Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 301233
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
733 AM CDT Sat Aug 30 2014

.SHORT TERM:  (Through Late This Afternoon)
Issued at 330 AM CDT Sat Aug 30 2014

Regional radar is showing a number of areas of showers and
thunderstorms across Missouri and western Illinois early this
morning. These are generally within a weak warm advection regime
ahead of a upper trof moving through the MS Valley and in advance
of the attendant cold front. While all the current activity should
continue moving east northeast this morning, the overall consensus
amongst the guidance and convection allowing models is that there
should be a general increase in the scattered activity currently
over southwest Missouri as the morning progresses and it moves
northeast. Additional development is also expected during the
later part of the morning into the afternoon in a broad southwest
to northeast zone ahead of the slowly advancing cold front and centered
through the southeast half of the CWA. Given the current temperatures
in the 70s, low-mid 80s looks reasonable for highs today.

Glass

.LONG TERM:  (Tonight through Friday)
Issued at 330 AM CDT Sat Aug 30 2014

Convective trends are not completely clear cut tonight. The main
upper trof axis should have passed to the east by early this
evening, but there is a weak lingering vort max still to pass and
the front appears to wash out across northeast Missouri and west
central Illinois. Sans the NAM, the model consensus keeps a chance
of showers and thunderstorms centered though the southeast half of
the CWA during the evening. Sunday looks largely dry and warmer
with possibly some isolated diurnal storms across southeast MO and
southwest Illinois. The threat of organized covection should
slowly spread into northeast Missouri late Sunday night with the
approach of a progressive long wave trof and attendant cold front and
intensifying southwesterly LLJ. Thunderstorms appear likely on
Labor Day and Monday night as the cold front moves slowly southward
into a moist unstable air mass, and as a southwesterly LLJ and the
upper trof contribute to lift and cap removal. This system will be
accompanied by deep layer shear of 30-40+ knots resulting in the
potential for organized severe storms. Showers and thunderstorms
could persist across the southern CWA Tuesday and maybe even into
Tuesday night and Wednesday in the vicinity of the front and then
as it retreats back northward late Wednesday.

Late in the week ahead the upper ridge is forecast to restablish
itself over the southeast half of the Nation, bringing a return of
more summer like weather/heat.

Glass
&&

.AVIATION:  (For the 12z TAFs through 12z Sunday Morning)
Issued at 732 AM CDT Sat Aug 30 2014

Cold front over northwestern Missouri to move southeast across
area today. South winds to veer to the southwest as front moves
through. VFR conditions expected though could see mvfr conditions
with storms that develop. Best chances of storms will be over taf
sites along I-70 corridor after 16z-17z and persist through the
afternoon hours before diminishing and moving out. Then frontal
boundary to washout and allow winds to become southerly once again
for the overnight hours.

Specifics for KSTL:
Cold front over northwestern Missouri to move southeast across
area today. South winds to veer to the southwest after 17z as
front moves through metro area. VFR conditions expected though could
see mvfr conditions with storms that develop, for now just have
vcts mention. Storms to persist through the afternoon hours before
diminishing and moving out by 00z Sunday. Then frontal boundary to
washout and allow winds to become southerly once again for the
overnight hours.

Byrd
&&

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

$$
WFO LSX





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