Issued by NWS Kansas City/Pleasant Hill, MO
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000 FXUS63 KEAX 231723 AFDEAX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 1123 AM CST MON NOV 23 2009 ...UPDATED AVIATION DISCUSSION... .DISCUSSION... IN THE SHORT TERM FAVOR THE NAM MASS FIELDS AS THE GFS IS TOO WET BELOW 800MB. IF ONE TOOK THE GFS AT FACE VALUE ALL OF MO WOULD BE CLOUDY RIGHT NOW...AND IT ISNT. MID CLOUDS HAVE PEELED OFF TO THE NORTH AS THE BETTER ISENTROPIC LIFT EXITS THE NORTHERN CWA. SO EXPECT TO SEE AT LEAST MORNING SUNSHINE. LOW CLOUD LOOP DOES SHOW QUITE A BIT OF STRATUS/FOG OVER CENTRAL KS WHICH IS TRENDING SLOWLY EAST. EXPECT SOME OF THIS MOISTURE TO MOVE EAST RESULTING IN SC/CU DEVELOPMENT BY LATE MORNING. ONE LAST DAY OF ABOVE NORMAL TEMPERATURES BEFORE REALITY SETS IN. ONLY MADE MINOR TWEAKS TO PREVIOUS MAX TEMPERATURE FORECAST PRIMARY ATTENTION WILL FOCUS ON THE EVOLUTION OF THE MUCH ADVERTISED UPSTREAM TROUGH. LATEST WATER VAPOR IMAGERY SHOWS UPPER TROF DIGGING INTO THE CENTRAL ROCKIES. DRYING IN WATER VAPOR IMAGERY OCCURRING NEAR THE 4-CORNERS SUGGESTS THE UPPER LEVEL SPEED MAX OF 90 KTS IS DROPPING INTO THE BASE OF THE TROUGH AND AIDING IN THE STRENGTHENING/DEEPENING PROCESS. 00Z GFS/ECMWF/SREF/GEM MODEL RUNS CONTINUED THEIR PAST TREND OF SHOWING VERY GOOD AGREEMENT BETWEEN MODELS AND RUN-TO-RUN CONSISTENCY. THE 00Z NAM HAD CONTINUED TO BE THE SLOW POKE AND OUTLIER MODEL WITH A MORE SOUTHERN TRACK. INTERESTING TO SEE THE 06Z NAM HAS SPED UP AND DECIDED TO JUMP ON THE BAND WAGON AND IS MUCH CLOSER TO THE OTHER MODELS. THIS GIVES MORE CONFIDENCE THAT THE UPPER LOW WILL TRACK CLOSE TO THE GFS/ECMWF PATH WHICH WILL TAKE IT INTO CENTRAL KS TONIGHT BEFORE LIFTING NORTHEAST THROUGH NW MO ON TUESDAY. LOW LEVEL MOISTURE CONTINUES TO BE A PROBLEM IN THE DOWNSTREAM ENVIRONMENT AND WILL LIKELY BE THE PRIMARY REASON FOR DELAYING THE ARRIVAL OF RAIN INTO THE CWA TONIGHT. SO HAVE LOWERED EVENING POPS BUT HIT THEM HARD AFTER MIDNIGHT...IN ESSENCE SHIFTING THE TIMING BY 3-6 HOURS. DID NOTICE THAT THE MODELS ARE DEVELOPING A SOUTHERLY LOW LEVEL JET LATE TONIGHT WHICH WILL AID IN TRANSPORTING ADDITIONAL MOISTURE FROM THE SOUTHERN PLAINS AS WELL AS INCREASING THE WARM AIR ADVECTION. 00Z GFS CONTINUES TO STEEPEN LAPSE RATES TONIGHT RESULTING IN MOST UNSTABLE CAPES OF 100-200 J/KG. THIS MAY BE ENOUGH FOR A FEW RUMBLES OF THUNDER TONIGHT. EXPECT A BLUSTERY DAY ON TUESDAY WITH A DRY SLOT LIKELY PUSHING THE RAIN OUT OF THE SOUTHERN CWA EARLY. NORTHERN 1/2 OF THE FORECAST AREA SHOULD SEE OFF AND ON RAIN WHILE WRAP AROUND CLOUDS/PATCHY RAIN ASSOCIATED WITH THE DEFORMATION ZONE SPREAD BACK INTO THE WESTERN CWA IN THE AFTERNOON. WILL NOT MENTION ANY SNOW IN THE CWA WITH THIS SYSTEM AS COLD AIR WILL NOT BE IN PLACE AND DYNAMIC COOLING WITHIN THE DEFORMATION CLOUD BAND MAY NOT BE SUFFICIENT FOR A CHANGE OVER TO SNOW. GFS/NAM WET BULB TEMPERATURES ONLY DROP INTO THE UPPER 30S WITHIN THE DEFORMATION ZONE. BETTER TO HOLD OFF ON ANY MENTION OF SNOW FOR NOW. BACKWASH CLOUDINESS AND MODERATELY STRONG COLD AIR ADVECTION WILL LIMIT WARMUP ON WEDNESDAY AND THEN A CLIPPER TYPE SYSTEM QUICKLY DIVES SOUTHEAST THROUGH THE NORTHERN PLAINS/MN WEDNESDAY NIGHT AND DISPLACES THE AFOREMENTIONED UPPER LOW AND SENDS A SHOT OF COLD CANADIAN AIR INTO THE REGION FOR THURSDAY. HAVE LOWERED MAX TEMPERATURES A BIT FOR WEDNESDAY AND THURSDAY. BULK OF ENERGY/LIFT/MOISTURE WITH THIS CLIPPER SYSTEM WILL MISS THE CWA AND FEEL NO NEED TO GO ANY HIGHER THAN SLIGHT CHANCE POPS FOR THE NORTHEAST PORTION OF THE CWA. MJ && .AVIATION... FOR THE 18Z TAFS...VFR CONDITIONS WILL CONTINUE THIS AFTN WITH THE MAIN CONCERN BEING TONIGHT. A STRONG UPPER LEVEL LOW PRESSURE SYSTEM WILL MOVE EAST INTO MISSOURI TONIGHT AND LIKELY PRODUCE RAIN AFTER MIDNIGHT. MOISTURE IS RATHER LIMITED AHEAD OF THIS SYSTEM...BUT STG FORCING SHOULD BE ABLE TO PRODUCE A PERIOD OF RAIN. THE SFC LOW AND ASSOCIATED SFC LOW WILL MOVE ACROSS NW MO AROUND SUNRISE. CIGS AND VSBYS WILL INITIALLY BE IN THE MVFR RANGE AHEAD OF THE LOW AND FRONT...BUT ONCE THE FRONT MOVES THROUGH...BETTER SATURATION WILL OCCUR AS TEMPS COOL. AS A RESULT...IFR CIGS ARE EXPECTED TO OCCUR BEGINNING A COUPLE OF HOURS AFT SUNRISE. DB && .EAX WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. && $$
