JKL issues Area Forecast Discussion (AFD) at Mar 31, 2:45 AM EDT308
FXUS63 KJKL 310645 AAC
AFDJKL
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
245 AM EDT Mon Mar 31 2025
.KEY MESSAGES...
- Multiple rounds of showers, and some thunderstorms, are expected
into Monday. The greatest coverage for the area as a whole will
be from tonight into early Monday morning.
- There is an Slight to Enhanced Risk of severe thunderstorms
this evening into early Monday. Damaging winds are the main
threat, but an isolated tornado or two can not be ruled out.
- After briefly cooler temperatures Monday night into Tuesday,
temperatures return to above normal levels Wednesday into next
weekend.
- Parts of eastern Kentucky may see another round of strong to
severe storms Wednesday night.
- There is a strong signal for repeated rounds of heavy rain and
thunderstorms for the middle to latter parts of next week
across parts of the lower and middle Ohio River Valley. It is
unclear at this time how much of an increased flooding potential
extends into eastern Kentucky.
&&
.UPDATE...
Issued at 240 AM EDT MON MAR 31 2025
Several counties west of the line of storms has been cleared from
the Severe Thunderstorm Watch. This line will remain strong to
severe as it nears the WV and VA borders, and thus additional
counties will be clear from the watch within the next hour or so.
UPDATE Issued at 1118 PM EDT SUN MAR 30 2025
Convection over central KY has congeal into a line with a history
of wind damage upstream. This line remains fairly well organized
with SPC mesoanalysis and RAP forecast as the line moves into the
CWA has 500 to 1000 J/kg of MLCAPE suggesting the line should
remain surface based into the CWA. Effective shear of 35 to 45KT
on average and western parts of the area effective SRH may reach
as high as 200 to 300 m2/s2. 0-3km shear vectors become more
parallel to the convection just west of Lake Cumberland at this
point and a little more favorably oriented further north in
Central KY. Damaging winds will remain the primary threat as the
line moves east, but any mergers into the line that may occur
could result in a brief spin up. Severe Thunderstorm Watch 80 has
been issued for the entire CWA through 6 AM EDT on Monday.
UPDATE Issued at 845 PM EDT SUN MAR 30 2025
At present, eastern KY was free of any shower or thunderstorm
activity though a line of convection extends from OH and southern
IN into parts of western KY down into MO and AR. There remains
some uncertainty as to how quickly the northern end of this line
may reach the CWA, however, it may arrive as early as 10 to 11 PM
near or northwest of I-64 and then later further south and east.
Made some adjustments to hourly pops, lowering them from the
previous forecast areawide over the next couple of hours, before
merging into the higher pops nearer to midnight and into the
overnight. As this line of storms arrives it will pose a risk of
mainly strong to damaging wind gusts.
&&
.SHORT TERM...(This evening through Monday night)
Issued at 415 PM EDT SUN MAR 30 2025
19Z sfc analysis shows a decent pressure gradient between low
pressure now entering the western portions of the Ohio Valley and
high pressure east of the Appalachians. This is supporting breezy
south to southwest winds of 10 to 15 mph with gusts up to 25 mph
across eastern Kentucky as well as propping up temperatures
despite the multiple layers of clouds. It is also helping to surge
more moisture into the boundary layer providing the fuel for
storms this evening and overnight. Currently, readings are topping
out in the low to mid 70s most places while the dewpoints have
breached the lower 60s west and are up to the mid 50s in the far
east. On radar, scattered activity of mostly showers continue
through the area while the biggest storms are pounding locations
just northwest of the state closer to the sfc low and its
developing, east-bound cold front.
The models, and their individual ensemble suites, are coming into
better agreement aloft through the short term portion of the
forecast. They all depict weak energy in mid-level southwest flow
passing through eastern Kentucky into the evening. This is before
the approach of a stronger trough at 5h punches into the Ohio
Valley with a core of energy that will strafe northern parts of
the state into the first half of the night. This initial trough
will send 5h height falls through eastern Kentucky after midnight
while fast southwest mid level flow continues. The trailing
impulses will then settle the larger trough through the state on
Monday - helped along by the placement of the right entrance
region of a strong 3h jet streak over our area from the winds in
the upper atmosphere racing southwest to northeast through the
Ohio Valley and eastern Great Lakes - along with another decent
wave of energy crossing the JKL CWA by 00Z Tuesday. This happens
in the fast mid level flow that becomes more zonal through the
night with ample lingering packets of energy to pass overhead.
The, now smaller, model spread aloft supported using the NBM as
the starting point for the forecast grids through the period. Did
make some adjustments mainly to incorporate the newest CAMs
guidance into the PoP and thunder grids through the first half of
the period.
Sensible weather features mainly scattered activity around eastern
Kentucky until later in the evening until the kinematics aloft
moves closer to our area. This will likely allow some of the
instability from the daytime heating to fade, but wind fields will
only get better for organized storms through the evening. The sfc
trough out ahead of a late arriving cold front is expected to
create a QLCS of storms that will drop southeast through eastern
Kentucky late this evening into the late night hours. We will
continue to need to monitor any discrete cells out ahead of this
line for rotation and potential tornados - especially in the
locations west of the I-75 and northwest of I-64 where the latest
HRRR runs suggest a couple of updraft helicity swaths are
possible from west to east through those areas this evening. The
main severe threat for the bulk of the area arrives with the
linear storms toward late evening in the northwest and spreading
southeast during the night. Potentially damaging wind gusts and a
possibility for spin-up, brief, tornados will accompany the
stronger storms in the line. Generally lighter and steadier
showers follow into dawn, held up a bit by a wave moving along the
front, for most places before ending from northwest to southeast
during the morning and into early afternoon on Monday. This will
also bring cooler conditions for the afternoon on westerly winds.
The cooling continue into the night where if we would see clearing
some frost may be possible - generally just for locations west of
I-75.
The changes to the NBM starting point consisted primarily of
adjusting the PoPs per CAMs timing and placement through Monday
afternoon. Did not deviate too far from the NBM for temperatures
and dewpoints given the higher moisture content through the bulk
of the period followed by steady CAA.
.LONG TERM...(Tuesday through Sunday)
Issued at 304 PM EDT SUN MAR 30 2025
Tuesday morning, patchy frost may be present mainly west of the I-75
corridor. Otherwise, high pressure builds into the area through the
day, with dry conditions remaining across Eastern Kentucky up until
Wednesday morning.
Cold air advection will continue through Tuesday, keeping
temperatures seasonable, in the upper 50s to mid 60s from north to
south. During the day, a large scale 500-mb trough deepens over
western CONUS. From this an upper level low ejects out of The
Rockies into the Upper Great Lakes. Winds will likely veer, becoming
southerly through Wednesday. Eastern Kentucky will be in the warm
sector out ahead of the next approaching system mentioned above.
This will lead to continued warm air advecting in and temperatures
returning to 10-15 degrees above normal, in the upper 70s to low
80s. Clouds will increase through the day with a chance of off and
on showers through the day. Heading into the afternoon and evening
the attached cold front is modeled to extend from the Ohio Valley
down through the Mid and Lower Mississippi Valleys. Shower and
thunderstorm chances exist for the state, with the SPC having
Eastern Kentucky under a 15% a risk of severe weather. Breezy
conditions are possible Wednesday, with the NBM guidance showing
gusts around 30 mph. LREF 00Z ensemble data continues to have mean
wind gust of 40 mph, with the general spread between the 25th and
75th percentile being 35-45 mph. We'll continue to monitor this
threat.
Deterministic models and ensembles have the front late Wednesday
becoming rather stationary over Kentucky and surrounding states
through Saturday. With precipitable water consistently modeled
between 1 and 1.5 inches each day, flooding could be a possibility.
The WPC has highlighted this threat with placing a portion of the
area under a marginal risk for excessive rainfall. For Thursday,
showers and thunderstorms continue across Eastern Kentucky. With the
lack of a progressing front and persistent rain, the WPC has put the
area under a slight risk and marginal risk for excessive rainfall.
Current guidance has this stationary boundary further west across
Western and Central Kentucky, and surrounding areas, which is why
that area is in a moderate risk for excessive rainfall. Temperatures
will likely remain 10-15 degrees above the climatological averages,
in the upper 70s to low 80s.
During the day Thursday, an area of low pressure rides the lee side
of a ridge, into the deep trough over Western CONUS. While being
slow to propagate downstream, it will eventually be what moves the
stationary front away from the state, later Sunday or Monday. With
winds currently expected to veer Saturday into Sunday from a
southwest wind to a northwest wind, cold air advection may temper
temperatures Sunday, rising into the low 60s to upper 60s going
north to south.
&&
.AVIATION...(For the 06Z TAFS through 06Z Monday night)
ISSUED AT 235 AM EDT MON MAR 31 2025
Primarily VFR and MVFR was observed at issuance with some sites
reporting IFR or lower within stronger showers and a few
thunderstorms. As a cold front approaches, the lower levels should
saturate enough that by 11Z and after, prevailing MVFR should
begin to develop in the higher terrain near the KY/VA/TN border
area near KI35 and K1A6 as well as from near KSYM to KLOZ and
points west. In these more western locations some IFR is
anticipated between 12Z and 18Z and as another disturbance
passes, a few hours of IFR between 18Z and 00Z. MVFR should
prevail from KSJS to KLOZ to KSME and south through the end of
the period with some MVFR arriving further north by around the end
of the period. Thunder chances diminish from northwest to
southeast with the frontal passage.
Wind gusts in excess of 30KT are possible with a leading of
convection nearing the VA border over the first hour or so.
Winds outside of storms should average south to southwest at 5 to
10KT through 12Z, with some gusts to around 20KT at times. The
main cold front will pass between about 12Z and 20Z, with winds
becoming west and then northwest at generally 5 to 10KT.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JP
SHORT TERM...GREIF
LONG TERM...GINNICK
AVIATION...JP
Source:
JKL issues Area Forecast Discussion (AFD) at Mar 31, 2:45 AM EDT---------------
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