086 FXUS63 KLSX 050016 AFDLSX AREA FORECAST DISCUSSION...UPDATED AVIATION NATIONAL WEATHER SERVICE ST LOUIS MO 616 PM CST MON FEB 4 2013 .SHORT TERM... ISSUED AT 303 PM CST MON FEB 4 2013 (TONIGHT) COLD FRONT STILL OVER FORECAST AREA AS OF 20Z...MAINLY ALONG AND SOUTH OF PARIS ILLINOIS TO SPRINGFIELD MO LINE. SO COLDER AIR AND SC DECK IS SLOW TO MOVE INTO NORTHERN PORTIONS OF FORECAST AREA. THUS TEMPS HAVE WARMED UP A BIT MORE THAN ORIGINALLY FORECAST...SO ADJUSTED HOURLY TEMPS FOR THE EVENING HOURS. OTHERWISE...SURFACE RIDGE TO BUILD IN OVERNIGHT WITH TEMPS DROPPING INTO THE 20S. CURRENT SATELLITE PICS SHOW THAT SC DECK THAT IS MOVING INTO NORTHERN PORTIONS OF FORECAST AREA IS A BIT DIURNALLY DRIVEN...WITH IT THINNING OUT A BIT QUICKER...BUT HIGH CLOUDS CONTINUE TO STREAM SOUTHEAST TOWARDS FORECAST AREA...SO WILL LEAVE SKIES PARTLY TO MOSTLY CLOUDY OVERNIGHT. RAIN THAT HAD DEVELOPED OVER SOUTHERN MO/SOUTHERN IL EARLIER TODAY HAS MOVED AWAY FROM FORECAST AREA...SO SHOULD SEE DRY CONDITIONS TONIGHT. BYRD && .LONG TERM... ISSUED AT 303 PM CST MON FEB 4 2013 (TUESDAY-THURSDAY) NO MAJOR CHANGES TO GOING FORECAST AS 12Z GUIDANCE IS MAINTAINING GOOD RUN TO RUN AND MODEL TO MODEL CONSISTENCY WITH UPCOMING SYNOPTIC TRENDS OVER THE CENTRAL CONUS...AND TRANSITION OF UA PATTERN TO ZONAL FLOW LOOK BY MIDWEEK. THERE ARE TWO SHORTWAVES THAT ARE PROGGED INTO THE REGION DURING THE SHORT TERM. THE FIRST WILL BE PASSING TO OUR N TOMORROW...AND WHILE IT MAY BRING A FEW CLOUDS TO N SECTIONS OF THE CWA PRECIP THREAT WITH THIS FEATURE SHOULD REMAIN WELL TO OUR N. HOWEVER...THE DYNAMICS ASSOCIATED WITH THE NEXT SHORTWAVE SHOULD PASS DIRECTLY OVER OUR AREA LATE WEDNESDAY NIGHT AND THURSDAY BRINGING THE ENTIRE AREA A THREAT OF SHOWERS. MODELS HAVE DEVIATED VERY LITTLE WITH THE SPEED OR INTENSITY OF THIS SYSTEM...SO WITH THE PROGGED MOISTURE RETURN HIGH CHANCE/LOW LIKELY POPS STILL SEEM REASONABLE. NAM LOOKS A BIT FAST WITH THE EWD PROGRESSION OF THE PRECIP ACROSS THE AREA...AND HAVE FOLLOWED THE SOMEWHAT SLOWER TREND WHICH IS MORE IN LINE WITH MODEL CONSENSUS AND ENSEMBLE MEANS. AS CAN BE SEEN BY THE TEMPERATURE TRENDS OF THE PAST FEW DAYS AND NIGHTS...AND ESPECIALLY TODAY...THE PASSAGE OF EACH SHORTWAVE HAS BROUGHT ABOUT FAIRLY DRAMATIC AMS CHANGES TO THE REGION. AND WHILE THE NEXT TWO SHORTWAVES WILL ALSO BRING SOME SWINGS IN TEMPS...THE TRANSITION TO A MORE ZONAL FLOW PATERRN WILL MEAN THAT THE PENETRATION OF THE COLD AIR BEHIND EACH SHORTWAVE WILL BE MUCH LESS DRAMATIC....AND OVERALL TEMPERATURES WILL BE TRENDING ABOVE AVERAGE. (FRIDAY-MONDAY) MAIN CONCERN IN THE MEDIUM RANGE CONTINUES TO BE LARGE STORM SYSTEM THAT IS PROGGED TO WORK FROM THE WESTERN U.S. INTO THE NATIONS MIDSECTION DURING THE WEEKEND. MODELS CONTINUE TO TREND A BIT SLOWER WITH EWD PROGRESSION OF THIS SYSTEM SO WILL KEEP SATURDAY DRY...AND ALLOW SHOWERS AND THUNDERSTORM TO OVERSPREAD THE REGION SATURDAY NIGHT AND SUNDAY. AMS AHEAD OF THIS SYSTEM WILL BE MODERATING NICELY...AND HAVEN'T GONE WARMER DURING THE WEEKEND DUE TO INCREASING CLOUDS ON SATURDAY...AND RAIN THREAT ON SUNDAY. TRUETT && .AVIATION... ISSUED AT 546 PM CST MON FEB 4 2013 COLD FRONT HAS MOVED SE OF THE TAF SITES EARLY THIS EVNG WITH N-NWLY SFC WINDS AS THE SFC RIDGE EXTENDING FROM NERN KS NE THROUGH WI BUILDS SEWD INTO OUR AREA. THE SFC WIND WILL BECOME LIGHT LATER THIS EVNG AND INTO THE OVERNIGHT HOURS AS THE SFC RIDGE AXIS SHIFTS SWD THROUGH OUR AREA. THE SFC WIND WILL BECOME S-SWLY BY EARLY TUE MRNG AS THE SFC RIDGE WEAKENS AND SHIFTS S-SE OF OUR AREA AND A COLD FRONT APPROACHES. THE SFC WIND WILL VEER AROUND TO A NWLY DIRECTION TUE AFTN AFTER FROPA. A BAND OF MVFR CLOUDS AROUND 1500-2000 FT IN HEIGHT OVER NERN MO W CNTRL IL WILL ADVECT SEWD INTO THE ST LOUIS METRO AREA LATER THIS EVNG. MORE PATCHY MVFR CLOUDS ACROSS NWRN MO MAY ALSO IMPACT COU AS WELL. THESE MVFR CLOUDS SHOULD ADVECT SE OF UIN AND COU LATE TGT AND SE OF THE ST LOUIS METRO AREA EARLY TUE MRNG LEAVING JUST SOME MID-HIGH LEVEL CLOUDS OVER THE AREA. SPECIFICS FOR KSTL...BAND OF MVFR CIGS...AT 1500-2000 FT SHOULD ADVECT SEWD INTO STL AROUND 0130-0200Z TUE. WITH A NOCTURNAL INVERSION THESE CLOUDS MAY NOT SCATTER OUT TIL EARLY TUE MRNG. OTHERWISE JUST MID-HIGH LEVEL CLOUDS FOR LATE TGT AND TUE. N-NWLY SFC WIND WILL WEAKEN THIS EVNG AS THE SFC RIDGE MOVES SEWD THROUGH OUR AREA...THEN BECOMES SWLY TUE MRNG AND STRENGTHENS AS THE SFC RIDGE SHIFTS SE OF STL AND A COLD FRONT APPROACHES. THE SFC WIND WILL VEER AROUND TO A NWLY DIRECTION BY LATE TUE AFTN AFTER FROPA... THEN DIMINISHES TUE EVNG. GKS && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX