Scientific Forecaster Discussion
fxus63 kjkl 170552
Area forecast discussion
National Weather Service Jackson Kentucky
152 am EDT Tue Sep 17 2019
issued at 149 am EDT Tuesday Sep 17 2019
Updated the forecast to input the latest observations and trend
through the overnight and into the predawn hours. Adjusted the
pops and cloud cover to account for the isolated showers and the
weak cold front dropping south. A minor update considering the
Update issued at 1046 PM EDT Monday Sep 16 2019
A few showers continue to progress into the Cumberland Valley this
evening. Given this kept the pops going just a bit longer, but the
lightning has ended and therefore dropped the thunder out the
grids. These showers will continue to decline through the late
evening. No other big changes were made this update.
Update issued at 803 PM EDT Monday Sep 16 2019
A weak cold front continues to push across eastern Kentucky this
evening, with isolated convection developing along the moisture
convergence. Overall this convection will die off through the
evening and clearing skies will follow. Updated to get pops inline
with the current radar trends and blend in the latest obs. All
edits have been sent to ndfd.
Short term...(this evening through Tuesday night)
issued at 447 PM EDT Monday Sep 16 2019
The latest surface map features a weak cold front draped across
the Ohio Valley, with high pressure centered near the Great Lakes,
as well as near the middle Mississippi Valley. Aloft, a Stout Ridge
axis is aligned along the Mississippi Valley, with troughing out
west, as well as in the east. The weak surface cold front, as well
as a subtle short wave trough nudging southeastward on the front
side of the ridge, have allowed for a few showers to pop up
across portions of eastern Kentucky. No thunder has been noted as
of yet across our area; however, there have been a few pulses
noted just upstream, closer to the better instability.
A stray shower or storm will continue to threaten eastern Kentucky
through early this evening, as the surface front pushes closer to
the area. The threat will diminish as we lose heating tonight.
The cool air advection behind this boundary looks weak later
tonight. Models are playing up low clouds and or fog behind the
boundary; however, given our ongoing dry conditions in place, feel
these might a bit overdone. Consequently, lows will be a little
trickier, as guidance suggests milder readings. Have undercut the
numbers somewhat, generally low to mid 60s.
Clouds will mix out during the day on Tuesday, with highs at least
a few degrees cooler than today, generally upper 80s to around 90.
Tuesday night will feature mostly clear skies, patchy valley fog,
and lows in the low to mid 60s, with a few upper 50s possible in
the northeastern valleys.
Long term...(wednesday through monday)
issued at 447 PM EDT Monday Sep 16 2019
Upper level ridging and dry weather will be the main story
through the weekend, as capping should be enough to prevent
convection each day. Stuck fairly close to the blended guidance
for the highs/lows, besides the normal terrain adjustments, which
allowed for slightly cooler valley temperatures in the east. Highs
will average in the mid to upper 80s, still around 10 degrees
above normal for this time of year.
By early next week, the models differ on bringing a more robust
short wave trough and surface front across the Ohio Valley. The
GFS is much more robust with these features, while the European model (ecmwf)
weakens these significantly as they approach eastern Kentucky.
Given the ongoing dryness in place, will side closer to the European model (ecmwf).
As such, have only allowed for slight chance pops by next Monday.
Aviation...(for the 06z tafs through 06z Tuesday night)
issued at 153 am EDT Tuesday Sep 17 2019
Convection has waned as the last of the showers have dissipated.
Predawn the fog potential in the valleys will increase. Given the
dry conditions, and the rain that did fall, will at least go MVFR
at loz and IFR at sme. The Post frontal stratus potential looks
low based on the lack of upstream stratus and the fact that this
is a weak boundary. This fog will burn off around 13 to 14z on
Tuesday leaving US with VFR cigs and visible through the remainder of
the taf period. However, some diurnal cumulus remains possible for
Tuesday afternoon at around 5 kft. The winds will remain light
out of the north and northeast as weak front passes.