LMK issues Area Forecast Discussion (AFD) at Dec 23, 12:25 AM EST953
FXUS63 KLMK 230525
AFDLMK
Area Forecast Discussion
National Weather Service Louisville KY
1225 AM EST Mon Dec 23 2024
.KEY MESSAGES...
* Above normal temperatures Tuesday through the end of the week.
Multiple disturbances to bring rain chances most days.
&&
.SHORT TERM /THROUGH TUESDAY/...
Issued at 341 PM EST Sun Dec 22 2024
Currently, surface high pressure off the Mid-Atlantic Coast extends
southwest through the Southeast, resulting in light south to
southeast winds through the Lower Ohio Valley. Skies are mostly
clear over southern Indiana and central Kentucky, but there are a
few passing high level clouds and a dissipating mid-level deck over
parts of southern Indiana.
Tonight, the aforementioned surface high moves farther off the East
Coast, but high pressure will remain centered over the
Tennessee/North Carolina border. This will cause light winds over
the CWA to continue slowly veering towards the south. With clear
skies and limited warm air advection, temperatures will return to
the 20s.
Tomorrow, upper flow will push a surface low over Texas east towards
the Lower Mississippi River Valley while a different surface low
moves east across the western Great Lakes. Together these lows will
increase the pressure gradient over the CWA, and during the
afternoon, 5-10 mph southerly winds will begin gusting to around 15-
20 mph. At the 800mb level, a 35 knot low level jet flowing toward
the low will increase moisture levels to saturation. This will cause
stratus to begin dropping southeast into the CWA. A few sprinkles
will likely fall out of this deck during the evening hours across
southern Indiana, but model soundings show dry air above around
750mb and below around 850 mb. This should really limit rain
potential. Temperatures will warm into the mid 40s to low 50s.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Issued at 341 PM EST Sun Dec 22 2024
Mon Night - Tues (Christmas Eve)... Split upper pattern will
develop over the CONUS at the start of the long term as the northern
branch features a shortwave trough pushing through the Great Lakes
as ridging build into the Ohio Valley ahead of a second shortwave
trough coming out of OK/AR. Associated sfc boundary from the Great
Lakes shortwave will push southward towards the Ohio River before
washing out over the area during the day Tues. Scattered light rain
Mon night into Tues (20-30 percent) is possible, mainly along and
north of the Blue Grass and Western KY Parkways as exiting LLJ
allows for additional lift. Another challenge for light rain Mon.
Night/Tues morning will be dry air below 900mb, with initial
perception falling as virga before the lower layers become
saturated. The rest of the day Tues. looks to be dry as upper
ridging build in from the south, allowing for some drier low-level
air to work in from the south. Temperatures will be above normal
warming to near 50 for the afternoon.
Tues. Night - Wed. (Christmas Day)... Precipitation chances increase
Christmas Day as the aforementioned shortwave trough associated with
the southern branch of the jet works across the Ohio/Tenn River
Valleys. Continued WAA will provide above normal temperatures as
well as increasing the deep layer moisture. Nearly stalled, inverted
sfc trough will be present over the Ohio Valley allowing for the
scattered showers to be around during the day. Precipitation is
expected to diminish Wednesday afternoon into Wed. night. Highs on
Christmas will be in the low/mid 50s.
Thursday... Upper level ridging will start to increase ahead of
another approaching trough coming out of the Four Corners and over
the ArkLaTex by Thursday night. Thursday looks to be warm and dry
with highs warming into the mid/upper 50s.
Friday - Weekend... Forecast becomes more uncertain for the end of
the week and into the weekend. While we will hold on to unseasonably
warm and above normal temperatures (15-20 degrees above normal),
with highs in the upper 50s to low 60s, it also become more active
as a series of shortwave trough continue to work across the region.
Deterministic models start to differ on the handling of the the
aforementioned trough lifting out of the ArkLaTex region on Friday.
GFS wants to take this slightly negatively tilted trough more north
and west of the CWA as it interacts with ridging over the
Appalachians. This scenario brings keeps rain chances around but
keeps the best forcing dynamics to the west and north. The ECMWF on
the other hand pushes these upper-level disturbances right through
the Ohio Valley with high chances of rain but also the possibility
of thunderstorms and low probability of severe. Confidence remains
low but it is worth noting and something to monitor for the end of
the week and into the weekend.
&&
.AVIATION /06Z TAFS THROUGH 12Z TUESDAY/...
Issued at 1224 AM EST Mon Dec 23 2024
VFR conditions expected through the valid TAF period, with winds
veering from SE to SSW in the morning as return flow takes hold
behind departing high pressure. Look for sustained 10-12 kt during
the afternoon, with LEX seeing gusts just shy of 20 kt. Warm
advection aloft will eventually bring in a mid-level ceiling by late
afternoon and a gradual lowering after dark. SDF could see light
precip in the planning period, which we'll handle with a PROB30 to
include potential MVFR vis at that time.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...None.
IN...None.
&&
$$
SHORT TERM...KDW
LONG TERM...BTN
AVIATION...RAS
Source:
LMK issues Area Forecast Discussion (AFD) at Dec 23, 12:25 AM EST---------------
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