Scientific Forecaster Discussion
fxus63 kpah 212311
Area forecast discussion
National Weather Service Paducah Kentucky
610 PM CDT Mon Oct 21 2019
updated aviation section for 00z taf issuance
Short term...(tonight through Wednesday night)
issued at 228 PM CDT Mon Oct 21 2019
A cold front is approaching the forecast area and will move east
of the region between 00z and 01z this evening. There is enough
moisture still in place to produce a few showers along the front.
Although instability is very weak, there is an isolated chance for
a rumble of thunder. Skies should clear overnight behind the front.
On Tuesday, high pressure will move east from the Southern Plains
toward the southeast US. Cooler air will filter in providing
highs only in the lower to middle 60s under a mostly sunny sky.
Stronger winds aloft have mixed down in many areas and winds are
gusting 20 to 30 mph. Wind gusts will be limited after sunset but
southwest to west winds will stay up at 5 to 15 mph. Wind gusts
will pick back up on Tuesday with gusts once again approaching 30
mph. This will stay below advisory criteria.
Winds will die down Tuesday evening and with the high pressure
building in overnight lows will dip down into the upper 30s for
Long term...(wednesday through monday)
issued at 228 PM CDT Mon Oct 21 2019
At the beginning of the extended forecast period, the pah forecast
area will be under quasi-zonal flow aloft as the center of high
surface pressure moves by to our south, giving US seasonable temps,
a southwesterly breeze, and mostly clear skies.
The pattern aloft will gradually turn more southwesterly and
slightly cyclonic by Thu, according to the GFS solution and most of
its ensemble members. This scenario seems to be less likely. In
contrast, the European model (ecmwf) and CMC deterministic models continued to have a
consistently different solution by Thu...more of a split flow, with
anti-cyclonic flow aloft over US ahead of a cut-off low initially in
the Southern Plains. As a result, the GFS forecasted a thoroughly
wet Thu/Thu night, while the other models forecasted just a
flirtation of pops in the northwestern fringe of the pah forecast
area Thu night as the main shortwave energy approaches and moves
through our vicinity. In the European model (ecmwf)/CMC solutions, most of the pcpn
was suppressed by the developing anti-cyclonic flow aloft. As a
result, the initialization blend yielded limited pops for showers
late Thu as a compromise, peaking Thu evening mainly in the
northwestern half of the region.
After a mostly dry and partly cloudy Fri/Fri night, the European model (ecmwf)/CMC
solution showed warm advection rains will commence on Sat to the
east of the ejecting Southern Plains low, which may become nearly
stacked by early sun. The initialization blend indicated a
compromise of course, with limited pops peaking Sat evening and
diminishing rapidly sun as heights and pressures rise in the low's
wake. Once again, adjustments were made to the too-optimistic sky
cover forecast to accommodate this possible weekend's scenario.
Temps are forecast to be generally below seasonable averages after
Thu. The progressive nature of the two possible pcpn-generating
systems should limit quantitative precipitation forecast to generally an inch or less.
issued at 610 PM CDT Mon Oct 21 2019
The back edge of the MVFR cigs was inching eastward across southeast
Illinois and the extreme western counties of Kentucky as of 23z. Some of this
cloudiness is cumuliform cloudiness that will scatter out with the
loss of daytime heating. Even so, the forecast arrival of VFR
conditions has been delayed until 04z at kpah/kevv/kowb. Skies have
already become clear at kcgi and kmvn. Gusty southwest winds will
diminish this evening.
On Tuesday, expect clear skies and excellent vsby. Winds will become
rather gusty again, but not as gusty as today.