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Area forecast discussion
National Weather Service Jackson Kentucky
405 PM EDT Wednesday Apr 23 2014
Short term...(this evening through friday)
issued at 310 PM EDT Wednesday Apr 23 2014
There was very little frost reported this morning in eastern Kentucky.
However...with current dewpoints in the middle 20s to lower
30s...and winds expected to be lighter tonight than last night...will
continue with a forecast of patchy frost. We expect sheltered valley
temperatures to fall into the 30s tonight...but high clouds will
also be on the increase late tonight...and this would be a limiting
factor for frost formation. Frost is mentioned in a Special Weather
Statement...and with patchy nature of any frost tonight there will
be no advisory issued.
For Thursday the main concern is once again low relative humidity
and the enhanced threat for wild fires. Relative humidity on Thursday
looks to be a little lower than today with some spots down to 20
percent or even a little lower. However...winds look to remain under
10 miles per hour for most areas...and look especially light in the east where
the lowest humidity is expected.
For Thursday night into Friday the focus shifts to a cold front which
is forecast to pass through the area early Friday. The main model
differences with this system are timing issues and how long to hold
onto rain chances into Friday. The 12z GFS is faster than the 12z
NAM...12z Gem...and 00z European model (ecmwf). Used a blended approach and held onto
precipitation chances into Friday morning for all but the far
southwest counties. Stability will be limited but there looks to be a
50 knot 800 mb jet impacting the area late Thursday night into Friday
morning...and some upper level jet support as well. Could have some
thunder with any showers near the front...but while overall rain
chances will be in the 60 to 70 percent range for Thursday
night...will only carry a slight chance of thunder.
Long term...(friday night through wednesday)
issued at 405 PM EDT Wednesday Apr 23 2014
The models start out in good agreement with the upper trough moving
to the east of the area by Friday afternoon. There is a strong upper
trough over the West Coast and some weak ridging over The Rockies.
With time...the upper trough digs over the West Coast and the ridging
increases over The Rockies. The trough that had moved east of the
area stalls over the East Coast and is able to push a weak cold front
across the area on Sunday. This front will move back across the area
on Sunday Monday morning as a warm front. A strong system is working
across the area on Tuesday. This looks to be have a negatively tilted
upper trough...so the risk of severe thunderstorms could become a
concern. One of the factors will be the time of day it will move
across the area. Right now...it looks to be in the afternoon...so
will have to keep a close eye on the severe potential. There is quite
a bit of disagreement with the timing of this system...so things
could change quite a bit by the time the system moves across the area.
Used the model blend for the temperatures and then nudges them toward
the European model (ecmwf) and made some adjustments for terrain effects. With the timing
issues near the end of the forecast...did not want to go out on a limb.
Aviation...(for the 18z tafs through 18z Thursday afternoon)
issued at 1238 PM EDT Wednesday Apr 23 2014
VFR and light winds will occur through the period. There is a middle
level ceiling at 10-15k feet above ground level expected to develop after about 08z.