Area Forecast Discussion
Issued by NWS St. Louis, MO

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000
FXUS63 KLSX 280855
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
355 AM CDT Sat Mar 28 2015

.SHORT TERM:  (Through Late This Afternoon)
Issued at 352 AM CDT Sat Mar 28 2015

Focus this morning will be on the potential for accumulating snow...
primarily across central MO. Widespread cloudiness has moved into
the area overnight in advance of a short wave dropping SE in the NW
flow. Not much sfc reflection to this feature with most of the
forcing coming from the mid levels. Radar not at all impressive at
0345 with just light returns showing up from wrn IA into cntrl MO
with only a few stations even reporting precip. Models indicate that
coverage/intensity should gradually increase 9Z-12Z as the precip
continues to slide SSE. Guidance has shifted the precip axis a
little further west now showing most of the QPF west of the CWA so
have attempted to tighten up the eastern edge of the going PoP fcst.
That being said...I still believe areas along and west of a Columbia
to Jeff City line may still get a few tenths of an inch this morning
before the system rapidly slips south of the area. It appears that
most of the precip will be in EAX and SGF CWAs this mrng with the
system just grazing our common border. Any threat of measurable
precip should be well south of the FA by 18Z. The rest of the day
will feature seasonably cold temps in the 40s which is 10-15
degrees below average.

Miller

.LONG TERM:  (Tonight through Friday)
Issued at 352 AM CDT Sat Mar 28 2015

High pressure retreats to the east of the area tonight resulting in
the onset of low level warm advection. The WAA combined with large
scale ascent associated with a short wave digging through the
northern Plains is expected to produce a band/region of showers in
advance of the next cold front. Present indications are the
precipitation will remain just northwest of the CWA through
daybreak, centered from eastern IA into northwest MO. Developing
southerly flow tonight and increasing clouds will help keep
temperatures warmer than the chilly readings of early this morning.
Strong low level WAA and ascent with the digging short wave will
maintain a decent band/region of prefrontal showers spreading across
the area on Sunday in advance of the front. Current thinking is that
the increasing southerly flow will help push temperatures above
freezing before the onset of rain during the morning from northeast
MO into west central IL.  Precipitation should have exited the CWA
by late afternoon with the cold front progressing across the area
from the afternoon into the early evening. Weak surface high
pressure dominates Sunday night into Monday in the wake of the
front, with backing winds on Monday afternoon allowing temperatures
to warm back towards normal levels. Rather non-descript conditions
exist Tuesday into Wednesday as the flow aloft deamplifies and
another weak boundary flirts with the area. Despite this boundary,
warming low and mid levels should translate into warmer temperatures.

Confidence in forecast details diminishes quite a bit during the
later part of the week and beyond as there are some rather big
differences in the flow aloft in the deterministic models. For
late next week the main issue is the timing of a late week cold
front and associated precipitation chances.

Glass

&&

.AVIATION:  (For the 06z TAFs through 06z Saturday Night)
Issued at 1156 PM CDT Fri Mar 27 2015

Mid and high clouds have moved in ahead of shortwave which will
slide through region through mid morning. Best chances of light snow
will be over central MO and areas to the west, so kept mention in
KCOU taf between 09z and 14z Saturday with mvfr cigs/vsbys. Rest
of taf sites to remain vfr through forecast period, though a few
flurries not out of the question late tonight/early Saturday
morning. As for winds, to veer to the east then southeast then to
the south towards end of forecast period.

Specifics for KSTL:
Mid and high clouds have moved in ahead of shortwave which will
slide through region through mid morning. Best chances of light snow
will be over central MO and areas to the west. Metro area to
remain vfr through forecast period, though a few flurries not out
of the question late tonight/early Saturday morning. As for winds,
to veer to the southeast then to the south after 04z Sunday.

Byrd

&&

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

$$

WFO LSX






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