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000
FXUS63 KLMK 211723
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
123 PM EDT Sun Apr 21 2024

...Updated Aviation Discussion...

.KEY MESSAGES...

*   Frost Advisory in effect tonight through Monday morning.

*   Showers and an isolated thunderstorm or two Tuesday night. No
    severe weather.

*   Shower and thunderstorm chances Friday-Saturday.

*   No significant frost threats after tonight. Coolest night in the
    extended forecast will be Wednesday night with lows in the upper
    30s in southern Indiana and north central Kentucky.

&&

.UPDATE...
Issued at 1023 AM EDT Sun Apr 21 2024

Sfc high pressure currently over the central US will nose eastward
through the day. We are already seeing the high clouds slowly
eroding and moving eastward on the latest satellite imagery. Cold
air will advect in from the north keeping temperatures well below
normal in the 50s. As the colder advects in we could see some
scattered Cu develop and we`re already seeing that on visible
satellite imagery over central IN. Current forecast is in good shape
and no changes will be made.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 313 AM EDT Sun Apr 21 2024

Currently... Nighttime microphysics shows high clouds streaming
through the region along the periphery of southern stream troughing.
High pressure centered over the central Plains is lending to light
northwesterly winds bringing in cooler and drier air. Low
temperatures around sunrise will be in the upper 30s and low 40s.

Today... Another shot of cool air will reinforce below normal
temperatures along a shortwave trough swinging through the region.
Mid-high level clouds will continue to stream overhead through most
of the day. High temperatures will be cooler than yesterday in the
upper 50s.

Tonight... Ridging aloft and high pressure at the surface will move
over the Ohio Valley allowing for clear skies and calm to light
winds. Ample radiational cooling will bring temperatures into the
mid 30s by Monday morning. These are all ingredients for frost,
therefore, a Frost Advisory will be in effect from 05-13Z for all
counties. It is recommended to cover sensitive vegetation during the
overnight hours tonight.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
Issued at 313 AM EDT Sun Apr 21 2024

High pressure advancing from the Ozarks to the Piedmont will provide
us with mostly sunny skies Monday and afternoon temperatures only
about 5 degrees below normal, in the mid 60s. No frost issues Monday
night as clouds begin to increase slightly ahead of the next system
with a steady south breeze and lows in the low to mid 40s.

A 500mb shortwave trough over the Pacific Northwest this morning
will glide into the Ohio Valley by Tuesday evening. The moisture
supply with this feature will not be great, with surface high
pressure blocking most of the Gulf and shunting moisture
northwestward into the southern Plains. Very little instability, too
-- not expecting much more than an isolated rumble of thunder. As a
result, QPF is light, on the order of one or two tenths of an inch.

Wednesday and Thursday high pressure crossing the Great Lakes will
return dry weather to the region with just some scattered mid and
high clouds. Wednesday night will be the chilliest of the Long Term,
with lows mostly in the upper 30s and lower 40s. At this time
temperatures look too warm and winds a little too high for much of a
frost threat.

GEFS/CFSv2 are indicating the middle part of the country will enter
into a stormy period by late this week and continuing into the first
week of May. Deep upper troughing is expected to dig into the
Intermountain West with impulses ejecting northeastward across the
Plains into the Midwest. While this will induce general upper
ridging from the Great Lakes to the Gulf of Mexico, occasional waves
passing by to our northwest will temporarily suppress the ridge
overhead as they move by. The Gulf will be open with surface high
pressure sprawled along/near the Eastern Seaboard, allowing moisture
to flow northward. CIPS/CSU-ML/SPC/GEFS/CFSv2/DESI LREF all keep the
best chances of *severe* storms to our west over the central and
southern Plains, but we`ll still need to have chance PoPs of showers
and thunderstorms in the Ohio and Tennessee Valleys by Friday and
Saturday. Highs will be in the 70s Friday and around 80 on Saturday.

&&

.AVIATION /18Z TAFS THROUGH 00Z TUESDAY/...
Issued at 120 PM EDT Sun Apr 21 2024

Few scattered mid-level Cu along with gusty northwest winds will be
around through the afternoon to just after sunset this evening.
Winds will diminish and clouds will clear as sfc high over the
Central Plains works eastward overnight. It will remain VFR with
mainly clear skies and light winds for most of the rest of the
forecast period.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...Frost Advisory from 1 AM EDT /midnight CDT/ to 9 AM EDT /8 AM
     CDT/ Monday for KYZ023>043-045>049-053>057-061>067-
     070>078-081-082.
IN...Frost Advisory from 1 AM EDT /midnight CDT/ to 9 AM EDT /8 AM
     CDT/ Monday for INZ076>079-083-084-089>092.

&&

$$

UPDATE...BTN
SHORT TERM...SRM
LONG TERM...13
AVIATION...BTN