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000
FXUS63 KLSX 030253
AFDLSX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ST LOUIS MO
853 PM CST Sun Mar 2 2014

.UPDATE:
Issued at 853 PM CST Sun Mar 2 2014

Making updates to cancel winter weather advisories where the snow
has already stopped over central Missouri and south central Illinois.
There is some over southeastern Kansas and southwest Missouri, but
believe that this will staying mainly south of central Missouri.
In addition, very dry arctic air is undercutting the snow which
will likely hinder any additional accumulations. Main concern in
these areas will be wind chills later tonight.

Snow is ending from north to south this evening across the St. Louis
metro area as the dry air moves end. Additional sleet and snow is
expecting over southeast Missouri into southwest Illinois the rest
of night with this region expected receive 6+" of snow/sleet by
morning.

Britt

&&

.SHORT TERM:  (Through Late Tonight)
Issued at 401 PM CST Sun Mar 2 2014

A winter storm will continue to affect the region tonight. In
addition to fresh accumulating snowfall across southern MO/IL, wind
chill values will fall below -15 deg F late tonight and early Monday
morning across parts of central and northeast MO and west central IL
due to a combination of very cold ambient air temperatures and a
light breeze. A Wind Chill Advisory remains in effect for these
areas.

A band of light to moderate snow redeveloped during the afternoon
and lifted into northeast MO/west central IL. Locations which remain
beneath this band for several hours could pick up an additional 1-3
inches of snow before the band moves away from that area. Initial
thoughts are to let the Winter Weather Advisory for northeast MO
expire at 6pm, although some light snow might continue into the
early evening hours.

The upper level shortwave axis was located near the TX/NM border at
20z. Models are in good agreement that the shortwave will continue
shifting eastward then slightly southeastward with time, becoming
positively tilted by 03/12z. The greatest snowfall accumulations
tonight are expected to occur with the deformation zone accompanying
the shortwave. Based on extrapolating satellite and radar trends,
the deformation zone is likely to move over southern/southeastern MO
into southern IL and western KY. There is some uncertainty about the
northern extent of the deformation zone snow in MO and whether it
will clip the southern St. Louis metro area. We will continue the
Winter Storm Warning across the southern CWA for tonight`s expected
deformation zone snow.

As for the rest of the CWA, the Winter Storm Warning has already
verified in many locations due to the one-half inch of sleet
accumulation earlier today. Additional precipitation tonight is
expected based on upstream radar trends, but the new sleet and snow
accumulations probably won`t reach warning criteria over a
widespread area. In this particular situation, it`s a toss-up
between keeping the Winter Storm Warning (because it`s the same
event, which is ongoing and has already verified) or converting to a
Winter Weather Advisory (because the one-half inch of sleet has
already occurred and the new precipitation amounts are expected to
remain below warning criteria). We chose the latter because the
Winter Weather Advisory product more accurately portrays the
expected future weather.

The bitterly cold arctic airmass combined with sustained northerly
winds of 10-20 mph are already pushing wind chills to near advisory
criteria over our far northern counties (3pm on March 2nd???).
Sustained winds and continued temp drop should easily allow
wind chill values of around -15 to get as far south as a
JEF-Carlinville line by daybreak Monday...and current wind chill
advisory still looks quite good.

Kanofsky

.LONG TERM:  (Monday through Next Sunday)
Issued at 401 PM CST Sun Mar 2 2014

(Monday-Thursday)

Any lingering snowfall over southeast Missouri shortly after
daybreak should wind down quickly during the early morning
hours...leaving dry but almost crazy cold early March weather in its
wake.  Temperature trend on Monday should be an "interesting" battle
between the unseasonably cold airmass reinforced by the snow covered
ground, and the increasing sun angle of early March.  I`ve generally
gone with conditional climatology for max temps, which is about a 16
degree climb from morning lows.

A very slow warming trend will be the primary weather highlight
heading into midweek as the westward extension of the arctic high
will be reluctant to loosen its grip on the mid-Mississippi Valley,
and it looks like widespread highs in the 40s won`t arrive until
Thursday.  Min temps will also exhibit a slow moderation, and will
be very tricky as westward extension of ridge and existing snow
cover attempt to produce fairly large and atypical March diurnal
swings, with some of the radiational cooling at least partially
offset by some cloud cover.  For now have used all blend of guidance
for both max and mins, which is little change from going forecast.

With ridging and associated dry air remaining locked over the area,
will keep forecast dry at midweek, with only a few clouds expected
with passage of upper trof.

(Friday-Sunday)

There is general consensus in the medium range solutions that next
upper trof will begin to swing into the central CONUS by the end of
the week, with a chance of rain around Saturday.

Truett

&&

.AVIATION:  (For the 00z TAFs through 00z Monday Evening)
Issued at 556 PM CST Sun Mar 2 2014

Winter storm continues to impact areas along and south of the I-70
corridor. MVFR/IFR flight conditions in light snow will prevail in
these areas. Snow will clear from the west/northwest as the
system moves through the Mississippi Valley. Northerly wind around
15 kts with occasional gusts to 20-25kts will continue. After the
snow clears the area, expect VFR flight conditions to prevail.

Specifics for KSTL:

Lambert will be on the northern edge of the snow this evening.
Expecting drier air to work into the area between 02-03Z. Until
then, expect MVFR CIGs and VSBYs to prevail, with an occasional
dip to around 2SM VSBY. After 03Z, drier air should bring the snow
to an end and expect VFR flight conditions to prevail. North wind
around 15 kts with gusts up to 25 kts will continue overnight,
diminishing early Monday morning.

Carney

&&

.CLIMATE:
Issued at 351 PM CST Fri Feb 28 2014

Potentially historically cold arctic air moving into the area at
this time...with this cold air lingering into Tuesday.
Several records are in jeopardy of being broken at our three
official climate sites which can be seen below:

St. Louis, MO (1874-present):

Date    Record low              Record low maximum
3/2      2 (1980)                19 (1943)
3/3      1 (1943)                19 (2002)
3/4     -1 (1978)                15 (1960)

Columbia, MO (1890-present):

Date    Record low              Record low maximum
3/2     -5 (1890)                17 (1943)
3/3      1 (1900)                16 (2002)
3/4     -5 (1978)                12 (1960)

Quincy, IL (1901-present):

Date    Record low              Record low maximum
3/2     -2 (1980)                21 (1960)
3/3     -1 (1913)                14 (2002)
3/4     -8 (1978)                11 (1960)


&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...WINTER STORM WARNING until 6 AM CST Monday FOR Crawford MO-Iron
     MO-Jefferson MO-Madison MO-Reynolds MO-St. Francois MO-Ste.
     Genevieve MO-Washington MO.

     WIND CHILL ADVISORY until 10 AM CST Monday FOR Audrain MO-Boone
     MO-Callaway MO-Cole MO-Knox MO-Lewis MO-Lincoln MO-Marion
     MO-Moniteau MO-Monroe MO-Montgomery MO-Pike MO-Ralls MO-
     Shelby MO-Warren MO.

     WINTER WEATHER ADVISORY until 6 AM CST Monday FOR Franklin MO-
     Gasconade MO-Osage MO-St. Charles MO-St. Louis City MO-St.
     Louis MO-Warren MO.

IL...WINTER STORM WARNING until 6 AM CST Monday FOR Monroe IL-
     Randolph IL.

     WIND CHILL ADVISORY until 10 AM CST Monday FOR Adams IL-Brown IL-
     Calhoun IL-Greene IL-Jersey IL-Macoupin IL-Pike IL.

     WINTER WEATHER ADVISORY until 6 AM CST Monday FOR Bond IL-
     Clinton IL-Fayette IL-Madison IL-Marion IL-St. Clair IL-
     Washington IL.

&&

$$

WFO LSX