Area forecast discussion
National Weather Service Springfield MO
357 PM CDT Monday may 20 2013
..potential for severe weather and heavy rain this afternoon
through tonight...
Mesoscale discussion...
issued at 223 PM CDT Monday may 20 2013
The ingredients necessary for an episode of severe thunderstorms
are coming together over extreme southeast Kansas and the Missouri
Ozarks.
Data up to 400mb from an 18z special sounding has been
analyzed...and confirms that the Ozarks airmass is quite moist and
unstable.
Zero cape below 3 km was measured on the special sounding...but
this could change with time...as partial clearing occurs from
southwest to northeast. This partial clearing can be seen over
northeast Oklahoma on visible satellite. Observations around
Tulsa showed temperatures spiking into the lower 80s once this
clearing took place. Good low level cape would evolve if
temperatures in southern Missouri can warm into the lower 80s.
Both deep layer shear is sufficient for organized
thunderstorms...while low level shear is strong enough for
tornadoes. However...the 18z sounding showed a critical angle of
around 75 to 80 degrees. If surface winds can back more to the
south southeast...this would create a better environment for
stream wise vorticity into future updrafts...increasing the risk for
tornadoes.
With decent normalized cape within the hail growth zone...hail to
the size of Golf balls will be possible with any rotating updraft.
Any organized line segments could produce damaging wind gusts up
to 70 miles per hour.
Its going to be a busy afternoon / evening.
&&
Short term...(this afternoon through Tuesday night)
issued at 310 PM CDT Monday may 20 2013
The active weather pattern will continue this afternoon into
Tuesday as a strong storm system interacts with a very moist and
unstable airmass. A cold front extends across eastern Kansas into
central Missouri this afternoon. Storms are developing along the
front from west central Missouri down to central Missouri this
afternoon. Instability and deep layer shear are resulting in these
storms being supercellaur in nature.
Cloud cover has remained over the area all afternoon and
temperatures have remained in the 70s. The clearing line is
surging across northeastern Oklahoma and temperatures are quickly
jumping into the 80s once behind the clearing line. The clearing line
will surge into extreme southeastern Kansas and southwestern
Missouri in the next couple hours and will see temperatures
quickly warm into the 80s. Expect the storms across Oklahoma to
track northeast. Hail to the size of hen eggs and tornadoes will
be possible with any supercells and there is the potential for a
strong tornado again if the clouds can clear and temperatures warm
into the 80 late this afternoon into early this
evening. This potential seems to generally be along and south of
Interstate 44 and west of Highway 65.
A line of storms should develop and sweep across the region this
evening into the overnight hours. Winds to 70 miles per hour will be
possible. Given the low level shear in place there will also be
the potential for mesovortices tornadoes within any Bow sections
in any line of storms that develop.
Models show a boundary setting up over southern Missouri tonight...and
with the low level jet tonight could see round of storms track
over the same locations into the overnight hours with very heavy rain
and flash flooding possible.
Storms may linger into Tuesday morning. Additional storms may
develop across the Eastern Ozarks Tuesday afternoon and evening as
the cold front moves through the area. The area will be worked
over from today and tonights storms and shear will not be as
strong. Depending on how much instability that can develop there
could be a severe hail risk this Tuesday afternoon.
Long term...(wednesday through monday) issued at 310 PM CDT Monday
may 20 2013
The upper level low that has brought the active weather to the
region through Tuesday will finally kick off to the east on
Wednesday and upper level ridging will build over the central US
through the weekend. This will bring more seasonable temperatures
to the region through the long term period. A few weak disturbance
may ride through the ridge and bring scattered showers and
thunderstorms to the region this weekend.
&&
Aviation...(for the 18z tafs through 18z Tuesday afternoon)
issued at 1255 PM CDT Monday may 20 2013
A MVFR cloud deck is currently over the area early this afternoon.
The clouds should cover and expect VFR ceilings to develop later
this afternoon into the overnight hours. A few shower or storms
may develop early this afternoon but the better potential is late
this afternoon into this evening. There could be multiple rounds
into of storms persisting into the overnight hours. IFR
visibilities will be possible within any thunderstorms. These
storms will also have the potential to become strong to severe
with heavy rainfall overnight.
&&
Sgf watches/warnings/advisories...
MO...Flash Flood Watch from 8 PM CDT this evening through Tuesday
morning for moz055>058-066>071-077>083-088>098-101>106.
Kansas...Flash Flood Watch from 8 PM CDT this evening through Tuesday
morning for ksz073-097-101.
&&
$$
Mesoscale...Cramer
short term...wise
long term...wise
aviation...wise
