Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 192106

306 PM CST Wed Nov 19 2014

.SHORT TERM...(Tonight through Friday night)
Issued at 305 PM CST WED NOV 19 2014

A cold front is located from near Mt Carmel to near Du Quoin
Illinois as of 2015Z. A little line of cu has developed along the
eastern end of it, but they are trapped below a very strong
inversion located around 825mb. Head of the front west southwest
winds continue to gust well into the 20s. Temperatures south of
the deepest snow cover climbed right up to the lower 50s, while in
the deeper snow pack, temperatures are a bit cooler due to the
melting. Either way, it is much warmer today than it has been so
far this week. Behind the front temperatures will fall a bit
across southern Illinois.

A band of low clouds extending westward from KSTL will make a
glancing blow across the I-64 corridor late this afternoon, and
most of that which reaches south into our area should dissipate
with sunset/loss of mixing. Northwest winds will be rather light
behind the front tonight, so cold, dry advection may not be as bad
as advertised. This forecast may be too dry and therefore too cold
for lows tonight. There is some hint in the NAM and GFS low-level
RH fields that some low clouds or even fog could develop and help
to hold temperatures up. However, if we stay clear, and the
dewpoints make it into the teens, we will be looking at another
cold night. Generally went on the cold side of guidance for lows.

Surface high pressure will settle over the region late tonight
through Thursday. Went at or above the warmer MAV guidance in
most locations for highs Thursday.

As a mid/upper level disturbance moves eastward into the Plains
Thursday night, moisture will begin to push northward through
TX/LA/AR/OK, but the 12Z model consensus now keeps any light
precipitation to our southwest through daybreak Friday. Therefore,
the wintry mix has been removed from the forecast. Patches of
light rain or showers should slowly spread northeast across the
area mainly Friday afternoon and Friday night. The best PoPs
should be over southeast Missouri and southern Illinois.

There is quite a disparity between the MAV and MET numbers for
highs Friday. Stayed closer to the warmer MAV over much of the
area. Friday night will be tricky with increasing clouds and winds
veering to due south. Figure that there may be a quick drop in the
northeast and then a steady climb overnight. Temperatures in the
southwest may not move much at all through the night. Used the
superblend as a guide for trends through the night.

.LONG TERM...(Saturday through Wednesday)
Issued at 305 PM CST WED NOV 19 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 to severe
storms cannot be ruled out, depending on the exact track of the
surface low.

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 12z ecmwf indicates sufficient moisture and instability
to warrant some concern about severe weather on Sunday, while the
12z gfs and gefs indicate near zero capes. 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. 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. Official grids contain gusts around 30 knots, but this
assumes cloudy skies and poor mixing.

Prior to the arrival of the main shortwave late Saturday night,
there is not much in the way of qpf or wind in the forecast.
Forecast pops will be only in the chance category on Saturday.

Looking ahead to the next workweek, cooler air will gradually return
to our region in the wake of the cold front. Since the low level
flow will be westerly in the wake of the cold front, the rate of
cooling will be rather slow initially. By Tuesday however, high
temps should be back in the 40s with lows in the 20s. Surface high
pressure will pass over our region Wednesday, accompanied by chilly
air, lots of sunshine, and light winds.


Issued at 1140 AM CST WED NOV 19 2014

Gusty southwest winds are expected to weaken through the
afternoon, as a cold front approaches the area. Guidance is very
consistent in developing lower clouds in the vicinity of the
front generally straddling 00Z. It appears that these clouds will
be VFR, but a period or two of MVFR ceilings will be possible at
KEVV and KOWB. Behind the front, a light northwest wind is
expected, so cannot completely rule out some fog or low cloud
development late tonight and Thursday morning.




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