Area Forecast Discussion
Issued by NWS Jackson, KY

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000
FXUS63 KJKL 190845
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
445 AM EDT Tue Mar 19 2024

.KEY MESSAGES...

- Gusty southwest winds transport will warmer air into the region
  today, but dewpoints will be slower to rise, leading to very low
  afternoon relative humidity and an enhanced Fire Weather
  threat.

- A passing dry cold front brings another day of Fire Weather
  concerns for Wednesday.

- Temperatures will average near to below normal at times through
  the weekend, before trending well above normal by early next
  week.

- A good chance of rain will return to the forecast Friday, with
  mainly dry weather for the second half of the weekend and into
  early next week.

&&

.SHORT TERM...(Today through Wednesday)
Issued at 445 AM EDT TUE MAR 19 2024

08Z sfc analysis shows high pressure off to the southwest of
eastern Kentucky with low pressure to the northeast. Between this,
the pressure gradient has kept winds stirred through the area
overnight. Combined with the stubborn clouds that are only now
starting to clear out more quickly through much of the JKL CWA
temperatures have been kept up more than they otherwise would be.
Given the quickening clearing, still expect most places to see
mid 20s for lows by dawn. Currently, readings vary from the upper
20s in the southwest, with the first clearing, to the mid 30s
under the thickest clouds. Meanwhile, dewpoints have fallen into
the mid and upper teens most places. This is creating humidity
values around 50 percent representing poor recovery from
yesterday`s drier afternoon values.

The models, and their individual ensemble suites, are in excellent
agreement aloft through the short term portion of the forecast.
They all depict the fast moving trough heading away from the
region this morning - off to the east. This process leaves behind
lower than normal 5h heights over this part of the state with
swift northwest mid-level flow. Another trough then heads south
through the Ohio Valley later tonight - pushed by the deep low
shifting south of the Hudson Bay. This evolution speeds up the
northwest flow aloft into Wednesday, but keeps the bulk of any
energy well north of the state. Given the minuscule model spread,
have again favored the NBM as the starting point for the forecast
grids with mainly just some terrain distinction added to the
hourly temps and low temperatures tonight, but also favoring the
10th percentile of the NBM for this afternoon`s dewpoints.

Sensible weather will feature a dry and breezy day with plenty of
sunshine enabling a quick rise in temperatures from chilly
morning lows. The gusty southwest winds will help contribute to
further drying by midday as deep mixing taps into drier air aloft.
As a result, humidities are expected to fall to near 20 percent
for much of the area this afternoon. This, combined with those
increasing southwest winds of 10 to 20 mph and higher gusts -
approaching 30 mph over the Bluegrass area - will lead to enhanced
fire weather danger this afternoon and into the first part of the
evening. Red Flag Warning criteria may be hit at many sites by
late afternoon - depending on how quickly the fuels dry out.
Coordination later this morning may yet yield such a warning, but
for now will run with the current SPS highlighting the fire
weather dangers today.

More clouds and winds staying up tonight will mitigate the colder
temperatures with only a small ridge to valley temperature split
anticipated. Then on Wednesday warmer temperatures will help
humidities fall to near 25 percent even as the dewpoints will be
significantly higher than those of today. Again breezy conditions,
this time on west to northwest winds, will mean some concern for
fire weather, but to a much lesser extent than today`s.

The main adjustments to the NBM starting point were to add some
small terrain distinctions into the low and hourly temperatures
tonight. Did also favor the 10th percentile from the NBM for
dewpoints this afternoon. PoPs were near zero from the NBM and
kept there through Wednesday evening.

.LONG TERM...(Wednesday night through Monday)
Issued at 430 AM EDT TUE MAR 19 2024

The long term begins with a deeper elongated trough positioned from
central Canada through New England and the Mid-Atlantic region.
Further southwest, a short wave trough will be moving over New
Mexico. At the surface, high pressure will be nosing southeast into
the Ohio Valley, with cooler low level northeasterly flow allowing
for another chilly night across eastern Kentucky Wednesday night, as
temperatures dip into the mid and upper 20s at most locations. The
southern stream short wave will continue eastward through the end of
the work week, with a surface low traveling along the Gulf Coast
states and portions of the Deep South. Temperatures will remain
somewhat below normal out ahead of this system across our area,
with highs ranging from the upper 40s north of I-64, to the mid
and upper 50s bordering Tennessee for Thursday. Meanwhile, deeper
short wave energy will swing through the Great Lakes and portions
of the Ohio Valley within the northern stream, allowing a cold
front to push southeast across the region into the start of the
weekend. Models have come into somewhat better agreement regarding
PoPs, although the operational GFS does remain on the stronger-
side of the ensemble envelope with the wave and its associated
moisture return. Still, will maintain the blended PoPs, with
values peaking at 50% on Friday. Winds will also veer more out of
the southeast on Friday, helping to boost temperatures back to
near normal, with highs in the 55 to 60 degree range.

Drier weather will return across the area for the second half of
the weekend, with short wave ridging moving building in across the
Ohio and Tennessee Valleys in response to a deep trough evolving
across the West. Temperatures will average somewhat below normal
once again for the first half of the weekend, but then rebound
back to near normal by Sunday. By early next week, the trough will
shift east, with moisture eventually returning out ahead of a
cold front. Given the amplitude of this system and southeasterly
low level flow out ahead of it, have allowed for a slower arrival
of eventual slight chance PoPs towards the end of the period.
Temperatures will also be rebounding to well above normal, as
highs return to well into the 60s by Monday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
ISSUED AT 155 AM EDT TUE MAR 19 2024

Mostly cloudy skies, with ceilings ranging from 4-6k feet agl,
are holding on for another few hours, before scattering out from
northwest to southeast in the pre-dawn hours, as a deep upper
level disturbance exits. Once the lower clouds diminish, only
some passing high ones will be seen through the rest of the
period. Northwest winds of around 5 kts will continue through
dawn. Winds will then back to the southwest during the first part
of the morning. These will then increase to 12 to 17 kts, with
gusts of 20 to 25 kts, by late morning - peaking during the
afternoon hours. As they start to slacken at the sfc toward dusk
winds will continue strong just off of the sfc creating some LLWS
in the evening and overnight.

&&

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

$$

SHORT TERM...GREIF
LONG TERM...GEOGERIAN
AVIATION...GEOGERIAN/GREIF


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