655
FXUS63 KLSX 301923
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
223 PM CDT Thu May 30 2024

.KEY MESSAGES...

- Another round of showers and scattered thunderstorms will move
  across the area late Friday into Saturday.

- There will be a continued chance for showers and thunderstorms
  into next week with temperatures climbing above normal.

&&

.SHORT TERM...  (Through Late Friday Night)
Issued at 221 PM CDT Thu May 30 2024

We are enjoying another dry day with near normal temperatures as a
surface high centered over the Great Lakes continues to usher
relatively dry air into the area.  The HREF is showing the upper
ridge currently over western Missouri moving east across the area
tonight keeping the area dry.  This will change tomorrow as the
trough over the Plains will deepen on Friday and then move across
Missouri and Illinois on Friday night.  The GFS/NAM is in reasonable
agreement showing the attendant surface low moving northeast across
the CWA late Friday night into Saturday.  Latest runs of the CAMS
including the HRRR are showing that the chance for showers and
thunderstorms will not move into central Missouri until late
tomorrow morning, with likely/categorical PoPs spreading from west
to east across the CWA tomorrow afternoon and evening as there will
be stronger ascent from the upper low and a low level jet.  These
high chances will not exit the eastern CWA until late Saturday
afternoon when upper low moves east of the area.  Overall, rainfall
amounts look to be on the order of 0.5-1.0"+ with this system, but
with PWATS near 1.7", a few of the showers and thunderstorms
will be capable of producing some locally heavy rainfall.

Temperatures will be close to normal through Saturday as 850mb
temperatures remain near 10C with the increased clouds and rain
chances with the upper low.

Britt

&&

.LONG TERM...  (Saturday through Next Thursday)
Issued at 221 PM CDT Thu May 30 2024

Global models and the LREF is showing the pattern becoming quasi-
zonal early next week before an upper trough enters the north
central CONUS by the middle of next week.  This still causes a
certain amount of uncertainty with regards of the timing and
strength of the shortwave troughs that will move across the area
Sunday into Tuesday that will bring showers and thunderstorms to the
region.  At this point, it still appear that Sunday into Sunday
evening will have lower chances for rain (10-30%) as a shortwave
ridge moves across the area, while there will be higher chances(40-
60%) on Monday into Tuesday as a pair of troughs move across
Missouri and Illinois.  It should be noted that while some of the
raw QPF from the global models looks too high because of convective
feedback, there could be some locally heavy rainfall as the LREF has
PWATS near 1.6".  There will be an additional chance of showers and
thunderstorms into Wednesday as the attendant cold front of the
upper low moves across Missouri and Illinois.  While there is some
potential for a few strong storms next week, the CAPE/shear setup is
not particularly impressive for organized severe storms.

It still looks like we are on track for a warm up next week as the
LREF is showing 850 temperatures climbing to near 20C between Monday
and Wednesday with low level southwesterly flow before the cold
front moves through midweek.  The NBM 75th percentile for highs are
showing highs AOA 90 degrees early next week, so few spots certainly
could reach 90 ahead of the cold front where there is less rain and
more sun.  Overall confidence in the warmup remains high as the NBM
IQR is around 5 degrees or less ahead of the cold front, but then
increases to around 10 degrees behind the cold front next Thursday.

Britt

&&

.AVIATION...  (For the 18z TAFs through 18z Friday Afternoon)
Issued at 1230 PM CDT Thu May 30 2024

Dry and VFR conditions are expected through the end of the period.
The only exception is that there is a chance of showers and
thunderstorms over central Missouri after 15Z on Friday morning
and at STL on Friday afternoon. These chances are too low to
include in the TAFs at this time. Winds will remain out of the
southeast at around 10 knots through the period.

Britt

&&

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

$$

WFO LSX