703
FXUS63 KLSX 071119
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
619 AM 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 12z TAFs through 12z Monday Morning)
Issued at 615 AM CDT Sun Jul 7 2024

VFR flight conditions through forecast period for all TAF sites
except KUIN. Otherwise, showers and storms develop early this
evening, but coverage is scattered, so just have vicinity
thunderstorm mention after 00z-01z Monday at KUIN, KCOU and KJEF.
Could see a brief period of MVFR ceilings at KUIN after 10z
Monday. Metro area TAFs will remain dry through the forecast
period. As for winds they will be light from the south through
the day today, then become light and variable by this evening.

Byrd
&&

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

$$
WFO LSX