Scientific Forecaster Discussion
fxus63 kjkl 190300 aaa
Area forecast discussion...updated
National Weather Service Jackson Kentucky
1100 PM EDT Wed Sep 18 2019
issued at 1100 PM EDT Wednesday Sep 18 2019
Did a quick update to the grids mainly to adjust sky cover through
the rest of the night - lower early then upping them late - and
also to add in the latest obs and trends for the T/TD grids.
These have been sent to the ndfd and web servers.
Update issued at 745 PM EDT Wednesday Sep 18 2019
23z sfc analysis shows strong and cool/dry high pressure off to
the northeast of Kentucky while lower pressure and warmer/more
moist air is found through the area and points southwest. The
nearby high was not enough to keep a few showers from springing up
along the Virginia border where even some lightning developed
just on the other side. These are drying up currently. Plenty of
cu remains in that part of the County Warning Area and much of the eastern
portion. Do expect the clouds to mostly dissipate for a time
following sunset before increasing again towards dawn. The
redevelopment should limit the fog formation to right along the
river banks overnight and into Thursday morning. Currently,
temperatures are running in the upper 70s to lower 80s most places
while dewpoints vary from the lower 60s north to the mid and upper
60s south - with even some lower 70s in the Middlesboro area.
Have updated the forecast mainly to adjust the pop and sky grids
in the near term while incorporating the latest obs and trends for
the T/TD ones. Did also tweak the fog through the night. These
updated grids have been sent to the ndfd and web servers.
Short term...(this evening through Thursday night)
issued at 355 PM EDT Wednesday Sep 18 2019
The latest surface map features high pressure centered across New
England, with an area of low pressure moving across south central
Canada. Meanwhile, dew point Imelda is churning across southeast Texas,
with a subtle inverted trough nosed in across the Tennessee Valley
as well as eastern Kentucky. Aloft, upper level ridging remains in
place across the Mississippi Valley, with troughing across the
western Atlantic and deeper troughing still across the west.
A similar day with regards to temperature and sky cover across our
area has been the case. Most highs have been in the mid to upper
80s; however, there have been some locations that have made it
into the lower 90s in between the clouds. Dew points are slightly
higher compared to yesterday at this time as well.
Quiet weather will continue to be on tap for our area, as the
ridge axis remains in place from the Great Lakes down to the deep
south. At the surface, high pressure will shift from New England
down across the eastern side of the Appalachians. The models have
been struggling with temperatures and moisture, having gone too
moist in the column and consequently too diurnally limited with
temperatures. As such, have stuck with persistence through the
Diurnally driven cumulus should dissipate into this evening. Some
high clouds may advect in from the northwest later tonight, and
some additional cumulus may also develop closer towards dawn.
Again, the models have been overdone with moisture, so will only
allow for scattered to broken cloud cover. Lows will range from
the upper 50s in some of the cooler sites, to the low to mid 60s
elsewhere. Surface winds will also be veering from the east to
southeast, which should help keep fog formation at Bay.
Scattered clouds look to hang in through Thursday morning, before
thinning in the afternoon. Temperatures will be cooler, with highs
generally in the low to mid 80s. Drier dew points by Thursday
afternoon, should set up a cooler night for Thursday night. Lows
will range from the mid to upper 50s in the valleys, to the lower
60s on the ridges.
Long term...(friday through wednesday)
issued at 355 PM EDT Wednesday Sep 18 2019
Unfortunately, the models continue to show disagreement with
regards to smaller scale features for the latter half of the
extended period. Ridging will remain in control across the Ohio
and Tennessee valleys from Friday through Saturday night, before
troughing gradually cruises east across the northern portion of
the conus, allowing for a return of unsettled weather, mainly
affecting locations to our north. The European model (ecmwf) has been slower and
less aggressive with the moisture, while the GFS persistently
shows a faster progression as well as a more moist outcome. Given
the lack of model agreement, a combination of persistence and the
latest blended guidance was used for the forecast.
The broken record of dry and above normal temperatures will carry
on across eastern Kentucky through Sunday, with highs generally
in the mid to upper 80s, and lows in the 50s and 60s. Pop chances
will increase towards dawn Monday morning and continue to peak in
the chance range on Monday, before generally dry weather returns
for Tuesday and Wednesday. Highs will reduce a bit into Tuesday
and Wednesday, with highs in the low to mid 80s
Aviation...(for the 00z tafs through 00z Thursday evening)
issued at 805 PM EDT Wednesday Sep 18 2019
VFR conditions are expected to prevail through the period.
Scattered cumulus ranging from 3-5k feet agl will dissipate for a
time this evening and into the overnight before redeveloping late
building to a broken deck by mid morning for most places. Look for
east winds of around 5 kts to gradually veer around to the
southeast and south by early Thursday afternoon.