Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus63 kjkl 220345 aaa 

Area forecast discussion...updated
National Weather Service Jackson Kentucky
1045 PM EST Thu Nov 21 2019

issued at 1045 PM EST Thursday Nov 21 2019

Updated the grids to allow for a bit of a lull in the higher pops
until later in the night. Also redid the temps and dewpoints
through dawn Friday. The latest obs and trends have been included
for the T/TD grids, as well. These updates have been sent to the
ndfd and web servers along with a freshened set of zones.

Update issued at 650 PM EST Thursday Nov 21 2019

23z sfc analysis shows a cold front moving into the Ohio Valley
with a somewhat tight pressure gradient. This is keeping the
southwest winds up out ahead of the boundary with even some peak
gusts to around 30 mph reported over the Bluegrass region just to
our west. On radar, plenty of spotty light rain and pockets of
sprinkles are found through the state drifting through eastern
Kentucky this evening. The southerly winds and position ahead of
the front is also keeping the temperatures rather warm this
evening - generally in the mid and upper 50s while dewpoints are
running in the upper 30s to lower 40s all under overcast skies.
For this update have adjusted the pops higher through the night
per the radar trends and the latest cams guidance - particularly
in the east for the rest of the evening. Also added in the latest
obs and trends for the T/TD grids. These updates have been sent to
the ndfd and web servers.


Short term...(this evening through Friday night)
issued at 300 PM EST Thursday Nov 21 2019

The general trend in precip for the rest of today looks to be for
isolated to scattered rain showers to move across the area from
time to time. Some locations may see patchy sprinkles instead of
showers due to very dry air in the lower levels below cloud bases.
The current rain showers are forming in the vicinity of a warm
front that is currently situated across portions of western
Indiana and western Kentucky. This trend will continue over the
next several hours. Once the front finally begins moving slowly
eastward tonight, showers will increase in coverage. The latest
model data is suggesting that the widespread rain will not reach
eastern Kentucky until around 9z tonight. However, due to model
uncertainty and differing forecast solutions being offered by
surrounding offices, compromised and now have precip first
entering our western counties around 6z. The more widespread
precip is then forecast to the area around dawn on Friday. The
rain should persistent across all of eastern Kentucky through
early Friday afternoon before retreating to the south, along with
the cold front that spawned the rain in the first place. While the
front is situated to our south, we should see a brief respite
from the rain from late Friday afternoon through late Friday
night. By early Saturday morning, however, the rain should begin
to overspread the area again from the south, as a wave forms along
the western end of the front and begins to moves across the
Tennessee Valley. This wave of low pressure will pass by just to
our south and will allow for a secondary wave of rain for our area
beginning early Saturday morning.

Temperatures the next two nights should generally be above normal,
especially tonight, when we will likely see lows in the mid to
upper 40s across the area. Things will be cooler Friday night, as
cooler air spills into the area north of the departed cold front.
Lows that night should fall into the mid to upper 30s north of the
mountain parkway, and into the lower 40s south of it. A we may see
a bit of snow mixing with the rain for a time late Friday night
into early Saturday morning due to the colder air in our northern
counties. Rainfall amounts for the event as a whole should range
from 8 to 9 tenths of an inch north of the mountain parkway and
from around an inch to an inch and a half south of the mountain
parkway down to the Tennessee border.

Long term...(saturday through thursday)
issued at 405 PM EST Thursday Nov 21 2019

In general the pattern remains amplified and progressive. Model
solutions have definitely trended in a more agreeable direction
during the last couple of runs. But still seeing some significant
differences in timing and especially strength of main, larger
scale features.

Cut off low opens up into a trough as it swings through the Ohio
Valley early in the period (sat-sun). A weak shortwave, or more of
a weak impulse passes through the region Monday ahead of what may
be a stronger shortwave during the mid-week time frame. The
operational European model (ecmwf) has trended more amplified with this mid week
system. The European model (ecmwf) is also slower than the GFS. But confidence is
low for any scenario at this point as both GFS/European model (ecmwf) ensemble
solutions advertise a considerable spread in h500 patterns. Thus
allowed the the blended (nbm) initialization to ride relatively

Sensible weather features an active pattern with a system through
our area every couple to few days. Temperatures will more likely
average above normal through the period than below, though expect
some decent short lived swings in daily temps to below normal
with the progressive nature of the pattern. Pops exist just about
the entire extended time frame, though there is a lull or break in
the threat of rain from Sunday afternoon through Monday.


Aviation...(for the 00z tafs through 00z Friday evening)
issued at 725 PM EST Thursday Nov 21 2019

VFR conditions currently will fall to MVFR before the evening is
out for most sites as cigs lower and steadier rains develop.
Conditions are then expected to deteriorate further through the
night as the cold front settles nearby keeping the slugs of
moisture and rain over the area into Friday. The breezy southwest
winds will start to diminish later this evening and lose their
gustiness well ahead of a switch to the west and then north later
Friday - changing from northwest to southeast across the area.


Jkl watches/warnings/advisories...


National Weather Service Glossary of Abbreviations