National Weather Service National Headquarters

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS63 KLSX 100538
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1138 PM CST TUE FEB 9 2010

.UPDATE...
/740 PM CST TUE FEB 9 2010/

NORTHWEST WIND HAS RELAXED A BIT AND DO NOT ANTICIPATE WIDESPREAD
BLOWING AND DRIFTING SNOW ACROSS THE CWA TONIGHT. EXPECTION MAY BE
ACROSS NORTHEAST MISSOURI AND WEST CENTRAL ILLINOIS WHERE 6 INCHES
OF SNOW FELL AND WINDS WILL REMAIN A BIT HIGHER. HAVE ALSO LIMITED
PRECIPITATION TO FLURRIES WITH ONLY A DUSTING OF FLUFF OCCURRING.
OTHERWISE...FORECAST ON TRACK WITH WARMING TEMPERATURES FROM THE
NORTHWEST THIS EVENING...DROPPING LATER TONIGHT ON A MORE TYPICAL
DIURNAL CURVE.

CVKING

&&

.DISCUSSION...
/355 PM CST TUE FEB 9 2010/

MAIN FORECAST FOCUS WILL BE SHORT-TERM CONCERNS TONIGHT AS WELL AS
THE BEGINNINGS OF A NEW MID LEVEL REGIME SETTLING IN FOR LATE WEEK.

SEVERAL ITEMS OF NOTE FOR TONIGHT. TEMP ROLLER COASTER HAS HIT ITS
DOWNWARD SWING AS LO LEVEL CAA HAS MAXED OUT AND MOVED E...WITH AREA
OF STRONG WAA NOW MOVING IN FROM THE NW. THIS WILL RESULT IN RISING
TEMPS THRU THE EVENING HOURS BEFORE NORMAL DIURNAL TRENDS TAKE OVER.
INTENSE COLD AIR WAS FOUND AT THE SFC EARLY THIS MORNING DISPLACED
JUST TO THE N OF THE STACKED LO AND THIS HAS SINCE TRANSLATED EWD
WITH THE STACKED LO THRU THE NRN FA. SO WRAPPED UP IS THIS LO THAT
WARM AIR HAS MOVED ALL AROUND IT ON ITS NRN FLANK AND WILL GIVE US
OUR TEMP RECOVERY AFTER SS.

TWO MAIN AREAS OF SHSN...ONE IS BEING DRIVEN BY POWERFUL VORT MAX
LOCATED AT THE HEART OF THE STACKED LO THAT WILL BE SE OF THE FA BY
00Z. THE OTHER IS HIGHLY WRAPPED UP LEFTOVERS OF THE DEFORMATION
ZONE PCPN THAT WILL TAKE A FINAL SWING THRU MAINLY THE NERN FA...OR
AREAS N AND E OF KSTL...THIS EVENING. MINOR ADDITIONAL SNOW ACCUMS
OF HALF INCH OR LESS ARE POSSIBLE.

GUSTY NWLY SFC WNDS WILL CONTINUE THRU THE NIGHT...WITH GUSTS AS HI
AS 30 MPH...AND THIS WILL CREATE CONTD AREAS OF BLSN WITH REDUCED
VSBYS AT TIMES. SFC WNDS AND BLSN MAY BE A FACTOR INTO WED MRNG...
BUT BELIEVE REDUCTION OF VSBYS WILL BE MUCH LESS AND HAVE LEFT OUT
OF FCST.

OTRW...GENERALLY FOLLOWED A BELOW NORMAL TEMP FCST WITH DRY CONDS
THRU THURSDAY NIGHT. THE COLDEST MORNING STILL SET FOR EARLY
THURSDAY MORNING AS SFC HI PRES RIDGE IS OVERLAYED WITH MOCLR SKIES.
WENT SEVERAL DEGS BELOW THE COLDEST MOS...EXCEPT TEMPERED IT IN THE
SWRN FA WHERE MID AND HI CLOUDS WILL HAVE MOVED IN BY 12Z/THU.

BY FRIDAY WE WILL SEE THE FIRST OF SEVERAL CLIPPER SYSTEMS THANKS TO
LONGWAVE H500 TROF THAT IS CURRENTLY BEING CARVED OUT BY POWERFUL
WINTER STORM HEADING E. HAVE INTRODUCED POPS...NOT FROM ANY
INFLUENCE OF THE SRN BRANCH AS ORIGINALLY THOUGHT POSSIBLE...BUT
FROM THE NRN CLIPPER. MINOR SNOW AMNTS OF AN INCH OR LESS POSSIBLE
AT THIS TIME.

FOR THE EXTENDED PERIOD (FRIDAY NIGHT - TUESDAY)...DECENT MODEL
CONSENSUS CONTINUES TO ADVERTISE A PROLONGED PERIOD OF NWLY FLOW AT
THE MID LEVELS WHICH WILL EFFECTIVELY KEEP US IN A BLO NORMAL TEMP
WITH INTERMITTENT CLIPPER SYSTEMS REGIME DURING MUCH OF THIS PERIOD.
ENOUGH OF A MODEL SIGNAL NOW...WITH THE 00Z/06Z GFS BEING THE MAIN
OUTLIER...12Z GFS LESS SO...TO NOW INCLUDE LOW CHC POPS AND FLURRIES
MENTION IN THE FORECAST FOR THE PERIOD FROM FRI NGT THRU SUNDAY.
POTENTIAL SNOW AMOUNTS LOOK TO BE LIGHT...BUT OVER A PROLONGED TIME
THESE COULD ADD UP. LOOK FOR A SLOWLY INCRSG INFLUENCE OF A CANADIAN
HI PRES HEADING INTO EARLY NEXT WEEK. SOME MODELS ARE ADVERTISING
YET ANOTHER SHORTWAVE CLIPPER LATE ON TUESDAY...BUT WILL AWAIT
BETTER CONSENSUS BEFORE INCORPORATING THIS INTO THE FORECAST.

TES

&&

.AVIATION...
/1128 PM CST TUE FEB 9 2010/

KSTL...CIGS CONTINUE TO BE THE REAL QUESTION FOR THE REST OF THE
NIGHT. STILL SEEING CIGS BTWN 1500-1900FT ACROSS PORTIONS OF
NORTHEAST MO/WEST CENTRAL IL WHICH COULD ROTATE DOWN ACROSS THE
TERMINAL. BUT MY CONFIDENCE LEVEL IS NOT HIGH ENOUGH TO INCLUDE
IN THE TAF AT THIS TIME. ALSO...TIMING THE EVENTUAL SCATTERING OUT
WEDNESDAY MORNING IS TOUGH. MOVED IT BACK A FEW HOURS SINCE THE
CLEARING LINE IS NOT MOVING VERY FAST THRU SOUTHEAST IOWA...AND
THIS MAY YET BE TOO OPTIMISTIC.

FOR THE REMAINING AREA...SCATTERED LIGHT SNOW OR FLURRIES WILL
CONTINUE...MAINLY ALONG AND SOUTH OF THE I-70 CORRIDOR FOR MUCH OF
THE REST OF THE NIGHT. VSBYS COULD BRIEFLY DIP INTO MVFR RANGE IN
SOUTHEAST MO OVER THE NEXT FEW HOURS...BUT VFR VSBYS SHOULD
PREVAIL. NOTICED A DIP INTO IFR CIG RANGE AT KUUV THIS HOUR. THIS
IS THE ONLY IFR CIG I`VE NOTICED IN THE BI-STATE REGION ALL
NIGHT...SO I THINK THIS IS ASSOCIATED WITH AN ISOLATED HEAVIER SNOW
SHOWER AND SHOULD BE VERY BRIEF. MAJORITY OF THE AREA SHOULD
PREVAIL 2000-3000FT CIGS WITH INTERMITTENT DIPS TO BETWEEN
1500-1900FT ESPECIALLY OVER NORTHEAST MO/WEST CENTRAL IL UNTIL THE
CIGS SCATTER OUT. WEST-NORTHWEST WINDS WILL BE GRADUALLY CALMING
DOWN THRU THE FORECAST PERIOD.

CARNEY

&&

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

$$

WFO LSX