Severe Thunderstorm Warning 234, NWS Springfield, MO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPRINGFIELD MO
324 PM CDT Thu Sep 19 2013

.SYNOPSIS...
Issued at 315 PM CDT THU SEP 19 2013

Water vapor imagery depicts a short wave trough digging southeast
across the northern High Plains. Height falls and a surface cold
front out ahead of this trough have resulted in thunderstorm
development up across the Corn Belt region. Additional convection
has developed from northeastern Oklahoma into northern Arkansas on
the edge of an increased mid/upper level moisture feed and an
overall diffluent flow aloft. This general region has also reached
their convective temperatures based on regional 12 UTC RAOBs. With a
rather breezy southwest wind, mid-afternoon temperatures were in the
upper 80s to lower 90s.

&&

.SHORT TERM...(Late this Afternoon through Saturday Night)
Issued at 315 PM CDT THU SEP 19 2013

From late this afternoon into this evening, there is some concern
for microburst potential given low level theta-e differentials in
the 25 to 30 Kelvin range. The main threat will be along and south
of the Ozark Plateau. That cold front will then move into extreme
southeastern Kansas and west-central Missouri late tonight. Showers
and thunderstorms will increase in areal coverage along and behind
that front. We could see some gusty winds with that activity,
however the overall severe threat looks fairly low.

That front will then make steady progress southeast across the area
on Friday. Showers and thunderstorms will continue across the area,
but will eventually end from northwest to southeast throughout the
day. We were not too quick to end the threat of precipitation as an
upper level jet streak will become favorably positioned to perhaps
keep some shower activity going well behind the surface front. Cool
air advection and the widespread rainfall will keep temperatures
from getting out of the lower to middle 70s.

Any leftover activity will then end across south-central Missouri
Friday evening. This will set the stage for a dry weekend with
seasonably cool temperatures. We are looking at highs in the 70s
with lows in the upper 40s to middle 50s.

.LONG TERM...(Sunday through Thursday)
Issued at 315 PM CDT THU SEP 19 2013

For Sunday through Thursday, the 12z suite of medium range model
output continues to produce an increasingly amplified pattern.
Five wave charts do show a trough of increasing strength over the
western half of the CONUS with digging preferred in the
Rockies/High Plains. Upper level ridging will be in control of our
weather regime for much of the week. A shortwave trough looks to
briefly knock down the strength of this ridge in the
Monday/Tuesday time frame. The GFS is most bullish with this
feature, while the ECMWF, GFS ensemble mean, GEM and UKMET are a
bit more dampened. Given that this wave is heading into confluent
flow, expectations are that this wave should weaken with time.
There are some differences in QPF output from the models, but
given the dearth of deep layer moisture, have held off from
mentioning any rain bearing PoPs. Will continue to keep an eye on
this system as an increase in moisture would lend to a risk for
some shower activity. Otherwise, the week looks to be mainly dry
and seasonably warm.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday Afternoon)
Issued at 1246 PM CDT THU SEP 19 2013

Complex forecast over the next 24 hours. This afternoon will
feature an increase in cloud cover with scattered shower and
thunderstorm development affecting areas southeast of the I-44
corridor (including the SGF/BBG aerodromes). Have handled this
with VCTS for the time being. Winds will remain gusty this
afternoon, especially at JLN/SGF where gusts out of the southwest
will near 25kt from time to time. Next, attention turns to a cold
front that is gathering strength to our northwest. Showers and
storms will develop along this feature as the day progresses,
congealing into a large complex this evening. This will begin to
approach from the west and northwest during the mid/late evening
hours, with periods of rain persisting through the end of the TAF
cycle. Ceilings will gradually lower, with MVFR expected after the
front passes during the overnight hours. MVFR visibility is
expected with the heavier downpours of rain. Cannot rule out bouts
of IFR late tonight into Friday morning, however confidence is not
high enough to include at this juncture.

&&

.SGF WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&

SYNOPSIS...Schaumann
SHORT TERM...Schaumann
LONG TERM...Schaumann
AVIATION...Gagan

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