768
FXUS63 KLSX 061718
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1218 PM CDT Thu Jun 6 2024

.KEY MESSAGES...

- Today and tomorrow will be dry before the chance of showers and
  thunderstorms arrives Friday night through Sunday. The greatest
  potential for widespread precipitation will be Saturday (40 to
  70% maximized in southeast Missouri). Dry conditions are
  expected after rain exits Sunday night.

- Temperatures will remain near to below average through early
  next week. The coolest days of the period will be Sunday and
  Monday with highs in the mid to upper 70s.


&&

.SHORT TERM...  (Through Late Friday Afternoon)
Issued at 219 AM CDT Thu Jun 6 2024

A weak, dry cold front is pushing through the forecast area this
morning. The front is expected to exit the area by mid-day, but
temperatures won`t take much of a hit. Highs in the upper 70s to mid-
80s are forecast today, with areas in southeast Missouri forecast to
be warmer than they were yesterday. Lows tonight, however, will be
slightly cooler than what we`ve seen lately due to surface high
pressure promoting radiational cooling conditions. Widespread mid to
upper 50s are forecast for tonight as a result with cooler
temperatures likely in sheltered areas.

Friday will be very similar to today with highs in the 80s and
mostly clear skies. High clouds will begin to move in from the west
in the afternoon ahead of our next rain-making system. The arrival
of high and eventually mid and low-level clouds will work in tandem
with low-level warm air advection to boost low temperatures back to
average Friday night. Low 60s are forecast areawide.

Jaja

&&

.LONG TERM...  (Friday Night through Wednesday)
Issued at 219 AM CDT Thu Jun 6 2024

Deterministic guidance is converging on an MCS moving through the
region Saturday morning. There are still discrepancies concerning
the exact timing and track of this feature, but trends are
consistent in having the majority of the showers and thunderstorms
passing through between the pre-dawn hours and midday. Latest
guidance is pulling the system further north as well, increasing the
chance of precipitation areawide. Of course, the track of the system
may still wobble north or south before Saturday, but as of now most
deterministic guidance pulls precipitation chances as far north as
KUIN, a notable change from this time yesterday. Ensemble members at
this time yesterday (12z June 4 run) had a 20 to 30% probability of
precipitation at KUIN, whereas today (12z June 5 run) that
probability has increased to 40 to 50%. For this reason, I think the
NBM`s increase in PoPs in this area from 15 to 35% is justified.

A cold front will follow the MCS Saturday afternoon through Saturday
night. Most global models show convection developing along the front
as it moves through the forecast area. How much of the area that
sees convection depends on the speed and timing of the cold front,
which varies among guidance. Right now, confidence is highest in
southeast Missouri seeing additional showers and thunderstorms
Saturday afternoon and again overnight Saturday as convective
activity increases along the exiting cold front. After the cold
front exits completely, largely dry conditions will persist through
at least early next week.

Temperatures from Saturday through Wednesday will remain near
average with Sunday and Monday forecast to be the coolest days of
the period. These days are forecast to feature widespread 70s
despite partly cloudy to mostly clear June skies. Monday will be the
cooler of the two as a weak backdoor cold front reinforces ongoing
cold air advection. Temperatures will begin to rebound thereafter,
bouncing back to above average by late next week under the influence
of upper level ridging. It`s difficult to say how long the ridging
will last, but the latest CPC 8 to 14 outlook favors above average
temperatures and below average precipitation for the middle of this
month, so this pattern change may stick around.

Jaja

&&

.AVIATION...  (For the 18z TAFs through 18z Friday Afternoon)
Issued at 1209 PM CDT Thu Jun 6 2024

Dry and VFR conditions are expected through the period. Northwest
to west winds will gust above 20 knots this afternoon before
decreasing after sunset. Winds will pick up again tomorrow
afternoon at St. Louis.

Britt

&&

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

$$

WFO LSX