859
FXUS63 KJKL 121428
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1028 AM EDT Wed Mar 12 2025

.KEY MESSAGES...

- Unseasonably warm weather will persist through Saturday.

- Low relative humidity will result in another heightened threat
  of wildfires today.

- A dynamic storm system is expected to bring multiple rounds of
  showers, and possibly thunderstorms, to the area this weekend.

&&

.UPDATE...
Issued at 1027 AM EDT WED MAR 12 2025

The forecast is largely on track, with no significant changes from
the previous thinking. Did update to initialize the gridded forecast
with the latest hourly observations.

UPDATE Issued at 801 AM EDT WED MAR 12 2025

A strong ridge-valley temperature split is noted across eastern
Kentucky this morning with low 30s in the coldest hollows ranging
up to the mid 50s over the thermal belt slopes/ridgetops. No
substantive changes were made other than to blend the latest
observations into the hourly forecast.

&&

.SHORT TERM...(Today through Thursday)
Issued at 435 AM EDT WED MAR 12 2025

Mainly clear skies and light winds with a dry air mass in place have
once again allowed for the formation of a sharp ridge-valley
temperature split overnight. The air mass has modified substantially
compared to yesterday as temperatures range from the mid 30s in the
coldest sheltered valleys to the mid 50s to around 60 atop the
warmest thermal belt ridges/slopes. The latest 500H analysis shows
eastern Kentucky sandwiched under quasi-zonal flow between broad
ridging over the Gulf of America/Deep South and broad troughing over
Eastern Canada/Great Lakes. Further upstream, another southern
stream trough is crossing the Desert Southwest. Translating down the
surface, these features manifest as ridging extending across the
Southeast CONUS from an ~1020 mb surface high over the Central Gulf
of America. Meanwhile, a cold front extends from a triple point low
over the southeast Quebec/Gulf of the St. Lawrence to along the New
England Coast then inland across the Central Appalachians and
westward roughly along/just north of I-64 from Huntington, WV to
Louisville, KY. Winds remain southerly south of the boundary but
have turned northerly behind it.

For our area, this boundary will likely linger over/just north of
Fleming County through sunrise before retreating back to the north
during the day as heights rebound behind the departing northern
stream trough. Some weak energy aloft and high-level moisture is
likely to generate a passing band of high clouds later this morning
and afternoon. These will be of little sensible impact though other
than to filter the bright March sun at times. Southwesterly return
flow will boost temperatures a few degrees warmer than yesterday
with highs in the mid to upper 70s expected for most locales. A few
of the warmest valleys could even flirt with 80F. The air mass will
remain quite dry, leading to another afternoon of widespread sub-30
percent relative humidity readings. Additionally, BUFKIT mixed-layer
momentum transfer supports peak wind gusts of 15 to 20 mph with
locally higher gusts over/northwest of the Pottsville Escarpment.
These winds and low humidity levels in combination with dry fuels
will lead to elevated wildfire risk this afternoon and early
evening.

The approaching southern stream 500H trough and its increasingly
lagging weak surface low reflection will pass from the Red River
Valley of the South to over the Lower/Mid-Mississippi Valley
tonight. Shortwave ridging over eastern Kentucky ahead of the system
will set the stage for another dry, fair night with light winds and
a relatively large ridge-valley temperature split. Look for lows
ranging from around 40F in the cooler sheltered valleys to the mid
50s over thermal belt slopes/ridges. On Thursday, the surface low
will deteriorates altogether over the Ozarks as it lags so far
behind the parent trough that it succumbs to synoptic scale
subsidence. The parent trough continues eastward but broadens and
weakens with time as passes over the Commonwealth/Southeast CONUS. A
modest surge of deep layer moisture (PWATs rising to 0.8 to 0.9"
over eastern Kentucky) will spread across Kentucky later tonight and
especially on Thursday ahead of the trough, manifesting primarily as
increased cloud cover. While there will be some marginal instability
(up to around 1,000 J/kg of MLCAPE toward Central Kentucky), the
dampening nature of the trough overall and the lack of focused
surface forcing mechanism renders convective initiation on Thursday
uncertain. Should, deep convection develop, it could become tall
enough to produce thunder. However, it would remain pulsy in nature
due to a lack of substantial shear. For now, overall PoPs remain low
(10% eastern Pike County to 30% over the Southeast Bluegrass) due to
minimal activity depicted in both the hi- and low-res guidance The
increased cloud cover and surface dew points rising toward or above
50F will favor slightly cooler temperatures on Thursday with highs
primarily in the middle 70s.

.LONG TERM...(Thursday night through Tuesday)
Issued at 431 AM EDT WED MAR 12 2025

The forecast period begins with lingering but isolated shower
activity leftover from the system that`s forecast to move through
the area Thursday. Those lingering showers will taper off as the
system dissipates overnight Thursday into Friday. Surface high
pressure will return for Friday with a return to dry weather and
warm temperatures.

By Friday afternoon, a potent surface low will eject off the Rockies
into the Central Plains before lifting northeast into the Upper
Midwest by Saturday morning. As mentioned above, the area will stay
dry through the day Friday but due to increasing southerly flow, due
to the LLJ, increased surface winds and drier air which could lead
to localized fire weather concerns. However, Tds are forecast to be
in the mid-40s which equals out to minimum afternoon relative
humidity values in the upper-30% to low-40%. Once flow turns more
southerly and moisture advection, ahead of the approaching front,
occurs; those Tds will climb into the mid to upper-50s for Saturday.
These increased Tds will help set the stage for the severe potential
that`ll exist for Saturday afternoon. The cold front, that`s
associated with the surface low tracking into the Great Lakes is
forecast to be on the doorstep of the CWA by Saturday morning.
Showers and isolated storms will be possible with this boundary;
however, as a secondary reinforcing trough quickly moves eastward,
another surface low will develop on the tail of the departing cold
front. Between these two features, there could be enough recovery
which would allow for severe weather chances along and ahead of the
secondary system. Favorable severe weather forecast soundings for
Saturday afternoon have continued to increase the likelihood of
severe weather. Both the GFS and ECMWF have seen increases in both
SBCAPE and MUCAPE as well as continued vertical and speed shear on
Saturday afternoon. All of which, combined with the lift from the
approaching system, will lead to those increased threats for severe
weather. These finer details will be hammered out once short-term
models begin to key into the pattern. Also, PWs approaching 1.5" has
also occurred which has lead to an increase in total QPF for the
event. Yesterday, at this time, total QPF was less than 2" across
the CWA but with this forecast package, rainfall totals have climbed
to almost 3" in far western Wayne county. Almost 2" or more can be
expected from the I-75 corridor and west with decreasing amounts to
1.25" along the West Virginia border. The bulk of the heaviest
precipitation will move off to the east as the system ejects to the
northeast and FROPA occurs during the day Sunday. Surface high
pressure will build back into the region for early Monday morning
and will persist through much of the remainder of the forecast
period before another system arrives for the middle of the week.

Overall the period will feature lingering but isolated showers from
weak system on Thursday. A second and much stronger, system is
forecast to impact the region from late Friday through the weekend
before high pressure returns for early next week. Temperatures will
run above average for the first part of the period as highs will
climb to near 80 for Friday and Saturday before a cold front brings
cooler temperatures for Sunday into Monday. Overnight lows will
follow this trend as well.

&&

.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
ISSUED AT 801 AM EDT WED MAR 12 2025

VFR conditions with clear to partly cloudy skies will prevail
through the period. Generally variable to southwest winds around 5
kts or less this morning will pick up again toward midday to
between 5 and 10 kts with occasional gusts approaching 20 kts
through the afternoon.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...CMC
SHORT TERM...GEERTSON
LONG TERM...VORST
AVIATION...GEERTSON