Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 290550 AAA

National Weather Service Jackson KY
150 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. Statocu 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

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 through Tuesday)
Issued at 326 PM EDT TUE MAR 28 2017

It appears that an active weather pattern will be in place during
the extended period, as a series of weather systems move across
the CONUS. The period should begin with a warm front approaching
from the south on Thursday. As this boundary makes its way north,
scattered showers and a few thunderstorms are expected to fire
along and just ahead of it. The thunder chances should begin early
Thursday afternoon, and should come to an end by late Thursday
night, after the cold front has passed by. Some rain showers are
expected to linger along and just behind the cold front Friday
morning. A few more thunderstorms may fire Friday afternoon, as an
area of low pressure aloft moves by just to our north and we see
an uptick in vertical motion and instability. Wrap around
moisture on the back side of the low should allow for isolated to
scattered rain showers to linger across the area into late
Saturday morning. A ridge of high pressure is forecast to settle
over the region from Saturday afternoon through early Sunday
evening. This will bring warm and dry weather back to eastern
Kentucky. Another area of low pressure is then progged to move
across the area Sunday night through Tuesday, bring more
precipitation to eastern Kentucky. Numerous showers and a few
thunderstorms are expected on Monday as the low moves past us.
Temperatures in general should again run above normal through out
the extended, with daily highs in the 60s and 70s expected.
Nightly lows should be in the 40s and 50s across the area.


.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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