the short term as well, resulting in neutral to rising
heights across the lower/mid Ohio Valley through the period. At the
surface, Great Lakes high pressure will shift eastward to the east
coast, veering our north-northeasterly gradient winds increasingly
out of the east-southeast over the next 24 to 36 hours.
Sensible weather features a continued warming of our daily high
temperatures back up to near normal levels by tomorrow. However,
with drier air mixing down during the daylight hours and a minor
advection of drier air into eastern Kentucky from the northeast,
minimum afternoon surface dew points are expected to fall into the
50s. As a result, overnight lows will be cool and pleasant,
generally in the 50s tonight and tomorrow night. Western valleys
will likely not cool as much tomorrow night as southerly return
flow begins to kick in. Thermal belt temps will also be a bit
warmer tomorrow night. But overall, we will still see overnight
lows averaging a few degrees below our normal low-mid 60s. The
lower overnight temperatures will be aided by a gradual decrease
in cloud cover over eastern Kentucky as well. Otherwise, our
weather will be dry and generally uneventful through the short
term. With less cloud cover overall, conditions will be more
favorable for the development of some radiation fog within the
valleys. However, with cross over temps being so low, expect the
most impactful valley fog (lower visibilities) to remain closer to
water sources.
.LONG TERM...(Thursday through Tuesday)
Issued at 355 PM EDT TUE AUG 13 2024
The large scale upper flow pattern to begin the extended will
feature a large trough of low pressure off the east coast of Maine,
with another trough moving steadily through the Great Lakes to end
the week and eventually into New England over the upcoming weekend.
What will likely be Hurricane Ernesto will be churning northward off
the southeastern CONUS toward Bermuda. Broad ridging aloft will be
in place along the Rocky Mountains, across the four corners region,
and into the desert southwest and southwestern CONUS and southern
Plains. Another trough aloft, based on the latest GFS, will be
pushing onshore. The pattern in the east will shift eastward, with a
cold front moving through the Ohio and Tennessee Valleys Thursday
night and Friday. This front will bring showers and storms to
eastern Kentucky beginning Thursday evening, with scattered activity
slowly spreading into the area overnight. By Friday morning, the
front should finally begin to make a concerted push through the
area, with numerous showers and storms expected across the area by
early Friday afternoon. The rain will linger through Saturday night,
as the front stalls out over the area. We should see additional
rounds of showers and storms Saturday night through Sunday, after
the front has moved away and its parent upper trough spins its way
by to our north. The GFS and WPC analysis were in pretty good
agreement with regards to timing and evolution of the upper trough
and surface front.
The first few days of the period will see temperatures at or just
above normal before the front arrives. After the front has gone, we
should see a cooler air mass filtering into the region, which will
lead to daytime temperatures a few degrees below normal heading into
the first of the upcoming work week. The only weather hazard in the
extended will the normal danger from lightning during thunderstorm
activity.
&&
.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
ISSUED AT 120 AM EDT WED AUG 14 2024
VFR flight conditions will prevail through the period at the TAF
sites. Mainly just passing cirrus is anticipated and a few valley
locations immediately near larger bodies of water may experience
valley fog between about 06Z and 13Z with reductions to MVFR.
However, fog is not expected to impact any of the TAF locations.
Winds will be light through the period, averaging between northeast
and east.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JP
SHORT TERM...RAY
LONG TERM...AR
AVIATION...CMC
Source:
JKL issues Area Forecast Discussion (AFD) at Aug 14, 1:20 AM EDT---------------
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