Area Forecast Discussion
Issued by NWS Springfield, MO

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FXUS63 KSGF 131822

Area Forecast Discussion
National Weather Service Springfield MO
122 PM CDT Fri Apr 13 2018

Issued at 122 PM CDT Fri Apr 13 2018

Have extended the wind advisory to 6 pm for southwest Missouri and
southeast Kansas as winds still exceeding criteria in those area.

18Z special sounding from SGF still shows a stout cap in place,
but there was significant cooling noted between 12Z and 18Z. Will
see this cap further erode as the afternoon wears on. Convection
was beginning to form over south central Kansas along the dry line
with an uptick in convection over eastern Oklahoma as well, but
still elevated. Convective allowing models still showing the
potential for discrete supercells later this afternoon/evening,
but have been inconsistent with coverage. Will be watching 2
distinct areas for development. The first along the dry line/cold
front as it moves eastward and the second over northeast
Oklahoma, which would lift northeast into the southwest Missouri.
Parameters are in place for robust updrafts supporting large hail
and damaging winds along with the potential for tornadoes.


.SHORT TERM...(Today and tonight)
Issued at 330 AM CDT Fri Apr 13 2018

A very warm early morning was occuring with temps in the upper
60s to near 70. Very strong, gusty winds were occuring as well
across the western half of the area with sustained winds of
20-30mph and gusts to 45mph. These winds were being mixed down
from a very strong 60kt llj. Surface dewpoints were also on the
increase with upper 50s across the western cwa. Low 60 dewpoints
were in Oklahoma and poised to move north today as a strengthening
surface low over Kansas pulls moisture north. Surface dry line
currently from Central KS into Western OK will be a main player in
the forecast today. Subtle disturbances in the southwest flow out
ahead of the main upper level trough will also be key to
determining when and where convection will develop out ahead of
the dryline.

Expectations for the morning hours are that quiet conditions will
occur with perhaps an elevated shower or storm possible. A very
strong elevated mixed layer (CAP) has advected into the area from
the west. 00z soundings from west Texas showed this very well and
current RAP analysis now showing 700mb temps from 10-12C across
KS, OK and Missouri. Therefore the atmosphere is well capped and
significant inhibition remains. With temps starting off so warm,
it will not take many peaks of sun to boost temps up. Models have
underdone high temps the last few days and therefore went slightly
higher than guidance with middle 70s likely for highs. Its
possible 80 degree temps could occur across the JLN area.


By mid afternoon, convective allowing models (CAMS) are showing
thunderstorms developing from Eastern Oklahoma into Western
Arkansas and moving northeast. RAP forecasts show a weak wave
around 700mb moving through during this time and this may be a
trigger however the cap is very strong. It may take the arrival of
the 80kt 500mb speed max to approach and break the cap. HREF CAMS
ensembles are insistent that there will likely be two areas of
storms. One area being the batch that moves out of Arkansas and
the other area being the discrete storms along the dryline. Latest
runs of the HRRR do show this with the first batch moving in from
Arkansas between 4-7pm with additional discrete cells along the
dryline during that period to the west of the area and moving
east. The RAP shows the dryline stalling on the Missouri/Kansas
border with the cold front over taking it during this time. The
NAM and especially the 3km NAMnest is much slower with the storms,
with storms not reaching the SGF area until well after 9pm, this
is the slowest of all the models. A few models also develop two
rounds of storms that move out of Arkansas into South Central
Missouri. Therefore there is still some uncertainty in the exact
timing and evolution of the storms today and will have to closely
monitor short term model trends.


Forecast soundings show significant convective inhibition until
about 21z. ML CAPE values are progged to be between 1500-2000j/kg.
Wind shear will be high with effective bulk wind differences of
50-70kts during the evening hours. SRH values will also be high
with 0-3km SRH around 300m2s2. Parameters are well supportive of
severe thunderstorms.

Storm Mode and Hazards:

Any discrete supercell storms will be capable of producing hail
up to the size of baseballs. SARS analogs on the forecast
soundings for this evening match several previous events where
hail of baseball size or larger occurred. The instability and
wind shear combo is supportive of this. The most likely area for
the significant hail will be along and west of US Highway 65
where storms will reside in the more unstable air longer.

Wind gusts up to 70mph are also possible not only in any discrete
supercells, but also in any line segments given the strong wind
fields. Models also show some dry air in the mid levels which will
also aid in this potential. A slightly higher wind potential will
exist across southern and southcentral missouri where storms will
attempt to move in from Arkansas as line segments.

There will be an isolated tornado threat given the progged wind
shear and instability. There will be about 100-150j/kg of low
level cape which will be available. Surface winds look to back to
the southeast slightly as we head into the mid to late evening as
the low level jet increases. One potential negative to the
tornado threat may be a veer/back/veer wind profile on the
soundings which sometimes is a slight negative for tornado
development. One other thing to keep in mind is that 0-3km wind
shear will be out of the southwest at about 40-50kts therefore
will need to monitor any QLCS`s moving out of Arkansas for
mesovort tornado potential.

Area interests should pay attention to forecast updates today
regarding the severe weather potential.

.LONG TERM...(Saturday through Thursday)
Issued at 330 AM CDT Fri Apr 13 2018

Saturday and Sunday will be a far cry from recent days with cloud
cover and much cooler temps. Some showers will be possible
Saturday night into Sunday morning as the system wraps up and
moves overhead. This looks more likely across Central Missouri.
Temps will fall to around freezing for Sunday morning and will
need to monitor for any frost/freeze potential however there will
likely be plenty of cloud cover and continued northwest winds.

Sunday looks raw with highs struggling to get into the lower 40s
with cold air advection. Sunday night we will clear out and likely
reach the upper 20s for lows Monday morning. A Freeze Warning will
likely be needed for Monday Morning.

A quiet weather week is expected from Monday through Thursday with
moderating temps. Precip chances return for next weekend.


.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1157 AM CDT Fri Apr 13 2018

Had some showers and a few thunderstorms develop over the TAF
sites earlier this morning but these have since moved out of the
area. This activity will redevelop later this afternoon around 21z and
exit the TAF sites anyway around 04z. In addition...strong and
gusty southerly winds will also persist through the afternoon.

Once the dry slot moves in...ceilings will lift and winds will
relax a bit and become southwesterly.


MO...Wind Advisory until 6 PM CDT this evening for MOZ066>068-077>080-

KS...Wind Advisory until 6 PM CDT this evening for KSZ073-097-101.



SHORT TERM...Burchfield
LONG TERM...Burchfield
AVIATION...Gaede is the U.S. government's official web portal to all federal, state and local government web resources and services.