913 
FXUS63 KLSX 292029
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
229 PM CST Mon Nov 29 2021

.SHORT TERM...  (Through Late Tuesday Night)
Issued at 228 PM CST Mon Nov 29 2021

Tonight a weak cold front will pass through our area. It will do 
little to drop temperatures, although a wind shift from 
southwesterly to northerly will work to hinder warm air advection 
into the region through Tuesday. The second half of Tuesday will see 
a small chance of rain as a shortwave approaches. Rain chances 
should stay primarily in northeastern Missouri and west-central 
Illinois. Although model soundings depict a saturated 850-700 mb 
layer, the atmosphere underneath it will be extremely dry. Any rain 
that does develop will have a difficult time making it to the 
ground. Ensemble guidance as well as the NBM, for the most part, 
brush off the possibility of rain at all for this region. However, 
the chance of short-lived, light rain is still present and thus 
mentionable. 

Jaja

.LONG TERM...  (Wednesday through Next Monday)
Issued at 228 PM CST Mon Nov 29 2021

By Wednesday morning, surface winds will again be southwesterly. 
These winds will advect a thermal gradient into our area raising 
high temperatures to the upper 50s/low 60s. An upper level ridge 
moving toward us will aid in keeping temperatures unseasonably warm 
for the rest of the week. Highs Thursday will peak in the upper 
60s/low 70s. This is around 20 degrees above normal (~50F) for this 
time of year. The NAEFS 850 mb temperatures show that these 
conditions are above the 99th climatological percentile. High 
temperature records will be in jeopardy areawide. 

Friday will be similar to Thursday, albeit a few degrees cooler. The 
chance of rain will skirt the southern CWA Friday night. A warm 
front associated with a low pressure system over Texas will lift 
toward Missouri, but how far north it will get is uncertain at this 
time. The majority of deterministic guidance places our CWA 
completely north of the warm sector. If this is the case, we will 
remain rain-free. Since there is still uncertainty at this time, 
slight chance PoPs remain in our far southern counties.

The slight chance of rain returns again on Sunday as a cold front 
sweeps into the area. Although there is consensus among models that 
a cold front will pass Sunday, timing of the front and precipitation 
chances associated with it are still uncertain. Because of this, the 
NBM was used to handle PoPs. 

Jaja

&&

.AVIATION...  (For the 18z TAFs through 18z Tuesday Afternoon)
Issued at 1145 AM CST Mon Nov 29 2021

Currently, southwesterly winds are increasing in speed as a cold 
front approaches the area. This cold front will be weak, only 
serving to change wind direction from southwesterly to northerly as 
it passes. Marginal LLWS is a possibility for the St. Louis 
metropolitan terminals between 02 and 05Z tonight, but confidence in 
its presence is low. It will not be impactful to the terminals. VFR 
conditions are expected throughout the TAF period.

Jaja

&&

.CLIMATE...  
Issued at 252 AM CST Mon Nov 29 2021

High Temperature Records:

December 2nd
KSTL: 75F (2012)
KCOU: 72F (1917)
KUIN: 67F (1982)

December 3rd
KSTL: 76F (1970) 
KCOU: 75F (2012) 
KUIN: 74F (2012)


&&

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

$$

WFO LSX