JKL issues Area Forecast Discussion (AFD) at Aug 22, 2:46 PM EDT
686
FXUS63 KJKL 221846
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
246 PM EDT Thu Aug 22 2024
.KEY MESSAGES...
- Below normal temperatures are expected today, with above normal
temperatures returning this weekend.
- Dry weather persists into early next week, before small rain
chances (20%) make a return towards the end of the period.
- Heat indices of 95 to 100 degrees return for some locations by
early next week.
&&
.UPDATE...
Issued at 1103 AM EDT THU AUG 22 2024
There are no changes to the forecast with the late morning update.
UPDATE Issued at 732 AM EDT THU AUG 22 2024
Hourly grids were updated based on recent observations and trends.
Temperatures have bottoming out in the mid 40s to mid 50s across
the region. The valley fog should gradually lift and dissipate
over the next couple of hours.
&&
.SHORT TERM...(Today through Friday)
Issued at 449 AM EDT THU AUG 22 2024
Early this morning, an upper level low was centered in the New
England vicinity with an associated trough axis south across the Mid
Atlantic states and into the Southeast. An upper level ridge was
centered over portions of the Southern Plains/western TX area. This
ridge extended northeast to the Upper MS Valley and western Great
Lakes. In between these two systems, northwest to northerly flow
aloft lingers. At the surface, a ridge of high pressure extended
from the Great Lakes across the Appalachians to the VA and Carolina
coasts. 850 mb temperatures are analyzed generally in the 10 to 12C
range at this point. Under the influence of the sfc high,
temperatures have cooled into the upper 40s to low 50s for most
locations with a few mid 50s on some coalfield ridges and in areas
of more open terrain. Valley fog was also present per satellite
imagery along area rivers as well as some of their larger tributary
creeks and adjacent lakes and was generally most prevalent south of
the Mountain Parkway.
Today and tonight, the upper level low initially over the New
England vicinity is expected to gradually track northeast toward the
Canadian Maritimes while a trough axis should extend south to near
Cape Cod and then east of the Mid Atlantic states to the eastern
Gulf of Mexico. At the same time, the upper ridge should become
centered a bit further northeast over the Southern Plains with the
axis of this ridge shifting into the Great Lakes. Locally, 500 mb
heights are progged to rise from around 583 dm at present to about
588 dm this evening and to near 590dm near sunrise on Friday. The
sfc high pressure ridge should shift east during this time and
become centered over the mid Atlantic states, though the sfc and
upper ridge will continue to remain dominant over the OH Valley and
Commonwealth. At the same time, 850 mb temperatures should rise to
about 13 to 15C by sunrise on Friday. Afternoon mixing should allow
dewpoints to again drop below NBM deterministic values with min
dewpoints in the mid to upper 40s in the north and east to the low
to mid 50s southwest. A general north to south gradient in high
temperatures should occur as well and the dry airmass should warm to
about 3 to 4 degrees warmer as compared to Wednesday. This would
again result in Max T below normal, but by only about 5 to 7
degrees. Min humidity should also have a gradient of lower values
north and east and somewhat higher values nearer to the TN border.
On Friday, further height rises at 500 mb are anticipated across
eastern KY as the upper level ridge builds from the Southern Plains
into the mid MS to OH and TN Valleys. The ridge of sfc high pressure
will remain across much of the eastern Conus during this time with
the center of the ridge moving to the eastern seaboard. 850 mb
temperatures are forecast to rise to about 16 to 17C. This should
result in highs about another 3 to 5 degrees warmer than today, with
highs nearing normals for this time of year. Rather deep mixing
should again result in afternoon min dewpoints below NBM
deterministic values of around 50 north if not a few upper 40s with
upper 50s to near 60 southwest.
As for sensible weather, the valley fog should lift and dissipate
within about 2 to 3 hours past sunrise or by the 9 to 10 AM EDT
timeframe. With the surface and upper level ridge in place, another
ridge valley temperatures split is favored tonight with upper 40s in
deeper sheltered valleys in the north and east to the 50s elsewhere.
Once again, valley fog is again expected to from along area rivers
as well as some of their larger tributary creeks and adjacent lakes
and should again be most prevalent south of the Mountain Parkway.
This fog will likely begin to form by around midnight or shortly
thereafter and lift and dissipate by the 9 to 10 AM EDT period on
Friday.
.LONG TERM...(Saturday through Thursday)
Issued at 246 PM EDT THU AUG 22 2024
Upper-level ridging will continue to be in place over much of the
central CONUS. This will keep an omega blocking pattern across the
CONUS as a circulation remains over the Pacific Northwest and one
remains over the Northeast. In eastern Kentucky, hot and dry
conditions will continue to remain overhead through the weekend into
early next week. High temperatures are forecast to climb into the
upper-80s to low-90s with overnight lows falling into the upper-50s
in the valleys and low-60s everywhere else. As moisture builds into
the region for Tuesday, ahead of a frontal boundary, heat indices
will begin to climb and approach 100 degrees in a few places. Also,
due to the increase moisture and the passage of a weak boundary;
isolated (10-20%) PoP will be possible Tuesday afternoon mainly
north of the area but can't rule out a shower/storm popping up
across the far eastern portions of the CWA. This will be possible
again Thursday as another boundary sweeps through the region;
providing a little bit better of a chance (20%-30%) of a shower or
storm for a big portion of the CWA. Otherwise, the area will
continue to be hot and dry with heat indices climbing toward the
middle of next week and slight chances of showers and storms with
the passage of a couple of weak fronts.
&&
.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
ISSUED AT 120 PM EDT THU AUG 22 2024
With high pressure dominating, VFR is expected to prevail through
the period, with one exception. Valley fog should again develop
between about 04Z and 07Z tonight along the larger creeks, rivers,
and lakes, with reductions to MVFR or IFR conditions. Winds will
generally be light and variable through the period.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...CMC
SHORT TERM...JP
LONG TERM...VORST
AVIATION...CMC
Source: JKL issues Area Forecast Discussion (AFD) at Aug 22, 2:46 PM EDT (https://mesonet.agron.iastate.edu/p.php?pid=202408221846-KJKL-FXUS63-AFDJKL)
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