978
FXUS63 KSGF 081737
AFDSGF

Area Forecast Discussion
National Weather Service Springfield MO
1237 PM CDT Wed May 8 2024

.KEY MESSAGES...

- Severe thunderstorms expected today with very large hail up to
  the size of baseballs, damaging winds up to 60-80 mph, and
  tornadoes. First round in the morning to mid afternoon with
  round two in the late afternoon and evening. Highest potential
  for severe storms along and southeast of a Joplin to Warsaw
  line.

- Localized heavy rainfall may result in flooding, especially
  for areas northeast of a line from Stockton to Marshfield to
  Eminence. A Flood Watch has been issued for this area, where
  storms may drop 1 to 3 inches of rain with locally higher
  amounts of 3 to 6 inches.

- Drier and cooler conditions for late week and weekend.

&&

.MESOSCALE...
Issued at 1218 PM CDT Wed May 8 2024

A warm from was located across central Missouri and was a focus
this morning, and will continue to be, for storms into this
afternoon. A cold front was also located across eastern Kansas
into eastern Oklahoma. This places the Ozarks and far
southeastern Kansas in the warm sector this afternoon. Several
boundaries have been notes on satellite across the region as
well thanks to earlier convection, differential heating from
cloud cover and other small scale waves.

The region has seen temperatures increase to around 80 degrees
with Td`s around 70. This is helping to produce a favorably
unstable airmass over the area. Models as indicating between
2500-4500 J/kg of CAPE with little to no CAP over the region.
The latest runs show 0-6KM Bulk shear in the 40-50kt range from
the WSW with a 35 to 45kt LLJ over the region. This is
accompanied by upper level support from a strong 250mb Jet
streak.

As a result, A Tornado Watch is in effect until 00z (7PM) with
the potential for large hail, to baseballs in size, with
1000-1300 j/kg of CAPE in the hail growth zone (-10 to -30 *C).
This, coupled with a relatively long straight Hodograph support,
supercells with splitting cells possible. Winds from 60 to 80
mph will also be possible along with tornadoes.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 430 AM CDT Wed May 8 2024

Focus is on potential for significant severe weather this
morning through this evening. Expecting two rounds of severe
storms:

Round 1: Strong southerly flow is pulling moisture northward
quickly. A cloud deck can be seen on satellite over southeast OK
into central AR, which will arrive over the southern CWA around
11Z, which is right in line with what models have been showing.
This moisture, along with the nose of the strong LLJ moving
east toward the area and a surface warm front will be the
catalyst for the development of elevated thunderstorms as early
as 6 AM over the western CWA.

Models show uncapped elevated instability rapidly developing
early this morning, with 2,000-3,000 J/kg of CAPE developing by
12Z when lifting from the 850mb. Expectation is for this
elevated convection to rapidly become severe with very large
hail (golf ball or larger) being the primary risk and damaging
winds being the secondary risk. Expect these storms to increase
in coverage and push east through the northern half of the CWA
this morning into mid afternoon as multicell clusters or
perhaps growing upscale to an MCS. These storms should stay
along and north of the warm front, which should stall in an
east-west orientation somewhere over the central CWA, but
confidence is limited in exact location. If storms don`t form
into an MCS, there is a concern that storms sticking to the warm
front over the eastern CWA may be able to root near the surface
and ingest helicity from the front, resulting in a tornado
threat. This would be especially true if the front orients in a
straight west-east line or in a WNW-ESE line, which would cause
storms to move even more to the right of the right moving storm
motion today and increase storm relative inflow. If ideal storm
mode and frontal interaction occurs, significant tornadoes
could result but that is a very conditional threat. South of the
warm front, surface based storms should hesitate to form
through early to mid afternoon. However, if storms do develop
south of the front they could quickly become severe with
primarily a very large hail and damaging wind threat.

Guidance shows repeated development of elevated storms over
portions of central MO (NE CWA) this morning into the afternoon,
which may result in flooding. 00Z HREF LPMM shows potential for
locally up to 6 inches of rain through this afternoon. Have
issued a Flood Watch to cover this threat.

Round 2: A cold front will push through the area late today,
initiating additional convection over the western CWA late this
afternoon and pushing that through the southeastern CWA by
midnight tonight. These storms look to be more discrete
supercells that will have access to a very unstable environment
(SBCAPE of 3,000-4,000 J/kg) and deep layer shear around 50 kts.
Initially, wind fields will be more unidirectional, which will
favor baseball (if not larger) size hail and 60-80 mph winds as
the primary risks NW of I-44. Models have been trending slower
with the eastward progress of these storms, which is
problematic for areas SE of I-44 because we are also seeing a
trend to having better shear profiles in the evening and
potentially some backing surface winds. Latest RAP and HRRR
both show arcing hodographs that lead to 0-1km Helicity
increasing to 200-300 M2/S2 and Significant Tornado Parameter
values of 5-10. A lot could happen to disrupt this tornado
threat, but if ideal conditions present themselves as shown by
the RAP and HRRR, a significant tornado threat could result
south of I-44 this evening. Stay tuned for updates through the
day. Additional significant threats of baseball or larger hail
and 60-80 mph winds are also expected south of I-44.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Issued at 430 AM CDT Wed May 8 2024

Thursday through Saturday looks dry, with chances for rain
increasing Sunday into Tuesday. Temperatures will be near
normal.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1218 PM CDT Wed May 8 2024

Through 00z to 03z or slightly later, the regions terminals may
be impacted by strong thunderstorms. Away from storms flight
conditions will be MVFR with brief periods of VFR conditions.
Ceilings will be the primary concern. Where storms occur, flight
conditions will deteriorate quickly with MVFR to IFR conditions.
Airfields may see high wind and hail impacts with the strongest
storms.

The storm system will progress through the region likely by 03z
though some light precipitation may linger. However, behind the
storms, flight conditions will improve to VFR as ceilings lift
and cloud cover becomes scattered to few.

&&

.SGF WATCHES/WARNINGS/ADVISORIES...
KS...None.
MO...Flood Watch until midnight CDT tonight for MOZ055>058-067>071-
     078>083-091-092-098.

&&

$$

MESOSCALE...Hatch
SHORT TERM...Titus
LONG TERM...Titus
AVIATION...Hatch