Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 290708

National Weather Service Jackson KY
308 AM EDT Wed Mar 29 2017

Issued at 140 AM EDT WED MAR 29 2017

Did a quick update to the grids to fine tune Sky cover and patchy
valley fog through the rest of the night. Also tweaked the T and
Td grids per the latest obs and trends. These have been sent to
the NDFD and web servers.

UPDATE Issued at 1102 PM EDT TUE MAR 28 2017

Current conditions across eastern Kentucky feature the cloud cover
across the area now showing a bit more breaks. Though some of the
cloud cover is hanging on over the eastern higher terrain due to
some upslope. Recent observations have shown more of a northerly
to north-northeast direction and thus some decrease is the
upslope. So lowered the cloud cover a bit and added a bit more fog
to the southern locations. If this eroding of the cloud cover
continues, an update will be needed to lower cloud cover, lower
temps, and add more areas of dense fog. A new zfp has issued for
this update.

UPDATE Issued at 743 PM EDT TUE MAR 28 2017

Current conditions across the area feature low level cloud cover
in north to northwesterly flow moving south through the area. The
challenging part to this update is the fact that there are
noticeable small breaks win the cloud cover and where this
occurs, there will likely be a drop in surface temps, especially
in the valleys as well as fog development. For now, have updated
to input the latest temps and dew points. Also adjusted the cloud
cover slightly less but nothing worthy of a new zfp at this point.
The upslope flow across the area will tend to keep the cloud
cover over the area for the remainder of the night. The forecast
remains on track but the current cloud cover situation will be
continually be monitored.


.SHORT TERM...(This evening through Wednesday night)
Issued at 312 PM EDT TUE MAR 28 2017

A shortwave trough and surface low pressure continue to depart to
the north and east of the region while surface high pressure is
beginning to nose into the OH Valley. Height rises are also occurring
the wake of the departing shortwave trough with the axis of this
ridge currently extending from the central Gulf of Mexico northwest
toward the Mid Ms Valley region. Upslope flow, especially above the
surface is combining with daytime heating to produce shallow light
rain showers and sprinkles or drizzle. Stratocu and cumulus have
been rather persistent, but breaks and thin spots in the clouds
have allowed many locations to experience temperatures climbing
into the low to mid 60s under the increasingly strong late March
solar insolation.

The surface low and shortwave trough will continue to depart to the
east and northeast tonight while upper and surface ridging build
into the OH Valley and Appalachians. Through this evening, isolated
to scattered showers or light drizzle should persist, but wane this
evening with loss of daytime heating and low levels stabilize.
However, low level moisture is expected to remain trapped below a
subsidence inversion tonight and the degree of clearing is uncertain
though give the current rather extensive area of clouds currently
over the Great Lakes and OH Valley at this time. This and model
forecast soundings of persistent moisture at about 850 mb and below
and time heights through this evening and tonight, only some partial
clearing especially in the south is anticipated. Radiational valley
fog is possible and a mix of this and stratus build down fog is also
possible, though confidence in the details is not high.

The axis of the upper level ride is expected to continue to move
east and should move across the area Wednesday evening while the
next in a series of upper level troughs/upper lows moves from the
Southern Plains and begins to nears the MS Valley late. Meanwhile
surface low pressure is expected to track from West TX to MO. Clouds
should decrease on Wednesday morning, with milder temperatures
compared to today. The pattern of upper level ridging beginning to
depart and surface high pressure departing is favorable for some
valley fog as well as at least a small to moderate ridge valley
split with favorable net radiational cooling conditions for the
normally colder eastern valley locations.

.LONG TERM...(Thursday night through Tuesday)
Issued at 308 AM EDT WED MAR 29 2017

A shortwave trough will advance east across the region Thursday
night into early Friday morning sending widespread showers and a
few thunderstorms across the region. Given good moisture and lift,
will maintain the categorical pops through this period. The mid
level low will cross northern Kentucky Friday afternoon with
numerous showers likely well into the afternoon, making for
another cloudy, cool, and damp day. Rain showers will wind down
into Friday night, but may transition to some patchy drizzle as
some low level moisture will remain left behind. Any drizzle will
come to an end by midday Saturday with the rest of the weekend
featuring a return to dry weather as a surface ridge spreads
eastward across the region.

Our next storm system looks to arrive on Monday and Monday night
sending another round of rain showers into eastern Kentucky. Looks
like pretty strong southeast winds with this system through
Monday, so we`ll have to see how much that eats away at potential
rainfall given the downsloping conditions. In fact, some areas may
struggle to measure with the kind of solution models are currently
centering around. Eventually forcing will win out and we should
see some showers or storms over most of the area, certainly by
Monday night. Wrap around moisture may keep a chance of showers
going into mid week with another system following on the heels of
this system yet again. The active and wet weather looks to
continue. Models also support a continuation of the mild weather
outside of a cooler day on Saturday with the clouds.


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

Low level cigs - mainly IFR - will be in place across most of the
area through the rest of the night locked in place by northerly
flow. The exception will be in the Cumberland Valley where a
reprieve its underway - though a period of low cigs are still
possible towards dawn. Look for clearing for to overtake the rest
of the TAF sites between 15 and 18Z. While fog development in the
valleys will be hindered due to the persistent low level cloud
cover, a few spots with visibility below IFR are anticipated
through dawn but should not affect any TAF site. Winds will
remain light - generally from the northeast to southeast through
the period.




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