Sebastians Branch, Kentucky Weather Forecast Discussion

979
FXUS63 KJKL 101448
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1048 AM EDT Wed Sep 10 2025
.KEY MESSAGES...
- Mostly dry weather is expected to persist for the next week.
- Temperatures should warm to near or above normal by the weekend.
&&
.UPDATE...
Issued at 1048 AM EDT WED SEP 10 2025
The forecast is on track with no changes needed. The last of the
fog has burned off in the last half-hour in the Cumberland Valley.
UPDATE Issued at 755 AM EDT WED SEP 10 2025
Hourly grids were freshened up based on recent observations and
trends. Valley fog still lingers along area rivers, larger
creeks, and lakes but has begun to lift. This fog should lift and
mix out by the 9 to 10 AM EDT timeframe. Temperatures will
continue their gradual moderation trend, likely reaching about 2
to 3 degrees warmer than on Tuesday.
&&
.SHORT TERM...(Today through Thursday)
Issued at 537 AM EDT WED SEP 10 2025
Early this morning rather broad troughing extended across the
eastern Conus from an upper low over the Hudson Bay/western Quebec
vicinity. A couple of shortwaves moving through this trough were
upstream of the Lower OH Valley/eastern KY with one working across
western KY/Lower OH valley region while another extended from
Lake Superior to IA. This trough was located in between upper
ridging in the Atlantic centered northeast of Bermuda and another
ridge extending from northern Mexico into the High
Plains/portions of the Central Conus. Further west, an upper low
and trough were gradually working into the western Conus. At the
surface, a ridge of high pressure extended from the Northeast to
the Appalachians. Locally, a moderate ridge/valley temperatures
split is in place with valleys in the mid and upper 40s around 50
with mid to upper 50s observed on the ridges. Valley fog has again
developed and may be dense in a few spots. In addition, although
skies have been mostly clear to clear overnight, there have been a
few patches of low to mid level clouds have traversed the region.
Today and tonight, the initial shortwave trough should work
gradually east and across eastern KY through this evening with the
next upstream shortwave trough moving into the Central to Eastern
Great Lakes to Lower OH Valley region as the upper low moves
across northern sections of Quebec. At the sfc, a ridge of high
pressure will persist across the Appalachians.
This shortwave will be moisture starved, but some guidance has
some weak showers/spotty QPF over parts of central KY and some as
far east as the I-75 corridor or the Lake Cumberland region late.
Some sprinkles are not completely out of the question late in the
southwest part of the area, but at this point appear more
probable over central KY. As the trough continues to move east on
Thursday, some of the Convective allowing models as well as some
of the recent GFS and ECMWF have light spotty QPF or showers in
the southwest CWA. For now kept pops near the NBM PPI values for
Thursday afternoon to early evening and added a slight chance of
sprinkles for the southwest with pops near 10 percent there. This
shortwave works east of eastern KY on Thursday evening/night which
should end any chance for sprinkles with high pressure dominating
late.
Valley fog is likely to form once again and with any clouds
also clearing out a small to moderate ridge/valley temperature
split should once again develop. Highs should continue a gradual
increase, but still remain a few degrees below normal.
.LONG TERM...(Thursday night through Tuesday)
Issued at 520 AM EDT WED SEP 10 2025
The period is expected to begin with an upper trough from the
Maritimes/Lower St Lawrence Valley southwest across New England to
the mid Atlantic states to Appalachians to the Southeast. This
trough should be located in between upper ridging in the Atlantic
centered east and southeast of Bermuda and another area of upper
ridging extending from Mexico across the Southern and Central
Plains to the Upper MS Valley and western Great Lakes. Also at
that point, a broad upper low and associated trough are expected
to be in place across the western Conus with an upper trough
upstream of that from the Gulf of the AK into portions of the
eastern Pacific. Also as the period begins, an upper level low is
progged to be over the western portions of Hudson Bay with a
shortwave trough south to portions of Manitoba and Quebec. At the
surface, a ridge of high pressure is progged to extend from
Quebec to the Mid Atlantic to the Appalachians and Southeast as
the period begins.
Thursday night to Friday night, a couple of weak shortwaves
moving through the trough extending across the Appalachians may
cross eastern Ky as the period begins though the axis of this
troughing should move east of the Appalachians for Thursday. Some
modest height rises should follow across eastern KY as upper
ridging centered over northern Mexico into the Southern Plains
builds into the Lower OH Valley to Southeast. Also at that point,
the upper low in Canada should reach northwestern Quebec by late
Friday night with the associated shortwave trough south to the
northern Great Lakes. Further west the center of the broad
western Conus upper low should meander to the northern Rockies to
Alberta and Saskatchewan border with MT vicinity as the next
shortwave begins to near the BC to Pacific northwest. At the
surface, a ridge high pressure is expected to remain centered in
the vicinity of the Southern Appalachians while a frontal zone
associated with the upper low reaching Quebec may slide to the
across much of the Great Lakes region.
Across eastern KY, with high pressure dominating, any cloud cover
associated with the trough moving east should diminish quite
quickly on Thursday night and give way to mostly clear skies
through Friday and Friday night. The airmass should moderate
further with highs nearing normal for this time of year on Friday.
Under this pattern, for both Thursday night and Friday small to
moderate ridge/valley temperature splits will be favored along
with valley fog development both nights.
Saturday to Sunday night, the upper low and trough are expected
to move toward the Maritimes and New England/Northeast while upper
level ridging remains from northern Mexico to the Southern Plains
and builds into the MS Valley and western Great Lakes. GFS
generally continue with the upper low track further northeast from
eastern KY compared to ECMWF runs and have higher heights over
the weekend across eastern KY as compared to the ECMWF runs.
Further west and northwest, a series of upper lows or troughs are
progged to move from the western Conus to sections of the Central
and Northern Plains toward the Canadian prairies. Meanwhile the
sfc boundary initially north of eastern KY may sag toward the OH
valley region as a wave moving along it may reach the mid Atlantic
and sfc high pressure builds across the central Great Lakes.
For eastern KY, with the variation in heights there is uncertainty
with temperatures over the weekend. NBM guidance as well as the
ECMWF keep temperatures nearer to or at normal while the GFS
would favor temperatures several degrees above normal. For now did
not stray from the middle of the road NBM numbers.
Monday and Tuesday,the ECMWF and GFS continue to vary with the
upper pattern across the Conus though the consensus is for upper
ridging to dominate with some modest height rises for eastern KY
and the OH Valley. The GFS continues a trend of higher heights
for the region compared to the ECMWF so uncertainty remains. At the
surface, the weak boundary may sag across the area with no
notable change in sensible weather anticipated. The NBM guidance
was more or less middle of the road with highs a few degrees above
normal though if the GFS were to verify larger departures are
probable. With the potential boundary moisture-starved, the
current pop forecast from the NBM of less than 15 percent still
appears reasonable and the dry or mainly dry weather should
persist.
&&
.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
ISSUED AT 800 AM EDT WED SEP 10 2025
With sfc high pressure continuing to dominate, valley fog remained
at issuance time with reductions to as low as IFR or LIFR though
fog was not affecting the TAF sites. The fog should lift and
dissipate through the 13Z to 14Z timeframe. Thereafter, VFR
conditions, with winds less than 10 kts are forecast for all
areas through the end of the period, with the exception of some
MVFR to IFR and perhaps locally lower reductions in fog for
valley non TAF site areas between about 04Z to 12Z.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...CMC
SHORT TERM...JP
LONG TERM...JP
AVIATION...JP

NWS JKL Office Area Forecast Discussion