602 FXUS63 KLSX 282101 AFDLSX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ST LOUIS MO 301 PM CST SAT JAN 28 2012 .DISCUSSION... /252 PM CST SAT JAN 28 2012/ A RELATIVELY BENIGN WEATHER PATTERN WILL PERSIST ACROSS THE REGION OVER THE NEXT FEW DAYS. A SHORT WAVE WILL DIG THROUGH THE UPPER MIDWEST BRINGING ANOTHER REINFORCING COOL SHOT TO THE AREA. THIS COLD FRONT WILL ENTER THE NORTHERN PORTION OF THE CWA TONIGHT AND THEN PROGRESS THROUGH THE REMAINDER OF THE CWA ON SUNDAY MORNING. WARM ADVECTION AHEAD OF THE COLD FRONT TONIGHT WILL MAKE LOWS A LITTLE TRICKY AND WENT A TAD ABOVE MOS AT ALL LOCATIONS EXPECT FOR THE RESIDUAL SNOW COVER IN FAR NE MO AND WEST CENTRAL IL. THE COOL AIR SHOT WITH THIS FRONT WILL BE SHORT LIVED WITH RETURN SOUTHERLY FLOW AND WARM AIR ADVECTION GETTING UNDERWAY BY SUNDAY EVENING. AND EVEN THE COOL AIR IS NOT ALL THAT COOL WITH TEMPERATURES NEAR AND ABOVE SEASONAL AVERAGE FOR SUNDAY. LOW LEVEL WARM AIR ADVECTION WILL KICK INTO FULL GEAR ON MONDAY WITH S-SWLY LOWER TROPOSPHERIC FLOW AND H85 TEMPS RISING TO +7 TO +9 DEGC. THIS SHOULD TRANSLATE TO A BIG WARM-UP ON MONDAY WITH HIGHS SOME 20 DEGREES OR SO ABOVE AVERAGE. WE WILL HAVE TO KEEP AN EYE ON FIRE WEATHER CONCERNS DURING THE AFTERNOON...ESPECIALLY IF FUEL MOISTURE VALUES ARE LOW. THE ABOVE AVERAGE TEMPERATURES SHOULD PERSIST INTO TUESDAY BUT THERE IS LESS CONFIDENCE IN HOW WARM TEMPERATURES WILL GET. ALL OF THE MODELS SHOW A TREMENDOUS RETURN SURGE OF LOW LEVEL MOISTURE LATE MONDAY NIGHT AND ESPECIALLY INTO TUESDAY...WITH RH LEVELS IN THE LOWEST SEVERAL KM IN THE 90-100 PERCENT RANGE BY AFTERNOON. THIS MOIST LAYER IS CAPPED BY VERY LOW MID LEVEL RH VALUES AND WEAK ASCENT TUESDAY AFTERNOON AND NIGHT AHEAD OF THE NEXT ADVANCING COLD FRONT. THE STRATIFICATION WOULD BE SUGGESTIVE OF A CHANCE OF VERY LIGHT RAIN OR DRIZZLE. WE CURRENTLY HAVE SILENT 20 POPS IN THE FORECAST ON TUESDAY INCREASING INTO THE CHANCE RANGE ON TUESDAY NIGHT. THESE LOOK ACCEPTABLE RIGHT NOW BUT MAY NEED TO ADD THE MENTION OF DRIZZLE IN FUTURE FORECASTS. THE ABOVE AVERAGE TEMPERATURES SHOULD PERSIST THROUGH WEDNESDAY BUT THEREAFTER FROM THURSDAY INTO THE WEEKEND A GREAT DEAL OF UNCERTAINTY EXISTS. THERE IS VERY LOW CONFIDENCE IN THIS LONGER RANGE PERIOD DUE TO A LACK OF RUN TO RUN MODEL CONTINUITY AND LARGE MODEL TO MODEL VARIABILITY. IT SEEMS THE MODELS WANT TO DEVELOP A LARGE CLOSED UPPER LOW SOMEWHERE OVER THE WESTERN TW0-THIRDS OF THE NATION BUT THE POSITIONS VARY BY AROUND 1000 MILES. GLASS && .AVIATION... /1119 AM CST SAT JAN 28 2012/ VFR FLIGHT CONDITIONS AND WEST-SOUTHWEST FLOW WILL PREVAIL ACROSS THE BI-STATE REGION. SOME MODERATE GUSTS IN THE 20-25KT RANGE ARE POSSIBLE THIS AFTERNOON. THE WIND WILL BACK TO THE SOUTHWEST AND DIMINISH THIS EVENING. WIND WILL INCREASE WITH HEIGHT TO 30-35KTS BUT SHOULD DO SO GRADUALLY ENOUGH THAT LLWS WILL BE MARGINAL. WIND WILL VEER BACK TO A WESTERLY DIRECTION EARLY SUNDAY MORNING AS ANOTHER COLD FRONT PASSES THROUGH THE AREA. VFR CONDITIONS WILL CONTINUE WITH NO PRECIP ASSOCIATED WITH THE FRONT. SPECIFICS FOR KSTL... VFR FLIGHT CONDITIONS AND WEST-SOUTHWEST WIND WILL CONTINUE TO PREVAIL AT LAMBERT. COULD SEE SOME GUSTS TO AROUND 20KTS THIS AFTERNOON...BUT ANY GUSTINESS WILL SUBSIDE AROUND SUNSET AND THE WIND WILL BACK TO A SOUTHWESTERLY DIRECTION. WIND WILL INCREASE AND VEER WITH HEIGHT TO AROUND 35KTS AT 1000FT...BUT THE CHANGE SHOULD BE GRADUAL ENOUGH SO LLWS WILL BE MARGINAL. WIND WILL VEER BACK TO A WESTERLY DIRECTION SUNDAY MORNING BEHIND ANOTHER WEAK COLD FRONT. VFR FLIGHT CONDITIONS AND DRY WEATHER WILL CONTINUE TO PREVAIL BEHIND THE FRONT. CARNEY && .CLIMATE... RECORD HIGHS FOR MONDAY JANUARY 30TH KSTL 67 IN 1884 KCOU 68 IN 1890 && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX