Area Forecast Discussion
Issued by NWS Louisville, KY

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KLMK 180707
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
307 AM EDT Mon Mar 18 2024

.KEY MESSAGES...

* Unseasonably cool through Tuesday morning, with subfreezing
  temperatures possible both nights.

* Dry and breezy on Tuesday, resulting in some fire weather
  concerns.

* Near normal temperatures and precipitation chances return towards
  the second half of the week.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 307 AM EDT Mon Mar 18 2024

The core of the unseasonably cold air mass will descend on the Ohio
Valley today, as an upper vort lobe drops SE through the Great Lakes
and 1031mb sfc high continues to build from the Red River Valley of
the North.

H8 temps today will drop to -8 or -9C, so max temps this afternoon
will struggle into the lower/mid 40s. We`ll have steep low-level
lapse rates allowing mixing up into a shallow layer of moisture
around 800-750mb, resulting in some high-based strato-cu this
afternoon. Very dry air near the sfc will keep any precip from
reaching the ground, but wouldn`t be surprised to see some virga
this afternoon.

Tonight will be another cold one as the sfc ridge expands eastward,
mainly into the Tennessee Valley. Could see a brief decoupling of
the boundary-layer, but with SW return flow trying to develop by
daybreak Tuesday our temps won`t completely bottom out.  Still
looking for another hard freeze with lows in the mid 20s. Growing
season is not yet underway based on partner feedback, but there is
just enough early-developing vegetation to warrant a Special Weather
Statement highlighting the subfreezing temps.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
Issued at 307 AM EDT Mon Mar 18 2024

Tuesday - Wednesday...

Troughing over the eastern CONUS and Rex blocking over the western
CONUS will be the main feature at the beginning of the long term
period. On Tuesday and Wednesday, a series of shortwaves will move
through the region, keeping temperatures near normal. Ahead of the
850mb trough on Tuesday, a 40-45kt LLJ will move through the region.
At the surface, high pressure building into the north-central Gulf
of Mexico will lead to backing winds out of the southwest. This type
of atmospheric set-up will allow for dry air to mix down to the
surface, lowering RH into the low-mid 20% range and bringing winds
on the order of 15-20mph and gusting 30-35mph. These conditions may
lead to elevated fire danger concerns, however, the limiting factor
to this is that fuels may not dry out given high temperatures in the
mid 50s. Elevated fire danger will be a concern, however, not at a
critical level at this point.

Wednesday Night - Sunday...

Wednesday night, the low pressure center over the Great Lakes will
begin to eject to the northeast bringing broad troughing with it,
and the Rex blocking to the west will begin to break up. The low
height center that was featured over the SW CONUS will begin to
propagate eastward. At the same time, a shortwave riding along the
Hudson Bay low will move through the northern Great Lakes. These two
features will move through the Ohio Valley Friday and Saturday,
bringing increased rain chances. Currently, there is a 20% chance of
seeing greater than 0.25 inches of rain from this system. If the two
troughs phase just to the west of the region, we could see a higher
probabilities of higher QPF.

Once this system move off to the east, it may become the next
Nor`easter off the mid-Atlantic coast. Over the Ohio Valley, weak
ridging aloft and high pressure at the surface will build into the
region leading to slightly above normal temperatures through the
weekend.

&&

.AVIATION /06Z TAFS THROUGH 12Z TUESDAY/...
Issued at 118 AM EDT Mon Mar 18 2024

VFR conditions expected through the valid TAF period, with
persistent WNW flow and cold advection. Look for speeds to increase
around 15Z with deeper mixing, bumping winds up to a steady ~12 kt
with frequent gusts around 20.  Also expect a high-based strato-cu
ceiling, perhaps near 5000 ft at LEX but higher at SDF and BWG.

Winds will slack off and strato-cu will dissipate after 00Z Tue as
heating (if we can call it that) is lost.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...None.
IN...None.

&&

$$

SHORT TERM...RAS
LONG TERM...SRM
AVIATION...RAS


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.