100
FXUS63 KSGF 200600
AFDSGF

Area Forecast Discussion
National Weather Service Springfield MO
100 AM CDT Mon May 20 2024

.KEY MESSAGES...

- High confidence in above average temperatures today into
  early this week (mid to upper 80s).

- Chance for two rounds of showers and thunderstorms through
  Monday. First is late tonight into early Monday morning along
  and west of Highway 65 (20-50% chances). Second is Monday
  afternoon/evening along and north of Highway 32/I-44 (15-30%
  chances). Large hail and damaging winds possible with these
  storms (5% chance).

- Slight (2 of 5) risk to Enhanced (3 of 5) risk for severe
  weather Tuesday evening through Tuesday night. Damaging wind
  gusts are the primary concern (15-30% chances) with large hail
  (15% chance) and a few spin-up tornadoes (2-5% chances) being
  a lower-end threat.

- Potential for another round of severe weather Wednesday toward
  south-central Missouri (15% risk/confidence).

- Unsettled weather may persist through the end of this week and
  into Memorial Day Weekend (daily 30-50% chances for showers
  and thunderstorms).

&&

.SHORT TERM /THROUGH TUESDAY/...
Issued at 1231 PM CDT Sun May 19 2024

Large-scale mid- and upper-level ridging is currently very
slowly exiting our area as broad W`ly flow moves in from the
west. A longwave trough associated with the polar jet is
situated over the Pacific NW, as seen on current water vapor
imagery. A shortwave associated with a subtropical jet max is
currently exiting NM/CO. This shortwave will be responsible for
the short-term weather threat as it moves overtop a dryline in W
TX and an E-W oriented stationary boundary across central
KS/MO. An upper- level low associated with the subtropical jet
over the east- central Pacific ocean will be responsible for the
longer term weather threat.


Above average temperatures today into early this week:

The aforementioned ridging along with clear skies and light
8-12 mph S`ly winds will allow high temperatures to reach into
the upper 80s today. Current observations are already in the
mid-80s, suggesting that some places may break 90 F.

Even though a shortwave will move through the region tonight,
the largewave pattern will remain with the WSW`ly flow of the
polar jet remaining over the northern states, allowing ridging
to persist. This, along with 850mb in the 16-18C range will
continue to keep temperatures in the mid and upper 80s Monday.
Lows will also be quite mild as thunderstorms out over the
central Plains will generate cloud cover over our region at
night. This will keep lows in the upper 60s tonight and Monday
night, with areas near the MO/KS border in the lower 70s which
is near the record low maximum.


20-50% chances of thunderstorms late tonight into Monday morning:

A robust thunderstorm complex is forecast to traverse KS today
through tonight. This complex will begin to dissipate in east KS
as it escapes upper-level support and enters more stable air
from the nocturnal boundary layer. The 12Z HREF run depicts the
complex falling apart right along the MO/KS border after 10 PM.
However, most CAMs are known to poorly handle convective cold
pools. With a substantial cold pool expected to develop with
this system in KS, the complex has a 20-50% chance to reach
further east than model guidance. Indeed, mean MUCAPE across
our region will be >1000 J/kg with 0-6 km bulk shear at 15-25
kts which would support this scenario. The MPAS models--which
use a refined microphysics scheme--seem to handle the MCS
progression better than others and brings the MCS to Hwy 65. As
such, there is a 20-50% chance of leftover stratiform rain and
embedded thunderstorms along and west of Hwy 65 with the highest
chances along the MO/KS border. These storms would be at the
I-49 corridor between 10PM-2AM timeframe and the Hwy 65
corridor by the 2-7 AM timeframe. Additionally, small hail and
isolated 60 mph wind gusts are possible along the MO/KS border
before the leading line of the MCS completely breaks apart.
Nevertheless, even if thunderstorms do not make it across the
border, at least light isolated to scattered showers should
persist until 7-9 AM at the latest.


15-30% chances of thunderstorms Monday afternoon/evening:

Given the robust convection expected across the Plains, an MCV
is likely to develop along with the thunderstorm complex and
migrate somewhere through central/northern MO. Additionally,
surface outflow from the overnight storms could also be in the
vicinity. Wherever these features set up could be the focus for
new thunderstorm development Monday afternoon into the evening.
This threat is quite conditional, however, as lift from surface
outflow and mid-level support from vorticity advection
associated with the MCV will need to overcome upper-level
subsidence due to rising heights ahead of another shortwave.
Capping may also develop across the area (20-30% chance of -50
J/kg according to the HREF), especially if a sufficient cold
pool persists across the area. These conditionalities lead to a
15-30% chance of scattered thunderstorm redevelopment along and
north of the Hwy 32 to I-44 corridor during the afternoon hours.
If storms do form, the environment will be characterized by
1000-2000 J/kg MLCAPE and 20-30 kts of 0-6 km bulk shear which
could support a few marginally severe multicells. Inverted-V
low-level soundings suggest a few 60 mph damaging wind gusts as
the main threat, but 7.5-8.5 C/km mid-level lapse rates would
also support small to marginally severe (quarter- size) hail.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Issued at 1231 PM CDT Sun May 19 2024

Potential for severe storms Tuesday evening into Tuesday night:

Our greatest potential for severe weather comes Tuesday evening
through Tuesday night as the SPC has an Enhanced (3 of 5) risk
NW of a line from Pittsburg, KS to Osage Beach and a Slight (2
of 5) risk elsewhere. The aforementioned upper-level low over
the east-central Pacific will lift NE through the four corners
region. Additionally, a shortwave associated with the polar jet
will drop SE from the Pacfic NW. The two waves will somewhat
phase together, creating a unified SW`ly jet across the Plains.
This will force a greater surface mass response across the
Plains. The stronger S`ly low-level flow will advect lower 70s
dewpoints across the western area of our CWA and 19-22C 850mb
temps across the area. This will bring a hot and muggy airmass
across our area with highs in the upper 80s, potentially above
90. A surface cold front associated with the surface
cyclogenesis will drop SE from the NE/IA region into east KS and
central MO. This will force thunderstorms Tuesday evening, with
some potentially severe, within this region. These will drop SE
ahead of the front through the overnight hours.

Without a doubt, the environment will be ripe for severe
weather, especially in the Enhanced risk where mean NBM CAPE
values exceed 2000 J/kg, 0-6 km bulk shear values generally
lying within the 40-50 kt range with forecast hodographs
supporting supercells, and lapse rates in the 7.5-8.5 C/km
range. There are questions, however, in the level of forcing,
degree of capping, and evolution of convection. The greatest
upper-level forcing will be displaced to N MO/IA where the most
vigorous shortwave PVA is located. The surface cold front could
be enough lift to overcome the lack of upper-level forcing,
however, the 700 mb wave is looking to be somewhat positively-tilted
which is placing warmer temperatures the further south you go
from the mid-level shortwave. This could create a robust capping
inversion, especially across our slight risk areas, which could
shunt any convection along the cold front.

Nevertheless, if storms are to initiate along the front in east
KS/west-central MO, supercells are likely to be the initial
storm mode. This would be in the Tuesday late afternoon hours. With
a SE cold front moving at approximately 3-5 m/s and the
forecast bunkers right motion expected to be only 5 m/s faster
than the front, these storms will likely stay on the boundary.
This paired with shear vectors largely parallel to the front
will promote quick upscale growth. A line of storms is then the
most likely mode as the storms progress further into our CWA.
This means that initially, all hazard will be possible
(generally just outside our CWA, but potentially reaching into
our extreme NW counties. Then, damaging winds will be the main
threat as the line organizes and moves through our CWA. However,
there is still the potential large hail given the thermodynamic
profiles, and a spinup tornado or two given the kinematic
profiles. They are just lesser threats. A better idea of exact
hazards and intensities will be evaluated in future forecasts.

The line is expected to move through our CWA during the evening
and into the overnight hours. The cold front will slowly sag
SE, so by the morning hours, storms may not completely be out of
our CWA. The exact evolution is still in question, but latest
trends have been slower and slower making the severe threat an
overnight threat for areas east of I-49.


Potential for another round of severe storms Wednesday:

With the sagging nature of the surface cold front and the later
trend of its progression, it is forecast to be somewhere across
the I-44 corridor by midday Wednesday. This will promote highs
in the mid 70s NW of I-44, and in the lower 80s SE of I-44.
Storms may be ongoing at midday, which brings up uncertainties
in the evolution and potential redevelopment of storms ahead of
the front. Nevertheless, a very unstable airmass is expected to
be in place SE of the front (SE of I-44). The NBM mean is around
3000 J/kg with the 90th percentile pushing 5000 J/kg.
Additionally, 45-55 kts of 0-6 km bulk shear will be present
thanks to the SW`ly mid- level speed max overhead. This will be
more than enough to support organized severe thunderstorms SE of
I-44, if they can redevelop amid ongoing convection and upper-
level support being displaced well off to the north. With mean
flow being SW`ly, parallel to the surface cold front, convection
will likely be linear along the front with the potential for
training storms. This would also promote a flooding threat. The
WPC does have a Slight (2 of 4 level) risk for excessive
rainfall across south- central MO. While more details are needed
to advertise specific locations/timing/hazards, given cold
frontal forcing and parallel flow, the main hazards will likely
be damagaing winds and large hail. This will continue to be
evaluated in future forecast updates.


Unsettled weather may persist through the end of this week:

Daily max precipitation chances of 30-50% persist through the
weekend as ensembles agree on the longwave pattern producing a
trough over the west coast with a suptropical jet pumping into
the Southern Plains. This will allow multiple rounds of
showers/thunderstorms through the weekend. CSU machine learning
guidance also does place portions of our area in a 15% risk for
severe weather each day through Sunday. This guidance, however,
is based on the GEFS ensemble, which at this range is unable to
resolve shortwave features. So while the synoptic pattern exists
for showers/thunderstorms and the potential for severe weather
each day, exact timing and locations of each round will depend
on where and when ejecting shortwaves move through the area. At
this point, ensemble agreement is too low to try and pinpoint
any specific areas at any specific time.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1248 AM CDT Mon May 20 2024

Cloud cover associated with a storm system moving across the
norther portions of Missouri will bring VFR ceilings through the
day. A few showers and storms may also impact portions of the
region mainly along and north of I-44 including the KJLN and
KSGF airports into early this morning. After sunrise, convection
looks to diminish with lingering cloud cover through tonight.

&&

.CLIMATE...
Issued at 100 PM CDT Wed May 15 2024

Record High Temperatures:

May 20:
KSGF: 90/1964
KJLN: 92/1956
KUNO: 89/1964

May 21:
KSGF: 91/1987
KJLN: 91/1987


Record High Minimum Temperatures:

May 20:
KSGF: 71/1902

May 21:
KSGF: 70/1902

&&

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

&&

$$

MESOSCALE...Burchfield
SHORT TERM...Price
LONG TERM...Price
AVIATION...Hatch
CLIMATE...Burchfield