FXUS63 KLSX 231133
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
533 AM CST WED DEC 23 2009

.DISCUSSION...
/448 AM CST WED DEC 23 2009/

WAA SHRA WITH EMBEDDED TSRA ONGOING EARLY THIS MORNING INVOF 
QUASISTATIONARY BDRY STRETCHED ACROSS KS/MO/IL WITH MORE DISCRETE 
CONVECTION NOTED ACROSS NERN OK CLOSER TO THE SFC LOW. WFO LSX HAD 
ACCUMULATED 0.7 INCHES OF RAIN AS OF 10Z AFTER A FEW CONVECTIVE 
ELEMENTS PASSED DIRECTLY OVER THE OFFICE AND PROVIDED A FIRSTHAND 
LOOK AT THE MODERATE TO HEAVY RAINFALL RATES OCCURING ACROSS PARTS 
OF THE CWA. SREF/NAM/LOCAL WRF KEEP THIS BDRY NEARLY STATIONARY 
THROUGH THE MORNING WITH SOME NWD MOVEMENT BY AFTERNOON. TEMPS WILL 
CONTINUE RISING THROUGH THE DAY AND REMAIN NEARLY STEADY OVERNIGHT 
AS S-SELY WINDS TRANSPORT WARM AND MOIST AIR NWD. GIVEN THE OBSERVED 
DOWNPOURS OVER FROZEN GROUND EARLY THIS MORNING...HAVE CONTINUED THE 
GOING FLOOD WATCH. 

WATER VAPOR IMAGERY DEPICTS AN IMPRESSIVE STORM SYSTEM OVER THE SWRN 
US AND A SHORTWAVE IN CANADA OVER THE BC/AB BORDER. CANADIAN 
SHORTWAVE WAS POISED TO DROP SWD AND INTERACT WITH THE SRN SYSTEM 
/FUJIWHARA EFFECT/ BEFORE THE VORTICITY CENTERS MERGE OVER THE 
MIDWEST BY FRIDAY. WHILE MODELS HANDLE THESE SYSTEMS COMPARABLY...I 
HAVE TWO SIGNIFICANT CONCERNS WITH RESPECT TO SYSTEM EVOLUTION. 
FIRST...FLOW REMAINS BLOCKED OVER ERN CANADA WITH NO SIGNS OF 
DECREASED MOISTURE CONTRAST ON WATER VAPOR IMAGERY...SUGGESTING THAT 
BLOCKING WILL CONTINUE FOR THE NEAR FUTURE DESPITE PROGRESSIVE 
SOLUTION DEPICTED BY ECMWF/GFS/GEM/UKMET. SECOND...23/00Z GEM AND 
23/06Z GFS HAVE SHOWN A SEWD TREND WITH THE LOCATION OF THE SFC LOW 
AS COMPARED TO PREVIOUS RUNS. A MORE SEWD TRACK FOR THE SFC LOW 
WOULD RENEW CONCERNS FOR ACCUMULATION OF ADVISORY CRITERIA SNOWFALL 
AFTER THE HEAVY RAIN ENDS...ESPECIALLY IN WRN PARTS OF THE CWA. 
LATER SHIFTS WILL NEED TO MONITOR THESE TRENDS. THAT SAID...I STILL 
EXPECT RAIN TO CHANGE TO SNOW LATE TOMORROW NIGHT AS COLD AIR 
WRAPS AROUND THE BACK SIDE OF THE DEPARTING LOW. TIGHT PRESSURE 
GRADIENT WILL CREATE STRONG GUSTY WINDS THU NIGHT THROUGH FRI NIGHT. 
NO CHANGES MADE PAST 00Z SUN.

KANOFSKY

&&

.AVIATION...
/531 AM CST WED DEC 23 2009/

FOR THE 12Z TAFS...

IFR CEILINGS ALONG WITH -SHRA AND TSRA WILL CONTINUE TODAY AND
TONIGHT AS WARM ADVECTION CONTINUES IN VICINITY OF A WARM FRONT.
LIFR CONDITIONS TO REMAIN IN PLACE NORTH OF THE WARM FRONT ACROSS
NORTHERN MISSOURI. WIND TO REMAIN EAST-SOUTHEAST.

CVKING

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...FLOOD WATCH FROM NOON CST TODAY THROUGH THURSDAY AFTERNOON FOR 
     AUDRAIN-CRAWFORD-FRANKLIN-GASCONADE-IRON-JEFFERSON-KNOX-
     LEWIS-LINCOLN-MADISON-MARION-MONROE-MONTGOMERY-PIKE-RALLS-
     REYNOLDS-SHELBY-ST. CHARLES-ST. FRANCOIS-ST. LOUIS-ST. 
     LOUIS CITY-STE. GENEVIEVE-WARREN-WASHINGTON.

IL...FLOOD WATCH FROM NOON CST TODAY THROUGH THURSDAY AFTERNOON FOR 
     ADAMS IL-BOND IL-BROWN IL-CALHOUN IL-CLINTON IL-FAYETTE IL-
     GREENE IL-JERSEY IL-MACOUPIN IL-MADISON IL-MARION IL-MONROE 
     IL-MONTGOMERY IL-PIKE IL-RANDOLPH IL-ST. CLAIR IL-
     WASHINGTON IL.

&&

$$

WFO LSX