Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 280016
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
816 PM EDT Thu Apr 27 2017

.UPDATE...
Issued at 816 PM EDT THU APR 27 2017

Went ahead and added the potential for patchy fog across portions
of the CWA overnight, given the saturated ground from todays
rains, combining with the clearing conditions overnight and light
and variable winds. This addition was also reflected in the
aviation grids. Also went ahead and updated the near term grids
with the latest observations to make sure near current conditions
were still well reflected. All changes have been saved and sent to
NDFD/web. A new ZFP will be sent out to reflect weather element
changes for overnight as well.

UPDATE Issued at 632 PM EDT THU APR 27 2017

Updated near term grids to bring them up to speed on current
trends. Loaded in the latest observations to make sure the temps,
dew points, and winds were on track with the current conditions,
and also decreased cloud cover over the next few hours to show the
ongoing clearing trend. All showers and thunderstorms are now
east of the CWA, which was reflected in the ongoing forecast, so
no major updates to the pops were needed for this evening. All
changes have been saved and sent to NDFD/web, however they were
not substantial enough to warrant a new ZFP or HWO.

&&

.SHORT TERM...(This evening through Friday night)
Issued at 300 PM EDT THU APR 27 2017

The short term period will be mostly dry, as a strong ridge of
high pressure exerts its influence on the region tonight and
tomorrow. The ridge will begin to break down late tomorrow
afternoon, as a strong area of low pressure aloft begins to move
eastward toward the Ohio valley. The ridge, however, is going to
be stubborn and will not simply exit the area. The ridge should
weaken just enough to allow a warm front to push through the area
tomorrow, while keeping an approaching cold front from invading
the area Friday night. At this time, the model data is suggesting
that our northern counties will see showers and storms Friday
night into early Saturday morning, with areas along and south of
the Hal Rogers Parkway and Highway 80 corridor possibly staying
dry. Well above normal temperatures are expected Friday and Friday
night, with tomorrows highs maxing out in the low to mid 80s and
tomorrow nights lows only falling into the low to mid 60s.

.LONG TERM...(Saturday through Thursday)
Issued at 445 PM EDT THU APR 27 2017

The models are in fairly good agreement aloft through the long
term portion of the forecast. They all depict a strong ridge
dominating the southeast portion of the nation while a deep trough
digging through the Desert Southwest on Sunday deepens
dramatically before lifting into the Central Plains by Monday
morning. All the while, the ridge holds fast over eastern
Kentucky. However, the shear size of the upper low at this point
will influence our CWA with very fast southwest flow at mid levels
and a node of energy lifting through the area early Monday. The
models are not quite in synch with each other during the time with
the GFS tending to outrun the ECMWF throughout the transition
while the CMC is more supportive of the latter. Accordingly, will
lean toward the ECMWF solution through Monday. In the wake of this
large low lifting through the Great Lakes, more zonal and still
fast flow will remain over Kentucky through midweek with the bulk
of any energy staying north of the area. Reamplification of this
pattern begins by Thursday morning with a large trough developing
further east into the Southern Plains - but some sig differences
in the models at this point. Accordingly, confidence is low toward
the end of the extended.

Sensible weather will feature a very warm weekend across the CWA
south of a well defined warm front and in the midst of a surge of
humid air from the south. Cannot rule out a stray storm during
this time, but the bulk of the area will be dry so will keep PoPs
below 14 percent through Sunday. The systems cold front them
arrives that evening with another round of storms expected, though
winds will be breezy throughout the day and into the night making
for gusty showers to go along with the potential for strong
thunderstorms. Much cooler weather follows this boundary along
with drier conditions. A developing warm front then lifts back
toward the area with a renewed threat of showers and storms for
Wednesday afternoon. Depending on the eventual solution, showers
and storms could be ongoing through Wednesday night and Thursday
as a deep low to the southwest pumps moisture over that front
across our area.

Did make some minor adjustments to temperatures each night -
particularly for ridge to valley differences Sunday night and
again Tuesday night. Also, fine tuned the PoPs early on, mainly to
lift them further north similar the ECMWF rather than the
SuperBlend.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
ISSUED AT 812 PM EDT THU APR 27 2017

Conditions continue to improve this evening after a cold front
and associated precipitation moved through this morning and
afternoon. Clouds are clearing out quickly as drier air takes
hold, and winds will continue to calm as we lose daytime heating.
The main concern overnight will be fog development, given the
saturated ground and the combination of clearing conditions and
light winds overnight. Generally expect fog to impact both
valleys and ridges, however fairly low confidence on actual
impacts at each TAF site. Based on the NAM12, LOZ and SME have the
best chance to see predominate IFR conditions late tonight into
Friday morning, but the remaining sites could see anywhere from no
direct impacts, to MVFR or IFR. Will continue to monitor and
update as needed as fog begins to develop overnight. Fog should
lift after 12Z and quickly dissipate, leaving VFR conditions for
the remainder of the TAF period. Winds may increase throughout the
afternoon with gusts between 15 and 20 knots possible by 18Z.

&&

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

$$

UPDATE...JMW
SHORT TERM...AR
LONG TERM...GREIF
AVIATION...JMW



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