Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Paducah Kentucky
240 PM CDT Sat Apr 18 2015
Short term...(this evening through Monday night)
issued at 240 PM CDT Sat Apr 18 2015
Somewhat complicated forecast as models having trouble figuring out
the evolution of a currently closed 500 mb trough and its associated
surface lows as the upper opens up and moves eastward across
the central/Southern Plains.
This evening conditions will begin to deteriorate as upper level
energy lifting northeast toward our area taps into deep moisture.
Precipitation chances increase after midnight tonight as the upper
level energy induces a surface low to our south that is forecast to
track directly across our area.
In the wake of the upper level disturbance/surface low there may be
a brief respite...although probably not totally precipitation free
..from late morning through middle afternoon. As we head into late
Sunday afternoon the approach of yet another upper level disturbance
will induce a surface low on an approaching frontal boundary. In
addition to the approach and passage of the upper level energy and
front...Sunday afternoon into the evening hours a number of severe
weather parameters (instability...middle level lapse rates >6
c/km...wind shear)...are forecast to come together with the
potential of storms becoming severe generally over the southern half
of our County Warning Area.
Precipitation with this system may linger into Monday morning over
the southeast half of our County Warning Area. Beyond that high pressure should keep
the region dry with slightly cooler temperatures.
Long term...(tuesday through saturday)
issued at 240 PM CDT Sat Apr 18 2015
We will be in west northwest flow aloft to start the period...as a
large closed upper low migrates across the Great Lakes.
Therefore...the cooler weather will continue into Tuesday with highs
in the low 60s. Models diverge with regards to chances for
precipitation as early as Tuesday night. Both models indicate some
energy moving through aloft but the GFS is more pronounced with how
much quantitative precipitation forecast is generated. However...after midnight Tuesday and into
Wednesday...a frontal boundary will be advancing from the north and
possibly give US a better chance for rain. However...moisture return
is questionable so not sure how widespread the precipitation will
be. Therefore...will maintain small probability of precipitation for now.
Models are not in synch with the timing of this front and how
quickly it sags south of the area Wednesday night. GFS forecast
precipitation ensembles are all over the place as well. So we will have to
continue with chances for rain. However...high pressure starts
nosing into the area by Thursday and this lasts through at least
Friday afternoon...giving US dry conditions.
The next system to affect our area looks to arrive by Friday night
into Saturday...bringing more chances for rain. Again...timing
continues to an issue...as models do not agree when to exit the
system over the weekend.
Temperatures will be at or below normal for middle to late week (normal
high in Paducah/Evansville is 70/69 respectively)...as we stay under
the influence of the midwestern upper level low. This feature starts
moving east by the end of the week.
issued at 1241 PM CDT Sat Apr 18 2015
VFR conditions will slowly deteriorate to MVFR then IFR with
showers as a storm system approaches and crosses the region during
the period. Toward the end of the period conditions may improve
back to MVFR along with precipitation ending at kcgi/kpah. Winds
out of the east to southeast at or below 10 knots will gradually swing
around to the west to northwest.
long term/fire weather...CW