Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 242235
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
635 PM EDT Thu May 24 2018

.UPDATE...
Issued at 635 PM EDT THU MAY 24 2018

The forecast is on track so far this evening. Only needed to
ingest and blend current observations. Kept clouds and isolated
PoPs in the far southeast early this evening since there are a
few clouds on satellite with slight returns on radar. However,
this will likely dissipate in the next hour or so.

&&

.SHORT TERM...(This evening through Friday night)
Issued at 332 PM EDT THU MAY 24 2018

The afternoon surface analysis shows surface high pressure
remains centered across western PA. This in combination with upper
level ridging will keep most of the area dry. There still could
be some isolated convection that fires up right along the VA
border through the afternoon in proximity to a weak surface
trough, but most locations will remain dry for the remainder of
the day into tonight. Did keep some patchy valley in the grids
tonight with some what of a ridge valley split expected.

The upper level ridging will continue to weaken as a upper level
trough pushes into the Midwest. This in combination with building
instability and increasing PWAT values will give way to isolated
to scattered thunderstorms on Friday afternoon. Given the lack of
shear across the region the biggest threats will be for heavy
rainfall and frequent lightning. The focus for convection will
likely remain in the higher terrain for the most part. Some of
these showers and thunderstorms could extent into Friday night,
but will probably wain in coverage overall. There could be the
potential for more fog, but kept this in the river valleys at
this point. There could be more spots that see fog given the
potential for rain, but that will have to be fine tuned as
rainfall occurs.

.LONG TERM...(Saturday through Thursday)
Issued at 332 PM EDT THU MAY 24 2018

Deep moisture will be back in place by the start of the period, with
our area positioned on the east side of a large but weak upper
trough axis from the mid Mississippi Valley south to the Gulf of
Mexico. Weak features will favor a largely diurnally driven
convective pattern during the weekend. A tropical system moving
north from the Gulf of Mexico will likely influence our weather
during the next work week. At this stage in time and development,
there is still considerable uncertainty. Early indications are that
upper level flow will close off around the tropical system,
temporarily putting our area in a col with very little flow early in
the workweek. This could still allow for diurnal convection, but
probably with less coverage. As the tropical system moves inland and
weakens, its closed flow will open up, and deep tropical moisture
could then stream northeast over us as the system is sheared apart.
This presents a higher probability of precip again around mid
week.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
ISSUED AT 140 PM EDT THU MAY 24 2018

The VFR conditions are expected to continue as surface high
pressure remains in control. The short term guidance continues to
show isolated thunderstorms will be possible near the VA border,
but this will be limited to those areas. Given the limited
coverage will leave the mention of anything out of the TAF sites.
We have seen cumulus develop along the higher terrain this
afternoon and did add a layer of 5 kft to LOZ/SME based on GOES-16
trends. There will be the chance of fog once again tonight, but
this will be limited to the river valleys and perhaps any location
that receives additional moisture from the isolated convection
this afternoon. Given the previous statement, have kept the
mention of fog out of the TAF sites. The surface high will also
keep winds light through the TAF period.

&&

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

$$

UPDATE...CGAL
SHORT TERM...DJ
LONG TERM...HAL
AVIATION...DJ



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