Area Forecast Discussion
Issued by NWS St. Louis, MO
FXUS63 KLSX 080804
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
304 AM CDT THU OCT 8 2015
.SHORT TERM: (Through Tonight)
Issued at 304 AM CDT Thu Oct 8 2015
Forecast focus thru this period will be precip chances.
Trends mentioned yesterday continue today with latest guidance.
Mdl solns continue to suggest region will remain cut off from Gulf
moisture. Mdls also suggest the upper trof out of sync with the
sfc fnt across the area. Believe better chances for precip will
exist E of the CWA with the sfc low and better upper level
dynamics as well as to the W with better low level forcing and a
stronger s/w within the trof. Still believe precip will develop
along the fnt, but coverage continues to look less. Have therefore
lowered PoPs closer to latest MOS guidance. As for timing, appears
SHRA with isod to sct TS will develop across srn IA late this
afternoon and push swd into nrn portions of the CWA into the
evening hours. This precip shud gradually dissipate. However, as
the upper trof approaches, it appears precip will switch to more
stratiform. Timing of this remains uncertain and have kept lower
PoPs further nwd to account for it.
As for temps today, while the upper low over nrn Mexico is
expected to drift swwd today, a leading s/w currently over ern
NEB/KS is expected to provide ample cloud cover thru at least the
morning hours. With less lower and mid level clouds, expect temps
to rise into the 80s with swly flow at low levels. Have trended
twd the cooler guidance again today due to questions of cloud
cover, but also due to the amount of CU that developed and temps
across the Plains yesterday.
Temps tonight will be difficult to pin down as the fnt pushes swd
tonight. Generally, trended cooler across the nrn third and warmer
across the srn third based on cloud trends and timing of fropa.
.LONG TERM: (Thursday through Next Wednesday)
Issued at 354 PM CDT Wed Oct 7 2015
The surface reflection of the shortwave will move from Minnesota
southeast into the Great Lakes region by 06Z Friday. The associated
surface front should enter northern Missouri by 00Z Friday and will
move south through the area and should be south of Farmington by 12Z
or so. Should be pretty warm ahead of the front on Thursday in west-
southwest flow, so I leaned toward the warmer guidance members.
Still think scattered showers and a few thunderstorms are likely
along and ahead of the front; however I am reluctant to go higher
than 50 PoPs with the FROPA due to lack of deep moisture return. A
cool Canadian high will drop down into the Mississippi Valley behind
the front on Friday. Expect temperatures to fall back to near or
just below seasonal normals with this high.
Cool down will be short-lived though as the ridge shifts southeast
and southwest flow returns to the mid Mississippi Valley.
Temperatures will rise back above normal Sunday and then drop again
Tuesday and Wednesday as another front moves through the area. The
FROPA looks dry at this time due to lack of moisture return.
.AVIATION: (For the 06z TAFs through 06z Thursday Night)
Issued at 1140 PM CDT Wed Oct 7 2015
High clouds will continue to spread across the region tonight.
Light winds will allow for radiational fog at KSUS and KCPS and
possibly a brief window at KCOU. The visibility with the fog
should be in the MVFR flight category however KSUS could fall to
IFR. VFR flight conditions expected on Thursday and likely
Thursday night as well. There is a chance of showers attending a
cold front moving across the area, but confidence is low that the
intensity and coverage will amount too much and hence have only
mentioned PROB30 in the forecast.
Specifics for KSTL:
VFR flight conditions should prevail through most of the forecast
period. At this time I am thinking there is only a low probability
of fog overnight and hence haven`t mentioned it. If it does
materialize then I think it will be somewhere in the 09-12z time
frame and the visibility shouldn`t be lower than 5-6sm. There is a
chance of showers attending a cold front moving across the area on
Thursday night, but confidence is low that the intensity and
coverage will amount too much and hence have only mentioned
PROB30 in the forecast.
.PRELIMINARY POINT TEMPS/POPS:
Saint Louis 82 59 68 50 / 10 40 30 0
Quincy 82 54 65 45 / 20 40 10 0
Columbia 82 54 68 46 / 10 40 20 0
Jefferson City 83 55 69 46 / 10 40 30 0
Salem 80 58 71 48 / 5 40 40 0
Farmington 80 57 66 47 / 5 40 40 0