JKL issues Area Forecast Discussion (AFD) at Feb 26, 11:05 AM EST977
FXUS63 KJKL 261605
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1105 AM EST Wed Feb 26 2025
.KEY MESSAGES...
- The warming trend continues today, with highs potentially
reaching 70 degrees.
- A couple of cold fronts will move through the area on Wednesday
night and Thursday evening. Rain showers are possible with both,
and a rumble of thunder or two is possible on Thursday afternoon.
&&
.UPDATE...
Issued at 1105 AM EST WED FEB 26 2025
Hourly temperatures are lagging a bit behind the forecast late
this morning, likely due to an area of mid-level cloud cover over
much of eastern Kentucky. Expect that temperatures will rebound
more rapidly heading into early afternoon as this area of cloud
cover passes, allowing for a few hours of nearly full sun before
more widespread clouds arrive later in the afternoon.
UPDATE Issued at 805 AM EST WED FEB 26 2025
Only minor adjustments were made to temperatures and sky
condition by blending obs into the forecast.
&&
.SHORT TERM...(Today through Thursday)
Issued at 511 AM EST WED FEB 26 2025
A positively tilted upper trough over the upper Midwest and
northern plains early this morning is rotating through a larger
scale trough over eastern North America. It will make its way
over the Great Lakes and Ohio Valley tonight, supporting a surface
low tracking from IA early this morning to the lower Great Lakes
by Thursday morning. Moisture will be limited, but the system is
expected to be strong enough to result in a band of light precip
along its cold front which will pass southeast through our area
late tonight and early Thursday. Guidance, including MOS, supports
mostly likely POPs for the JKL forecast area, and that's what has
been carried in the forecast. Lapse rates aloft will be fairly
steep (near moist adiabatic) as the system comes through, but the
moist forecast soundings show little or no CAPE. Have held off on
mentioning thunder tonight or Thursday morning.
However, Thursday afternoon and early evening look more
interesting in terms of thunder. The cold front will exit
southeast in the morning and take the precip with it, but after a
break, additional showers are expected to develop. Another
shortwave trough aloft, following on the heels of the first one,
will dive southeast over the Ohio Valley and toward the
Appalachians late in the day. Despite the cooler surface air mass
behind the front, very cold air moving over the area aloft will
again bring steep lapse rates. With the help of dynamic support
from the shortwave, at least isolated to scattered convection
should develop. This time around, forecast soundings show a bit
more instability, albeit only through a shallow layer below 500
mb. However, it looks like the shallow convective currents would
extend upward beyond -20C, possibly resulting in thunder. With the
air mass as cool as it will be, the convection could easily bring
small hail or graupel.
.LONG TERM...(After midnight Thursday night through Tuesday)
Issued at 613 AM EST Wed Feb 26 2025
A rather active, yet progressive weather pattern continues through
the long term forecast period. Multiple upper-atmospheric
disturbances and their associated surface frontal boundaries are
expected to push through the Greater Ohio River Valley over the
course of the next seven days. Towards the beginning of the period,
the disturbances are likely to be relatively moisture-starved. This
will limit their ability to produce widespread, significant amounts
of precipitation, although some mesoscale enhancements may still
yield localized bursts of showery activity. One such burst will be
ongoing at the start of the forecast period on Thursday evening, and
upslope precipitation chances have been added to Saturday night's
forecast to account for another. A different, potentially more
significant set-up emerges early next week, but heightened levels of
forecast uncertainty beyond Monday preclude the mention of specific
details at this moment in time.
When the period opens on Thursday evening, an upper level trough
axis will be positioned directly over Eastern Kentucky. This feature
is forecast to deepen and dig southeast overnight as it interacts
with an embedded shortwave disturbance aloft. Collectively, this
should allow ongoing convective showers to sustain themselves as
they move ESE across the forecast area overnight. A rumble of
thunder or two is possible north of the Mountain Parkway after
sunset, as are some small hailstones or graupel. By midnight, the
entire system will have propagated to the east of the Appalachian
Mountains, resulting in a loss of favorable cyclonic vorticity
advection and dynamic lift. This eastward movement and the
subsequent passage of a surface cold front will, however, shift
winds to the NW, potentially resulting in lingering upslope showers
early on Friday morning. The mesoscale nature of this particular set-
up means that the coarsely-gridded long-term NBM guidance does not
accurately resolve the potential for this activity. Thus, after
coordination with neighboring offices, slight chance PoPs were
added across the northeastern half of the forecast area on Thursday
night and continued into the far eastern terrain before sunrise on
Friday morning. A few snowflakes cannot be ruled out in high-terrain
locations as lows bottom out in the 30s on Friday morning, but
liquid-equivalent accumulations on Thursday night will likely be
limited to less than a tenth of an inch. No significant impacts are
expected.
A lull in precipitation is expected on Friday as shortwave ridging
and surface high pressure temporarily build back into the region.
Winds will intensify and back towards the southwest as the the day
progresses, and the resultant warm air advection will foster
afternoon highs in the mid/upper 50s. On Friday night, a clipper-
type system will quickly dive out of Canada and into the Southern
Great Lakes. Its trailing cold front will push across Eastern
Kentucky early on Saturday, with the best dynamic lift and
precipitation chances initially displaced to the north of the Ohio
River. The daytime hours on Saturday will feature highs in the 50s
and increasing cloud coverage. On Saturday night, however, the
influence of yet another embedded shortwave disturbance will cause
the parent troughing aloft to dig deeper into the region. This will
advect marginal amounts of cyclonic vorticity into the region, which
may combine with a post-FROPA regime of NW surface flow to produce
upslope precipitation. The NBM once again struggled to resolve this
mesoscale set-up, so PoPs were manually added to the forecast grids
in the eastern half of the forecast area on Saturday evening/night.
The cold air advection behind the weekend system is expected to be
more potent than the first, and thus this orographically-forced
precipitation may fall in the form of snow closer to the Virginia
and West Virginia state lines. Sunday looks drier, but colder as a
Canadian surface high builds in behind the Saturday system. Expect
highs in the 40s and dewpoints near 10 degrees under mostly clear
skies.
Monday morning starts out cold, clear, and dry with ridgetop temps
in the upper 20s and valleys in the lower 20s. Guidance generally
resolves a building longwave ridge across the eastern CONUS through
midweek, but models disagree upon the evolution of an upper level
low as it ejects out of the Rockies. Some open it up and dissipate
it as it approaches the Midwest; others track a more-defined trough
into the forecast area on Tuesday. Some also signal a second,
negatively-tilted upper level trough moving into the Plains by mid-
week. The evolution of the first trough will directly affect the
positioning and timing of the second one, and the compounding
effects of model spread greatly reduces confidence in sensible
weather specifics for Monday afternoon and beyond. The current
forecast grids depict a general warming trend in accordance with the
commonly-resolved mid-level height rises. Highs should warm from the
50s on Monday to the 60s on Tuesday. Likewise, rain chances
generally increase through the end of the forecast period as some
type of trough approaches the region. It is too certain to come to
any conclusions regarding convective potential or hydrological
impacts, but we will closely keep an eye on these systems as the
latest data comes in. For now, interests are encouraged to keep an
eye out for relevant safety and preparedness information as we kick
off Kentucky's Spring Severe Weather Awareness Week on March 1st.
&&
.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
ISSUED AT 805 AM EST WED FEB 26 2025
VFR conditions are forecast through most of the TAF period.
Ceilings in the 10-15K ft AGL range are expected to develop late
today and early this evening, lowering to the 4-6K ft AGL range
from the northwest late tonight as showers arrive, and then
falling to MVFR in most places by dawn.
Winds will pick up out of the south to southwest during the day,
with gusts near 20 kt late in the day, before gusts subside in
the evening.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GEERTSON
SHORT TERM...HAL
LONG TERM...MARCUS
AVIATION...HAL
Source:
JKL issues Area Forecast Discussion (AFD) at Feb 26, 11:05 AM EST---------------
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