Area forecast discussion
National Weather Service Springfield MO
614 PM CDT Sat may 18 2013
Short term...(late this afternoon through tonight)
issued at 313 PM CDT Sat may 18 2013
A very warm and moist air mass is currently in place across the
region this afternoon. Temperatures are currently in the upper 70s
to the lower 80s early this afternoon and will continue to warm
into the lower to middle 80s. There are also warm temperatures
aloft which is creating steep middle level lapse rates and a very
unstable air mass. However...these warm temperatures in the middle
levels have created a strong cap which will limit convective
development through the rest of this afternoon into early this
evening.
A strong low level jet and isentropic lift will spread into the
area later this evening into the overnight hours. Convection may
develop on the nose of the low level jet across Kansas and spread
to the northeast. The better potential for this activity will
likely be west and north of the area. There are questions if the
jet will be able to overcome the cap across the area this far
south. This activity would be elevated in nature.
Long term...(sunday through saturday)
issued at 313 PM CDT Sat may 18 2013
The potential for multiple severe weather events continue to take
shape for late Sunday afternoon through Tuesday with the potential
for severe thunderstorms producing large hail...damaging
winds...isolated tornadoes...and flooding.
An upper level ridge will migrate east of the region Sunday while
an upper level trough digs into The Rockies. An isolated elevated
storm cannot be ruled out Sunday morning with the aid of a low
level jet...and passage of a minor impulse.
The upper trough will come into the plains and take a more negative
tilt while a surface low develops and tracks into eastern Nebraska.
Very warm and breezy conditions will develop out ahead of this
system across the Ozarks on Sunday. The lower troposphere will become
moderately unstable but remain capped for much of the day across
the Ozarks and Osage Plains.
A powerful upper level jet will punch into the plains Sunday
afternoon and evening while the surface cold front edges eastward
across eastern Kansas. Strong deep layer shear greater than 40 kts
will overspread the area late Sunday afternoon and low level shear
profiles may be enhanced Sunday evening as the low level jet
strengthens. Meanwhile southeastern Kansas and southwestern
Missouri will become positioned within the exit region of the
upper jet which will further enhance lift.
Surface based cape will generally range from 2500-3000 j/kg. Prognosticated
soundings suggest a significant amount will be available within the
hail growth layer which could result in very large hail.
The overall signal for severe weather remains fairly unchanged but
there remains uncertainty on the exact timing and evolution of this
potential severe weather event.
In general expect convection to ignite across the plains Sunday
afternoon then spread east into western Missouri late Sunday
afternoon and evening as strong height falls shift east and the
region comes under the influence of increasing jet dynamics.
Shear profiles suggest thunderstorm Mode may evolve from supercells
to more of a linear convective complex as convection spreads into
the area. 0-3km environmental helicities of 200-400 will support the
potential for tornado development.
In any event strong to severe thunderstorms will impact southeastern
Kansas and southwestern Missouri generally northwest of a Branson to
Rolla line late Sunday afternoon and Sunday night and especially
west of Highway 65. At this time it appears the storms will arrive
in extreme southeastern Kansas to the Interstate 49 corridor between
5 and 8 PM...and the Highway 65 corridor between 9 PM and
midnight.
On Monday...the upper trough will shift into the northern plains
which will maintain a belt of westerlies across the region. The
associated cold front will sag southward into the region and become
oriented parallel with the flow aloft. Ample instability and deep
layer sheer will be in place to support strong to severe storms
especially Monday evening as a jet streak comes across eastern Kansas
and western Missouri. The risk for severe will increase if ample
clearing and subsequent destabilization occurs.
In addition a rich supply of moisture will interact with the front
to support heavy rainfall rates. Given the orientation of the front
and the potential for training storms the risk for flooding will
increase Monday and Monday night.
On Tuesday...models differ on the timing of the frontal passage but
in general have slowed it down. This will maintain the potential of
severe weather and flooding going into Tuesday especially east of
Highway 65.
For the remainder of next week...upper level ridging will gradually
build into the region as the trough shifts to the east. Models
continue suggest periodic chances of convection as minor disturbances
come over the ridge but details on timing and coverage are
uncertain. Otherwise seasonably warm weather is expected.
&&
Aviation...(for the 00z tafs through 00z Sunday evening)
issued at 615 PM CDT Sat may 18 2013
Expect VFR conditions with occasional periods of MVFR due to
ceilings to dominate southwestern Missouri airfields for the
duration of the taf forecast period. A warm moist southerly flow
of air streaming northward from the Gulf of Mexico will keep the
Missouri Ozarks under very humid and variably cloudy conditions
into Sunday afternoon. An upper level high pressure system
currently over Missouri will continue to shift eastward through
Sunday. This will be followed by a seasonably strong storm system
that will bring strong to severe thunderstorms to the area along
with periods of heavy rain...shortly after the end of this taf
forecast period. Included two periods of low level wind shear at
jln later tonight and early tomorrow morning as a low level
southwesterly jet begins to set up.
&&
Sgf watches/warnings/advisories...
MO...none.
Kansas...none.
&&
$$
Short term...wise
long term...Foster
aviation...colucci
