Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 031145
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
645 AM CDT Wed Jun 3 2015

.UPDATE:
Issued at 635 AM CDT Wed Jun 3 2015

Quick update to the forecast this morning to account for the
stratus that has developed/expanded across the southeastern half
of the CWA and to increase PoPs especially across central MO as
decaying MCS appears that it will make it further east than
originally anticipated. Did not have a chance to look at
temperatures for today, but increased cloud cover could keep them
cooler than currently forecast.

CVKING

&&

.SHORT TERM:  (Through Late This Afternoon)
Issued at 340 AM CDT Wed Jun 3 2015

Primary forecast question for today is how far southeast the MCS
over Nebraska will get.  Short range guidance suggests that the bulk
of the precip will stay out of our central/northeast MO counties
today as it should hit a wall of dry and stable air.  That being
said, the southern end of the MCS still looks pretty impressive and
the 850mb low level jet should continue to pump moisture into
western Missouri through the morning.  Wouldn`t be surprised to see
some of the last gasps of the MCS dribble into our far western
counties before noon so have continued the slight chance/low chance
PoPs for today over those areas.  Rest of the area looks to remain
dry with temperatures finally getting to near or even slightly above
normal.

Carney

.LONG TERM:  (Tonight through Tuesday)
Issued at 410 AM CDT Wed Jun 3 2015

Warm pattern with increasing chances for thunderstorms still looks
likely through the weekend.  The upper level ridge currently over
the Great Plains tries to build eastward into the Mississippi Valley
Friday, but all guidance shows ridge-running shortwaves weakening
the ridge to a more or lesser degree.  Difficult to say if the
shortwaves are caused by convection, or if the waves help to
initiate precipitation, but all guidance shows periods of precip
from tonight through the weekend.  The best chances for rain still
look to be across northern Missouri and west central Illinois, but I
don`t have a lot of confidence in the exact timing and coverage of
each wave of convection.

ECMWF and GFS shift the pattern in the medium range for early next
week.  Both models shift the upper level ridge back over the western
Plains and Rocky Mountains.  The GFS is more amplified with a full
latitude trof developing over the central U.S. and southern Canada
by Monday/Monday night, while the ECMWF is more zonal with the
pattern over the eastern 1/2 of the CONUS.  Would like to see more
consistency in the guidance before going with higher PoPs, so have
maintained just low chance/slight chance for Monday and Tuesday.
Temperatures look to remain warm through the period with highs
generally in the mid to upper 80s and lows in the 60s.

Carney

&&

.AVIATION:  (For the 12z TAFs through 12z Thursday Morning)
Issued at 639 AM CDT Wed Jun 3 2015

MVFR stratus expanded overnight and now encompasses much of east
central, southeast Missouri as well as southwest Illinois.
Meanwhile, increasing mid level and high level clouds are moving
in from the northwest ahead of a decaying MCS. May be too quick to
scattered low clouds this morning in St. Louis Metro sites given
low level flow, but hoping that June sun will be able to break
them up. Not sure how far east the showers and thunderstorms will
progress as they are running into a ridge of high pressure at the
surface. For now have included a VCSH at KCOU, but given latest
radar trends and mesoscale models a predominant rain/thunder group
may be needed in the near future. Winds remain light from the
southeast.

Specifics for KSTL:

Stratus built back over the terminal this morning. Hoping that
June sun angle can lift and scatter the MVFR cloud deck by 16Z.
Otherwise, an increase in mid an high level clouds can be expected
as decaying MCS will be edging toward the area. Can`t rule out a
remnant shower late in the day, but believe vast majority of the
precip will dry up before reaching east central Missouri. Light
southeast wind to continue.

CVKING

&&

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

$$

WFO LSX





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