Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 260620 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
220 AM EDT Wed Jul 26 2017

.UPDATE...
Issued at 155 AM EDT WED JUL 26 2017

Latest loop of the GOES16 Nighttime Microphysics channel shows the
fog forming in the far eastern valleys, otherwise not much has
been noted in the obs, despite the mostly clear skies, owing to
the drier air in place. Have touched up the sky cover and fog
through the rest of the night and also added in the latest obs and
trends for the T/Td grids. These have been sent to the NDFD and
web servers.

UPDATE Issued at 717 PM EDT TUE JUL 25 2017

High pressure will make for an overall pleasant summer night
across eastern Kentucky. Valley fog will develop late this evening
into early Wednesday morning as clear skies prevail underneath
subsidence and light winds. Should see this remain confined to
mainly valley locales where greater cooling will occur since
crossover temperatures may have a difficult time being reached on
ridges.

&&

.SHORT TERM...(This evening through Wednesday night)
Issued at 359 PM EDT TUE JUL 25 2017

High pressure was passing by to our north today behind the cold
front which passed through. Drier air has struggle to make it
into our area , but it succeeded to the point that the weather
has been dry with only fair weather cu. Precip has been held to
our south and west in TN and western KY.

Dry weather is expected to hold through tonight and the day
Wednesday. However, an upper level trough will begin to deepen
over the Great Lakes and New England, allowing another cold front
to drop south. Warm air advection will return to our area ahead of
the front, bringing moisture return on Wednesday night. Models
suggest this could result in some showers or thunderstorms
Wednesday night, but there`s not much in the way of
forcing/features outside of warm/moist advection and isentropic
lift. Have used just a slight chance of precip late.

.LONG TERM...(Thursday through Tuesday)
Issued at 323 PM EDT TUE JUL 25 2017

The extended portion of the forecast begins on Thursday with an
amplified upper level pattern for this time of year. With a stout
ridge in place over the western CONUS, a shortwave will drop
southeast through the Midwest into the OH valley for Thursday as a
surface cold front will push southeast into the area. Good low
level moisture and temps rising into the mid 80s, will mean a good
chance for showers and thunderstorms by Thursday afternoon as the
front approaches. In fact, instability will suggest a slight
severe potential with the main threat being wind as the freezing
level will likely be pretty high for any hail development. Model
soundings would suggest more of a downburst threat with some DCAPE
values preset. Thursdays activity will wane into the night.
Renewed convection will be likely as well into the day on Friday
with a slowed boundary draped over the area will be enough for
another round of convection Friday afternoon. Less instability
though for Friday afternoon will mean a lesser severe threat if
any.

After the last of the forcing or whats left of the boundary exits
southeast and southern KY by Friday night, a period of dry weather
will settle in. Aloft, the mid level ridge axis will shift east
over the area in conjunction with a surface bubble of high
pressure will keep eastern Kentucky dry for the rest of the
extended. In addition to this pattern, the lack of a return flow
in this pattern will allow for cooler temps and less muggy
conditions than what we have seen heading into the start of next
week.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
ISSUED AT 220 AM EDT WED JUL 26 2017

VFR conditions will prevail for most sites as mainly valley fog
develops through the early morning hours. SME should stand the
best chance of an extended period of sub-VFR visibilities with a
nearby water source, but SJS/SYM may see a period or two of
degraded conditions through the night. LOZ saw drier air mix to
the surface this afternoon, so this may limit the fog potential
there, while any development at JKL would likely be brief early
Wednesday morning as valley fog lifts past the ridgeline before
dissipating. VFR conditions will return for all by mid morning
with light west/southwest winds of less than 5 knots the rule
through the day.

&&

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

$$

UPDATE...GREIF
SHORT TERM...HAL
LONG TERM...SHALLENBERGER
AVIATION...GUSEMAN/GREIF


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