Scientific Forecaster Discussion
fxus63 kjkl 051140
Area forecast discussion
National Weather Service Jackson Kentucky
640 am EST Thu Dec 5 2019
issued at 640 am EST Thursday Dec 5 2019
Very minor update to blend in the latest obs and trends, but
otherwise forecast is on track at this time.
Short term...(today through friday)
issued at 352 am EST Thursday Dec 5 2019
The morning surface analysis shows surface high continues to nose
northward out of the lower Mississippi River valley. This feature
will shift east today and bring weak southwest to southerly flow.
Given the mostly sunny skies and southerly flow expect
temperatures to actually warm just a couple of degrees above
normal today. Tonight expect increasing clouds through the evening
ahead of an upper level wave evident on water vapor imagery
across Utah and Nevada this morning. This feature will eject east
into the plains by this evening and eventually move eastward
through the remainder of the period. This feature will bring
chances of showers back into the forecast early Friday morning
into early Friday afternoon. Did opt to go likely pops this cycle
given the good agreement among the model suites, but given the
lack of better lower level moisture and lift think amounts will be
light. Should see a downward trend in pops through the afternoon
on Friday, as window for better upper level Omega decreases
quickly. Temperatures Friday should remain around normal for this
time of year even with chances of precipitation.
Long term...(friday night through wednesday)
issued at 400 am EST Thursday Dec 5 2019
The models have maintained agreement with a progressive and more
zonal-like long wave pattern for this weekend, before amplification
occurs into next week. There is a decent consensus regarding
smaller scale features early in the extended portion of the
forecast, before timing issues crop up into next week.
Consequently, did not deviate much from the blended guidance for
A modest short wave trough axis will be exiting eastern Kentucky
Friday night, with deep enough moisture lingering in the low
levels to support at least a slight chance of precipitation
through the evening. Clouds may be harder to clear out through the
rest of the night, as moisture in low level northeast flow,
becomes trapped under a subsidence inversion aloft. Skies should
at least partially clear out on Saturday as high pressure builds
in and heights recover aloft. By late Saturday night and
especially Sunday, clouds will be on the increase once again, as
deeper troughing takes shape west of the Mississippi River.
Eventually, this deepening trough and an associated surface cold
front will gradually move through the Ohio and Tennessee valleys
Monday through Wednesday. The GFS is much more progressive with
this front, while the European model (ecmwf) is slower. Persistence and overall
continuity would lean toward a slower solution, so will maintain
this idea. After the mostly dry weekend across eastern Kentucky,
unsettled conditions will return early next week. Pops will peak
Monday night into Tuesday, with much colder air following the
front, with some potential for a little snow as deeper moisture
exits Tuesday evening. Wednesday looks to be dry and cold.
Temperatures will trend above normal into early next week, before
dipping well below normal by next Wednesday.
Aviation...(for the 12z tafs through 12z Friday morning)
issued at 634 am EST Thursday Dec 5 2019
High pressure will provide VFR conditions through the taf cycle.
We will see mid to high level clouds spread east tonight, as an
upper level shortwave approaches from the west. The high pressure
pushes east today leading to light southerly flow at 5 knots or