Area Forecast Discussion
Issued by NWS St. Louis, MO

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS63 KLSX 112116
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
316 PM CST THU FEB 11 2016

.SHORT TERM:  (Through Late Tonight)
Issued at 1230 PM CST Thu Feb 11 2016

A northwest flow shortwave now dropping southeastward into western
SD will move quickly through our area tonight.  Light snow will
spread southeastward into northeast MO early this evening, then
through the St Louis metro area around midnight.  Still looking like
a quick shot of dry, powdery snow with most places picking up to 1
inch of accumulation, but there may be a narrow band of 1-2 inches
extending from near IRK southeast through the St Louis metro area.
Latest NAM and HRRR model runs have the band a little further west
than previous model runs.  Most of the accumulating snow should
shift southeast of our forecast area by 12Z Friday.  Low
temperatures will be similar to the previous night, and around 5
degrees below normal.

GKS

.LONG TERM:  (Friday through Next Thursday)
Issued at 316 PM CST Thu Feb 11 2016

A strong cold front will move southeastward through our forecast
area on Friday with strengthening winds as the surface pressure
gradient tightens as a strong 1040-1045 mb surface high builds
southeastward into the area from the northern Plains behind the cold
front.  Temperatures may begin to fall in northeast MO behind the
front already by Friday afternoon.  Much colder temperatures are
expected for Friday night and Saturday with wind chills down to
around 10 below zero late Friday night and early Saturday morning
across northeast MO and west central IL.  Snow should spread
southeastward into at least northeast MO and west central IL late
Saturday night as low-mid level warm air advection increases ahead
of an approaching northern stream shortwave.  It still appears that
the ECMWF model is a little too quick bringing precipitation into
our forecast area already be Saturday afternoon and evening with an
initially very dry boundary layer on the backside of the surface
ridge. The better chance of precipitation should occur on Sunday as
a southwesterly low level jet brings increasing low level moisture
into our area ahead of the shortwave.  It is too early to pin down
exact snow totals, but it initially appears that 2-4 inches is
possible across northeast MO and west central IL with lesser amounts
of 1-2 inches further south for Saturday night and Sunday.  Another
round of precipitation is expected, mainly on Monday, as a southern
stream shortwave and associated surface low pass south of our area.
This precipitation should be confined mainly to southeast MO and
southwest IL.  With temperatures trending up as we head into the
next work week there may also be precipitation type issues with a
mix of snow, sleet and rain possible.  Will keep the rest of the
forecast dry with a warming trend, although the ECMWF model does
depict some weaker weather systems bringing a brief period or two of
light QPF to our area.  The GFS model is dry for the remainder of
the period after Monday with a dry cold frontal passage on Tuesday
afternoon and evening.  Both the GFS and ECMWF models depict a warm
weather pattern by Thursday with upper level ridging over the region
along with strong s-swly low level winds likely leading to well
above normal temperatures.

GKS

&&

.AVIATION:  (For the 18z TAFs through 18z Friday Afternoon)
Issued at 1237 PM CST Thu Feb 11 2016

SC has dissipated over taf sites, so will see VFR conditions
through early this evening as mid and high clouds stream in ahead
of next clipper system. Timing still similar to last set of tafs
with snow moving into KUIN/KCOU by 02z Friday and STL metro area
by 04z Friday. With onset of light snow, will see cigs dip down to
MVFR with brief IFR visbys as heavier bands of snow move through.
Snow to taper off between 09z and 10z Friday for taf sites, though
mvfr cigs to persist. KCOU on western periphery so should see
mvfr cigs scatter out by 16z Friday. As for winds, to remain from
the northeast to east as system moves through, then become light
and variable. By mid morning on Friday, winds to pickup from the
northwest.

Specifics for KSTL:
SC has dissipated over metro area, so will see VFR conditions
through early this evening as mid and high clouds stream in ahead
of next clipper system. Timing still similar to last set of tafs
with snow moving into STL metro area by 04z Friday. With onset of
light snow, will see cigs dip down to MVFR with brief IFR visbys
as heavier bands of snow move through. Snow to taper off by 10z
Friday, though mvfr cigs to persist for rest of taf forecast
period. As for winds, to remain from the northeast to east as
system moves through, then become light and variable by 10z Friday.
By 17z Friday, winds to pickup from the northwest around 10 kts.

Byrd

&&

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

$$

WFO LSX


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.