027 
FXUS63 KLSX 161111
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
611 AM CDT Sun Oct 16 2022

.SHORT TERM...  (Through Late Monday Afternoon)
Issued at 304 AM CDT Sun Oct 16 2022

Aloft we remain in northwesterly flow on the southwest side of a 
robust trough centered over Ontario, while a weak ridge is stretched 
across the western CONUS. At the surface a dry cold front is moving 
through the region early this morning, currently stretching from 
west-central Missouri to west-central and north-central Illinois, 
behind which a surface high will move into the region. The passage 
of the front will usher in Arctic air and bring near record breaking 
temperatures for the first half of the work week. While 850 mb 
temperatures will begin to cool today, conditions will still be 
similar to yesterday across the region, dry with near to slightly 
below normal temperatures under a mostly clear sky.

Cooling will continue tonight into Monday, CAA along the northerly 
flow will cool 850 mb temperatures into the single negative digits. 
Under a clear sky overnight lows will cool into the 30s, 10 degrees 
cooler than last night. Mixing during the day Monday will bring 
cooler temperatures aloft down to the surface, and high temperatures 
will peak in the mid 40s to mid 50s across the area, 15 to 20 
degrees below normal. Temperatures will come close to breaking the 
low maximum temperature records at all climate sites (see Climate 
section below). In addition, mixing and a tighter surface 
pressure gradient will keep winds elevated between 15 and 20 mph 
and gusting into the upper 20s, resulting in a cold and blustery 
day.

Winds will diminish with sunset, and a clear sky and continued CAA 
will allow temperatures to drop into the 20s or even teens across 
the valleys and cooler spots of the forecast area. The spread of 
solutions for the overnight lows continues to be small, increasing 
confidence that these sub-freezing temperatures will be realized. A 
Freeze Watch has been issued for the forecast area accordingly. Most 
of the area is expected to drop below 28, which will result in a 
killing freeze for these areas and an end to the growing season. Low 
temperature records for Tuesday morning at COU and UIN are in danger 
of breaking, while the urban heat island is expected to keep the 
temperature at STL above the record low.

MRM

.LONG TERM...  (Monday Night through Saturday)
Issued at 304 AM CDT Sun Oct 16 2022

CAA will continue in the low levels Tuesday along northerly flow. 
850 mb temperatures will persist in the negative single digits, at 
the 0.5th percentile for this time of year. Despite the clear sky 
and ample sunshine, the cold start to the day and CAA will keep 
temperatures on Tuesday cold, about 20 degrees below normal. Even 
so, low maximum temperature records are safe for Tuesday. A clear 
sky overnight and light winds will push temperatures Tuesday night 
back into the 20s across the area, approaching record value.

While northwesterly flow continues in the mid-levels, the center of 
the trough will shift southeastward through the Great Lakes region 
by Wednesday. This is mirrored in the lower levels, and flow will 
shift from northerly to northwesterly, and advect warmer air from 
the thermal ridge into the region. This will bring an end to our 
near record cold snap and begin to moderate temperatures across the 
region. Through the end of the work week and into the weekend the 
mid-level trough lifts out of southeastern Canada, and the weak 
ridge across the western CONUS begins to break down. This signals a 
pattern shift for the weekend and beyond. Another trough will come 
onshore over the weekend, and throw the mid-Mississippi Valley into 
southwest flow aloft. Likewise in the lower levels southwesterly 
flow will become established by the weekend, continuing the warming 
trend. The southwesterly flow may also open the region back up to 
Gulf moisture, and could bring precipitation back to the region. 
Some ensemble members are indicating light precipitation next 
weekend, but a majority of them keep the area dry. At this point, 
will stick with the NBM, which keeps the weekend dry.

MRM

&&

.AVIATION...  (For the 12z TAFs through 12z Monday Morning)
Issued at 606 AM CDT Sun Oct 16 2022

VFR flight conditions will continue through the end of the period.
A dry cold front is passing through the terminals this morning, 
winds will become northwesterly and strong behind the front. Winds
will diminish with sunset.

MRM

&&

.CLIMATE...  
Issued at 215 PM CDT Sat Oct 15 2022

                MON       TUE       WED
                17        18        19
STL--
    LOW MAX   49(1976)  42(1880)  42(1989)
    LOW MIN   29(1943)  27(1976)  25(1972)

COU--
    LOW MAX   48(1976)  38(1898)  41(1930)
    LOW MIN   26(1976)  25(1952)  22(1972)

UIN--
    LOW MAX   46(1989)  45(1989)  41(1989)
    LOW MIN   27(1943)  24(1948)  20(1972)


&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...Freeze Watch from Monday evening through Tuesday morning for 
     Audrain MO-Boone MO-Callaway MO-Cole MO-Crawford MO-
     Franklin MO-Gasconade MO-Iron MO-Jefferson MO-Knox MO-Lewis 
     MO-Lincoln MO-Madison MO-Marion MO-Moniteau MO-Monroe MO-
     Montgomery MO-Osage MO-Pike MO-Ralls MO-Reynolds MO-Saint 
     Charles MO-Saint Francois MO-Saint Louis City MO-Saint 
     Louis MO-Sainte Genevieve MO-Shelby MO-Warren MO-Washington 
     MO.

IL...Freeze Watch from Monday evening through Tuesday morning for 
     Adams IL-Bond IL-Brown IL-Calhoun IL-Clinton IL-Fayette IL-
     Greene IL-Jersey IL-Macoupin IL-Madison IL-Marion IL-Monroe 
     IL-Montgomery IL-Pike IL-Randolph IL-Saint Clair-Washington 
     IL.

&&

$$

WFO LSX