958
FXUS63 KLSX 090914
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
314 AM CST TUE FEB 9 2010
DISCUSSION
/300 AM CST TUE FEB 9 2010/
SNOW BEGINNING TO TAPER OFF OVER THE WRN PTN OF THE CWA AS DRY
SLOT AND CLEARING MOVING EWD INTO THE WRN EDGE OF THE CWA. MOST OF
THE ACCUMULATING SNOW SHOULD PUSH E OF THE CWA BY 12Z TUE. MAY
STILL HAVE A LITTLE LEFT OVER SNOW OVER FAR ERN OR SERN COUNTIES
DURING THE EARLY MRNG HOURS. DEEP MID LVL LOW WAS CURRENTLY OVER
ERN NEBRASKA WRN IA. THIS FEATURE WILL DROP SEWD THRU NERN MO THIS
MRNG AND THRU SRN IL THIS AFTN. SCT SNOW SHOWERS ARE EXPECTED IN
THE VICINITY OF THIS MID LVL LOW DUE TO COLD MID LVL TEMPS AND
STEEP LAPSE RATES FROM LATE THIS MRNG UNTIL EARLY THIS EVNG. THE
BEST COVERAGE OF THESE SNOW SHOWERS SHOULD BE OVER THE NRN AND
NERN PTN OF THE CWA. BLOWING AND DRIFTING SNOW IS ALSO FCST TDA
INTO THIS EVNG AS THE NWLY SFC WNDS STRENGTHEN AND BECOME GUSTY
DUE TO THE TIGHTENING SFC PRESSURE GRADIENT OVER THE CWA BETWEEN
THE DVLPG SFC LOW OVER THE OH VALLEY AND THE STRONG SFC RDG OVER
THE PLAINS. COLD TEMPERATURES CAN BE EXPECTED TDA WITH TEMPS
FALLING THIS MRNG FROM STL S AND E AS AN ARCTIC CDFNT MOVES SEWD
THRU THE REST OF THE CWA. ALTHOUGH THE CLEARING LINE WAS MOVING
EWD THRU WRN MO...MORE LOW LEVEL CLOUDINESS WILL DROP SEWD THRU
THE CWA LATER THIS MRNG INTO THE AFTN HOURS. MODELS ARE ALSO
FORECASTING VERY COLD 850 MB TEMPS ACROSS THE CWA OF ONLY -16 DGRS
C AT 18Z TUE NEAR THE MID LVL LOW CENTER. WILL CONTINUE THE WINTER
WEATHER ADVISORY OVER NERN MO AND W CNTRL IL AND A PORTION OF
SWRN IL DUE TO ADDITIONAL ACCUMULATING SNOW GENERALLY AROUND ONE
INCH PLUS BLOWING SNOW REDUCING VSBYS TDA. MAY STILL HAVE A FEW
SNOW SHOWERS OVER THE ERN PTN OF THE CWA THIS EVNG BUT THESE
SHOULD END BY LATE TGT WITH JUST A FEW FLURRIES LEFT. WILL FCST
TEMPS BELOW MOS GUIDANCE TDA THRU WED NGT DUE TO NEW SNOW COVER.
THE LOW LEVEL CLOUD COVER SHOULD CLEAR OUT WED MRNG AS A LARGE N-S
SFC RDG MOVES EWD INTO THE AREA FROM THE PLAINS...AND THE MID-UPR
LEVEL TROF MOVES WELL E OF THE AREA. TRANQUIL AND COLD WEATHER FOR
WED THRU THU NGT AS THIS SFC RDG MOVES EWD THRU THE CWA. THE
MODELS FORECAST A SRN STREAM SHRTWV TROF TO MOVE WELL S OF THE
AREA THU THRU FRI AND IT APPEARS THAT ANY SNOW FROM THIS FEATURE
WILL REMAIN S OF THE CWA. THE GFS MODEL BRINGS SNOW INTO THE AREA
ON FRI AHEAD OF A RELATIVELY STRONG NRN STREAM...NW FLOW SHRTWV
TROF BUT THIS SOLUTION DOES NOT SEEM TO BE SUPPORTED BY ANY OF
THE OTHER MODELS.
GKS
AVIATION
/1135 PM CST MON FEB 8 2010/
KSTL...SEEING AT LEAST A COUPLE OF ADDITIONAL SNOW BANDS ON RADAR
WEST OF KSTL WHICH SHOULD BE AFFECTING THE TERMINAL OVER THE NEXT
4 HOURS OR SO. COULD SEE VSBYS DROP TO 1SM OR LESS IN THE HEAVIEST
SNOW. BLOWING SNOW COULD BE A PROBLEM AFTER FROPA THIS
MORNING...THO I'M NOT CONFIDENT THAT WILL CAUSE SIGNIFICANT VSBY
TROUBLES AT LAMBERT SO HAVE LEFT OUT OF TAF FOR NOW. SCATTERED
SNOW SHOWERS LOOK PRETTY LIKELY THIS AFTERNOON...BUT DECIDED TO
COVER WITH VCSH IN TAF AT THIS TIME BECAUSE I'M NOT CERTAIN HOW
LOW TO GO IN THE SHOWERS.
FOR THE REMAINING AREA...LIGHT SNOW WILL CONTINUE OVER CENTRAL AND
NORTHEAST MO FOR THE NEXT FEW HOURS BEFORE THE SKY CLEARS OUT
BRIEFLY THIS MORNING. COLD AIR STRATO-CU WILL THEN FORM DURING THE
MID MORNING AND I EXPECT SCATTERED SNOW SHOWERS TO DEVELOP. EAST
OF THE MISSISSIPPI RIVER...SNOW REDUCING VSBYS TO 1-2SM WILL
CONTINUE THRU THE REST OF THE NIGHT. I THINK CLEARING WILL BE
LIMITED (IF ANY) THIS MORNING BEFORE WE SEE THE LATE
MORNING/AFTERNOON SNOW SHOWERS REDEVELOP. GUSTY WINDS UP AROUND
30KTS WILL BE POSSIBLE THRU THE DAY.
CARNEY
LSX WATCHES/WARNINGS/ADVISORIES
MO...WINTER WEATHER ADVISORY UNTIL 6 AM CST EARLY THIS MORNING FOR
AUDRAIN-BOONE-CALLAWAY-COLE-CRAWFORD-FRANKLIN-GASCONADE-
IRON-JEFFERSON-LINCOLN-MADISON-MONITEAU-MONROE-MONTGOMERY-
OSAGE-PIKE-RALLS-REYNOLDS-ST. CHARLES-ST. FRANCOIS-ST.
LOUIS-ST. LOUIS CITY-STE. GENEVIEVE-WARREN-WASHINGTON.
WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR KNOX-
LEWIS-MARION-SHELBY.
IL...WINTER WEATHER ADVISORY UNTIL 6 AM CST EARLY THIS MORNING FOR
CALHOUN IL-JERSEY IL-MADISON IL-MONROE IL-RANDOLPH IL-ST.
CLAIR IL.
WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR ADAMS IL-
BOND IL-BROWN IL-CLINTON IL-FAYETTE IL-GREENE IL-MACOUPIN
IL-MARION IL-MONTGOMERY IL-PIKE IL-WASHINGTON IL.
WFO LSX
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