Area Forecast Discussion
Issued by NWS St. Louis, MO
FXUS63 KLSX 010425
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1125 PM CDT TUE MAY 31 2016
.SHORT TERM... (Through Wednesday)
Issued at 233 PM CDT Tue May 31 2016
Focus tonight will be on convective trends/PoPs. While isolated to
widely scattered showers/storms are possible across the entire area
late this afternoon into early this evening...believe the better bet
for more widespread activity will be from mid evening into the early
overnight period along a prefrontal trough/sfc convergence zone.
Tied highest PoPs overnight roughly along/ahead of this feature as
it slowly progresses eastward overnight. Have continued the likely
PoPs for most of central and northeastern Missouri as well as west-
central Illinois. Believe activity will weaken slowly overnight as
better forcing aloft translates out of the area and instability
wanes diurnally. As a result...have mid/high chance PoPs across
roughly the southeastern 1/2 of the CWA. Other change made to
tonight`s forecast was to speed up timing of higher PoPs as
aforementioned prefrontal trough looks to be the focus for
thunderstorms through tonight.
Lows tonight will continue to be seasonably warm with most areas in
the mid 60s.
Continued to favor highest PoPs along/ahead of the prefrontal trough
into Wednesday morning. Behind this front...taper PoPs off to the
northwest but did keep at least slight chance PoPs ahead of the
actual cold front which looks to move through the area about 6
hours behind the prefrontal trough.
Temperatures tomorrow look difficult as they will be heavily
dependent on clouds/precipitation. Leaned cool relative to guidance
for the southeastern 1/3 of the CWA which has the highest PoPs and
most clouds into the afternoon hours while northwestern sections I
actually leaned warmer than guidance...even behind the actual cold
front. This is because of a lag in the stronger cold advection at
low levels in addition to decreasing clouds through the afternoon.
As a result...probably will not be much of a difference across the
CWA in terms of high temperatures...most areas should be in the low
to mid 80s.
.LONG TERM... (Wednesday Night through Next Tuesday)
Issued at 233 PM CDT Tue May 31 2016
Frontal boundary to exit forecast area by Wednesday evening,
stalling out just south of Missouri border. So even though most of
area to dry out, southern portions of forecast area will see
lingering showers and thunderstorms due to the stalled front/over
running activity through Friday.
By Friday night, northern stream shortwave to slide southeast into
forecast area. So will see increasing chances of showers and
thunderstorms Friday night and persist through Saturday night before
tapering off on Sunday. Last half of weekend and early next week to
Temperatures to remain normal throughout the forecast period, lows
in the upper 50s to mid 60s and highs in the upper 70s to low 80s.
.AVIATION... (For the 06z TAFs through 06z Wednesday Night)
Issued at 1112 PM CDT Tue May 31 2016
VFR conditions expected overall for this forecast period...however
widely scattered showers and thunderstorms will continue
overnight ahead of a weak cold front...particularly from near KCOU
to KUIN. Showers could persist in the KSTL metro TAF sites until
mid morning on Wednesday. Light and variable winds will become
light northwest by mid morning as the front moves through.
Clearing skies are expected during the late afternoon and early
evening from west to east.
Specifics for KSTL: Widely scattered showers will continue through
mid morning ahead of an approaching weak cold front. Light and
variable winds will become light westerly by around 15Z as the
front moves through. Some scattered showers may form right along
the front by late morning and early afternoon...however most of
this activity should remain southeast of the KSTL metro TAF
sites. Skies should begin to clear by around 00Z.
.PRELIMINARY POINT TEMPS/POPS...
Saint Louis 68 82 64 81 / 40 50 30 10
Quincy 64 82 60 80 / 50 50 10 5
Columbia 65 81 61 79 / 50 30 20 10
Jefferson City 64 82 62 80 / 40 30 20 10
Salem 65 82 64 80 / 40 70 40 10
Farmington 63 81 63 79 / 40 60 40 30