Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 212026

326 PM CDT Thu May 21 2015

.SHORT TERM:  (Through Late Tonight)
Issued at 326 PM CDT Thu May 21 2015

High pressure centered over the Great Plains will continue moving
east-southeast tonight.  Expect any lingering stratocumulus to thin
out and finally dissipate over the Ozarks this evening.  Should have
a clear or mostly clear sky after the strato-cu dissipates.  With
the high settling down over the eastern Ozarks tonight wind should
become light and variable setting up excellent radiational cooling
conditions.  Chilliest readings will likely be over the eastern
Ozarks closest to the center of the high where lower 40s temps
should be widespread.  Might even see some upper 30s in the
valleys.  Mid and upper 40s that MOS is forecasting over the rest of
the area look reasonable since the wind will be turning around to
the west and coming up to around 5 to 8 mph before sunrise.


.LONG TERM:  (Tonight through Wednesday)
Issued at 340 AM CDT Thu May 21 2015

Not many changes to the prev forecast thru day 3. Large sfc ridge
remains in control of the wx pattern thru Fri. Mdls prog the sfc
ridge moving ewd out of the region on Fri with upper level ridging
occurring over the area. Differences among guidance begin early with
the ECMWF focusing the LLJ much further E than the other guidance.
All other mdls suggest the LLJ will remain focused on the wrn
fringes of the upper ridge. This soln seems more plausible, outside
from any MCS activity. While the ECMWF soln is possible, have
continued drier trend twd other solns. Regardless, mdls come into
better agreement Sat night as the upper ridge moves slightly E and
the LLJ becomes more focused over the region. This trend continues
thru at least Mon, perhaps longer if mdl trends continue. Confidence
quickly drops for Tues and beyond with differences among guidance
and due to the general flow across the region. Have kept chance PoPs
continuing thru the period.

As for temps, have continued cool temps thru Sat due to the sfc
ridge in place and then, precip/cloud cover expected on Sat. That
said, am somewhat concerned that mdls, esp the GFS, are overdoing
cloud cover. Will monitor trends, but going forecast may be too cool
this weekend if clouds do not materialize. Have temps moderating
thru the remainder of the forecast due to mdls suggesting heights
gradually rising. However, temps will be modified somewhat on any
given day due to cloud cover and precip.



.AVIATION:  (For the 18z TAFs through 18z Friday Afternoon)
Issued at 1225 PM CDT Thu May 21 2015

Some lingering low end VFR ceilings possible for first hour or
two at KSTL metro TAFS, but otherwise VFR conditions will prevail
through this TAF forecast period. Winds will continue light northwesterly
to westerly.

Specifics for KSTL: Ceilings just above 3000 feet will likely go scattered
by 19Z or so. Otherwise VFR conditions expected through the
forecast period. Light northwesterly winds will become west by sunset.



Saint Louis     52  75  57  77 /   0   0  10  10
Quincy          48  74  54  74 /   0   0  10  10
Columbia        48  73  53  75 /   0  10  10  30
Jefferson City  45  74  53  76 /   0  10  10  30
Salem           49  74  56  76 /   0   0   5   5
Farmington      44  73  52  76 /   0   5  10  10




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