Area Forecast Discussion
Issued by NWS Paducah, KY
FXUS63 KPAH 151814
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
1214 PM CST Sun Dec 15 2013
ISSUED AT 1214 PM CST SUN DEC 15 2013
The aviation section has been updated for the 18Z TAF issuance.
.DISCUSSION... /ISSUED 301 AM CST Sun Dec 15 2013/
SHORT TERM...(Today through Tuesday)
ISSUED AT 300 AM CST SUN DEC 15 2013
The weather system responsible for the light mix of precipitation
late in the week has shifted east of the area. In its wake, plenty
of remnant low level moisture has resulted in a continuation of
overcast conditions across the entire region early this morning.
And with no measurable precipitation in the forecast through the
short term, it is sky cover and its impact on temperatures that
serves as the primary forecast challenge.
My confidence in the overall cloud forecast over the next few days
is relatively low. Wintertime low clouds have a way of holding on
far longer than any model data would suggest, and I am somewhat
concerned that may be the case here. However, clearing continues
at a very slow but steady pace across Missouri early this morning.
Forecast models suggest this clearing will progress eastward into
the forecast area later today as low level flow backs from
northwest to more southwesterly. Less certain is how far east the
clearing line will progress, especially across the Wabash River
Valley. Opted to leave more cloud cover there through much of the
day. Temperatures will be quite cold with highs only in the upper
20s to lower 30s.
Tonight, a weak mid level disturbance will bring or maintain more
cloud cover across the northern and eastern 2/3 of the area. The
southwestern 1/3 - primarily southeast Missouri - may be more
prone to fog development as weak warm advection develops over top
a cold moist snow covered ground. Not ready to introduce fog quite
yet, but it is something worth considering in later forecasts.
Monday through Tuesday, below normal temperatures will persist as
the region remains in northwest flow aloft on the back side of a
longwave trough over the east. High pressure centered along the
Gulf Coast will provide a light west/southwest wind in the low
levels, which will help to slowly moderate temperatures through
the period. Highs by Tuesday should top the 40 degree mark in most
locations. Weak energy rotating across the Great Lakes may keep
more sky cover across the Evansville tri-state, but this influence
should lessen with time.
LONG TERM...(Tuesday Night through Saturday)
ISSUED AT 127 AM CST SUN DEC 15 2013
We start the long term with good model agreement upon surface high
pressure moving to and ridging to our east and nwlys aloft. This
means at least one more night (tue night) of cold with 20s
Southerlies develop Wed, beginning a warming trend, as the upper
level flow backs to westerlies. This will help bump highs back
into the 40s Wed and 50s for Thursday, as night time lows nudge
upwards similarly from 30s to 40s. Dry weather looks to hold til
By 00z Friday, low pressure in the Plains develops, and the
consistent fetch of s-swlys allows dew point temps to increase to
near 50F. Time/height cross sections and forecast model soundings
show the upper profile moistening, and some light shower activity
possibly developing, mainly along and just off to our north/west
The warming/moistening trend kicks in with earnest Thursday night-
Friday. While model differences begin to develop in the signal in
how low pressure evolves/tracks, there is good agreement that dew
point temps at the surface rise through the 50s and may even flirt
with 60F by Friday pm as a frontal boundary makes its way into the
FA. Elevated instability parameters such as the K index offer
support for a mention of thunder Thu night-Friday. 850mb winds
increasing to near 50Kts further support its mention.
Friday night-Saturday, the models diverge. The 00z GFS suggests
the moisture pushes on out with the boundary and the profile
pretty much stays warm in a more or less westerly flow pattern.
The ECMWF keeps the boundary in our neck of the woods as the srn
Plains trof deepens, resulting in west-southwesterlies continuing
for us along with continued pops. The contrasting surface temps
then offer a changeover chance pop mainly for our northern half of
the region through the time in question. We`ll keep such mention
in the either/or chance category with these model hints of
warmer/drier starting to be included in the ensemble, though not
enough yet to influence the blend. To be watched.
ISSUED AT 1214 PM CST SUN DEC 15 2013
Early afternoon satellite imagery and surface observations
indicated clearing pushing steadily east across southeast MO and
expect MVFR cig at CGI to become scattered around 20Z. KPAH will
follow a couple hours later while KEVV and KOWB will likely remain
under MVFR cigs throughout most if not all of the afternoon. Low
level clouds should become scattered to broken at KEVV and KOWB
this evening. A band of moisture about 6-9K feet is projected
southeast across the tAf sites tonight. Winds will increasingly
become southwest at 5 to 10 knots with lighter winds at KEVV and
KOWB tonight. Will have to watch for potential fog tonight there.