Severe Thunderstorm Warning 312, NWS St. Louis, MO

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1246 PM CDT Sun Jul 7 2024

.KEY MESSAGES...

- Above normal temperatures will return today along with a chance
  of afternoon thunderstorms across portions of central and
  northeast Missouri and west-central Illinois.

- Shower and thunderstorm chances (40-70%) will increase and expand
  across the entire CWA tonight through Monday.

- Depending on the track, the remnants of tropical cyclone Beryl
  could bring heavy rain to parts of southeast/east central
  Missouri and southern Illinois Tuesday through Tuesday night.

&&

.SHORT TERM...  (Through Late Monday Afternoon)
Issued at 348 AM CDT Sun Jul 7 2024

MCS sliding east along the MO/IA border will continue to weaken
early this morning, so expect little to no rain over portions of
northeast MO. With the surface ridge sliding off to the east,
southerly flow returns to the region once again today. So the
combination of increasing moisture/instability and any residual
outflow boundary, as well as a possible MCV, will be the trigger
for additional showers and thunderstorms by this afternoon,
especially over portions of central/northeast Missouri as well as
west central Illinois. Otherwise, today will be the warmest day
for the upcoming week due to the southerly flow and warmer temps
aloft (850mb temps 16-19C).

In the meantime, the majority of the latest deterministic as well as
ensembles still have an upper level trough deepen over the
northern/central Plains. Then the trough will slowly slide eastward
into the mid to upper MS Valley by Monday night. Ahead of the
trough, a southwesterly low level jet will develop and usher in a
series of shortwaves in addition to the increasing low level
moisture/instability. This combined with a cold front over the
central Plains will generate another round of showers and storms
late tonight through Monday, as the front moves into the region.

Byrd
&&

.LONG TERM...  (Monday Night through Saturday)
Issued at 348 AM CDT Sun Jul 7 2024

The latest NHC forecast has TC Beryl come on shore over the
middle portions of the Texas gulf coast Monday morning. In the
meantime with the very slow movement of the upper level trough, a
number of the latest deterministic as well as ensembles have the
remnants of TC Beryl recurve across the mid MS Valley and become
absorbed by the trough by Tuesday. There are still quite a few
differences among the models as far as the track of the associated
surface low. GFS is further north tracking near STL while the NAM
tracks it across the MO bootheel and the ECMWF is slower, but has
similar placement to the NAM. For now with some uncertainty,
stuck with the latest NBM solution, though did increase POPs to
likely/categorical across portions of southeast/east central MO,
as well as southern IL for Tuesday into Tuesday night. Latest WPC
qpf has increased rainfall amounts over the region with an axis of
2 to 4 inches, mainly along the I-44 corridor in MO and I-70
corridor in IL.

Beyond Tuesday night, the trough continues to weaken with the rain
tapering off by Wednesday afternoon. Expect mainly dry conditions
for the remainder of the work week and into early next weekend.
Otherwise, temperatures will remain near normal this week, though
Tuesday will be 5 to 15 degrees below normal due to the widespread
showers and storms.

Byrd

&&

.AVIATION...  (For the 18z TAFs through 18z Monday Afternoon)
Issued at 1237 PM CDT Sun Jul 7 2024

For KCOU, KJEF, and KUIN: Scattered showers and thunderstorms
will continue to develop across western MO this afternoon, and
eventually develop or move into central and northeast MO by late
afternoon and into the evening. This has prompted VCTS at KJEF,
KCOU, and KUIN generally within the 00-03/04z time frame, and if
there is a direct terminal impact then flight conditions will be
reduced and gusty winds will be possible as well. After around
04z, there will be potential for showers into the overnight hours
impacting these same terminals, and then some MVFR stratus on
Monday morning.

For KSTL, KSUS, and KCPS: At this time, the St. Louis region
terminals are expected to be VFR and remain east of the shower and
thunderstorm activity through tonight. Showers and maybe evening
a thunderstorm will be possible after 14-15z Monday however
confidence is low, hence at this time only VCSH has been
mentioned.

Glass

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

WFO LSX

Hazardous Weather Outlook
National Weather Service St Louis MO
359 AM CDT Sun Jul 7 2024

ILZ058>060-064-065-069-070-074-079-095>102-MOZ018-019-026-027-
034>036-041-042-047>052-059>065-072>075-084-085-099-080900-
Greene IL-Macoupin IL-Montgomery IL-Bond IL-Fayette IL-Clinton IL-
Marion IL-Washington IL-Randolph IL-Adams IL-Brown IL-Pike IL-
Calhoun IL-Jersey IL-Madison IL-Saint Clair IL-Monroe IL-Knox MO-
Lewis MO-Shelby MO-Marion MO-Monroe MO-Ralls MO-Pike MO-Boone MO-
Audrain MO-Moniteau MO-Cole MO-Osage MO-Callaway MO-Montgomery MO-
Lincoln MO-Gasconade MO-Warren MO-Saint Charles MO-Franklin MO-
Saint Louis MO-Saint Louis City MO-Jefferson MO-Crawford MO-
Washington MO-Saint Francois MO-Sainte Genevieve MO-Iron MO-
Madison MO-Reynolds MO-
359 AM CDT Sun Jul 7 2024

This Hazardous Weather Outlook is for portions of eastern and
central Missouri as well as west central and southwest Illinois.

.DAY ONE...Today and tonight.

There is a chance of thunderstorms across portions of central,
northeast Missouri, as well as west central Illinois this afternoon
through tonight.

.DAYS TWO THROUGH SEVEN...Monday through Saturday.

There is a chance of thunderstorms across the region Monday through
Wednesday afternoon. There is a small chance of thunderstorms again
Thursday afternoon.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

Byrd