000
FXUS63 KPAH 041727
AFDPAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
1127 AM CST Tue Mar 4 2014

.UPDATE...
ISSUED AT 1116 AM CST TUE MAR 4 2014

For aviation section only.

&&

.SHORT TERM /TODAY THROUGH THURSDAY NIGHT/...
Issued at 245 AM CST Tue Mar 4 2014

Main forecast concern in the short term is temperatures...which
will be critical for snow and ice removal efforts. Little if any
precipitation is expected in the short term.

Through Wednesday...a weak surface high will remain quasi
stationary over the forecast area. This high appears to be
an artifact of the shallow cold air mass being held in place by
the snow covered ground. Model soundings indicate the depth of the
mixed layer will be only around 1500 feet each day. Temps at 850
mb will range from plus 1 to plus 5 Celsius through the period.
There is a wide range in high temp guidance...with the gfs being
the coldest. 00z ecmwf is 11 degrees warmer than the gfs mos for
highs at pah Wednesday.

It would be tempting to go with the coldest guidance...but there
are a couple of reasons not to. The shallow nature of the cold air
combined with the relatively strong sun angle means that even
small differences in the mixing layer height would translate into
big differences in temps. Another reason is that the colder gfs
mos has often verified too cold over snow cover this winter. The
gfs mos was a few degrees too cold at PAH Monday. Will trend the
forecast a few degrees colder than the previous forecast...which
places it a little lower than the model consensus but still above the
gfs. Abundant sunshine combined with highs near or above freezing
will be at least marginally helpful for snow and ice removal
efforts each afternoon.

Overnight lows tonight will be a compromise between the colder
gfs and warmer nam mos. Again...this is a few degrees lower than
our previous forecast. Mainly clear and calm conditions overnight
should allow temps to radiate down through the teens. Each of the
next few nights...afternoon snow melt on paved surfaces will
refreeze on untreated surfaces.

The only precip potential of any kind will be Wednesday night and
early Thursday. A 500 mb shortwave will amplify as it moves east
across the Mississippi Valley late Wednesday night. The gfs and
ecmwf have been consistent in concentrating the energy over the
lower Mississippi Valley and Gulf Coast states by Thursday. Both
models keep precip to the south of the forecast area. The lone
outlier is the 00z nam...which deepens the shortwave over the mid
Mississippi Valley. Even so...the 00z nam keeps our region dry.
Will maintain 20 percent pops for large parts of our region Wed
night and Thurs morning. Precip type would be a mix...since 850 mb
temps will hover near or just above freezing.

.LONG TERM /FRIDAY THROUGH MONDAY/...
Issued at 245 AM CST Tue Mar 4 2014

Weak high pressure will result in dry weather Friday. Saturday, the
models move a marginal amount of moisture into the area, as the H5
flow takes on a split, with a low cut off over the SW U.S. / srn
Rockies, while a northern stream trof moves SE from the northern
Plains into the Ohio Valley region. Will keep small chance PoPs
going Sat/Sat night (light rain, then light rain or light snow).
Sunday, S/WV ridge builds across the area as the H5 low moves east.
Should help keep the wx dry. Return chance PoPs for rain later
Monday into Monday night as moisture spreads NE into the area in
advance of the approaching H5 low to our SW. Used a blend of the
prior two runs of both the ECMWF and GFS as a baseline for this.
Temps were a blend of weighted model output and raw model data.

&&

.AVIATION...
ISSUED AT 1116 AM CST TUE MAR 4 2014

Arctic high pressure moving across the northeast U.S. will bring
light winds and generally clear conditions through the period.

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
MO...NONE.
IN...NONE.
KY...NONE.
&&

$$

UPDATE...GM
SHORT TERM...MY
LONG TERM....CN
AVIATION...GM