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Area forecast discussion...updated aviation 
National Weather Service St Louis MO
621 am CDT sun Jul 13 2014

Short term: (through tonight)
issued at 340 am CDT sun Jul 13 2014

(today and tonight)

Showers and thunderstorms currently ongoing over northeast and
central Missouri and southwest Illinois are part of a larger band
of storms stretching from northern Indiana to eastern Kansas ahead
of an approaching cold front. Storms have been slow to progress
south due to warm temperatures aloft, and high resolution model
guidance indicates that while the activity should continue its
slow southward progression, it will gradually weaken through the
morning hours. The aforementioned cold front will move south
across the forecast area today and tonight, and given the moist,
unstable airmass in place ahead of it, particularly over the
southern half of the cwa, scattered convection should redevelop
this afternoon. Given cape values expected to range from 1500-2500
j/kg, as well as 0-6km bulk shear 25-30kt, organized convection is
possible, particularly over the southern half of the forecast
area. The Storm Prediction Center has placed portions of southeast Missouri as well as
southern Illinois in a slight risk for severe weather this
afternoon and tonight, with damaging winds being the primary
threat. Precipitable water values ahead of the front are around
2.00-2.25 inches as well, so very heavy rain is also possible with
any storms that develop. Temperatures today will range from the
mid 80s over northern portions of the forecast area to the low to
mid 90s south, as the thermal ridge is suppressed southward ahead
of the approaching front. As the front continues to move south
tonight, low temperatures in the wake of the front will be a bit
cooler than the last few nights, ranging from the mid 60s north to
low 70s over southeast Missouri and southern Illinois as well as
in the St. Louis Metro area.


Long term: (monday through saturday)
issued at 340 am CDT sun Jul 13 2014

Temperatures Monday will be a bit cooler, with upper 70s over the
far northern forecast area, and mid to upper 80s elsewhere. A
second cold front will move across the area on Monday, and given
modest recovery of the atmosphere in the wake of sunday's front,
models indicate cape values Monday afternoon around 1500 j/kg.
There is a slight risk of severe weather Monday for southeast
Missouri and southern Illinois, where widespread height falls and
increasing cyclonic flow could once again support organized
convection, with damaging winds the primary threat. The chance of
showers and thunderstorms will persist until the front moves south
of the area Monday night.

Strong cold air advection in the wake of monday's front will mark
a distinct change for Tuesday, with 850mb temperatures expected to
range from 7-10c, which translates to highs in the low to mid 70s
across the area. Temperatures will struggle to make it out of the
70s Wednesday as high pressure continues to build into the region,
though a moderating trend is expected by the start of the weekend,
with highs in the low to mid 80s expected Saturday. Much of the
extended should remain dry, though the GFS and European model (ecmwf) both indicate
a shortwave moving through the area Friday/Friday night. However,
given model discrepancies, have left the forecast dry for now.



Aviation: (for the 12z tafs through 12z Monday morning)
issued at 611 am CDT sun Jul 13 2014

An outflow boundary has pushed thru the region this morning. The
ongoing rain showers and isod thunderstorms and rain will diminish this morning. Thunderstorms and rain will
be possible again this afternoon at cou/sus/cps as the sfc fnt
lingers across the region. Strong to severe thunderstorms and rain will be possible,
but are expected to remain southeast of terminals. Thunderstorms and rain chances diminish
early this evening with VFR conditions expected thru the night
with nly to nnwly winds aob 10 kts.

Specifics for kstl: winds are expected to become wly later this
morning. Ongoing rain showers north of terminal are expected to dissipate over
the next couple of hours before reaching the terminal. Thunderstorms and rain are
possible this afternoon as the sfc fnt pushes S with winds
becoming nly with fropa. Chance for thunderstorms and rain will diminish early this
evening with VFR conditions expected overnight.



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