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fxus63 kpah 202316 
afdpah

Area forecast discussion
National Weather Service Paducah Kentucky
516 PM CST Mon Feb 20 2017

Update...
issued at 516 PM CST Mon Feb 20 2017

Aviation update.

&&

Short term...(tonight through Wednesday night)
issued at 245 PM CST Mon Feb 20 2017

Average confidence in the short term due to so-so model agreement.

At the time of this writing a deep north-S 500 mb trough is slowly pushing a
storm system/front out of the plains. With the approach of this
system, precipitation will begin to progress eastward across our County Warning Area
starting this evening. In the process the trough evolves into a
split flow regime where the northern stream pushes the front across
the Great Lakes region while in the southern stream the southern
part of the trough will become a closed low thus slowing down its
eastward progress. In addition, with the deepening of the low,
models are showing a surface low being induced on the front just to
the south of our area which will also slow its eastward progress.
What that means for our area is precipitation lingering across the
area longer. Precipitation chances should be greatest late tonight
into early Tuesday morning, then begin to slowly decrease from west
to east from Tuesday afternoon through the overnight hours before
ending. Minimal surface instability tonight so included isolated
thunder chances.

In the wake of this system, the area should remain dry through
Wednesday evening. Late Wednesday night models are showing a short
wave coming out of the plains tapping into a bit of deeper moisture
and cranking a sliver of quantitative precipitation forecast along the far eastern sections of our
County Warning Area.

Long term...(thursday through monday)
issued at 245 PM CST Mon Feb 20 2017

The above normal temperature trend will likely continue from
Thursday into Friday with near record maximum and minimum
temperatures prior to the frontal passage through the weather forecast office pah
forecast region early Saturday morning.

Recent runs of the medium range model guidance have suggested a
variety of longitudinal solutions with the Gulf of Mexico closed low
Wednesday and Thursday. The constant has been the slowing of
moisture moisture return/advection behind the closed low and ahead
of the broad western U.S. Trough.

For Thursday...the Canadian and European guidance have been hinting
and a low to middle level ridging building north into the weather forecast office pah
forecast area, shifting the baroclinic zone and impressed warm
frontal zone north of the area limiting convective activity. At this
time, maximum temperatures may still be too cool, so may have to
consider temperatures in the middle 70s as time GOES by.

For Friday, timing will be everything for instability and
thunderstorm coverage ahead of the cold front. Upper level wind and
thermal instability will be in the vicinity. The question will be
how much deep layer moisture can envelope the weather forecast office pah forecast area
to support long and sustained buoyancy to produce impressive
updrafts and storm organization. The preferred cmcnh and European model (ecmwf)
guidance are still somewhat marginal in this area. The Storm Prediction Center outlook
area for Friday may still be feasible, especially around the noon to
6 PM time period on Friday.

A return to near, but slightly above normal will occur Post-frontal
on Saturday, with a gradual warm-up through early next week above
normal. At this time, there is low confidence on the system early
next week but at least 50% confidence on the Friday weather system.

&&

Aviation...
issued at 516 PM CST Mon Feb 20 2017

Mainly high clouds this evening with light southeast winds. Will see some
mid clouds with time. By 06z, showers will start to spread NE
into semo, SW Kentucky. Arrival into the kcgi-kpah areas expected by
09z-12z. Will make slow eastward progress, toward kevv, kowb and
SW in / Kentucky pennyrile by 16-18z Tuesday. Once the showers begin,
and then after a couple of hours, cigs should lower to MVFR/IFR
with mainly MVFR vsbys. Light southeast winds will continue.

&&

Pah watches/warnings/advisories...
Illinois...none.
MO...none.

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