Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 302105
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
405 PM CDT Sat May 30 2015

.SHORT TERM:  (Through Late Tonight)
Issued at 338 PM CDT Sat May 30 2015

The initial short wave/vort max was located in southeast MO at 20Z with
the associated surface low/frontal boundaries between KBLV and
KMVN. Deep convection capable of high rainfall rates posing any
flood potential will remain along and east of the surface low/front
and be a potential impacts for next 2-3 hours. Thereafter the surface
low and associated fronts will move to the east of the CWA in
association with northeastward movement of the short wave. Have
trimmed the flash flood watch to this region/far eastern CWA through
700 pm. Elsewhere scattered showers will continue in the post-
frontal/low cyclonic flow and impact portions of eastern MO and
southwest IL during the evening hours as they also progress to the
east. Clouds will be locked in across the area tonight and temperatures
will be gradually falling with low level CAA.

Glass

.LONG TERM:  (Sunday through Next Saturday)
Issued at 338 PM CDT Sat May 30 2015

A broad trof is forecast to remain in the picture for the next few
days with development of a closed low within the southern portion
of the trof late tonight into Sunday. Models differ some on the
location of this low and infact several models show 2 lows, however
the main low is forecast to remain over the lower MS Valley. Will
need to monitor the possibility of a more northern low as well
moving northeast across portions of southern MO towards STL. The
GFS suggests this and thus generates some showers across the
southeast third or so of the CWA on Sunday and into Sunday evening
and Monday. It is an outlier compared to the other solutions but I
can`t totally rule it out. At this time I am keeping with a dry
forecast. Cool weather featuring below average temperatures will
be the main story Sunday into Monday with a good deal of clouds as
an expansive surface high centered in southeast Canada maintains
control.

A slowly progressive upper air pattern is forecast after Tuesday
and this will eventually lead to a ridge aloft building into the
central U.S. This change aloft, the retreat of the surface high
and return of southerly flow will lead to a big warm-up during the
later half of the week and into Saturday with highs well into the
80s. By next weekend we will need to monitor short waves trying to
top the ridge aloft and potential for an encroaching east-west
front from the north, all of which indicate an increase in
thunderstorm potential.

Glass

&&

.AVIATION:  (For the 18z TAFs through 18z Sunday Afternoon)
Issued at 1228 PM CDT Sat May 30 2015

Specifics for KCOU: Light to moderate rain showers will linger in
the vicinity of KCOU for the next few hours. Prevailing flight
conditions should fall to IFR tonight due to nocturnal cooling and
plenty of moisture in the lower atmosphere. Only slow improvement
is expected tomorrow morning.

Specifics for KUIN: A band of moderate rain showers was moving
through KUIN at TAF issuance, but should be just south of the
terminal by 18z. Showers continue in the vicinity for the next few
hours before tapering off. Prevailing flight conditions should
fall to IFR tonight due to nocturnal cooling and plenty of
moisture in the lower atmosphere. Only slow improvement is
expected tomorrow morning.

Specifics for KSTL: Light to moderate rain showers will continue
through most of the afternoon. Ceilings will most likely vary
between IFR and MVFR. Although prevailing flight conditions
should improve to MVFR for a few hours later this afternoon,
cloud bases quickly drop back to IFR tonight due to nocturnal
cooling and extensive moisture in the lower part of the
atmosphere. Only slow improvement is expected tomorrow morning.

Kanofsky

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...FLASH FLOOD WATCH until 7 PM CDT this evening FOR Bond IL-
     Clinton IL-Fayette IL-Marion IL-Montgomery IL-Washington IL.

&&

$$

WFO LSX






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