469
FXUS63 KSGF 171140
AFDSGF

Area Forecast Discussion
National Weather Service Springfield MO
640 AM CDT Sat May 17 2025

.KEY MESSAGES...

- 50-70% chance for showers and thunderstorms tonight into
  Sunday morning. A Marginal (1 of 5) to Slight (2 of 5) Risk
  exists for a few thunderstorms that may become capable of
  producing wind gusts up to 60 mph and hail up to the size of
  quarters.

- The unsettled weather pattern will continue across the area
  early next week. This includes the potential for strong to
  severe thunderstorms in addition to localized heavy rainfall
  and flooding. Uncertainty remains in the exact storm mode and
  evolution, which will impact main hazards.

- Active pattern is forecast to end after Tuesday, with mostly
  dry and cooler temperatures Wednesday onwards.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 345 AM CDT Sat May 17 2025

Current water vapor imagery depicts a hexagonal spinner over
MN/WI consistent with a deep vertically stacked low pressure
system. South of the low, mid-level dry air is noted within a
belt of 80-100 kt westerlies originating from a shortwave over
the Baja Peninsula. Extending from the stacked surface low are
two cold fronts that are currently draped from MI through MO,
and into the southern Plains states. The second cold front will
bring northwesterly winds, cooler temperatures this morning
(lows in the lower to middle 50s), and drier air. The front is
forecast to stall just south of the MO/AR border, so high
temperatures will range from the middle 70s in central MO, to
the lower 80s along the southern border.


Marginal to Slight Risk for severe storms tonight:

The stalled cold front boundary is forecast to very slowly lift
back north as an effective warm front starting this afternoon as
shortwave energy overspreads TX/OK. While the surface front will
still be south of the border tonight, the 850 mb front will lift
through southern MO. Associated southerly flow will then advect
warm and moist air over the surface boundary, bringing 500-1000
J/kg MUCAPE along and south of a Nevada to Eminence line as
noted by the 00Z HREF. Warm air advection and isentropic
upglide over the front should then force showers and
thunderstorms in far southwest MO after 7 PM. These will then
spread northeastward along with the lifting warm front, bringing
50-70% chances for rain. Modest 500 mb flow associated with the
incoming shortwave should generate 25-40 kts of effective
shear, according to RAP forecast soundings. Thus, some
thunderstorms may become organized enough to produce wind gusts
up to 60 mph, and with mid-level lapse rates at 7-8 C/km and
elevated instability, hail up to the size of quarters are also
possible.

Later overnight, the remnants of storms over southern
KS/northern OK may also make it into southern MO. These storms
would also pose a wind and hail threat late tonight into early
Sunday morning, depending on their longevity.


Slight (2 of 5) Risk for severe thunderstorms Sunday:

Elevated showers and thunderstorms may continue Sunday morning
and into the afternoon along the lifting warm front. Behind the
warm front, instability will gradually increase and overspread
the area as temperatures warm into the upper 70s and lower 80s
and dewpoints in the middle 60s. The HREF mean depicts
1500-2500 J/kg MLCAPE, and RAP/HRRR suggests upwards of
2500-4000 J/kg MUCAPE in extreme SW MO and SE KS. Deep layer
shear is also expected to increase to 40-50 kts as stronger
southeasterly surface flow undercuts persistent westerly mid-
level flow. Therefore, the environment during the day Sunday
will be primed for severe weather if storms can continue.
Forecast soundings depict 25 to 50 J/kg of capping during the
day, though persistent 850 mb warm air advection may promote
elevated convection. However, rising heights during the day may
suppress the weak synoptic forcing of WAA. Thus, severe
thunderstorm development is uncertain during the day Sunday. If
storms are able to initiate, supercells will be possible with
hail up to golf ball size and wind gusts up to 60 mph. If these
happen to be surface-based, a tornado or two cannot be ruled
out, especially in the vicinity of the warm front where
hodographs will be a bit more curved producing 100-150 m2/s2 0-1
km SRH. Though storm development during the day is uncertain,
there will more likely be storms Sunday night.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 345 AM CDT Sat May 17 2025

Slight (2 of 5) Risk for severe thunderstorms Sunday night:

While the airmass over the Ozarks will be deeply unstable and
sheared, forcing for ascent and convective initiation along and
south of the warm front is weak and uncertain. There is a much
higher likelihood for storms to develop along the dryline across
central KS/OK during the day. These will then progress eastward
into our area during the evening and overnight hours. Storm mode
and evolution for these are still uncertain as CAMs are all over
the place. Initial mode in KS/OK will likely be intense discrete
supercells given the environment and shear vectors directly
perpendicular to the dryline. However, the evolution is
uncertain. Discrete supercells could be maintained as shear
vectors persist westerly across our area. On the flip side,
efficient cold pools and an increase low-level jet could produce
an MCS. Then there could always be a mixed mode of both. Time
will tell how this shakes out, but the storm mode/evolution will
dictate our most likely hazards. If supercells can be
maintained, all hazards including hail up to tennis balls,
a couple tornadoes, and 60 mph wind gusts will be possible. If
an MCS is the dominant mode, wind gusts up to 60 mph, a couple
tornadoes (as low-level shear vectors will be westerly promoting
a QLCS spin-up threat), and quarter-sized hail will be the main
hazards.


Enhanced (3 of 5) Risk for severe thunderstorms Monday:

The same sort of setup as Sunday will exist Monday, except
slightly more amplified and the dryline shifting a bit eastward
into east-central KS/OK. Medium-range guidance suggests MUCAPE
greater than 3000 J/kg as dewpoints increase to the upper 60s, and
deep-layer shear greater than 50 kts as the flow aloft
increases ahead of a deepening trough. Therefore, again, storm
development is a low-end scenario during the day Monday, with
higher chances Monday evening/night as they move in from the
west. Hazards will once again be determined by storm
mode/evolution, however, with the initiating dryline shifting
eastward, there is a larger/longer window for discrete all-
hazards supercells (potentially significant hail) late Monday
afternoon/early evening before any potential change in
evolution. This combined with the amplified instability/shear
parameters is leading to an Enhanced (3 of 5) Risk for the
western 2/3rds of our forecast area.


Slight (2 of 5) Risk for severe thunderstorms Tuesday:

As the potent system translates eastward, severe thunderstorms
will once again be possible Tuesday. Global models seem to be a
bit more progressive with the warm sector forecast to be along
and east of Highway 65 after 12 PM Tuesday. With a crashing cold
front progged to accompany a deepening upper-level low severe
weather is possible as it moves through our CWA Tuesday
afternoon. Hazards are currently uncertain, but given the strong
frontal forcing, damaging wind gusts look to be a main hazard.


Compounding showers and storms could lead to localized flooding:

Along with the chances for severe weather each day, the
compounding effect if multiple rounds of showers and storms
(especially from heavy rain within severe convection) could
lead to localized flooding. The EFI is highlighting 0.6-0.8
values with a shift of the day every day through Tuesday.
Despite this, the location of any flooding is highly uncertain
right now, as it will depend on where storms go. Due to
smoothing of timing and location from every model, most areas in
our CWA are forecast to see between 2 and 4 inches through
Wednesday. However, if MCSs become the dominant storm mode each
night, and end up riding the warm front at the nose of the
nocturnal low-level jet, there could definitely be banded areas
that see well over 4 inches of rain. For example, the
experimental MPAS ensemble puts a band of 7-12 inches total
precipitation Saturday through Wednesday across central
Missouri. This is not to be taken literally, but it does
highlight the scenario of multiple MCSs riding a relatively
stationary warm front each day/night. Trends will continue to be
monitored.


Cooler and drier weather Wednesday onwards:

After the potent trough kicks through the region, cooler and
drier weather are forecast Wednesday onwards. Highs Wednesday
are forecast to be in the lower 60s with lows in the middle 40s
Wednesday night. These cooler temperatures will then gradually
warm to highs in the middle 70s and lows in the upper 50s by
Memorial weekend. Some rain chances return Friday and Saturday
within a northwesterly flow regime, but details are currently
uncertain.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 640 AM CDT Sat May 17 2025

VFR conditions will prevail at all TAF sites through at least
00Z. Light northwesterly winds will shift to easterly between
19-23Z. Then, chances increase for showers and thunderstorms
after 00Z ahead of a lifting warm front. There is still
uncertainty in exact timing, but the best 6 hour window for
storms at the TAF sites look to be between 03-10Z with ensemble
guidance suggesting a better window between 06-09Z. Have put
PROB30s for this time period.


&&

.SGF WATCHES/WARNINGS/ADVISORIES...
KS...None.
MO...None.

&&

$$

SHORT TERM...Price
LONG TERM...Price
AVIATION...Price