602
FXUS63 KSGF 220846
AFDSGF

Area Forecast Discussion
National Weather Service Springfield MO
346 AM CDT Sun Sep 22 2024

.KEY MESSAGES...

- Marginal (1 of 5) Risk for severe thunderstorms today and
  Monday afternoon and evening. Main hazards will be damaging
  wind gusts up to 60 mph, small hail, and brief heavy
  downpours.

- Multiple rounds of widespread showers and thunderstorms are
  expected today through Monday night (40-85% chance). Most
  locations will see an additional 0.50 to 2 inches of rainfall
  through Monday, with a flooding threat across the eastern
  Ozarks from localized higher amounts of 3 to 6 inches.

- A cold front will bring cooler temperatures next week with
  highs in the 70s with limited rain chances.

- Early Heads-Up: There is a 20-30% chance for a scenario late
  next week where a system sits over the south-central Plains
  bringing prolonged and widespread rain to the region. Trends
  will continue to be monitored.

&&

.SHORT TERM /THROUGH MONDAY NIGHT/...
Issued at 345 AM CDT Sun Sep 22 2024

Current water vapor imagery depicts a robust mid- and upper-
level low over the Four Corners region. Paired with radar
imagery and mesoanalysis, mid-level positive vorticity advection
and coupled upper-level jet streaks are forcing widespread rain
showers and thunderstorms across east KS and north MO. This
area of rain is out ahead of a surface cold front that stretches
from east IA, down through east KS and central OK, with a weak
surface low in NE KS. These features will be the focus for
multiple rounds of widespread showers and thunderstorms through
Monday night (some possibly severe and conducive for localized
flooding).


Marginal (1 of 5) Risk for severe thunderstorms today:

The cold front will push southeast through the region over the
course of today. This will bring a gradient of high
temperatures with values in the mid to upper 70s north of I-44,
and in the lower to mid-80s south of I-44. As the cold front
pushes SE, the widespread showers and thunderstorms just north
of our CWA will follow suit, pushing into our northern counties
early this morning (60-80 % chance along and north of the Hwy 54
corridor). As the morning goes on, the mid- and upper-level
wave will actually deamplify some, and coverage should decrease
into the afternoon (becoming 30-50% chances).

Meanwhile, along and south of I-44 will be mostly dry, with any
showers/storms being isolated. Despite mostly widespread cloud
cover, a few breaks in clouds leading to temperatures in the
80s, along with deeper low-level moisture, will lead to
500-1500 J/kg of MLCAPE. A 25-35 kt mid-level jet downstream of
the shortwave trough will produce 25-35 kt of unidirectional 0-6
km bulk shear overtop of the unstable sector. With a surface
cold front pushing through and sufficient support aloft,
scattered showers and thunderstorms should develop along and
ahead of the boundary after 2 PM (30-50%). Given the marginal
thermodynamics and kinematics described above, some of these
storms could produce wind gusts up to 60 mph and small hail.
HREF mean forecast soundings show relatively deep moisture in
the low levels with moderate dry air aloft. Much like what was
observed yesterday, this could lead to some very localized wet
microbursts with brief wind gusts up to 70 mph.

There is still question as to the best corridor for these storms
to develop. It will be somewhere along and south of I-44, but
recent model trends have the cold front pushing further south,
keeping the storms confined closer to the MO/AR border. Trends
will continue to be monitored. Nevertheless, these storms should
clear/dissipate by 9-11 PM.


Marginal (1 of 5) Risk for severe thunderstorms Monday:

After a brief lull, additional widespread shower and
thunderstorm development looks likely late Sunday night into
Monday morning (60-85% chance). This comes as a result to the
shortwave slightly amplifying thanks to a small energy boost
from a digging shortwave in the northern CONUS. This round of
convection is not expected to be severe and even creates
uncertainty in the degree of destabilization for severe
thunderstorm development Monday afternoon. Despite this
uncertainty, models suggest that a surface low progressing
eastward through extreme south MO will lead to some renewed
moisture and warm-air advection, bringing 500-1000 J/kg MLCAPE
in our counties along the MO/AR border. With the shortwave
slightly amplifying and the axis slowly progressing into our
region, 0-6 km bulk shear will also increase to 35-40 kts. In
this environment, any storms that move through the MO/AR border
corridor will be capable of producing wind gusts up to 60 mph
(localized 70 mph in wet microburst storms) and hail up to the
size of quarters. With CAPE profiles being rather meager and
skinny, the greater threat is wind gusts, with the potential for
some line segments thanks to bulk shear pushing 40 kts.

During this time, the cold front will be somewhere along the
MO/AR border, leading to highs Monday in the upper 60s to lower
70s.


Localized flooding threat across the eastern Ozarks:

In addition to the severe threat, any storm will have the
potential for heavy downpours and localized flooding as deep
moisture in the low-levels will lead to PWATs in the 1.75-2.00"
range. This alone can create a localized flooding threat under
the individual stronger storms, however, with the shortwave axis
sitting in one spot for much of the time through Monday night,
the belt of stronger flow/ascent aloft looks to force multiple
rounds of widespread showers and thunderstorms over the eastern
Ozarks. The HREF mean has widespread areas of 1.25-2 inches east
of Hwy 65, with 48-hour LPMMs pinpointing localized areas of
3-6 inches within Howell, Oregon, Shannon, and Texas counties.
With no drought conditions across the eastern Ozarks, and
multiple rounds of storms moving through, a localized flooding
threat may materialize across this area through Monday night.
Adding confidence to this threat, the Extreme Forecast Index is
at a 0.8 for QPF across the eastern Ozarks with 2 shifts of the
statistical tail, highlighting a potentially abnormal rainfall
event over the area for late September.


&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
Issued at 345 AM CDT Sun Sep 22 2024

Cooler temperatures next week with highs in the 60s/70s:

Precipitation should finally clear out by sunrise Tuesday
morning with only 10-20% chances of lingering light rain showers
in the eastern Ozarks. The cold front and mid- and upper-level
trough will also finally fully settle into the region, bringing
cooler temperatures and dry conditions. Highs Tuesday through
Sunday will be consistently in the lower to middle 70s with
lows in the middle 50s.


Potential next system arrives late week (20-30% chance):

Ensemble cluster analysis reveals a large divergence in model
agreement late next week. The Euro and Canadian ensembles favor
a shortwave breaking off as a cut-off low and sitting right over
the south-central CONUS Wednesday through the weekend.
Interestingly, both those deterministic models also show a
tropical system wrapping into the upper-level low for some good
ol` fashion Fujiwhara action. This scenario would bring
widespread and prolonged rainfall somewhere in the south-central
CONUS (including potentially our CWA) Thursday through Sunday.
Currently, there is a 20-30% chance for this scenario as other
models like the GFS/GEFS depict no upper-level low at all and
keep us warmer and drier. Once again, model trends will need to
continue to be monitored, but this scenario warrants a heads-
up since if it does pan out, it could potentially be a higher
impact event.


&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1245 AM CDT Sun Sep 22 2024

A lot going on weather-wise for this TAF period. A frontal
boundary will be hanging around the area, bringing N`ly winds at
times (most likely after 00Z, but there could be shifts at SGF
and JLN between 07-12Z), and SW`ly 8-12 kt winds for the other
times. Additionally, multiple chances for scattered showers and
thunderstorms will occur. For now, it looks mostly dry through
18Z, save for a 20-30% chance for a band of elevated showers and
thunderstorms to move through SGF between 10-13Z. The best
chance for showers and thunderstorms at all TAF sites is between
19-02Z (50-70%). Any storm that forms will be capable of
producing gusts up to 60 mph and small hail.

Otherwise, ceilings will gradually lower through the period.
After the fropa after 00Z, ceilings will reach MVFR with a
30-50% chance for IFR conditions.

&&

.CLIMATE...
Issued at 345 AM CDT Sun Sep 22 2024

Record Highest Minimum Temperatures (Springfield):


September 22:
70 (2017) Forecast: 70


&&

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

&&

$$

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