Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Jackson Kentucky
922 am EDT Wednesday Apr 1 2015
issued at 921 am EDT Wednesday Apr 1 2015
Current temperatures across the area have begun to warm this
morning. Have updated to better reflect the current temperatures and dew
points. Under clear skies and high pressure...winds will remain
light but relative humidity values are still expected to be low
today. With this...may decide to include low relative humidity in the severe weather potential statement this
morning and into this afternoon. The current forecast remains on
Update issued at 622 am EDT Wednesday Apr 1 2015
Temperatures have cooled quickly as winds died off early this
morning. Updated the morning forecast based on latest observation...but
there is no substantive change to the overall forecast.
Short term...(today through thursday)
issued at 318 am EDT Wednesday Apr 1 2015
High pressure over the region this morning will move east and warm
air advection will begin today. Moisture will not increase
significantly until later...and abundant sunshine will boost temperatures
and promote low level mixing today. Will expect relative humidity to bottom out
in the teens and 20s. Unlike yesterday...winds will not be a
concern for fire weather...but the dry air will continue to support a
heightened wildfire risk.
Tonight will start out clear. Without much wind initially...
valleys should decouple from the flow aloft and cool off rapidly.
Meanwhile...warm air advection will keep ridges milder. Low level
flow will increase during the night and eventually bring the
arrival of Gulf of Mexico moisture toward dawn. A shortwave trough
will move in from the west southwest at the same time...and could
bring a few showers and thunderstorms to our southwest counties.
The pop will increase on Thursday as the wave arrives...and will
also increase late in the day due to diurnal heating in the warm
air advection regime ahead of an approaching cold front.
Long term...(thursday night through tuesday)
issued at 340 am EDT Wednesday Apr 1 2015
A cold frontal boundary will be in place across Kentucky at the
start of the long term. Two areas of low pressure will ride along
this boundary on Friday from SW to NE across central Kentucky.
Models are in fairly good consensus with the evolution of this
system...with the exception of the low track. The 00z European model (ecmwf)
solution tracks the lows further west...keeping the heaviest
precipitation to our west and north. While the GFS is a bit further east
into our area with the low and associated precipitation. That being
said...we can still expect widespread rainfall on Friday before
the cold front and shortwave trough pushes eastward out of Kentucky late
With warm moist air in place...upper level dynamics from a strong
120kt jet...and plenty of lift from the surface
front...convection is possible on Friday. There is a marginal risk
of severe storms across our extreme northern counties per latest
Storm Prediction Center convective outlook. But there is also potential for some
flooding concerns given the rainfall that is expected on Thursday
in addition to the possible thunderstorms/frontal precipitation on
Friday. Precipitable water values will be above an inch...which is above the 90th
percentile...so whatever storms do develop could be high rain
This system should exit the region fairly quickly late Friday
night...pulling in much drier and cooler air. This will help
stabilize the air...quickly cutting off any further thunderstorm
development and precipitation. Expect thunderstorms and any lingering
thunder to taper off overnight. Both GFS and European model (ecmwf) show some
upslope showers through the first half of the day Saturday so
have left slight chance probability of precipitation in the east into the afternoon hours.
More zonal upper level flow will take hold through the remainder
of the weekend. After a drop in temperatures from the cold frontal
passage on Saturday...expect them to slowly moderate to near
or above normal. However...both the European model (ecmwf) and GFS are trying
to develop a weak frontal boundary along this zonal flow as we
head from Monday into Tuesday...with strong southerly flow and
abundant moisture flowing into the Ohio River valley off of the
Gulf of Mexico. If this continues to organize...could be looking
at another chance for rain and thunderstorms...though there is
still quite a bit of disagreement on intensity and coverage.
Aviation...(for the 12z tafs through 12z Thursday morning)
issued at 622 am EDT Wednesday Apr 1 2015
VFR conditions and light winds are expected through the period.