Scientific Forecaster Discussion
fxus63 kjkl 182037
Area forecast discussion
National Weather Service Jackson Kentucky
337 PM EST Thu Jan 18 2018
Short term...(this evening through Friday night)
issued at 355 PM EST Thursday Jan 18 2018
Current conditions across the region features clear skies with
high pressure centered over the Alabama/MS area with the axis nosing
northeast over the Ohio Valley. This setup will persist into
tonight with clear skies in place and winds decoupling right after
sunset. Radiational cooling and clear skies will allow temps to
plummet into the single digits in some of the deeper eastern
valleys. Ridgetop temps will be in the teens with a 10 degree
ridge to valley difference despite the weak southwesterly flow.
Speaking of that southerly flow, heading into tomorrow, the high
over the southeast shifts east allowing for increased gradient and
increased southwesterly flow as high temps tomorrow afternoon may
reach the 40 degree mark in many locations. In fact, increased
advection from the south heading into Friday night will allow for
more warm air pushed into the area along with some upper level
cloud cover. This will make for less of a ridge to valley
temperature difference as well as lows only dropping into the
middle 20s, even in the deeper valleys.
Long term...(saturday through thursday)
issued at 330 PM EST Thursday Jan 18 2018
The weekend portion of the extended forecast will begin with
zonal flow over the state of Kentucky, while a southern stream
cutoff low located to the south of the County Warning Area will move to the east.
This pattern will be disrupted as the next primary precipitation
system of focus moves through the region Monday afternoon. The
models are coming into better agreement with this system compared
to previous runs. However, the GFS is still slightly quicker in
terms of the arrival of the precip.
Warm air advection will be brought into eastern Kentucky via SW to S flow Saturday
into Sunday due to a surface high pressure system building to the
south and moving eastward. This pattern will usher in warmer
temps for the weekend. Also, an inverted trough to the east of the
County Warning Area will increase the possibility of precip Sunday afternoon.
However, the models are in disagreement with how much precip will
actually occur. The European model (ecmwf) favors more quantitative precipitation forecast versus the GFS which
favors little to no quantitative precipitation forecast. The cold front bringing in the main
precip will move in Monday. The warmer temps from the weekend will
cause initial precip to fall as all rain. However, cooler temps
will be brought in behind the cold front. This will lead to
increased chances for a Post-frontal mix of rain/snow showers
Monday night into Tuesday morning, particularly in higher
elevations, as the system moves out of the commonwealth. The main
story for the rest of the workweek will be cooler temperatures.
Aviation...(for the 18z tafs through 18z Friday afternoon)
issued at 1143 am EST Thursday Jan 18 2018
High pressure has settled through the area with clear skies
expected through the taf period. Thus VFR conditions are expected
throughout the taf period. Wind will generally by from the
southwest today from 5 to 10 knots before becoming light and
variable after 00z.