Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 140803

National Weather Service Jackson KY
403 AM EDT Sat Apr 14 2018

Issued at 1135 PM EDT FRI APR 13 2018

Forecast is on track, only ingested current observations and
blended into the forecast for this update. A new ZFP was sent.
Grid updates have been sent to NDFD and to the web.

UPDATE Issued at 855 PM EDT FRI APR 13 2018

Hourly temperatures and dewpoints were freshened up based on
recent observations and trends. This led to dewpoints a couple of
degrees lower in portions of the area, but overall no substantial
changes were needed at this time. Some valley locations are
starting to decouple and mainly high clouds are anticipated
overnight. It is possible min T for a few valley locations could
end up below the current forecast, but for now mid 50s seem
reasonable for those locations.


.SHORT TERM...(This evening through Saturday night)
Issued at 301 PM EDT FRI APR 13 2018

The primary forecast concerns in the short term will be the
potential for showers and storms on Saturday, the potential for
locally heavy rainfall, and the timing of the passage of a cold
front across the area. Most of the current model data is slowing
down the eastward progression of a cold front this weekend. In
fact, it is appearing more likely that it may be as late as
mid-morning Saturday before any appreciable precipitation moves
into eastern Kentucky. Enough ingredients will still be in place
to spawn a few thunderstorms across the area as the front moves
through. The latest model consensus is that the front will have a
difficult time moving very far to the east at first, due to the
influence of a stubborn ridge of high pressure that is forecast
remain in place across the southeastern CONUS. This ridge may not
begin to weaken and move off to the east until Saturday night into
Sunday, when the large trough of low pressure that is currently
parked over the Great Plains begins to make a big eastward push of
its own. With some uncertainty as to when rainfall will begin in
earnest across the area, and how quickly it will move through,
it was necessary to lower rainfall amounts a bit, especially
during the day on Saturday. This will bear watching to see if the
models continue to trend of later precipitation onset across
eastern Kentucky. Temperatures are still expected to be quite warm
over the weekend, as southerly to southwesterly flow ahead of the
approaching front keeps a steady flux of warm moist Gulf air
feeding into the region. We should see highs on Saturday in the
mid to upper 70s. Lows tonight and Saturday night will also be
mild, with lows ranging from the mid 50s to lower 60s around the
forecast area.

.LONG TERM...(Sunday night through Friday)
Issued at 358 AM EDT SAT APR 14 2018

Rain showers will be ongoing Sunday evening in an upslope flow/cold
air advection regime as the previously mentioned upper low pushes
east across the Ohio Valley. Will begin to see some snow showers mix
in after midnight as cold air continues to pour into eastern
Kentucky, bringing saturation to the -10 to -20C layer. Intermittent
rain/snow showers will continue Monday given the upper low`s slow
eastward progression across the upper Ohio Valley and Great Lakes.
Saturation will linger in the lowest 10,000 feet, helping to
maintain precipitation, especially in the higher terrain where
lift will be enhanced via upslope flow. Precipitation will taper
off Monday evening/early night as subsidence builds into eastern
Kentucky. Surface ridging nosing in from the south and west will
help to drop temperatures into the upper 20s to lower 30s by
Tuesday morning, spelling another round of widespread frost. Will
continue to highlight this impact in the HWO.

Following high temperatures remaining in the low 40s Monday, Tuesday
will bring an appreciable warmup into the 60s as the eastern extent
of upper ridging builds into the Appalachians. A quick moving upper
low migrating from the Canadian Prairies into the Midwest by midweek
will lead to a round of rain showers Wednesday afternoon and night.
Have opted to keep thunder out of the forecast for now given limited
moisture return and subsequent anemic instability. This system and
associated cold front will halt the warmup and bring another chance
of frost Thursday night into Friday morning. Although with the
cold air intrusion looking to be less robust than the one leading
to frost Monday night, will keep mention out of the HWO for now.

Upper ridging will eventually attempt to build back into the
Commonwealth for the end of the week into early weekend, prior to
another disturbance loading up across the Great Plains.


.AVIATION...(For the 06Z TAFS through 06Z Saturday night)

Expect VFR conditions through a good period of the TAF. Expect
southerly winds through much of the day with gusts up to 30 knots
in some locations. Showers will develop ahead of the approaching
cold front and move into the area by the afternoon with some
isolated thunderstorms. Will expect cigs to remain VFR for much of
the period before seeing some MVFR conditions with heavier showers
and thunderstorms moving in toward the end of the TAF period.




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