Area Forecast Discussion
Issued by NWS Springfield, MO

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000
FXUS63 KSGF 260013 AAA
AFDSGF

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE SPRINGFIELD MO
713 PM CDT Mon May 25 2015

...Risk for severe storms increasing across southern Missouri...

.MESOSCALE DISCUSSION...
Issued at 713 PM CDT MON MAY 25 2015

Yet another challenging mesoscale convective situation unfolding
for our area this evening. We are continuing to monitor mixed mode
convection across Arkansas. Discrete cells have developed ahead of
a squall line (and associated bookend vortex in far eastern
Oklahoma), moving to the north-northeast. The bookend vortex has
been weakening steadily with time, though the squall line remains
healthy and the discrete cells somewhat concerning. The big
question, is how healthy this convection will remain as it heads
north into a slightly less supportive environment. To say the
least, signals are mixed and confidence is good enough to increase
the risk of damaging wind gusts across southern Missouri and
introduce a limited risk for a tornado for areas (mainly) south of
the highway 60 corridor.

There are pros and cons to the evolution of convection over the
next few hours. Without a doubt, mixed mode convection is there
and for the time being thriving in an environment characterized by
0-6km shear of 40kt (give or take) and most unstable CAPE of
around 3000 J/kg. Over our neck of the woods deep layer shear is
weaker, though it will increase as the main shortwave to our
southwest enters the region. The bigger question is how much CAPE
can we sustain. The airmass in place at this time is much different
than what we experienced yesterday. Precipitable water values are
around 1 inch and low level moisture is comparatively less. That
said, this system is bringing with it its own shear/moisture. In
addition, a southerly low level jet will ramp up in intensity over
the next 6 or so hours.

Expectations are for convection to enter southern Missouri in the
next couple of hours. We will be closely watching the behavior and
evolution of the discrete convection ahead of the squall line as
it has the better potential for producing a few tornadoes. In
addition, we will be watching the health of the squall line as it
moves northeast as well. Any northward surge will bare watching as
(nearly) south to north oriented 0-3km shear vectors increase to
40kt and result in an increased potential for mesovortex development.

As mentioned above, the risk for severe has been increased across
southern Missouri. Decreasing most unstable CAPE values do suggest
a weakening trend to the strength of convection as it moves deeper
into the area. That said, most areas will look to receive rainfall
tonight. With the focus for the best rain potential along and
southeast of the I-44 corridor, will not issue a short fused flash
flood watch given the progressive nature of this shortwave. Will
continue to monitor far western Missouri and southeastern Kansas
for additional rainfall and ongoing flood aggravation.

&&

.SHORT TERM...(This Evening through Tuesday)
Issued at 320 PM CDT MON MAY 25 2015

The respite from the rain will be short lived as showers and
storms return tonight. Yet another shortwave trough tracking
northeast from the Texas Panhandle region will track into the
Ozarks later tonight. While isolated convection will be possible
through the late afternoon hours expect a swath of convection to
spread northeast from Oklahoma this evening in advance of the
shortwave.

The airmass will remain unstable into the early evening as the
storms approach while deep layer shear increases. This will pose
a limited risk for severe weather mainly across far southwestern
Missouri. However we will have to monitor the organization of this
activity and possible expansion of the severe weather risk.

Another round of moderate to locally heavy rainfall can be
expected. I opted not to issue a Flash Flood Watch given the
progressive nature of this system and areas most impacted are
already under warnings. However we will monitor for the potential
issuance of a short fuse watch dependent on the storm organization
to out southwest.

The shortwave will move off to the northeast Tuesday but
additional weak perturbations moving across the region will
maintain at least a chance for additional convection.

.LONG TERM...(Tuesday Night through Monday)
Issued at 320 PM CDT MON MAY 25 2015

The unsettled weather will continue through the week into next
weekend with a daily chance of showers and thunderstorms. This
occurs as series of shortwaves track through an active quasi-zonal
pattern. The coverage of rainfall will vary day to day but details
are difficult to determine given the uncertainty of the timing and
strength of passing shortwave troughs. Even with the chance of
rain most days will not be a wash out.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday Evening)
Issued at 554 PM CDT MON MAY 25 2015

VFR conditions early this evening will gradually become MVFR and
eventually IFR late tonight. A complex of convection and storms
will move up into the Missouri Ozarks later this evening. The best
timing will be between 02z to 05z followed by scattered showers.
Ceilings will drop to IFR after 06z for all sites. MVFR ceilings
early tomorrow morning will give way to VFR by late morning. Winds
will be southeasterly around 10 knots then becoming southwesterly
late tonight.


&&

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

$$

MESOSCALE...Gagan
SHORT TERM...Foster
LONG TERM...Foster
AVIATION...Griffin






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