National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS63 KJKL 251354
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
954 AM EDT Thu Apr 25 2024

.KEY MESSAGES...

- Below normal temperatures persist through tonight, with a bit
  of frost in some valleys each night.

- A warming trend begins on Friday, with well above normal
  temperatures then expected early next week.

- Thunderstorms are possible Friday afternoon and evening to the
  west of a Middlesboro to Flemingsburg line. Thunderstorms are
  then possible areawide from late Monday afternoon through
  Tuesday, and again Wednesday afternoon.

&&

.UPDATE...
Issued at 953 AM EDT THU APR 25 2024

Have blended morning obs into the forecast, including blending
satellite imagery into the sky forecast for the low clouds still
affecting portions of extreme eastern KY late this morning. The
clouds will eventually break up as heating/mixing occurs through a
deeper layer.

UPDATE Issued at 721 AM EDT THU APR 25 2024

Areas of low stratus continues to move southwest into the region
from the Ohio Valley and West Virginia, which necessitates some
increases to Sky grids for the next few hours. These low clouds
will burn off as the morning progresses, though they may be pesky
and persistent through mid-morning. Otherwise, the forecast is
largely on track with the latest observed trends blended into the
forecast.

&&

.SHORT TERM...(Today through Friday)
Issued at 314 AM EDT THU APR 25 2024

Surface high pressure continues to nose into the area from the
northwest and north under the negative vorticity advection region
between upper ridging over the Central US and downstream troughing
over the East Coast. This will support mostly sunny skies and light
north winds today, though some brief low stratus is possible in some
areas in the morning before burning off by midday. With the weak
cool advection from the north, highs will be slightly below normal
in the lower 60s north to lower 70s south.

Winds veer to easterly and then southeasterly overnight as surface
high pressure wedges down the eastern slopes of the Appalachians
while a surface low and attendant cold front move out onto the
Central Plains. With warm advection beginning in the southwest while
the surface high remains influencing the northeastern half of the
CWA, expect a wide range of temperature and sky cover, with warmer
temperatures in the 40s with increasing clouds over the southwestern
counties, while good radiational cooling in the sheltered valleys
will mean lows in the mid 30s and possibly cooler with some patchy
frost possible.

A warm front aloft moves across the area Friday and brings an
increase in cloud cover and moisture, though that will be mitigated
somewhat in our eastern counties directly downwind from the taller
mountains. Given the best dynamics and thermodynamics remaining west
of the area, and the mitigating influence of downslope drying in the
eastern counties, will only be carrying 20 PoPs or less, with the
best chance of a thunderstorm or two  mainly along and west of I-75
Friday afternoon, but even this is not high confidence given the
lack of instability indicated by most modeling. Nevertheless, even
with the increased cloud cover, the increasing warm advection and
southerly flow temperatures will return to the 70s to near 80
degrees, with warmest temperatures in our eastern counties where the
better downslope warming and drying will occur.

.LONG TERM...(Friday night through Wednesday)
Issued at 350 AM EDT THU APR 25 2024

SW flow will be the story for the majority of the period. This will
keep WAA across the region and lead to above average temperatures
throughout the period, with a handful of days likely topping 80
degrees for highs.

So what is driving this and what impacts can we expect other than
heat?

By the start of the extended period, we will have transitioned to a
upper level ridging pattern across the Ohio Valley and points north
and south. This will become amplified as two very strong upper level
low pressure systems develop across the Plains and farther to the
west, and then travel northeastward through the weekend and into
Monday. As this occurs, pressure gradients will tighten along the SW
flow side of the ridge, amplifying the amount of WAA and increasing
the winds. Much of the weekend, and even into Monday, could see some
breezy conditions as a result. The interesting part of this is that,
despite being in a somewhat higher instability pattern, most of the
energy will be confined to areas closer to the closed lows, which
are forecast to stay well west of the Commonwealth. It`s one of
those rare times where you get strong SW flow and don`t have to pay
the consequences in the form of unsettled weather. The CWA should
remain dry all weekend, from Saturday through Monday morning. These
are also 2 of the days that we should top the 80 degree mark for
highs (Sunday being the warmest). For Saturday and Sunday night, did
go ahead and include some ridge/valley differences in winds and
temps since we will be under mostly clear skies. However, given the
mixing ongoing even into the overnight, didn`t go too crazy on
lowering the temps in the deeper valleys.

There is a bit of a shift in the pattern during the day Monday. The
second of the closed lows will move north of Lake Superior by Monday
afternoon. The attached cold front will be oriented almost due north
to southward. As this system continues to push NE into Tuesday, the
cold front will slowly push eastward towards the Ohio Valley,
traversing the state from west to east. This will bring a line of
showers and thunderstorms to the region during this time, with the
main line/front moving through Tuesday morning based on latest model
runs. Would like to note that Tuesday is currently Day 6 of the
forecast, so this timing is subject to change a bit - but overall
models are in very good agreement considering how far out it is in
the forecast!

Once this system exits, the overall flow will begin to balance
itself back out, with no additional upper level lows expected to
producing troughing to our west. Flow will become more zonal
across the Ohio Valley for Tuesday and Wednesday. However, zonal
flow doesn`t induce a large airmass change for the region. For
instance, the high on Monday ahead of this cold front will be in
the low to mid 80s. Post frontal temperatures Tuesday will only be
several degrees cooler, in the upper 70s - still WELL above
normal for this time of year. Without a switch to NW to N flow,
and a colder airmass moving in, we should stay more moderate with
our temperatures.

As we head into Wednesday and Thursday, the model agreement starts
to quickly deteriorate. Both the GFS and ECMWF point at a potential
system impacting portions of the Ohio Valley during this time, but
the exact impacts are still very low confidence. The NBM went with
isolated to scattered showers and thunderstorms during this period,
with convection mainly isolated to the afternoon peak heating. Given
the uncertainty, didn`t have any reason to change it at this point,
but expect it to evolve over the coming days.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
ISSUED AT 712 AM EDT THU APR 25 2024

A thin MVFR stratus layer of clouds is moving southwest into far
northern and eastern parts of the forecast area, and will
primarily impact KSJS for the next few hours. However, this
stratus layer will burn off by late morning. Otherwise, high
pressure brings VFR conditions and north to northwest winds of
generally less than 10 kts becoming northeasterly after 00z
Friday.

&&

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

$$

UPDATE...HAL/CMC
SHORT TERM...CMC
LONG TERM...JMW
AVIATION...CMC