906
FXUS63 KLSX 071119
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
519 AM CST Thu Nov 7 2024

.KEY MESSAGES...

- Dry and seasonable weather is expected through Friday.

- Widespread showers and storms are expected Saturday through
  Saturday night, although rainfall amounts will be less than the
  previous system.


&&

.SHORT TERM...  (Through Late Friday Afternoon)
Issued at 247 AM CST Thu Nov 7 2024

Surface ridge will remain over the region with light north winds
gradually veering to the northeast to east by Friday. So dry and
cooler conditions today, then a slight warm up on Friday with
highs between 60 and 65 degrees. Otherwise, the main issue in the
short term is the lingering stratus deck that is sliding south
through the area this morning. The latest RH progs are still
indicating that RH will continue to lower by this afternoon, thus
clouds will diminish and move out.

Byrd
&&

.LONG TERM...  (Friday Night through Wednesday)
Issued at 247 AM CST Thu Nov 7 2024

In the meantime, the next weather system that will affect the
region is currently anchored over the Desert SW. The latest
deterministic as well as ensembles are still in fairly decent
agreement that the closed upper low will begin to lift out towards
the Central Plains on Friday. With low level flow becoming
southerly once again, moisture from the Gulf will spread northward
into the region.

The best chances of rain will be Saturday through Saturday night.
However, there are still some minor timing and placement differences
among the latest deterministic and ensembles as the system lifts
north northeastward through the central Plains and into the upper
Midwest. This system continues to be rather progressive and dynamic,
thus any precipitation that develops will not linger long over the
area. So despite PWATs now approaching 1.5 inches across portions of
the area, rainfall amounts will be under an inch as the latest LREF
indicates 15% or less probability of 1"+.

As the system exits the area to our north on Sunday, drier air will
filter in. However, the source for the airmass is more Pacific in
origin, thus do not expect a cool down behind this system. Highs on
Sunday will actually be a bit warmer than Saturday, due to less
clouds and no precipitation.

Beyond Sunday, weak upper level ridging will build in with highs
around 5 to 10 degrees above normal for this time of year. The
latest deterministic models indicate another system will approach
the region by Wednesday, but there are some timing, location and
strength differences, so stuck with the latest NBM solution with
chance POPs Tuesday night into Wednesday.

Byrd
&&

.AVIATION...  (For the 12z TAFs through 12z Friday Morning)
Issued at 518 AM CST Thu Nov 7 2024

Strato cu deck continues to slide slowly to the southwest this
morning. So added MVFR ceilings in the St. Louis metro TAFs and
at KJEF through midday before lifting and scattering out.
Otherwise, where skies are clear, across portions of
central/northeast MO and west central IL, some patchy fog has
developed, so added MVFR visibilities at KUIN and KCOU through
13z-14z. Otherwise, light north to northeast winds through the
forecast period.

Byrd
&&

.HYDROLOGY...
Issued at 218 PM CST Wed Nov 6 2024

Major river flooding continues or is forecast along portions of
the Meramec and Big Rivers. The Meramec river has crested closer
to the headwaters, with Steelville cresting last night and
Sullivan near crest currently. Farther downstream, crests between
Pacific and Arnold will occur over the next 2-3 days. For the Big
River, a crest at Byrnesville is forecast to occur this evening
with a rapid fall thereafter.

Widespread additional rainfall is expected on Saturday. However, with
this expected rain, little/no additional rises are expected. Any
rises, if any occur, from this rainfall would also occur at levels
well below observed or forecast crests over the next 48-72 hours.
This rainfall may slightly slow down the fall of the rivers late
this weekend/early next week, and may delay the time they get back
below flood stage in some locations.

Gosselin
&&

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

$$
WFO LSX