Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 151554

National Weather Service Jackson KY
1154 AM EDT Thu Mar 15 2018

Issued at 1154 AM EDT THU MAR 15 2018

Some mid level clouds across the middle of the forecast area are
associated with a jet streak. These will likely persist into the
early afternoon before diminishing by evening. Outside of this
area clear skies will prevail this afternoon. Have updated NDFD
based on latest observational trends and model data. Dewpoints
are still forecast to increase this afternoon which will be
important in preventing relative humidity from bottoming out too
much. Relative humidity is already down to 30 percent at the
McCreary County KY Mesonet site.

UPDATE Issued at 700 AM EDT THU MAR 15 2018

Did a quick update to the grids mainly to add in the latest obs
and trends. Winds have picked up from the southwest and helped to
mix out many of the colder spots, while some mid level clouds
still hold on in the east. These updated grids have been sent to
the NDFD and web servers.


.SHORT TERM...(Today through Friday)
Issued at 315 AM EDT THU MAR 15 2018

Current conditions across the area features some mid level cloud
cover passing through the area, mainly in the northeast and
eastern Kentucky. This is associated with the last of the upper
low exiting to the northeast as it brings some moisture south on
the back end of the low. This will clear out heading into the
coming day as westerly winds and clear skies will allow afternoon
temps to warm into the 50s and even around 60 in the south.
Increasing gradient from the ridge over the southeastern CONUS
shifting east and the exiting trough over the northeast will allow
strong westerly winds to engage through the day this afternoon.
In fact, may see some 25 to 30 MPH winds at times.

Heading into tonight, will expect clear skies to start off the
evening before some mid and lower level cloud cover to push in
from the east. This allow for a ridge to valley temperature
difference to begin the night but will slowly disappear as cloud
cover increases through the night and winds switching around to
the north. A warm front developing and extending east will allow
precip to develop into the area by mid morning. One change in the
model trends, shows a later arrival of precip, thus the cold air
should be scoured out of the valleys by this time. Will not expect
any freezing precip with this event as it unfolds into the late
morning hours of Friday. With the slow development, will expect
showers to develop into southern Kentucky. Many locations to the
north will not see any showers develop into the north until Friday
evening. This will also slow the northerly lift of the front
keeping temps fro Friday afternoon in the upper 40s and low 50s
for highs.

.LONG TERM...(Friday night through Wednesday)
Issued at 505 AM EDT THU MAR 15 2018

The models remain in only fair agreement aloft through the long
term portion of the forecast during this busy and progressive,
transition season, pattern. Some agreement at the largest scale
breaks down and become more disjointed at smaller scales through
the forecast period. This results in lower confidence in any
specific model solution and favors an ensemble and blended
solution as a starting point. The models depict 3 separate and
significant impulses to move through the region over the next
week. The first of these comes out of the Central Plains as a
closed low but dampens quickly as it slides east Friday night
into Saturday. The GFS is quicker and weaker than the ECMWF and
CMC with this feature. Fairly flat ridging follows for the area
into Sunday with still plenty of energy packets moving through the
swift mid level flow. For Monday, the next impulse will be
inbound with the GFS again fastest, but with similar strength. The
core of this dampening, but still distinct and healthy, wave
rides over eastern Kentucky early Tuesday morning. The pattern
then becomes more convoluted by mid week as more energy passes
through the Midwest and into the Ohio Valley with heights
falling and a full latitude trough taking shape over the region
into Wednesday - quicker, further south, and not quite as strong
in the GFS than the ECMWF - but similar enough to make for a clear
trend toward continued active and changeable weather. Despite the
larger than desired spread to the models it is clear that near
normal to mild regional temperatures early on will turn colder
toward the end of the period while damp conditions look to remain
in place or worsen with time.

Sensible weather will be quite active through the period with
several sfc lows passing through the Ohio Valley from Friday night
through Wednesday. The first of these will lift a warm front
through eastern Kentucky Friday night into Saturday morning. The
leading edge of this will push into cold and dry air in place over
the northeast parts of the JKL CWA and the pcpn may catch up to
this air to result in a brief period of mixed weather towards
dawn, though the amount of warming aloft should mitigate this
threat. In fact, the sfc low may also take advantage of its warm
surge on Saturday to kick off a few thunderstorms, but model
uncertainty precludes adding any TRW to the grids, at this time.
Cooler and mainly dry weather follows into Sunday before the next
warm front lifts into Kentucky early Monday with this later sfc
low passing right through the state with showers and potential
thunderstorms that afternoon followed by colder temperatures into
Tuesday. Some snow may start to mix in later Tuesday and into
Wednesday as the larger trough aloft takes shape and lowers sfc
pressure throughout the region - though significant uncertainty
remains at these later time steps.

Made only minor adjustment to most of the temperature grids
through the period, but did nudge them strongly toward the
CONSRaw blend Friday night into Saturday (along with dewpoints).
As for PoPs, again tried to limit them bulk of them to the sfc
features - focused on each successive wave passage.


.AVIATION...(For the 12Z TAFS through 12Z Friday morning)

Expect VFR conditions through the TAF period as high pressure
will be in place. Initially a mid level layer of clouds are
passing through the east. These will dissipate and slip off to the
east later this morning with SKC conditions before additional mid
level clouds move in from the west later tonight - mainly in the
south. Increased gradient from the southwest have mixed to the
surface and we could see some west winds gusting up to 25 knots by
midday. The winds will settle some this evening and shift to the




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