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000
FXUS63 KLSX 110033
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
733 PM CDT Mon Mar 10 2014

.SHORT TERM:  (Through Late Tonight)
Issued at 331 PM CDT Mon Mar 10 2014

Gusty southwest winds should be diminishing by late this
afternoon/early this evening as we move past max heating and we
begin to decouple.  Wind should stay south-southwesterly to night
across most if not all of the area.ahead of an area of low pressure
which is currently developing over eastern Wyoming.  The low will
move east overnight into the Great Plains and should be near or
along the Kansas/Nebraska border by 12Z Tuesday morning.  The
takeaway for our area will be continuing warm advection and
increasing high clouds overnight.  This should keep lows tonight
near or above this morning`s readings.

Carney

.LONG TERM:  (Tuesday through Next Monday)
Issued at 331 PM CDT Mon Mar 10 2014

(Tuesday)

Another unseasonably warm spring-like day is forecast for tomorrow with high
temperatures in some areas nearly 25 degrees above normal for early/mid March.
Went well above all guidance for high temperatures tomorrow as models have
850-hPa thermal ridge overhead...at least partial sunshine...and favorable
surface winds out of the southwest. In addition...soundings show deep mixing
during the day tomorrow.

(Tuesday Night - Wednesday)

Next system approaches area early Tuesday night. Vertical motion for ascent
will quickly be on the increase as 500-hPa vort max moves to the ESE and
strong mesoscale forcing via a DTC frontogenetical circulation combine to
provide strong lift across the region. Precipitation will begin as all rain
before transitioning to snow overnight to around the St. Louis metropolitan
area by daybreak Wednesday. Leaned on GFS/ECMWF for track of system and thermal
profiles which yields heaviest snow amounts from near MYJ to UIN. Amounts
around 2-3 inches are possible in this region. Further to the southeast...a
sharp cutoff is expected as boundary layer temperatures struggle to cool
sufficiently to turn over the precipitation to snow. In addition...warm ground
will be a concern everywhere and likely will require heavy precipitation rates
to begin accumulating in areas where surface temperatures do not cool below
freezing.

Snow or rain/snow mix should move out of the area during the morning hours
with a lingering threat of rain/snow showers along and east of the Mississippi
River as an upstream shortwave dives down late in the day. Wednesday`s
temperatures will be in sharp contrast to Tuesday...with highs some 35-40
degrees colder. Highs Tuesday will only be in the upper 30s/low 40s in most
areas which agrees more with cooler MET guidance. NWP soundings and cu rules
would indicate a copious amount of cu/stratocu for the eastern 2/3 of the area.

(Thursday - Monday)

A quick warmup is likely for late this work week as low-level return flow
begins during the day on Thursday. Once again...went much warmer than guidance
would suggest as models have really struggled in the transition season with
high temperature forecasts under sunshine. All in all...the end of this
work week looks very pleasant for any outdoor activities with highs in the
50s and 60s and plenty of sunshine.

Next chance of precipitation looks to be late Saturday through Sunday as models
have a system trying to amplify across and to the east of the area. However...
medium-range models diverge greatly witht he characteristic of this system as
ECMWF develops a cutoff low well to our south while the GFS has some light
precipitation associated with an upper-level disturbance which gets sheared
out as it heads southeastward. Regardless...does appear that at least some
light precipitation either in the form of rain or snow is possible for this
weekend along with below normal temperatures back across the area for Sunday
and Monday.

Gosselin
&&

.AVIATION:  (For the 00z TAFs through 00z Tuesday Evening)
Issued at 733 PM CDT Mon Mar 10 2014

With warm front developing across northern Missouri and lifting
north tonight, will see west winds back to the southwest to south
and lighten. Otherwise, highs clouds to continue streaming into region
ahead of next weather system. By mid afternoon on Tuesday, southwest
winds to pickup to near 15kts. Some gusts to near 25kts possible
at KCOU and KUIN. Low level moisture will be on the increase with
cu developing by mid afternoon as well but pcpn chances to hold
off til after 00z Wednesday.

Specifics for KSTL:
With warm front developing across northern Missouri and lifting
north tonight, will see west winds back to the southwest to south
and lighten. Otherwise, highs clouds to continue streaming into region
ahead of next weather system. By 21z Tuesday, southwest winds to
pickup to near 15kts. Low level moisture will be on the increase
as well with cu developing by 21z Tuesday but pcpn chances to
hold off til after 02z Wednesday, so added vcnty shower mention
under low end vfr cigs for now.

Byrd
&&

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

$$
WFO LSX