Area forecast discussion
National Weather Service St Louis MO
255 am CDT sun may 19 2013
Short term...(through wednesday)
issued at 253 am CDT sun may 19 2013
Active weather pattern expected through Wednesday in response to
a series of shortwaves moving across the region as an upper low/trough
moves from the Central Plains to the upper Mississippi River valley.
Several rounds of severe thunderstorms appear likely to occur...with
the potential of large hail...damaging winds and tornadoes.
Warm front is currently located to our southwest and linear
convection from the plains continues to decay as it moves into
western Missouri. Plenty of low level stratus and debris clouds from
western convection cover the County Warning Area early this morning.
Potential for a warm day with 850mb temperatures rising above
+20c...but residual cloud cover and lifting warm front has ME
cautious about going too warm. Have generally forecast highs in the
middle to upper 80s...which is in line with latest MOS guidance.
Short term model guidance continues to show isolated to scattered
convection developing along and north of the advancing warm
front...and likely some residual boundary pushing east from the
decaying convection. 0-6km bulk shear and cape of 2000-3000 k/jg
would support multicell development and the potential of some
marginal severe hail reports if initiation occurs. Think this will
mainly be along and east of the Mississippi River.
Attention will once again turn to our west late this evening as
severe convection is expected to develop across eastern Kansas and
western Missouri...eventually developing into a line and moving east
toward the western County Warning Area by late evening. Main threat with this
convection would be damaging wind gusts. Line of convection will
weaken as it moves further east toward the Mississippi River by
early morning with loss of instability.
Atmosphere should easily reset for Monday...with the potential for a
major severe weather outbreak to occur across at least the western
half of the County Warning Area during the afternoon and evening hours.
Instabily/shear combination is supportive of supercells with large
hail...damaging wind and tornadoes.
Still some uncertainty regarding convective trends for Tuesday and
Wednesday...but could see two more active days given position of the
longwave trough to our northwest and approaching cold front. Once
again...shear/instability combination supports supercells.
Cold front should finally move through the County Warning Area by Wednesday
night...ending the severe weather threat.
Cvking
Long term...(thursday through saturday)
issued at 253 am CDT sun may 19 2013
A reinforcing cold front will provide enough lift for at least a
chance of showers and thunderstorms on Thursday. High pressure
ridge in its wake should bring at least a couple dry days to the
County Warning Area Friday and Saturday before return flow brings increased
chances of thunderstorms back into the forecast for the latter
half of the Memorial Day weekend. Temperatures will remain
seasonal with highs in the 70s and lows in the 50s.
Cvking
&&
Aviation...(for the 06z tafs through 06z Sunday night)
issued at 1147 PM CDT Sat may 18 2013
An area of stratus had reached kcou and was moving northeastward at taf
issuance. This cloud deck may produce brief periods of MVFR ceilings at
metropolitan area taf sites. Scattered showers may affect the terminals towards
daybreak however the best precipitation chances will be towards or beyond the
end of the 24hr taf period. Southeasterly winds will turn southerly and gust to
around 20 kts during the afternoon.
Specifics for kstl...an area of stratus was moving northeastward towards
the terminal and may produce a brief period of MVFR ceilings before 09z
however the observation across the portion of the stratus headed towards
kstl was generally VFR at taf issuance. Scattered showers may affect
the terminal towards daybreak however the best precipitation chances will be
towards the end of the 30hr taf period. Southeasterly winds will turn southerly and
gust to around 20 kts during the afternoon.
Kanofsky
&&
Preliminary point temps/pops...
Saint Louis 89 74 87 67 / 30 40 50 80
Quincy 86 67 84 66 / 30 70 50 70
Columbia 87 67 83 65 / 10 60 60 80
Jefferson City 87 67 85 65 / 10 60 60 80
Salem 86 70 87 70 / 30 30 30 60
Farmington 86 69 85 68 / 20 30 30 80
&&
Lsx watches/warnings/advisories...
MO...none.
Illinois...none.
&&
$$
Weather forecast office lsx
