Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 110743
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
343 AM EDT Sun Apr 11 2021

.UPDATE...
Issued at 120 AM EDT SUN APR 11 2021

Hourly grids were freshened up to account for the area of showers
moving across the central sections of the CWA as measurable rain
is falling in some locations from these. Otherwise, put a bit of
valley fog in the grids across the southeast per obs and satellite
imagery, but as bands of clouds move across the area and there is
mixiness along and behind a cold front, there is much more
uncertainty with whether or not there will be any valley fog later
on. Thus opted to leave fog out of the grids for the later night
period. Whether or not valley fog develops later on or not will
continue to be monitored.

UPDATE Issued at 1150 PM EDT SAT APR 10 2021

Adjusted PoPs to be less widespread over our area but kept a
slight chance over the next few hours over the central portion of
the CWA. Brought in current satellite IR for sky cover and
blended into the overnight hours. Temperatures cooling down more
quickly than forecast despite the cloud cover in the east, have
blended in the 3z ob through the night.

&&

.SHORT TERM...(This evening through Sunday night)
Issued at 445 PM EDT SAT APR 10 2021

The upper level pattern remains amplified across the CONUS.
Ridging is currently aligned across the Eastern Seaboard, with an
upper level low currently rotating across northeastern Missouri,
with additional short wave energy inbound across the northern
Great Basin/Rockies region. At the surface, low pressure is
centered across west central Illinois with a cold front positioned
to the south across western Kentucky/Tennessee and then down into
the lower Mississippi Valley. A more subtle pre-frontal trough is
also branched southeast more across central Kentucky and through
portions of eastern Kentucky/Tennessee. Widespread showers are
ongoing across locations along and east of I-75, with temperatures
having retreated to the 60s at most locations, thanks to the
rain-cooled air.

The mid-Mississippi Valley upper level low will move east through
the Ohio Valley into Sunday, before diminishing and slowing up a
bit more as it reaches close to Lake Erie by early Monday morning.
Meanwhile, a more elongated cut off low will emerge across the
northern Plains, with the flow flattening out across the southern
half of the CONUS. At the surface, low pressure will gradually
fill and broaden as it moves into the Ohio Valley/Great Lakes
region into early next week. The surface cold front will continue
to move east, crossing the Appalachians late tonight into early
Sunday. By early Monday morning, modest high pressure ridging
will nose in across the southern and central Appalachians.

Widespread shower activity will shift off to the east and
northeast through early this evening, with scattered convection
continuing to threaten as the surface cold front moves towards our
area. Thunder chances will remain low, as only very weak
instability will remain in place. Should a storm develop, gusty
winds will accompany it, given the breezy low level wind profile
in place. Showers will dry up later tonight in the wake of the
cold front. Temperatures will cool off into the upper 40s and
lower 50s for most places by early Sunday morning. For Sunday,
the models have played up shower activity generally north of the
Mountain Parkway during the day, as the upper level low passes by
to our north. This will allow for a decent temperature gradient
from the north to south, with highs of only around 60 north of
I-64, where cloud cover will be more prevalent, to the lower 70s
near the Tennessee border, where more sunshine will be seen.
Shower activity will diminish into Sunday evening, with skies
clearing. Lows will range from the lower 40s in the cooler valley
locations within the Cumberland Valley, to the upper 40s on
ridges, where southwest winds of 5 kts will prevail.

.LONG TERM...(Monday night through Saturday)
Issued at 343 AM EDT SUN APR 11 2021

The extended period looks to be relatively quiet, with no
significant weather to speak in the forecast. A couple of periods
of rain showers will be possible, with a perhaps a more extended
period of rain possible going into next weekend. Aside from those
two periods of potential rainfall, we are expecting alternating
periods of above normal and below normal temperatures in the
extended. The warmest days should be Tuesday and Friday, when
highs in the upper 60s are expected for most locations. The
coolest days will see highs mainly in the lower 60s. Nightly lows
will vary from the upper 30s to lower 40s on the coldest nights,
to the mid to upper 40s on the warmest nights.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
ISSUED AT 200 AM EDT SUN APR 11 2021

Conditions were mostly VFR at the start of the period, with some
brief MVFR within an area of showers near an eastward moving cold
front affecting some locations between I 64 and the Hal Rogers
Parkway/Ky 80 corridor to include the area between KJKL and KSJS.
The other exception was some valley fog across the southeast
counties southeast of the TAF sites with vis reductions as low as
the IFR range and locally lower than that. The showers should
continue to affect eastern sections of the area through the first
one to two hours of the period with any brief MVFR improving to
VFR. As the cold front moves east, winds and cloud cover should
increase for improvement of vis where the fog is occurring over
the southeast and it may dissipate entirely. However, there is
some uncertainty with the evolution of valley fog overnight. At
this time, however, the TAF sites are not expected to be affect by
any of this. As the upper level low passes north of the area and
a couple of disturbances rotating around it move through the OH
Valley on Sunday, some low level moisture wrapping around it
should move across the OH Valley and affect northern sections of
the area with some clouds in the 5 to 6 kft range at times if not
lower across the northern half to two thirds of the area. This
should be most prevalent across the far north where MVFR ceilings
may reach as far south as the I 64 corridor and KSYM. A few
showers or sprinkles cannot be ruled out as well during the day on
Sunday, though this activity should generally be confined to
locations north of the Mtn Pkwy. Behind the front, southwest winds
at 10KT or less should prevail through 12Z, before winds increase
around 14Z into the 10 to 15KT range, with gusts reaching into
the 20-30 KT range. Winds will slacken toward

&&

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

$$

UPDATE...JP
SHORT TERM...GEOGERIAN
LONG TERM...AR
AVIATION...JP



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