Area Forecast Discussion
Issued by NWS Jackson, KY

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
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 KJKL 162008
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
408 PM EDT Sat Mar 16 2024

.KEY MESSAGES...

- Temperatures will remain about 5 to 10 degrees above normal
  through tonight.

- A deep trough passing aloft brings a threat of some rain/snow
  showers on Monday.

- Hard freeze conditions Monday night could kill any cold
  sensitive vegetation that has emerged prematurely due to early
  season warmth.

- Temperatures rebound back to near normal through mid-week, with
  lower confidence in the next potential chance of precipitation
  moving in towards the end of the work week.

&&

.SHORT TERM...(This evening through Sunday night)
Issued at 408 PM EDT SAT MAR 16 2024

Late this afternoon, an upper level low was centered over western
Ontario with the axis of a shortwave trough extending into the
western Great Lakes region to the mid MS Valley vicinity.
Additional weaker shortwaves were upstream moving south into the 500
mb trough. In advance of the approaching 500 mb trough axis, 500 mb
heights have begun to slowly fall across eastern KY. At the surface,
a ridge of high pressure extended from the TX and OK panhandle areas
to the TN Valley to eastern KY and WV. Meanwhile, a sfc low
associated with the upper low in Ontario was also centered in
Ontario with a cold front trailing into the Great Lakes region to
Central Plains. Ahead of the boundary, temperatures have warmed to
the low to mid 60s in most locations, or about 5 degrees above
normal for mid March. Some mid and high clouds were also moving
across the OH Valley region in advance of the sfc cold front and the
upper level trough.

This evening and tonight, the axis of the sfc ridge of high pressure
will slip to the southeast of eastern KY. Meanwhile, the sfc low
will track from Ontario and into Quebec with the trailing cold front
dropping into and across the OH Valley including the Commonwealth.
Meanwhile at 500 mb, the trough axis will effectively remain west of
eastern KY while an initial shortwave works across the Great Lakes
and the Lower OH Valley as the trough is reinforced by shortwave
dropping into it from the north tonight and into Sunday. Cold air
advection is expected behind the front for Sunday and Sunday night.
850 mb temperatures are forecast to drop to about the 0C to 4C range
by dawn on Sunday and then fall a few more degrees C trough Sunday
evening with a bit more dramatic drop on Sunday night to about -5C
to -9C to end the period.

Ahead of the front tonight, deeper valleys will likely decouple once
again and drop toward the 40 degree mark, if not the upper 20s in
some instances. These temperatures may rebound later in the night
near the time of the frontal passages. Otherwise, the front is
expected to be too moisture starved for any precipitation those low
to mid clouds will increase as moisture is progged to increase
generally near the 850 mb level and above to about the 750 mb level.
Winds should become a bit gusty behind the front Sunday as the
colder airmass is ushered in with some gusts upwards of 20 mph.
Despited the cold air advection on Sunday, temperatures should climb
to near normal. Sfc temperatures drop to under the cold air
advection on Sunday night to about 5 degrees below normal and the
colder airmass ushered in will set the stage for even colder lows
early in the long term period.

.LONG TERM...(Monday through Saturday)
Issued at 400 PM EDT SAT MAR 16 2024

The 16/12z model suite is in reasonably good synoptic agreement
Monday morning but still shows substantial deterioration, especially
after Wednesday. On Monday morning, a mean trough is in place over
Quebec/Eastern Ontario with an associated surface low over the Gulf
of St. Lawrence. A vigorous shortwave trough, extending from the
Eastern Lake Great Lakes to Mid-Mississippi Valley, is riding around
the southwestern periphery of the trough. Surface high pressure
spans west and north of the shortwave from northern Ontario to
the Southern Plains. Further west, an ~575 dam high is found over
the Pacific Northwest while an ~561 dam low is found over Arizona.
Another weak disturbance is passing over northeast Saskatchewan
between the ridging over the Pacific Northwest and troughing over
eastern Canada.

The leading vigorous upper level shortwave trough will pass over
the Ohio Valley/Central Appalachians on Monday into Monday night.
This will spread a chilly airmass across eastern Kentucky with
850 mb temperatures bottoming out to near -10C by late Monday --
cold enough for any precipitation to fall as a mix of snow and
rain or all snow. Uncertainty lingers as to how much moisture will
be available to this system. Model guidance continues to offer
solutions ranging from a completely dry scenario or spotty light
QPF of up to a few hundredths, primarily in the north and east.
The potential for moisture-enhancement from Lake Michigan appears
to have diminished as modeled low-level flow has largely trended
too westerly. Due to the resulting decline in model suite QPF,
PoPs were limited to the 10 to 20 PoP range for locations
northeast of US-421. Of note, the last few hours of the 15z RAP13
show soundings becoming much more favorable for at least some
snow shower activity. Hopefully, confidence in the occurrence of
any snow showers or flurries will improve as the entirety of day
comes into the range of the CAM suite. Whatever moisture
materializes for Monday should depart quickly Monday evening as
high pressure shifts from the Plains toward the Southeast US. In
any case, northwesterly winds will be blustery, gusting to between
20 and 25 mph on Monday before subsiding Monday night.
Additionally, the air mass will be quite chilly with Monday`s high
temperatures only in the upper 30s to mid 40s and frosty cold
Monday night lows deep into the 20s. A few upper teens cannot be
ruled out the most sheltered valley locales.

Looking ahead to Tuesday, the low level flow will quickly turn more
westerly ahead of second upper level shortwave trough riding around
the parent upper level trough. This system;s track is slightly
further to the east than the previous shortwave, but will still
drop another cold front into eastern Kentucky from the north on
Wednesday. No measurable precipitation is forecast with the
boundary. Ahead of the front, temperatures will make a quick
rebound on Tuesday back to between 50 and 55 for most locations.
Wednesday highs should be even warmer, reaching the mid 50s north
of I-64 where the front arrives early in the day and up to the mid
60s in the far southeastern valleys where the front moves in
later in the day. The core of the chillier air with the second
cold front will move into the Eastern Great Lakes/Mid-Atlantic
Wednesday night and Thursday, brushing our area in the process.
Compared to 24 hours ago, somewhat colder air may seep into
eastern Kentucky by Wednesday night and Thursday. This has led to
a lowering of the minimum temperatures on Wednesday night to
between 27 and 36. On Thursday, the NBM maximum temperatures were
also adjusted lower toward a blend of the the raw model data,
yielding highs around 50 in the northeasternmost locations of
Elliot, Rowan, and Fleming counties up to around 60 in the deepest
valleys near the Tennessee border.

Later in the week, the forecast still becomes notably less certain
due to considerable run-to-run and model-to model-spread.
Guidance is struggling with how the closed low initially over the
Desert Southwest interacts with northern stream energy passing
over the northern CONUS. It does seem, that a period of increased
PoPS is probable in most scenarios. Accordingly, the NBM forecast
was retained for Friday through Saturday and shows PoPs peaking
at high chance (40 to 50%) on Friday while temperatures rise back
to near normal levels.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
ISSUED AT 1236 PM EDT SAT MAR 16 2024

As of midday, fog and stratocumulus was mixing out with any
lingering instances of MVFR or IFR quickly trending to VFR.
Overall, VFR prevailed in most places as of 1630Z. Winds will
become southwest to west early in the period in the 5 to 10KT
range through about 06Z. Then, as a cold front drops across the
are, winds will shift to the west and then northwest late in the
period again at 5 to 10KT. Despite the passage of a cold front, it
will be rather moisture starved and VFR will prevail through the
end of the period.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...JP
LONG TERM...GEERTSON
AVIATION...JP


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