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Area forecast discussion...updated aviation 
National Weather Service St Louis MO
1206 PM CDT Thu Jul 10 2014

Short term: (through late this afternoon)
issued at 319 am CDT Thu Jul 10 2014

A surface high pressure center will move east of the area today,
allowing surface winds to turn easterly to southeasterly as the day
progresses. Meanwhile, a warm front will continue taking shape
across Arkansas through southwest MO into eastern Kansas. This warm front will
influence the weather across our area later tonight and tomorrow
after it lifts northeastward. Expected highs in the low to mid 80s
will be around 5 degrees below average for this time of year.

Northwest flow aloft persists today with two vorticity maxima of
note across the region. One disturbance will be moving through the
northern plains before reaching Minnesota by 00z, and the other
convectively-induced disturbance is forecast to move southward from
eastern Kansas into OK. It appears that even if the disturbance in Kansas
interacts with the lifting warm front this afternoon, any convection
would remain well to the southwest of the lsx County Warning Area.

Kanofsky

Long term: (tonight through wednesday)
issued at 319 am CDT Thu Jul 10 2014

Convection should move into northeastern MO late tonight due to
850 mb warm air advection, Theta E advection, and moisture
convergence on the nose of a swly low level jet ahead of a shortwave
moving east southeastward through the northern plains. The models
were also depicting upper level divergence ahead of this shortwave.
The convection should move east southeastward through west central
Illinois Friday morning. A warming trend will begin on Friday as the
surface wind becomes southerly as a surface ridge shifts east of the
region, and 850 mb temperatures gradually rise, increasing to around
20 degrees c over the northwest half of the forecast area. Should
see above normal temperatures by Saturday as a mid-upper level
ridge tries to build northeastward into southwest MO. It appears
that most of the convection will remain north of our forecast area
Friday night as shortwaves move east southeastward overtopping the
mid-upper level ridge. The potential for convection will increase
over the northern portion of the forecast area by Saturday afternoon
or night as an upper level trough begins to deepen over the northern
plains and Great Lakes region and the mid-upper level ridge begins
to get suppressed south southwestward, and a weak front sinks
southward into northern MO and west central Illinois. This weak front
will drop slowly southward through our forecast area on Sunday and
Sunday night with scattered convection possible along it. As a
strong shortwave drops southeastward through the northern plains and
into the Great Lakes region the upper level trough will deepen into
a closed low over the Great Lakes region. A strong cold front will
drop southeastward through our forecast area Monday afternoon and
night. Convection is likely along this cold front with much cooler
and less humid air filtering in behind it. A strong and large
surface ridge for July will build into the region for Tuesday and
Tuesday night with unseasonably cool temperatures expected. The
European model (ecmwf) model is a little cooler than the GFS and brings the
8 degree c 850 mb isotherm southward to just south of stl Tuesday
night. The threat for significant precipitation should end by
Tuesday with below normal temperatures for the remainder of the
extended forecast.

Gks

&&

Aviation: (for the 18z tafs through 18z Friday afternoon)
issued at 1201 PM CDT Thu Jul 10 2014

Vrf conditions with winds at or below 10 kts likely through the valid taf
period. Surface high pressure will by and large continue to
control the weather through Friday. Could be some rain showers up
across northeastern Missouri and west-central Illinois early on
Friday so did introduce a vicinity group in at uin. In
addition...there is also a weak area of sfc convergence that
spreads eastward across the area during the day tomorrow so could
not totally rule out an isolated shower/storm as instability
increases. Otherwise...winds by Friday morning will veer to the
south/southeast as aforementioned sfc high slides off to the east
and return flow commences.

Specifics for kstl:

Vrf conditions with winds at or below 10 kts likely through the valid taf
period. Surface high pressure will by and large continue to
control the weather through Friday. Any shower activity should
stay well north of terminal through early on Friday. There is
however a weak area of sfc convergence that spreads eastward
during the day tomorrow so could not totally rule out an isolated
shower/storm as instability increases but probability was much too
low to include anything in taf. Otherwise...winds by Friday morning
will veer to the south/southeast as aforementioned sfc high slides
off to the east and return flow commences.

Gosselin

&&

Lsx watches/warnings/advisories:
MO...none.
Illinois...none.
&&

$$

Weather forecast office lsx

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