Area Forecast Discussion
Issued by NWS Paducah, KY
FXUS63 KPAH 211909
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
109 PM CST Fri Nov 21 2014
.SHORT TERM...(Tonight through Sunday night)
Issued at 100 PM CST FRI NOV 21 2014
A weather system will take shape and move in with a wet forecast
as we head toward and into/thru the weekend.
Satellite currently shows clouds invading the southern FA and
advancing slowly northeastward, their stream sourced from deep
layered moisture over the Gulf and extending into east Tx. Surface
dew points were already approaching 30 in the southwest, and
will be continuing toward the peak in the 50s on Sunday.
In addition, the warming/moistening environ is also destabilizing
with time, and is supportive of thunder inclusion in the forecast
by Sunday. That is when the parent Low lifts from the lower MS
valley and over our Region, spiking pops at near certain. It will
drag a cold front thru Sunday night, as it lifts off and out with
its source moisture.
Todays highs in the 40s will climb toward and even into the 60s
this weekend, while lows make a corresponding rise.
.LONG TERM...(Saturday night through Thursday)
Issued at 340 AM CST FRI NOV 21 2014
The main concern in the long term is the rather potent storm system
that will affect our region this weekend. This system will bring a
soaking rainfall and a period of gusty winds. A few strong
storms cannot be ruled out, depending on the exact track of the
surface low. Right now, it appears that the more unstable conditions
will stay just sough of our region.
The primary 500 mb shortwave will take on a negative tilt as it
lifts northeast from the southern Plains into the Mid-Mississippi
Valley late Sat night/Sunday. Surface low pressure will deepen as it
tracks northeast across Missouri into the Great Lakes region. The
forecast area will be in the warm sector of the system, allowing
relatively warm and moist air to surge northward into the Lower Ohio
Valley. The ecmwf deepens the surface low to 983 mb over central
Missouri on Sunday, as the 850 mb jet axis of 50 to 60 knots passes
over the Lower Ohio Valley. Will increase pops to near 100 percent
for Sunday in this package. PWAT values near 2 SD above normal could
lead to locally heavy rainfall amounts over a large area. In
addition, a period of strong gradient winds is likely on Sunday,
especially if a dry slot allows for partial clearing and better
mixing in the afternoon.
Looking ahead to the next workweek, cooler air will gradually return
to our region in the wake of the cold front. Will need to keep
fairly high rain chances on Monday until the front makes it through
the region, but amounts should be on the light side.
By the Tuesday through Thursday time frame, a large trough will
be carved out across the country`s mid section and we will be
dealing with a series of embedded shortwaves that will be moving
into the region. On Tuesday, we will be dealing with one of these
waves, that originates from the northern Plains and dives
southeast toward the area. At this time, this system looks
moisture starved and should come through the area Tues/Tues night
with little fanfare, other than some cloudiness.
Yet another wave impacts the area on Wednesday into Wednesday
night and this one seems to have a bit more moisture associated
with it. But, not sure if it is worth mentioning at this point.
Trying to time these shortwaves this far out in time is
challenging at best so will wait for a little more continuity
before adding POPs. The GFS/ECMWF begin to diverge after Wed, with
the GFS flattening out the flow and the Euro keeps fairly strong
northwest flow in place. Each one of these waves acts to keep the
cooler air in place over the region, so we really won`t get out of
the upper 30s to mid 40s for a few days.
Issued at 100 PM CST FRI NOV 21 2014
Vicinity showers will commence as VFR cigs saturate down in the
near term. Showers affecting first KCGI/KPAH this evening will
likewise spread over KEVV/KOWB tonight, but should retain VFR
vsbys while cigs saturate on down to MVFR. Slys kick in late
tonight and become gusty tmrw, as low VFR to conditionally MVFR