326
FXUS63 KSGF 121728
AFDSGF

Area Forecast Discussion
National Weather Service Springfield MO
1228 PM CDT Wed Jun 12 2024

.KEY MESSAGES...

-  Warm-up starts today with temperatures reaching the 90s by
   Thursday into early next week. Heat index values generally in
   the mid 90s to around 103.

-  Low end thunderstorm chances on Thursday night(15-30%) as a
   front sags south into the area.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 133 AM CDT Wed Jun 12 2024

Current observations put the center of a weak surface high
pressure system over our region, creating weak and variable
winds and mostly clear skies. Some scattered upper-level cirrus
are present as a very weak mid- and upper-level disturbance
traverses AR, as noted by water vapor imagery. This disturbance
is embedded in weak upper-level flow as the polar jet stream
remains across the US/CA border. With the jet stream well to the
north, a summer pattern is beginning to settle in that will
bring warmer temperatures to our region.


Warm-up starts today:

As the surface high pressure shifts eastward today, SSW`ly flow
will overtake the region, advecting in warmer air. Additionally, 850
mb warm air advection across the Rocky Mountain front range and
into the central Plains will act to amplify a longwave ridge
across the Four Corners Region and into the southern Plains.
This pattern will slowly move eastward, allowing for a gradual
warming trend across our region, starting today. Clear skies and
17-20 C 850 mb temperatures overspreading the region will allow
high temperatures to warm into the middle to upper 80s today
after experiencing cooler morning temperatures around 60 F.

As night falls, the ridge axis will be over NM with NW`ly
upper-level flow over MO. Beneath this flow, an 850 mb
temperature gradient will be present with warmer temperatures
toward KS. This will support lows near 60 F in the eastern
Ozarks and near 70 F along the MO/KS border.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Issued at 133 AM CDT Wed Jun 12 2024

Temperatures will reach the 90s by Thursday:

The longwave pattern will continue to slowly shift eastwards
Thursday, creating height rises across our region as the ridge
axis shifts over the NM/TX border. A tongue of warmer 850 mb
temperatures will follow suit as 20-22 C temperatures advect
into southern MO. This, paired with clear skies, will allow high
temperatures to warm into the upper 80s and lower 90s. Areas
above 90 F will generally be off the Ozark Plateau (toward
central MO and the KS/MO border). Additionally, moist gulf air
will also continue to be advected into the region with SW`ly
flow behind the exiting surface high pressure system. Dewpoints
are expected to reach the upper 60s and lower 70s, making for a
muggy day. Nighttime temperatures will also be quite mild with
lows in the upper 60s and lower 70s.


15-30% thunderstorm chances Thursday night:

All while this ridging develops to the southwest, an upper-level
shortwave will traverse the upper Great Lakes, forcing a surface
cold front to sag southward. With such a humid airmass forecast
to be in place, thunderstorms are expected to develop Thursday
afternoon ahead of the front in southern IA/northern MO. The
front is expected to slowly sag southward through the night,
bringing thunderstorm chances with it. The front should stall
somewhere over central MO late Thursday night which introduces
the 15-30% chance of thunderstorms over our far northern
counties (north of Hwy 54). Medium range models suggest that
there could be upwards of 3000 J/kg of MUCAPE just ahead of the
front, though inhibition will be quite high. So any storms that
do happen to make it into our CWA late Thursday night will
likely be elevated, but given moderate to high CAPE and 30-40
kts of 0-6 km bulk shear, isolated marginally severe wind gusts
(up to 60 mph) and hail (up to quarter-size) would be possible.


Heat Index values between 90-103 through early next week:

With the upper-level shortwave quickly exiting off to the NE
states and the ridge continuing to build eastward, the cold
front across central MO will quickly dissipate Friday. The
longwave riding pattern will continue to slowly traverse
eastward with the axis over our region Saturday night into
Sunday, and the western edge of it exiting our region by
Wednesday. This will allow daily high temperatures in the lower
to middle 90s and lows in the lower to middle 70s. The hottest
day is looking to be Sunday when the ridge axis is over our
region (highs near 95 F and lows near 75 F).

Confidence is quite high that high temperatures will be in the
90s as NBM spreads are quite small. A lower end scenario would
have highs only down into the upper 80s and an upper-end
scenario is generally between 93-95. There are scenarios that
high temperatures exceed 95 F since the NBM is likely being
slightly bias corrected from the past week. This would be
especially true on Sunday where highs could reach the record
(see the Climate section below for more details). For example, 45%
of NBM models depict Joplin breaking its record high of 95 F
Sunday.

Of additional concern will be the humidity paired with the heat.
An open gulf will keep dewpoints hovering around 70 F everyday.
ESATs are marking the upcoming days to have >90th percentile
temperatures and specific humidity, furthering confidence in
multiple muggy days. The high temperatures and humidity will
bring Heat Index values into the middle to upper 90s, and
sometimes exceeding 100 F. Generally clear skies and somewhat
subdued winds will also bring Wet Bulb Globe Temperatures into
the middle 80s, which for our region brings the recommendation
of several breaks per hour when working outdoors, as heat
stress will be elevated. Additionally, since this will be the
first prolonged abnormal warm period, the heat and humidity may
be more impactful to some people. HeatRisk is suggesting areas
will be in a Major risk for heat-related impacts Saturday
through Tuesday. When required to be outside, taking extra
breaks, having effective cooling, and being adequately hydrated
is highly recommended.


Rain chances Saturday into Sunday?:

As the western edge of the ridge creeps into our region over the
weekend, there is a signal for a shortwave to lift just west of
the region. This could bring the possibility for rain chances,
though confidence is too low at the moment to introduce chances
greater than 15%. As details become clearer in the coming days,
these chances could increase.


Moderate Excessive Heat Risk (6/19 - 6/23):

In the extended range, the WPC is giving a moderate risk for
excessive heat between Wednesday, 6/19 and Sunday, 6/23 (40%
chance). This is a result of global ensembles giving a signal
for an amplified ridge and subsequent high pressure to build
over the eastern CONUS. Trends will be monitored as this enters
our forecast range, but this is meant to be a heads up call to
prepare for more heat later this month.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1214 PM CDT Wed Jun 12 2024

VFR conditions will prevail throughout the TAF period at all TAF
sites. SSW winds of 5-7 knots at KSGF and KJLN will increase to
10 knots by tomorrow morning, while winds at KBBG will remain
under 5 knots. A few cumulus clouds at the southern part of the
CWA will clear within the next few hours,leading to clear
skies.

&&

.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...Kenny
CLIMATE...Price