Preview of NWS' New Version of Forecast
This preview is not operational and should not be used for support decisions.

Area Forecast Discussion (AFD)

Issued by Jackson, KY (JKL)

FXUS63 KJKL 191212 AAA

National Weather Service Jackson KY
812 AM EDT Mon Aug 19 2019

Issued at 811 AM EDT MON AUG 19 2019

The forecast remains on track so far today. Mid and high level
clouds, associated with a passing short wave trough, will
gradually shift east and thin out through the rest of the morning
hours. Have freshened up the hourly temperatures to account for 
the latest trends in observations. Updates have been sent.  


.SHORT TERM...(Today through Tuesday)
Issued at 405 AM EDT MON AUG 19 2019

The latest surface map features high pressure situated across the
southeastern CONUS, with a quasi-stationary frontal boundary
draped from the Great Lakes to the Midwest and into the central
Plains. Aloft, a strengthening upper level ridge is centered
across southwest Texas. A short wave trough is moving east across
the Ohio and Tennessee valleys, with more zonal flow setting up
behind this feature. Plenty of high and some mid-level clouds have
overspread eastern Kentucky overnight, thwarting the diurnal drop
off compared to previous nights. Temperatures currently range 
from the mid to upper 60s in the cooler locations out east, to the
lower to mid 70s elsewhere. 

Hot weather will continue to be the main story through the
short term, as the upper level ridge builds further north towards
the Texas Panhandle today. This will allow for upper level 
ridging and higher geopotential heights to nose in across eastern 
Kentucky. Highs will average in the lower 90s. Forecast 850 mb 
temperatures have come in a bit cooler today, so did not go quite 
as high as it got yesterday, but still above MOS guidance. 
Moisture looks to be a bit higher as well, which should also help 
keep temperatures down a little. Besides a stray shower or storm 
near the Bluegrass region, the upper level ridging should keep a 
lid on convection this afternoon. 

Mostly clear skies will be seen tonight, with lows ranging from
the mid to upper 60s in the valleys, to the lower 70s on the
ridgetops. On Tuesday, the ridge will buckle a bit, as short wave
energy traverses the Great Lakes/Ohio Valley region during the
afternoon. This will allow for a weaker cap, and have gone with 
slight chance PoPs for most locations. Did go a bit higher near
the southeast terrain, as well as near the Bluegrass region, where
better forcing could be in play. Highs will average in the lower 
90s, but generally a bit cooler than today, given the additional 
cloud cover and slightly better storm chances. 

.LONG TERM...(Tuesday night through Sunday)
Issued at 343 AM EDT MON AUG 19 2019

The start of the extended period will become more active overtime,
as a cold front approaches and moves across the Ohio Valley. The
question for the period will be the progression of the front and
subsequently the amount of PoPs that come along with that. The
models suggest the better chances of seeing storms is now
Thursday, as frontal movement south is slower overall. There will
also be a bit better connection to the right entrance region of a
upper level jet progressing into the Northeast. The models are
struggling with consistency from run to run on how far south the
frontal boundary makes it, and the ECMWF has been slower before
the latest 00Z run opted to take it further into the Tennessee
Valley. Given the uncertainty couldnt see being too aggressive
in bringing drier air in area wide to end the week and also
typically these fronts struggle to make it south given the time of
year. However, did keep a good portion of the Bluegrass dry for
Saturday as a result of the latest guidance. By Sunday this
feature may actually shift back as an inverted surface trough, and
lead to some PoPs in the southeast portions of Kentucky at least.
It will be another warm day on Wednesday, but shouldnt be as
warm temperature wise given the increasing moisture. However, the
increasing moisture will make it steamy, but this will also depend
on cloud coverage. The remainder of the period will come in closer
to normal or perhaps just below for this time of year, with more
clouds and potential for storms.


.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)

VFR conditions will prevail through the majority of the time. 
Some patchy MVFR or worse river valley fog will burn off through
13z. This will likely form once again between 06 and 12z Tuesday.
While initial model guidance suggests visibility restrictions at
some TAF sites, will leave out the mention for now, as crossover
temperatures have been lower than forecast each day for the past
few days. Some diurnally driven cumulus at 4-6k feet agl will
occur this afternoon, before diminishing by dusk. Generally south
to southwest winds will average around 5 kts or less through the