Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 270458
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1158 PM CDT THU MAY 26 2016

.UPDATE...
Issued at 1015 PM CDT Thu May 26 2016

Current severe thunderstorm watch over central MO will be
canceled once the current thunderstorms move through the area and
stabilizes the atmosphere. Showers and thunderstorms continue
over central MO and are expected to slowly spread eastward through
the night. Atmosphere over eastern MO and southwest IL remains
unstable with pockets of strong low level moisture convergence. A
few of these storms could be strong overnight given effective
shear around 40kts.

Britt

&&

.SHORT TERM...  (Through Late Tonight)
Issued at 310 PM CDT Thu May 26 2016

Convection from morning MCS has finally shifted southeast of our
forecast area this afternoon. Convection was currently developing
across northwest MO and this activity may eventually shift east
into northeast MO this evening. New development is also expected
across southwest MO along a weak warm front and also along an
outflow boundary left over from the morning convective complex.
These storms should move northeastward into central MO this
evening. Activity may congeal into an MCS later this evening and
overnight and impact much of the forecast area, eventually moving
into our IL counties late tonight. Some of the storms this evening
may be severe, especially across northeast and central MO where
the better instability and shear exists.

GKS

.LONG TERM...  (Friday through Next Thursday)
Issued at 310 PM CDT Thu May 26 2016

A better potential for widespread showers/storms is expected on
Friday and Friday night as the upper level trough now over the
southwest US approaches our area. Will go with likely to
categorical pops. The high temperatures will be cooler on Friday
due to the cloud cover and widespread and potentially long lasting
precipitation. At least scattered showers/storms should occur on
Saturday and Saturday evening until the upper level trough shifts
northeast of our area. Quieter and drier weather is expected by
Sunday as a weak surface trough moves southeastward through the
forecast area with only slight chance pops over the southern and
eastern portion of the forecast area. Precipitation chances should
increase again by Tuesday as an upper level trough moves eastward
through the northern Plains sending a cold front southeastward
through our area. The ECMWF model is quicker than the GFS with the
progression of the upper level trough and associated cold front.
Potentially cooler and less humid conditions can be expected by
the end of the extended forecast period after the passage of the
cold front.

GKS

&&

.AVIATION...  (For the 06z TAFs through 06z Friday Night)
Issued at 1150 PM CDT Thu May 26 2016

Showers and thunderstorms will move through the St. Louis area
terminal and KUIN early in the period and then again midday Friday
as an upper level disturbance moves through the area. Any storms
will be capable of producing MVFR or possibly IFR conditions in
heavy downpours.

Specifics for KSTL: Showers and thunderstorms will move through
the terminal through 09Z and then again during midday Friday.
Any storms will be capable of producing MVFR or possibly IFR
conditions in heavy downpours.

Britt

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX


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