Area forecast discussion
National Weather Service Jackson Kentucky
350 PM EDT Wednesday Jun 19 2013
Short term...(this evening through Thursday night)
issued at 323 PM EDT Wednesday Jun 19 2013
The boundary that dropped into Kentucky on Tuesday evening and Tuesday night is now
located near the Tennessee border and is continuing to sag south. To our
north and northeast surface high pressure was located over Ontario. At
middle and upper levels a ridge of high pressure was centered over
northern Mexico and extending north through the plains with general
ridging also extending east across the Gulf of Mexico with an upper
low over the Pacific northwest.
Height rises are generally expected through tonight...but at the same
time some weak troughing or a weakness in the ridge is prognosticated over
the lower Ohio Valley and Tennessee Valley regions. The center of the surface high
will gradually shift east to off the eastern Seaboard with ridging
back into the central appalachian and lower Ohio Valley region. The
boundary will drop further into the Tennessee Valley and become ill defined
and will essentially dissolve. After some drier dewpoints advect in
around the surface high through this evening...low level moisture and
surface dewpoint should rise slightly on Thursday. With the weak upper trough
prognosticated to be to our west on Friday...and a slight increase in
moisture...quite a bit of cumulus should develop and some of the model
guidance develops some convection near the Tennessee and Virginia borders during
peak heating. The previous forecast had a slight chance on Friday
evening and we opted to extend this back into Friday afternoon near the
Tennessee and Virginia borders. The airmass should moderate a bit on Thursday...with
widespread middle 80s anticipated.
Each night valley fog should develop though it may become more
widespread and reduce visibilities more tonight and possibly lift up
to midslope and some Ridgetop locations by dawn on Thursday. With the surface
high pressure center exiting to our northeast tonight...there should
be a small Ridge/Valley split tonight that will be more pronounced
earlier than become smaller as the inversion lifts. Overnight lows
should moderate slightly for Thursday night with increased low level moisture.
Long term...(friday through wednesday)
issued at 349 PM EDT Wednesday Jun 19 2013
A rather stagnant pattern looks to be in place for most of the long
term portion of the forecast. Subtropical upper ridge will be in
place across the south central United States to start the
period...with the ridge eventually retrograding and building over
the western part of the country by the end of the period. Surface
high pressure off the southeast coast will keep a warm moist low
level flow across the area through the upcoming weekend and into
early next week. With this type of pattern in place there is little
to focus precipitation chances but models are hinting there will be
at least a slight chance of convection each day. There are
indications that chances for convection will increase by the middle
of next week as ridge builds in the western United States and we are
in a position on the northeast periphery of the ridge thus be more
susceptible to short wave troughs affecting the area. The Standard
blended Load showed this with the highest probabilities for
precipitation being next Tuesday and Wednesday. Temperatures will be
warming at the beginning of the long term portion of the forecast
with above normal temperatures expected into the middle of next
week.
&&
Aviation...(for the 18z tafs through 18z Thursday afternoon)
issued at 225 PM EDT Wednesday Jun 19 2013
Low clouds have finally lifted and mixed out at jkl to k22 area.
Mainly VFR is expected through the period as a cold front near the
Tennessee border continues to slip further south toward the Tennessee Valley and
dissolve. Valley fog is expected to develop overnight and possibly
affect both loz and sme with MVFR or lower conditions between about
8z and 14z. The fog may lift up out of nearby valleys affecting jkl
after 8z possibly reducing visible to MVFR or lower. Other valley locations
will fall to IFR or lower. The fog should lift and dissipate by 15z with
VFR anticiapted at the end of the period.
&&
Jkl watches/warnings/advisories...
none.
&&
$$
Short term...jp
long term...sbh
aviation...jp
