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Area forecast discussion 
National Weather Service St Louis MO
336 am CDT Fri Apr 25 2014

Short term: (through late this afternoon)
issued at 335 am CDT Fri Apr 25 2014

Showers will weaken and shift east southeast of our forecast area by
12z Friday as the upper level low over south central Illinois and the
associated surface low over east central Illinois move well east of our
area. The cloud cover should also advect east of the forecast
region later this morning. The low level cold air advection this
morning will be quickly replaced by warm air advection this
afternoon as the northwest wind backs around to a southwest
direction as the surface high center remains south of our area.
With the 850 mb temperatures warming to 9-11 degrees c across our
forecast area by 00z Saturday, and full sunshine later this morning
and this afternoon the high temperatures will be above normal again
today with the warmest readings over central MO and the coolest
readings across southwest Illinois.


Long term: (tonight through thursday)
issued at 335 am CDT Fri Apr 25 2014

(tonight and saturday)

An upper level ridge will prevail over our region during this time,
while a weak surface cold front slips in from the north on Saturday
and stalls. While the front is expected to be rather unremarkable
at this stage, carrying little moisture with it and getting little
to no upper level support, a 55kt low level jet will press into
western MO around sunrise and then continue to veer towards central
MO towards late Saturday morning. This jet will carry with it a
slug of respectable moisture and may be able to generate some
isolated to scattered thunderstorms and rain straddling the late morning and early
afternoon hours before fading as it tries to move into eastern MO
and cross the MS river.

Clear skies for a good part of the night and fairly light winds
should allow temps to dip into the 40s in spots tonight with the
rest in the lo 50s. Winds will have already turned from the S-southeast on
Saturday with enough sunshine to justify a return to around 80

(Sunday - tuesday)

Models remain in decent agreement on a strong Pacific storm system
crashing ashore tonight and making good progress eastward, reaching
the plains on Sunday as a negatively tilted system and then
gradually building towards the mid and upper MS valley heading into
Tuesday. While the brunt of the lift from this system remains to
our west until Monday and Tuesday, initial impulses getting kicked
out ahead of this system will likely ensure that thunderstorms and rain develops and
affects much of the area on late Sunday, too.

Strong dynamics and moderate instability favors severe weather
potential for a good part of our area late Sunday. And depending on
how things line up, but looking increasingly possible, additional
rounds of strong to severe thunderstorms and rain may also occur during the afternoon
and early evening hours of Monday and Tuesday as additional impulses
rotate around upper low as it slowly builds overhead. For now, it
looks like the severe wx potential will get increasingly shunted
more to the southeast with time as we head into Monday and Tuesday.

While Max temps can certainly break 80 again on Sunday, it will
become increasingly difficult to pull that off heading into Monday
and Tuesday if the system tracks as expected.

(Wednesday - thursday)

The low pressure area to our north and NE, now stacked by this time,
will maintain cyclonic northwest flow at the surface and continue a
favorable setup for diurnally generated rain showers. Clouds and a decently
cool airmass that is taking its time building in will maintain below
average temps with daytime highs struggling to make it out of the
50s. Nighttime temps should drop into the low 40s, perhaps pockets
of 30s, as clouds are anticipated to clear.



Aviation: (for the 06z tafs through 06z Friday night)
issued at 1141 PM CDT Thu Apr 24 2014

The cold front will pass through the St. Louis Metro area between
05-06z accompanied by MVFR and occasionally IFR cigs, light rain
and gusty NW winds. Clearing has just occurred at kcou and should
occur around 07z at KUIN and the St. Louis terminals between
09-10z. Thereafter VFR flight conditions/clear skies will
dominate with surface winds backing from northwesterly early
Friday morning to southwesterly by Friday afternoon.

Specifics for kstl:

The cold front will pass through the terminal between 05-06z
accompanied by a period of MVFR and occasionally IFR cigs, light
rain and gusty NW winds. Clearing should occur around 09z. Thereafter
VFR flight conditions/clear skies will dominate with surface
winds backing from northwesterly early Friday morning to
southwesterly on Friday afternoon.



Lsx watches/warnings/advisories:


Weather forecast office lsx