185
FXUS63 KSGF 131041
AFDSGF

Area Forecast Discussion
National Weather Service Springfield MO
541 AM CDT Thu Jun 13 2024

.KEY MESSAGES...

-  Heat and humidity will start ramping up today and continue
   into next week.

-  Low-end thunderstorm chances tonight and Friday (15-30%) as
   a front sags south into the area.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 133 AM CDT Thu Jun 13 2024

Large-scale mid- and upper-level ridging is beginning to inch
into our region as evidenced by clockwise flow over OK/KS in
current water vapor imagery. Mesoanalysis depicts the longwave
ridge axis centered over NM where 850 mb temps are reaching into
the 30-32 C range. At the surface and in the low levels, a high
pressure system centered over the Mississippi River valley in
AR/MO is slowly exiting to the east. In its wake, SW`ly low-
level flow is ramping up, advecting into the region warm 850 mb
temperatures from the west, and surface moisture from the Gulf.
This sets the stage for the beginning of a hot and humid pattern
for this time of year.


Heat and humidity will start ramping up today:

As mentioned above, height rises will continue to build into the
region today, supporting the beginning of an influx of heat and
humidity. A WSW`ly oriented low-level jet will bring in a nose
of 20-24 C 850 mb temperatures. For reference, according to the
SPC Sounding Climatology, the record high 850 mb temperature for
today is 22.9 C. This will allow high temperatures to warm into
the upper 80s and lower 90s. Additionally, SW`ly surface flow
will advect in dewpoints around 70 F. This will begin our muggy
pattern with Heat Indexes in the middle and upper 90s. Low
temperatures tonight will also be mild in the upper 60s and
lower 70s.


Low-end thunderstorm chances tonight (15-30%):

Meanwhile, a mid- and upper-level shortwave will traverse the
upper Great Lakes with an associated E-W oriented surface cold
front sagging southward through the northern Plains and Midwest
states. With SW`ly flow ahead of this front advecting in warm,
moist air, thunderstorms will develop ahead of the front in
southern IA/northern MO. These storms are expected to evolve
into an MCS thanks to generally stronger linear forcing along
the cold front. The MCS will drop south into north-central MO
during the late evening hours tonight. There is still the
question of how far south the storms will survive and how much
of our CWA will be impacted.

In an ingredient-based approach, substantial capping will build
over our region as night falls, thanks to very warm 850 mb
temperatures. However, the 00Z HREF suite suggests at least 1000
J/kg of MUCAPE north of I-44 within 25-35 kts of 0-6 km bulk
shear. HREF ensemble soundings depict this MUCAPE to be uncapped
above 700 mb. Therefore, if the MCS can continue to be forced,
elevated convection along the line could survive generally just
north of I-44. The stout capping inversion could prove difficult
to overcome, however.

From a dynamics approach, the cold front is expected to continue
to sag southward, providing persistent surface forcing on top of
forcing already generated by the MCS`s cold pool. Though the
cold front is not expected to be strong, convergence will be
characterized by 180-degree vectors (S`ly winds against N`ly
winds) which will aid surface forcing. However, the further the
thunderstorm complex sags south, the more it gets positioned
underneath synoptic-scale subsidence beneath the right exit
region of a jet streak. This would act to weaken the MCS
through the night.

All that being said, there is currently a 15-30% chance that
the MCS will make it to just north of I-44 before 1 AM. If
anything, it may be residual stratiform rain at this time. These
chacnes may increase as models come into better agreement. Some
HREF CAMs dissipate the MCS along Highway 54, while others
dissipate it over Springfield. Given the difficulty for most
CAMs to correctly model cold pool driven MCSs, leftover
scattered showers and thunderstorms reaching just north of I-44
seems the most reasonable outcome. Indeed, the MPAS models
(which have refined microphysics schemes to generally better
resolve cold pools) does show storms making it into the
Springfield area between 10 PM and 1 AM. Given the
aforementioned instabulity and modest shear, isolated marginally
severe wind gusts (up to 60 mph) and hail (up to quarters)
would be possible, especially along the Hwy 54 corridor where
shear is expected to be more favorable

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Issued at 133 AM CDT Thu Jun 13 2024

Low-end thunderstorm chances Friday (15-30%):

The cold front will continue its lollygag southward Friday,
positioning itself somewhere along the MO/AR border. The air
mass ahead of it will continue to be warm and moist (highs will
be around 90 F), contributing to 2000-2500 J/kg of SBCAPE and
1250-1750 J/kg of MLCAPE. With the boundary forcing into this
unstable air mass, thunderstorms are certainly possible,
generally south of I-44 (15-30% chacnce). The uncertainty is in
the amount of inhibition due to expected very warm 850/700 mb
temperatures. HREF plumes are quite split on the amount of CIN,
but the mean is progged at about -25 J/kg. While this is
sufficient to inhibit convection, forcing along the surface
boundary could be enough to promote a few isolated updrafts to
break the cap. As such, there is a 15-30% chance of showers and
thunderstorms south of I-44. Shear will be weak (<20 kts), so
severe weather is not anticipated with any storms that do form.


Heat and humidity continue into next week:

The longwave ridge will continue to trudge eastward through the
weekend with the axis being centered over MO Saturday night.
Also during this period, high pressure will solidly be in place
across the region. This will keep the hot and humid air mass
locked into next week. Daily highs will be in the lower to
middle 90s with nightly lows in the lower to middle 70s
(approaching record high minimums every night from Friday
through Tuesday). Dewpoints will hover around 70 F, producing
Heat Indices in the middle to upper 90s and Wet Bulb Globe
Temperatures in the lower to middle 80s, introducing some heat
stress for outdoor workers and vulnerable populations. The
hottest day looks to be Sunday with highs in the middle 90s.
With this being the first prolonged period of abnormal heat,
people should be cautious when being outdoors for extended
periods of time. Taking multiple breaks, having functional
cooling, and keeping adequately hydrated is highly recommended.

There is some uncertainty Monday onwards in how hot each day
will get. Cluster analysis shows that the EPS favors a much more
amplified ridge pattern while the GEFS favors a flatter ridge.
If the EPS scenario pans out, high temperatures could be higher
than currently forecast. If the GEFS scenario pans out,
temperatures could be slightly cooler. Trends will need to be
monitored, but for now, the forecast advertizes highs to
continue to be in the lower 90s with lows in the lower 70s.


Additional rain chances?:

As the ridge exits to the east Saturday morning, a shortwave
trough is forecast to approach the region from the west. This
wave may provide enough forcing for additional rain chances
Saturday morning through Sunday, though confidence is currently
low on the development, coverage, and evolution of any
precipitation associated with the wave due to warm 850/700 mb
temperatures.

Daily 15-20% chances of rain then exist next week as the
synoptic pattern brings a belt of SW`ly mid-level flow over our
region with an open Gulf to continue to provide moisture.


Moderate Excessive Heat Risk (6/19-6/24):

Both NAEFS and ECMWF ESATs are already beging to max out on mid-
and upper-level geopotential heights for next Wednesday (6/19)
through Monday (6/24). This means the forecasted geopotential
heights are higher than the 30-year climatology for this time
of year. This is due to the longwave synoptic pattern depicting
an amplified upper-level ridge to develop. This would force
hotter high temperatures than what we are experiencing this
week. The WPC has highlighted our region in a moderate (40%)
risk for excessive heat during this time period. This is a
heads-up call that temperatures could exceed 95 F during this
time period.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 518 AM CDT Thu Jun 13 2024

High confidence that VFR conditions will prevail through most of
the TAF period at all sites. SW`ly winds under clear skies will
pick up to 8-13 kts through the day today before decreasing
after 02Z. There is a 15-30% chance that remnant showers, and
perhaps a thunderstorm or two, will reach into the SGF and JLN
areas between 04-08Z. Confidence is low on this scenario, but is
mentioned given that some models support it. Trends will
continue to be monitored for a possible upgrade to a TEMPO
group.

&&

.CLIMATE...
Issued at 501 AM CDT Mon Jun 10 2024


Record High Temperatures:

June 16:
KSGF: 97/1952
KJLN: 95/2016


Record High Minimum Temperatures:

June 15:
KSGF: 74/2022

June 16:
KSGF: 75/2022

June 17:
KSGF: 76/2016

&&

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

&&

$$

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