Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 031657
AFDLSX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ST LOUIS MO
1157 AM CDT THU SEP 3 2015

.UPDATE:
Issued at 1157 AM CDT Thu Sep 3 2015

Forecast remains on track with only minor tweaks to it for this
afternoon. As with previous days, there remains a very low chance
for an isolated shower or brief thunderstorm but probabilities
remain low enough to preclude mention.

Otherwise, plenty of sunshine with max temps in the lower 90s,
with mid 90s in the STL metro area, closely following persistence.

TES

&&

.SHORT TERM:  (Through Late This Afternoon)
Issued at 313 AM CDT Thu Sep 3 2015

Weak warm advection over central Missouri is producing isolated
showers northwest of Columbia.  Expect this activity to continue
this morning for a few more hours...but should be ending between 12Z
and 15Z as the weak low level jet backs and warm advection shuts
off.  Remainder of the day looks to be a carbon copy of the past
couple with high pressure controlling our weather.  Expect highs in
the 90-95 degree range.  Wouldn`t be surprised to see an isolated
thunderstorm or two this afternoon, but overall chances are 10
percent or less across the area so have kept the forecast dry for
today.

Carney

.LONG TERM:  (Tonight through Wednesday)
Issued at 346 AM CDT Thu Sep 3 2015

Stagnant weather pattern will persist at least through Sunday as the
upper level ridge remains locked in over the center of the country.
The trof currently over the Pacific Northwest will move east across
the Rockies into the northern Plains by late Sunday causing
cyclogenesis over the Dakotas.  Resulting cold front plows southeast
into Iowa by Monday.  As a result, the temperature and precip
forecast becomes a little tricky Monday through Wednesday.  While
Monday may be a repeat of Sunday with respect to temperatures,
medium range ensemble guidance trends pretty sharply cooler into the
low to mid 80s on Tuesday, even though we`re still in the warm
sector with the front hanging back across Iowa.  Upper 70s is being
advertised by guidance across northeast Missouri with low to mid 80s
further south on Wednesday as the front finally dives southeast into
our CWFA.  While I do think mid to high chance for thunderstorms as
indicated by guidance is appropriate for Monday through
Wednesday...not sure about the temperature forecast.  There isn`t
any airmass change until the front pushes through, and the low level
thermal ridge is still over our region with 850mb temps in excess of
+20C.  Low to mid 80s just feels too cool to me until the front
moves through...regardless of the precip chances.  If I was
forecasting in a vacuum, I`d keep temperatures at least 5 degrees
warmer than guidance; however, have kept the forecast temperatures
close to the ensemble guidance to maintain consistency with
neighboring offices.

Carney

&&

.AVIATION:  (For the 12z TAFs through 12z Friday Morning)
Issued at 645 AM CDT Thu Sep 3 2015

Mid cloud deck (with bases aoa 10kft) and a few sprinkles are drifting
southeast across the region this morning. Radar indicates some of
this rain may effect KCOU next hour or so, but since precip is so
light no vsby restriction is expected. Otherwise, weather trends
today should be similar to those of yesterday, with high based
morning clouds giving way to scattered CU around midday, with this
diurnally driven cloudiness dissipating as we head into the early
evening hours. Did include some late night fog in the tafs for the
low lying locations of KSUS and KCPS.

Specifics for KSTL: VFR conditions are expected throughout the
period, with clouds aoa 5kft and south-southwest winds aob 10kts.

Truett

&&

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

$$

WFO LSX


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