-- Discussion containing changed information from previous version are highlighted. --
749
FXUS63 KSGF 141733
AFDSGF

Area Forecast Discussion
National Weather Service Springfield MO
1233 PM CDT Fri Jun 14 2024

.KEY MESSAGES...

-  Remnant showers and thunderstorms will gradually dissipate
   through this morning. Sub-severe hazards and minor flooding
   are possible.

-  Low-end thunderstorm chances today and Saturday (15-30%).

-  Heat and humidity will continue through much of next week.

-  Daily chances for isolated showers and thunderstorms Monday
   and onward (15-30%) thanks to the hot and humid air mass.

&&

.SHORT TERM /THROUGH TONIGHT/...
-- Changed Discussion --
Issued at 400 AM CDT Fri Jun 14 2024

Remnant showers and thunderstorms dissipating this morning:

A decaying MCS is currently spread over our CWA with an E-W
oriented line of marginally severe thunderstorms just passing
exiting MO into AR. A stratiform rain shield is then set up
over south-central MO. These storms are stewing within an area
of 1000-1500 J/kg of MUCAPE and generally weak shear. While
these storms have already overperformed in strength, duration,
and southward extent, they are slowly dissipating as they stray
further from upper-level support and the MUCAPE axis. However,
given recent reports of winds nearing 60 mph and some areas
receiving small hail, sub-severe hazards can be expected in any
of the stronger storms along they MO/AR border before they move
out of our CWA.


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

Today`s forecast got a bit more complicated with the widespread
MCS currently moving through the area. An E-W oriented cold
front currently progged over north KS/MO is forecast to drop
south and setup somewhere along the MO/AR border by this
afternoon. A low-end chance (15-30%) of isolated showers and
thunderstorms were forecast to develop along this front. The
current MCS adds a complication to this forecast, mainly how
long it survives, and subsequently, how much it modifies the
environment down to the MO/AR border. On one hand, if the MCS
lasts long enough and produces enough rainfall, the cold pool
may be strong enough to keep instability lower and further
south, inhibiting any thunderstorm development in our area. On
the other hand, with such a humid airmass in place, any airmass
modification could quickly recover by peak heating this
afternoon. Forecast intuition currently sides with option 2,
where the atmosphere recovers by the afternoon.

Despite the complications, the forecast basically remains
unchanged since there was already existing uncertainty in if
storms would initiate along the front, since they would have to
battle against subsidence from rising heights aloft. If the
atmosphere is able to fully recover, 00Z HREF ensemble soundings
suggest 2000-3000 J/kg of uncapped SBCAPE along the surface
front, south of I-44. This would support thunderstorm
development, but with the forecast subsidence, coverage is
likely to be isolated (and perhaps even 0% coverage).
Therefore, a 15-30% chance for showers and thunderstorms exists
south of I-44. These will not be severe as deep layer shear will
be minimal (<20 kts). These storms will dissipate after sunset.


Heat and humidity continue today:

Due to the cold front and MCS, some areas will be very slightly
cooler today. Highs north of I-44 will be in the middle to
upper 80s while areas south of I-44 will see highs near 90 F.
These highs could also be slightly lower if clouds from the MCS
hang around longer than forecast. Humidity will still be
present, though, with dewpoints forecast to reach near 75 F.
Latest ESATs suggest this low-level moisture is near maximum for
the this time of year in the 30-year climatology. This will
bring Heat Indices near 100 F along and just north of the MO/AR
border. Lows tonight will range from the mid-60s toward central
MO to near 70 F in the SW corner of MO.
-- End Changed Discussion --

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
-- Changed Discussion --
Issued at 400 AM CDT Fri Jun 14 2024

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

The upper-level ridge that is bringing the heat and humidity
will gradually shift east during the day Saturday as a shortwave
trough approaches the region from the west. Storms are expected
to form ahead of this shortwave along the Rocky Mountain front
range this evening and march across the Plains into Saturday
morning. CAMs suggest this will be another MCS. While many
dissipate it before the MO/KS border, the MPAS models take the
MCS at least into west MO. Given the hot and humid airmass in
place and what took place with this current MCS, would opt to
forecast that the MCS will make it into our CWA, bringing shower
and thunderstorm chances Saturday morning. At the moment, will
keep them 15-30% chances, but may be upped with future
forecasts.

Later in the day Saturday, the E-W oriented cold front that
will be positioned somewhere along the MO/AR border will begin
to slowly reorient to NNW-SSE and lift north as a warm front due
to mass response ahead of the shortwave. Along this warm front,
an axis of weakly capped 2000-3000 SBCAPE/MLCAPE will develop
over SW MO. With support from the approaching shortwave and weak
convergence along the warm front, isolated to scattered
thunderstorm development looks possible (15-30% chances). There
is higher confidence that this will occur than thunderstorm
chances Friday afternoon (today). Deep layer shear also looks to
be modestly stronger as the shortwave approaches. HREF mean
gives 25-30 kts of 0-6 km shear. Therefore, any storms would
have the potential to produce sub-severe wind gusts up to 40 mph
and small hail up to penny size. These storms would then
dissipate after sunset.


Heat and humidity will continue through much of next week:

Highs Saturday will continue to hover in the upper 80s and lower
90s with lows in the mid-60s to mid-70s (warmer temperatures
north of I-44). After the shortwave clears the area, the
longwave pattern will still have the western edge of an upper-
level high sitting over our area. This will promote SW`ly mean
flow, keeping persistent warm and moist air advection, locking
the hot and humid air mass in place across our region. 850 mb
temperatures will generally hover in the 18-22 C range
throughout next week, supporting daily highs in the upper 80s
and lower 90s and nightly lows in the upper 60s to middle 70s.
The hottest days look to be Sunday and Monday where highs will
reach the mid-90s and lows will reach the mid-70s (approaching
record high and high minimum temperatures). With dewpoints
constantly hovering in the upper 60s and lower 70s, max heat
indices will be in the middle to upper 90s, sometimes reaching
above 100. NBM mean Wet Bulb Globe Temperatures will also be in
the lower to middle 80s. With the prolonged nature of this
abnormal heat, HeatRisk is depicting a Major Risk (level 3 of
4) for heat-related impacts, especially on Sunday and Monday. As
we have been messaging for the past few days now, it will be
important to take frequent breaks, have methods of cooling
handy, and keep adequately hydrated when being outside for
extended periods of time.

Towards the end of next week, ESATs are maxxing out for 500 mb
geopotential heights just east of our CWA. This means that the
ensemble forecasts are all depicting the highest 500 mb
geopotential heights in the 30-year climatology. Our CWA will
not be under this maximum, but will be at the 99.5th percentile.
This will still support more prolonged heat. NBM spreads
continue to give a median high temperature of near 90 F through
next week, with the 75th percentile approaching 95 F after
Thursday. The WPC continues to have us in a Moderate Risk (40%
chance) for excessive heat during this timeframe. Needless to
say, there is no near-term end to the heat in sight.


Daily chances for showers and thunderstorms after Sunday:

The synoptic pattern for Monday onwards will feature the upper-
level high to our east and a trough to the west, putting us on
the edge of SW`ly mean flow. This pattern would allow for daily
chances for isolated to scattered showers and thunderstorms
either from subtle shortwaves interacting with the hot and humid
airmass in place, or leftover remnants of thunderstorm complexes
from the Plains moving into our area. Details are too far out
to determine what will be what, but if today was an indicator,
15-30% chances for showers and thunderstorms will exist as long
as this hot and humid air mass is in place and subtle upper-
level support remains overhead.
-- End Changed Discussion --

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
-- Changed Discussion --
Issued at 1220 PM CDT Fri Jun 14 2024

VFR conditions are expected throughout the TAF period. Winds of
5-10 knots will shift from northerly to south-southeasterly
through the TAF period in conjunction with a frontal passage.
There is a 15-30% chance of isolated thunderstorms for each TAF
site from 19z-01z, though confidence is too low to include in
the TAFs at this time. Any storms which do develop will lower
ceiling heights and visibilities, but will be isolated, small,
and short-lived.
-- End Changed Discussion --

&&

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

&&

$$

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