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000
FXUS63 KLSX 100431
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1131 PM CDT Sun Mar 9 2014

.UPDATE:
Issued at 853 PM CDT Sun Mar 9 2014

Satellite trends indicate that much of the cloud cover this
evening has remained just north of the CWFA.  Despite clear skies
across the area, temperatures have not fallen off very rapidly
this evening, and persistent southwest winds around 5-10kt should
be enough to prevent fog development overnight. Thus, the going
forecast remains well on track this evening, with only minor
tweaks to near term trends warranted.

JP

&&

.SHORT TERM:  (Through Late Tonight)
Issued at 357 PM CDT Sun Mar 9 2014

Surface ridge over the lower Mississippi Valley stretching back into
east Texas will continue to be pushed south-southeast tonight.
South-southwest flow will keep temperatures as much as 10-15 degrees
warmer tonight than they were last night.  This is in spite of a
mostly clear sky which would otherwise promote good radiational
cooling.  Wind is also the primary reason to leave fog out of the
forecast late tonight...though it is possible there could be some
patchy fog in sheltered areas.

Carney

.LONG TERM:  (Monday through Next Sunday)
Issued at 357 PM CDT Sun Mar 9 2014

(Monday through Wednesday Night)

Active period expected as we will go from two days of highs well
above normal on Monday and Tuesday to the potential of accumulating
snowfall over parts of the area on Tuesday night.  Still looks like
it will be dry Monday and through most of the day on Tuesday as just
weak vorts move across the area with little moisture to work with.
Still looks like temperatures will warm up nicely the next two days
under mostly sunny skies.  With mixing to 925mb on Monday, and above
850mb on Tuesday ahead of the cold front, think that a mix of the
GFS/NAM MOS temperatures look reasonable for highs.   The warmest
temperatures will be in the favored downsloped areas of the Ozarks.

GFS/NAM are in relatively good agreement that a cold front will have
moved to near I-70 by 00Z Tuesday evening, and the will proceed
south of the CWA by 06Z.  GFS/NAM/ECMWF thermal profiles all show
strong cold air advection in the northern CWA during the evening
causing deformation zone precipitation to switch over to snow during
the late evening and overnight hours.  Farther south, this
transition will occur toward daybreak.  The GFS/NAM are quicker to
pull the system out on Wednesday morning than the ECMWF, so there
are still some uncertainties with this system. At this point, it
appears that there is the potential for 1-2 inches of snow across
parts of northeast Missouri and west central Illinois late Tuesday
night and early Wednesday morning.

(Thursday through next Sunday)

Expect Thursday and Friday to be dry and warmer each day as winds
turn out of the southwest ahead of the next cold front that the
GFS/ECMWF show moving across the CWA on Saturday.  The GFS/ECMWF
show a trough dropping out of Canada on Saturday night and Sunday
with the GFS showing a better phased trough than the ECMWF.  Both
solutions will bring precipitation to the area during this time
period.

Britt

&&

.AVIATION:  (For the 06z TAFs through 06z Monday Night)
Issued at 1049 PM CDT Sun Mar 9 2014

Little cloud cover expected late tgt through Monday evng, mainly
just some high level clouds. A surface ridge will remain across
the srn Plains and Gulf Coast states with a weak front sagging
into nern MO and w cntrl IL Monday evng. Swly surface winds will
continue through the period. Relatively strong wly winds are
expected late tgt/early Monday mrng at 1500-2000 ft in height, and
may include LLWS in the tafs during this time period.

Specifics for KSTL: Just some high level clouds this forecast period
with continued swly surface winds. The LSX VWP was indicating swly
winds around 45 kts at 2000 ft in height, although it may be
depicting the winds at this level a little too strong in magnitude.
Will include LLWS in the STL taf late tgt into Monday mrng.

GKS

&&

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

$$

WFO LSX