Area Forecast Discussion
Issued by NWS St. Louis, MO

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000
FXUS63 KLSX 212320
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
620 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.

Carney

.LONG TERM:  (Friday through Next Thursday)
Issued at 402 PM CDT Thu May 21 2015

Not much change to the going forecast for the long term.
Temperatures will moderate on Friday as the surface high moves east
of the region and southerly flow returns.  Expect near normal
temperatures in the mid 70s across the area.  GFS moves what looks
like a grid-scale feedback vortmax across the area Friday night
which seems to be what kicks out rain.  The NAM keeps the precip
west of our area focused on the low level jet.  Have followed the
NAM more closely since the GFS vortmax looks squirrely.
Reintroduced some low chance PoPs into parts of central Missouri on
Saturday...primarily to cover the potential remnants of Friday night
convection to the west moving into central MO that morning.  PoPs
for the rest of the area begin ramping up Saturday night as
southwest flow aloft becomes well established and deep moisture
returns to the area.  Periods of showers and thunderstorms are
likely from Saturday night through the end of the forecast period.
Best chances of rain will be over northern and western portions of
the area, but expect that pretty much every part of the CWFA will
see some precipitation by the middle of next week.  Temperatures at
or above normal still look likely into midweek in the deep southwest
flow.

Carney

&&

.AVIATION:  (For the 00z TAFs through 00z Friday Evening)
Issued at 620 PM CDT Thu May 21 2015

VFR conditions will prevail at the TAF sites thru the valid
period. Look for light W-NW surface winds to back from the SW
early this evening, shortly after sunset, and then remain so until
around sunrise Friday morning when a TROF swings thru and shifts
these light winds from the NW thru the morning hours. Wind
directions will then become variable during the afternoon as a
high pressure RIDGE then moves thru.

Specifics for KSTL: VFR thru the period. Light surface winds will
back from the SW shortly after sunset and hold steady until Friday
morning when a TROF swings thru to veer them from the NW. A RIDGE
axis will then move thru on Friday afternoon resulting in variable
wind directions before settling on an easterly direction late in
the valid period.

TES

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX



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