Area Forecast Discussion
Issued by NWS St. Louis, MO
FXUS63 KLSX 090441
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1141 PM CDT THU OCT 8 2015
.SHORT TERM: (Through Late Tonight)
Issued at 332 PM CDT Thu Oct 8 2015
Looks like this will be a dry FROPA for most of the area tonight.
Short range guidance is in good agreement in developing isolated to
widely scattered showers during the early evening along and ahead of
the front. Some disagreement though as the evening wears on with
how much the showers will diminish. The NSSL and NCEP 4km WRF
models are the strongest, keeping a broken line of showers and
thunderstorms together as it moves through the CWFA from northwest
to southeast. Pretty much every other model weakens the showers and
storms through midnight tonight. Indeed, MOS PoPs are between 5-15
percent for most of the area. Have continued the trend of backing
down PoPs, and I now have 30% or less for the entire area. Cooler
air behind the front will lag behind the wind shift a bit, so I
don`t expect it to play much of a factor in lows tomorrow morning.
MOS lows in the low to mid 50s look pretty reasonable.
.LONG TERM: (Friday through Next Thursday)
Issued at 347 PM CDT Thu Oct 8 2015
Looks like another stretch of quiet weather in the long-term. Could
see some lingering showers on Friday along and south of I-44, but
any rain should be more or less done by noon. High pressure builds
southeast and should be centered over Missouri by 12Z Saturday which
should be our coldest morning of the next 7. The ridge continues
moving southeast and southwest flow will ramp up quickly Saturday
afternoon. Temperatures will warm back up above normal Sunday and
will remain at or above normal for the rest of the forecast period.
A strong shortwave will move quickly across the northern CONUS and
southern Canada Sunday night through Monday night. This will push
another cold front through the area, but the airmass behind the
front won`t be a cold as the airmass moving into the area Friday and
Friday night. The 12Z runs of the GFS and ECMWF both kick out a
little light QPF ahead of the front, but these are the first runs to
do this. Additionally, there will be little if any moisture return
ahead of the front so have kept the forecast dry.
.AVIATION: (For the 06z TAFs through 06z Friday Night)
Issued at 1133 PM CDT Thu Oct 8 2015
Coverage of showers and thunderstorms continues to diminish and push
southeastward. The St. Louis metro terminals have a risk of a
brief shower or sprinkle until cold fropa around 07z. VFR flight
conditions will persist until the predawn hours then deteriorating
flight conditions are expected into Friday morning as post-frontal
stratus invades the area with CIGS lowering into the MVFR flight
category. Cig heights should rise and clouds become more
cumuliform in the afternoon with clearing by early evening.
Specifics for KSTL:
A low risk of a brief shower or sprinkle will continue until the cold
fropa around 07z. VFR flight conditions will persist until around
15z Friday morning then post-frontal stratus invades the area
with CIGS lowering into the MVFR flight category. Cig heights
should rise and clouds become more cumuliform in the afternoon
with clearing by early evening.