Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 232034
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
334 PM CDT Tue Sep 23 2014

.SHORT TERM:  (Through Late Tonight)
Issued at 333 PM CDT Tue Sep 23 2014


(Tonight)

Upper-level low and attendant trough axis currently across the Dakotas is
forecast to slowly move eastward overnight tonight. Not much impact is
expected for our CWFA other than an increase in clouds for portions of
central and northeastern Missouri. Showers with embedded thunder should
stay to the west of the area in close proximity to aforementioned trough.
For lows tonight...started with this morning`s observed mins as a baseline
and added a few degrees due to airmass modification. Leaned a bit warmer
across the northwestern third of the area due to expected clouds.
Conversely...leaned toward cooler guidance for eastern Ozarks and portions
of southwest Illinois due to light winds near sfc ridge and a mostly clear
sky. All in all...another pleasant early fall night looks to be in store
for the bi-state region with lows ranging from the mid 40s to the mid 50s.


Gosselin


.LONG TERM:  (Wednesday through Next Tuesday)
Issued at 333 PM CDT Tue Sep 23 2014


(Wednesday - Saturday)

Mid/upper level pattern through at least the start of this upcoming
weekend looks nebulous/chaotic. Short to medium range guidance agree
that at least a portion of the trough across the northern Plains will
halt its eastward progression sometime Wednesday or Wednesday night
and begin to retrograde southwestward. Impacts of this feature will still
likely be minor and in the form of increasing clouds. However...would not
be surprised if a few showers is kicked up by the remnant midlevel low/
shear axis. Models are fairly bearish on precipitation..but some do have
a few hundreths of an inch over random 6-hr blocks of time. Conceptually...
a few widely scattered/isolated showers does make sense beneath cooler
midlevel temps aloft. However...with low-level ridging remaining entrenched
across the area collocated with very dry air...still maintaining a dry
forecast through Saturday at this time. Main theme in the Wednesday through
Saturday forecast period will be seasonably warm temperatures day/night
with highs in the upper 70s/low 80s and overnight lows in the 50s to low
60s...or around 5 degrees above normal for late September.


(Sunday - Tuesday)

GFS/ECMWF models diverge fairly quickly late this weekend with how to
handle cutoff low/shear axis. The GFS actually moves the low southeastward
on Sunday and phases it with a low across southeast Texas. The ECMWF
on the other hand retrogrades the low westward toward the mid-Missouri
Valley and brings the system northward from Texas much faster and
further northward when compared with the GFS. Needless to say...quite
a bit of uncertainty in the extended. If system does indeed stream
northward out of Texas...chances of showers and a few storms will return
to at least portions of the region...most likely across southeast Missouri
and southwest Illinois. However...outside of that particular system...
rain chances will remain very low. Temperatures will remain mild for late
September and continue to be above normal.


Gosselin


&&

.AVIATION:  (For the 18z TAFs through 18z Wednesday Afternoon)
Issued at 117 PM CDT Tue Sep 23 2014

Surface ridge just to east of forecast area, so winds have become
southeasterly. VFR conditions to persist through forecast period
with southeast to south winds becoming light and variable most
locations after sunset.

Specifics for KSTL:
Surface ridge just to east of forecast area, so winds have become
southeasterly. VFR conditions to persist through forecast period
with southeast winds becoming light and variable after 00z Wednesday.

Byrd

&&

.PRELIMINARY POINT TEMPS/POPS:
Saint Louis     55  79  60  81 /   0   0   5   5
Quincy          52  76  55  79 /   5  10   5  10
Columbia        53  78  55  80 /   5   5  10  10
Jefferson City  50  79  54  81 /   5   5   5  10
Salem           47  77  50  80 /   0   0   0   5
Farmington      46  78  51  80 /   0   0   0   5

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX





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