Area Forecast Discussion Issued by NWS Jackson, KY
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000
FXUS63 KJKL 190024 AAA
AFDJKL
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
824 PM EDT Mon Mar 18 2024
.KEY MESSAGES...
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- A deep trough passing aloft brings a threat of snow flurries early
this evening.
- A hard freeze later tonight could kill any cold-sensitive
vegetation that has emerged prematurely due to early season
warmth.
- Gusty southwest winds transport warmer air into the region on
Tuesday, but dewpoints are slower to rise leading to low
afternoon relative humidity and Fire Weather concerns.
- A passing dry cold front brings another day of Fire Weather
concerns on Wednesday.
- Temperatures rebound back to near normal for Wed into next
weekend, with lower confidence in the next potential chance of
precipitation moving in towards the end of the work week.-- End Changed Discussion --
&&
.UPDATE...
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Issued at 824 PM EDT MON MAR 18 2024
Mostly cloudy skies, isolated flurries, and a few snow showers,
are ongoing across the area early this evening. Looking upstream,
satellite reveals some thinning and this should continue as a
stout short wave trough axis exits off to our southeast. For now,
have delayed the cloud and flurry diminishment in the forecast for
the next few hours, given the current conditions. Forecast lows
look on target, but have adjusted the hourly temperatures to
better match up with the trend in the current conditions. Updates
have been sent.-- End Changed Discussion --
&&
.SHORT TERM...-- Changed Discussion --
(This evening through Tuesday night)
Issued at 437 PM EDT MON MAR 18 2024
The forecast is generally mostly clear and dry...and that poses a
problem.
At the moment, a strong upper level system is moving across the Ohio
Valley, resulting in mid-level cloud cover. The air below this cloud
deck is very dry. However, apparently not dry enough that a few
flurries and sprinkles aren`t making their way down to the surface
across the northern CWA. While we are just above freezing at the
surface, the air is much colder aloft, so most of the precip that
has made it to the ground has been frozen (flurries).
Meanwhile, winds are predominately out of the NW and with good
mixing, they have been a bit breezy. Gusts between 15 and 20 kts
have been on tap through much of the afternoon at the TAF sites. The
combination of this very dry llvl air and these breezy conditions
has elevated the fire danger across the region. This has been aided
by the lack of rain (nothing in the last 48+ hours according to the
KY Mesonet) and dry fuels.
While winds are expected to dissipate a bit overnight, they won`t
likely become calm and variable, at least not for long. There is
enough mixing with this system that we could see predominate W to SW
winds throughout the overnight, generally between 5 and 10 kts. Even
still, the lighter winds combined with increasing RH will lesson the
fire threat during the overnight. However, this doesn`t mean that
the overnight is without it`s own hazards. Due to the strong CAA and
clear skies that will accompany these lesser winds, all of the CWA
is forecast to drop into the 20s, with lowest temperatures in the
deeper valleys (generally low to mid 20s). Given abnormally warm
conditions we`ve been having over the last week, quite a few plants
have already started their spring blooms. This hard freeze could
damage these susceptible plants.
Fire weather concerns then ramps back up for Tomorrow/Tuesday.
Strong NW flow will remain in play aloft, continuing to advect in
very dry air. Temperatures will be aided by the continued SW flow
at the surface and abundant sunshine, warming to the low 50s by
the afternoon. Meanwhile, high pressure will still be in place
across the Commonwealth and points southward. Despite winds
becoming more SWrly at the low levels, the strong NW flow in the
mid and upper levels will overcome any moisture advection, keeping
RH very low. Nudged the dew points towards the 10th percentile of
the NBM, keeping RH in the upper teens to lower 20 percent range.
In addition, strong mixing will remain in place, ramping up
throughout the day. With such strong winds aloft, it won`t be
unlikely that we can tap into some higher gusts, generally 20 to
30 kts. The Bluegrass region of the CWA may have the highest
winds, with gusts in excess of 30 kts possible during the
afternoon. Sustained winds will range from 10 to 20kts, while the
Bluegrass will be between 15 and 25 kts. Then we take into account
the fuels, which are also quite dry across the state. The USFS at
the Daniel Boone National Forest noted that while the 1-inch
fuels are not overly dry, the leaves and the grass are CRISP. All
this to say, that if any fire is ignited during the day tomorrow,
it could very quickly get out of hand and spread. After
collaborating with the neighboring offices, there is still some
concern of only meeting borderline criteria for some of the Red
Flag Warning thresholds in many areas. Therefore it was decided to
give a heads up to our fire weather partners, and keep with Fire
Danger SPS and wording in the HWO, which our partners seemed okay
with. Would not be surprised, however, if things continue to trend
drier and windier, that some locations may end up upgrading to a
Red Flag during the day tomorrow. Either way, Red Flag or not,
fire weather and danger will be the top concern during the day.
Again, winds are expected to slowly dissipate during the overnight
Tuesday night, but should still remain somewhat mixed. RH will also
increase as temperatures fall. However, lows on Tuesday night should
not be quite a cold as the previous night as the NW flow continues
to relax a bit, and we were warmer during the day Tuesday compared
to today. Lows will bottom out in the mid and upper 30s in most
locations. This may still pose a frost risk for some locations,
especially in the deeper valleys, but not a hard freeze like
tonight.
.LONG TERM...(Wednesday through Monday)
Issued at 355 PM EDT MON MAR 18 2024
The large scale upper scale pattern across the CONUS to begin the
extended will feature ridging aloft along the west coast with a
developing small scale wave of low pressure aloft to the east of the
ridge. The northeastern quarter of the country looks to start off
under the influence of a broad trough of low pressure aloft,
especially the Great Lakes and New England. An elongated and flat
ridge of high pressure might also be in place along the Gulf Coast
to start things off. The southwestern CONUS trough will be our
initial weather maker in the extended, and should be moving through
our neck of the woods Thursday night through Saturday. Our highest
rain chances during that time should be from late Friday morning
through late Friday night, as the trough moves by to our south and
merges with a fast moving northern stream system that will be moving
through the Great Lakes and into New England. The GFS Ensembles did
a good job depicting the southern stream trough, while the GFS and
ECMWF operational runs contained more details on the northern stream
system and its evolution. High pressure will bring dry weather to
the area both Wednesday and Thursday, with Wednesday being the
warmer of the two days as strong sunshine and subsidence aloft will
be in place. Thursday should be a bit cooler, as winds shift to the
north and then northeast, as high pressure moves off to our east
ahead of the next incoming trough.
Clouds will be on the increase Thursday into Thursday evening, as
low pressure moves our way, and we should see the first rain moving
into our southern counties sometime late Thursday evening from the
southwest. We should see another breif period of dry weather from
late Saturday through early Monday morning, as we await the arrival
of another area of low pressure, that is forecast to bring another
round of rain to the area by Monday afternoon.
Regarding temperatures in the extended, readings should be above
normal on average, with most days seeing readings ranging from the
upper 50s to lower 60s Wednesday, Friday, and Saturday. We could see
highs reaching the low to mid 60s on Sunday, and the upper 60s to
lower 70s on Monday, as strong warm air advection occurs ahead of
the incoming storm system that day. We will also likely see very low
dewpoints again on Wednesday. With winds again expected to marginal,
and afternoon RHs also low, we will continue to monitor critical
fire danger thresholds across the area through mid-week.-- End Changed Discussion --
&&
.AVIATION...-- Changed Discussion --
(For the 00Z TAFS through 00Z Tuesday evening)
ISSUED AT 824 PM EDT MON MAR 18 2024
Mostly cloudy skies, with ceilings ranging from 3-6k feet agl,
will hang on through this evening, before scattering out from
northwest to southeast overnight, as a deeper upper level
disturbance exits. Some flurries and even an isolated snow shower
will also be seen early this evening, with KSJS seeing the best
chance of temporary MVFR/IFR conditions from these through 01z.
The rest of the terminals will remain VFR. Once the lower clouds
diminish, only some passing high clouds will be seen through the
rest of the period. West northwest to northwest winds of 8 to 12
kts, with gusts of 15 to 20 kts, will diminish to 5 to 10 kts
through 01 or 02z. Winds will then back to the southwest towards
dawn Tuesday. These will increase to 12 to 17 kts, with gusts of
20 to 25 kts, by late morning. Winds will peak during the
afternoon hours.-- End Changed Discussion --
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GEOGERIAN
SHORT TERM...JMW
LONG TERM...AR
AVIATION...GEOGERIAN