539 
FXUS63 KLSX 250952
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
352 AM CST Tue Feb 25 2014

.SHORT TERM:  (Through Tonight)
Issued at 313 AM CST Tue Feb 25 2014

Large upper trof will swing thru the region today pushing the sfc 
ridge swd. Mdls are in very good agreement thru the period regarding 
mass fields and thermal profiles as well.  As the trof pushes thru 
the region tonight, at least some moisture shud be squeezed out 
producing SN across the srn half of the CWA this evening. Still have 
some uncertainty regarding exact placement, more like ewd extent of 
the precip, but will therefore keep POPs in the chance range for 
now. Regardless, appears to be a low accum event and expect snowfall 
amounts to remain less than an inch. 

As for temps, think clouds will help keep temps down across nrn 
counties. However, clouds shud continue to thicken across the region 
during the afternoon. Shud mix to around 900mb today, which 
complicates the issue.  Overall, trended a little cooler as region 
shud see CAA thru the period. Made only small changes for tonight as 
prev forecast looked on track.


Tilly

.LONG TERM:  (Wednesday through Monday)
Issued at 320 AM CST Tue Feb 25 2014

(Wednesday through Thursday) 

With large sfc ridge in control of the pattern thru this period,
no precip is expected and focus will be on temps. 

Some rather large differences exist among MOS for temps.
Regardless, it appears cold temps will remain in place. Lowered
temps for Thurs with a reinforcing cdfnt expected to move thru the
CWA by 12z Thurs. 

(Friday through Monday) 

Focus quickly turns to system approaching the area on Friday. Mdls
are in remarkably good agreement thru Sat. The short term mdls
give good support to the global mdls thru 12z Fri. Even the DGEX
is in agreement, at least as far as mass fields and the big
picture are concerned. That said, differences do exist in timing
and location of better forcing, and therefore precip. Have raised
POPs for Fri across much of the MO counties. These POPs may need
to be raised yet again, with likely spread further ewd if trends
continue. Also raised POPs into Fri night, but kept in the chance
range as system may arrive/leave sooner than progd, keeping Fri
night largely dry. P-type shud remain all SN for this system,
which at least keeps that part of the forecast easy.  

Forecast then quickly turns to another system impacting the CWA
Late Sat thru Sun period. Some large differences emerge during
this period. 

Mdls continue to spread a warm wedge of air nwd into the area Sat
night into Sun. Chances of some sort of mixed precip are
increasing. The GFS/DGEX suggest this warm air reaching much
further nwd than the ECMWF or GEM. That said, the GEM is an
outlier keeping the baroclinic zone much further s than the other
solns. A great deal of uncertainty remains regarding timing and
location of this system. Have therefore opted to introduce SN or
IP wording across srn portions of the CWA. More than enuf time
remains to tweak the forecast as mdl solns come into better
agreement and wud like to prevent drastic changes in wording. No
matter the outcome of this event, it appears this system may have
a big impact on much of the region.  

As for temps thru the extd, with questions mentioned above,
generally trended twd a compromise until a signal becomes clear. 

Tilly

&&

.AVIATION:  (For the 06z TAFs through 06z Tuesday Night)
Issued at 1126 PM CST Mon Feb 24 2014

A couple of upper level disturbances will affect the region over
the next 24 hrs. The first is tracking across IA into IL tonight.
It has produced a band of snow north of the IA/MO border. It will
be a close call on whether KUIN sees any snow. Right now I think
an hour or two of flurries after midnight will be the extent of
the snow. The second disturbance is fcst to track thru sthrn MO
Tuesday evening. The best chance for snow should be south of
I70...but wouldn't be surprised if KCOU and the STL metro sites
have a few hrs of flurries after 00Z. If it snows any harder then
MVFR VSBYs will be possible. Otherwise expect CIGs aoa 5kft with a
NE becoming NW wind.

Specifics for KSTL:

VFR fcst with CIGs aoa 5kft and a chance of flurries after 00Z
tomorrow evening.

2%

&&

.PRELIMINARY POINT TEMPS/POPS:
Saint Louis     34  10  27  13 /  20  30   0   0 
Quincy          25   2  23   5 /  10   0   0   0 
Columbia        33   8  28  12 /  20  30   0   0 
Jefferson City  34  10  30  15 /  20  40   0   0 
Salem           35   9  22  13 /  10  30   0   0 
Farmington      38  12  28  17 /  10  40   0   0 

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX