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Claudette Impacts the Southeast U.S.; Severe Thunderstorms Sunday; A Heat Wave Persists in West

Heavy rainfall from Claudette may bring additional flash, urban and small stream flooding from Georgia into the Carolinas on Sunday. Scattered severe thunderstorms may occur Sunday across parts of the Midwest into the Great Lakes and Ohio Valley. The dangerous and record-breaking heat and critical fire weather conditions will continue across much of the western U.S. on Sunday. Read More >

FXUS63 KSGF 201125

Area Forecast Discussion
National Weather Service Springfield MO
625 AM CDT Sun Jun 20 2021

...12Z Aviation Discussion Update...

.SHORT TERM...(Today through Monday)
Issued at 301 AM CDT Sun Jun 20 2021

A backbuilding storm cluster was present along a westward moving
outflow boundary across central and north-central Missouri early
this morning. This thunderstorm activity should remain just to the
north of our CWA through the remainder of the early morning.

Another hot and humid day is in store today as increasingly
gusty southwesterly winds of up to 30 mph advect additional
moisture into the region ahead of an approaching cold front and
upper level shortwave. Local 850 mb climatology suggests high
temperatures will once again range from around 90 degrees into the
mid 90s, which, combined with the humid conditions, will lead to
heat index values in the mid 90s to low 100s.

Discrete thunderstorms will begin to develop along the cold
front, extending from central Kansas into northern Missouri during
the late afternoon and early evening along an axis of significant
instability. High resolution models hint at these storms
transitioning into clusters as they push southeastwards
throughout the evening hours into portions of western and central
Missouri. Some of these storms could become strong to severe, with
damaging wind gusts and large hail up to the size of quarters as
the main risks. However, this severe storm threat looks relatively
brief as the atmosphere becomes increasingly capped into the late
evening and overnight hours, which should lead to a gradual
weakening trend as the storms push southeastwards into the Highway
54 corridor. This agrees well with the SPC Day 1 Marginal
convective outlook area.

The upper level shortwave trough and cold front will continue to
push southeastwards through the area overnight into Monday,
leading to scattered to widespread showers and thunderstorms
across the area. Some pockets of heavier rainfall will be
possible, but no widespread heavy rain or flooding is expected.
Some modest instability ahead of the front across far south-
central Missouri late Monday morning into the early afternoon may
lead to a few stronger storms, though this will depend on how
quickly the front moves through the area. The majority of the
instability will be south of the area by this time on Monday.

Much cooler and drier air will usher into the area behind the cold
front, with high temperatures in the 70s likely occuring early in
the morning and temperatures continually dropping throughout the

.LONG TERM...(Monday night through Saturday)
Issued at 301 AM CDT Sun Jun 20 2021

Temperatures will continue to cool into Monday night, with lows
bottoming out in the low to mid 50s.

Sunshine returns on Tuesday, but the cooler and drier weather will
continue with highs in the mid 70s to low 80s.

A gradual warming trend will return to the area as an upper level
ridge slides back into the region. Temperatures look to bounce
back into the 80s on Wednesday and low to mid 90s again on

The WPC Cluster Prototype Analysis and ensemble model blends then point
to increasing precipitation chances for Friday into early next
weekend as an upper level trough and surface cold front move
through the region. It should be noted that there are still some
slight model differences regarding the exact timing and intensity
of the trough and surface cold front.


.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 624 AM CDT Sun Jun 20 2021

VFR conditions will prevail through early tomorrow morning at the
TAF sites. Some high level clouds will be present across the area
today ahead of an approaching cold front tonight. Winds will gust
upwards of 20 to 25 knots out of the southwest, with the highest
gusts at KSGF and KJLN late this morning into afternoon.

Scattered showers and thunderstorms will develop along the cold
front tonight and push southeastwards towards the TAF sites
towards the end of the TAF period and primarily after the end of
this TAF period. Some MVFR ceilings and visibilities will be
possible within any showers and thunderstorms. Some low level wind
shear will also be possible ahead of the cold front tonight.




SHORT TERM...Rothstein
LONG TERM...Rothstein