Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 210940

340 AM CST Fri Nov 21 2014

.SHORT TERM...(Today through Saturday)
Issued at 340 AM CST FRI NOV 21 2014

Today will start a prolonged period of unsettled weather. An upper
level ridge will build over the region today. Low level southerly
flow across TX/LA/AR is bringing decent low level moisture northward
toward the region. This moisture advection will continue resulting
increasing cloudiness today into tonight. Chances for rain today are
not too impressive. The morning looks to stay mainly dry but as
deeper moisture becomes established later today and tonight, chances
for rain will increase somewhat but still nothing widespread, yet.

Rainfall amounts should be rather light and the best chances for
rainfall this afternoon look to be over SEMO. The axis for best
chances tonight will shift to areas along and northwest of the Ohio
River (i.e. SEMO, southern IL, SWIN). This same corridor will be the
hot spot for rain chances on Saturday, as our main storm system
starts to move toward Texas. However, the NAM/GFS/ECMWF all indicate
that the heaviest rains should fall just a hair to our west, more in
the Springfield to St. Louis MO corridor. So, the best chances will
be in the far northwestern counties of the CWA.

Right now we have lows tonight above freezing. However, the freezing
line will not be too far north of our Wabash Valley counties. This
will need to be watched later on after dark if precipitation
develops, for the possibility of light freezing rain. Indications
are that we should be warm enough though. Just something to keep an
eye on.

Warmer air will be steadily moving into the region from the south
from today through the weekend. Temperatures today despite the
clouds, should reach into the 40s in most locales, with 50s
commonplace by Saturday.

.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 340 AM CST FRI NOV 21 2014

As surface high pressure drifts off to the east, low level
moisture will increase from the southwest through the period. As
such KCGI/KPAH will likely see VFR cigs (050) early, then possibly
MVFR cigs with vcsh toward the end of the period. VFR conditions
should prevail at KEVV/KOWB through the period, however cigs
around 050 may move across those sites after 21Z. Calm to light
and variable winds early will pick up out of the east to southeast
AOB 10 knots after 15Z.



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