Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 261210
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
710 AM CDT Fri Jun 26 2015

.SHORT TERM: (Tonight through Friday)
Issued at 322 AM CDT Fri Jun 26 2015

Active elements of large MCS over western MO will continue to move
south and southeast early this morning while the stratiform rain
area will continue to move east.  RAP and HRRR continue to support
the solution that stratiform rain area with moderate to occasionally
heavy rain will slowly move east across the CWA today.  RAP as well
as the GFS/NAM show strong 850-925 moisture convergence moving from
west to east across the area with PWATS near 2 inches.  Will
maintain going flash flood watch given these parameters and the
saturated soils.  Both the GFS and NAM show low level moisture
convergence shifting southeast of the CWA by 00Z with the upper
trough shifting east of the CWA by 06Z.  Think that that the current
end time of the flash flood watch of 00Z still is okay because the
heavy rain should have ended by then.  Rain chances overnight should
be just scattered showers over the southeast half of the CWA after
midnight.

Temperatures will be much cooler today behind the front with cloudy
skies, cold air advection, and rain.  Highs in most areas will only
be in the 70s.

Britt

.LONG TERM:  (Tonight through Thursday)
Issued at 322 AM CDT Fri Jun 26 2015

(Saturday and Sunday)

Dry weather is expect on Saturday as subsidence sets in behind the
exiting trough.  Then chances of showers and thunderstorms increases
Sunday and Sunday night as a shortwave trough dives down embedded in
the northwestly flow aloft.  MUCAPES will be in the 1500-2000 J/kg
range and deep layer shear will be in the 30-40kt range which may be
sufficient to produce a few isolated severe storms.

(Monday through Thursday)

Amplified upper pattern will dominate next week with shortwave
troughs moving through the area every other day.  This will keep a
chance of showers and thunderstorm in the forecast during the period
with below normal temperatures.

Britt

&&

.AVIATION:  (For the 12z TAFs through 12z Saturday Morning)
Issued at 650 AM CDT Fri Jun 26 2015

Area of rain with embedded thunderstorms will continue moving east
across the area today. Have seen visibility drop as low as 3/4SM
in the heaviest thunderstorms, but surprisingly the vast majority
of the area remains VFR. Think some lower ceilings across northern
Missouri will gradually work their way southeast across central
and eastern Missouri into Illinois later this morning...though I
am not certain this will occur. If the ceilings don`t move
southeast..my TAFs are too pessimistic. Rain should slowly come to
an end from northwest to southeast...with perhaps some showers
lingering over parts of eastern Missouri and west
central/southwest Illinois into the evening. Ceiling forecast is
low confidence into the evening, but it looks like there is a
decent chance much of the area will stay MVFR and possibly drop to
IFR range tonight.

Specifics for KSTL:

Heaviest thunderstorms should clear Lambert in the next hour or
so. Until then...there`s a decent threat for heavy rain dropping
visibility to 1-2 miles. Am unsure how long the lighter rain will
last...but it looks like it should stick around until early
afternoon at least. However, if there`s no redevelopment behind
the clearing line currently moving through central Missouri, my
TAF is too pessimistic. Do not have a great deal of confidence in
the ceiling forecast either. Guidance suggests that the lower
ceilings over northern Missouri will drop down into the STL area
later this morning/this afternoon. However, guidance hasn`t been
doing a stellar job, and it looks like the lower ceilings are
having some trouble making southward progress. Again, my TAF may
be too pessimistic if those ceilings don`t start coming south over
the next 2-3 hours.

Carney

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...FLASH FLOOD WATCH through this evening FOR Audrain MO-Boone MO-
     Callaway MO-Cole MO-Franklin MO-Gasconade MO-Jefferson MO-
     Knox MO-Lewis MO-Lincoln MO-Marion MO-Moniteau MO-Monroe MO-
     Montgomery MO-Osage MO-Pike MO-Ralls MO-Shelby MO-St.
     Charles MO-St. Louis City MO-St. Louis MO-Ste. Genevieve MO-
     Warren MO.

IL...FLASH FLOOD WATCH through this evening FOR Adams IL-Bond IL-
     Brown IL-Calhoun IL-Clinton IL-Fayette IL-Greene IL-Jersey
     IL-Macoupin IL-Madison IL-Marion IL-Monroe IL-Montgomery IL-
     Pike IL-Randolph IL-St. Clair IL-Washington IL.

&&

$$

WFO LSX






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