Area Forecast Discussion
Issued by NWS St. Louis, MO

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43
FXUS63 KLSX 291205

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
705 AM CDT Mon May 29 2017

.SHORT TERM...  (Through Late Tonight)
Issued at 331 AM CDT Mon May 29 2017

A cut off upper level low will continue to spin over the Upper
Midwest and south central Canada today.  Another shortwave will spin
around the base of the low today into tonight and this will drive
another reinforcing cold front south through the Mid Mississippi
Valley this afternoon and this evening.  Warm but dry westerly flow
ahead of the front will push temperatures up into the upper 70s and
to mid 80s across the area this afternoon.

Convergence along the front this afternoon combined with the
shortwave dipping across the area should be enough to produce some
isolated to widely scattered thunderstorms.  Any convection that
does develop should dissipate by 900 PM or shortly thereafter.
Remainder of the night looks quiet as high pressure drifts south of
the CWFA.  Temperatures should drop off to seasonably cool readings
in the mid 50s to low 60s.


.LONG TERM...  (Tuesday through Sunday)
Issued at 331 AM CDT Mon May 29 2017

Another shortwave trough will swing around the south side of the
large upper low over central Canada late Tuesday and Tuesday night.
This will cause an attendant cold front to move across Missouri and
Illinois on Tuesday afternoon and Tuesday night bringing scattered
showers and thunderstorms.  The upper low will then lift
northeastward and a surface high will move across the area on
Wednesday allowing for dry weather.  This high will move east by
Thursday allowing low level flow to turn out of the southwest and
Gulf moisture transport to increase into the area.  The chance of
showers and thunderstorms will persist over the area from Thursday
through Sunday as a frontal boundary meanders over Missouri and
Illinois at the same time a series of shortwave troughs move across
the Midwest.

Temperatures this week will remain close to normal, with the GEFS
mean guidance showing highs staying between the mid 70s and mid 80s.



.AVIATION...  (For the 12z TAFs through 12z Tuesday Morning)
Issued at 705 AM CDT Mon May 29 2017

A cold front over northwest Missouri will move southeast today.
Wind will shift from the west-southwest ahead of the front to the
northwest after it passes. Widely scattered showers and
thunderstorms are possible this afternoon and evening along and
east of the Mississippi River in east central and southeast
Missouri as well as southwest Illinois. VFR flight conditions are
expected to prevail outside of any showers or storms that form.


VFR flight conditions are expected to prevail at Lambert through
Tuesday morning. A weak cold front will move through the terminal
today...shifting the wind from the southwest to the northwest as
it passes. There`s an outside chance that a shower or thunderstorm
may affect the airport this afternoon. Any storm that does impact
the airport should be brief, but could briefly lower flight
conditions to MVFR or IFR this afternoon.





WFO LSX is the U.S. government's official web portal to all federal, state and local government web resources and services.