Issued by NWS Kansas City/Pleasant Hill, MO
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000 FXUS63 KEAX 231134 AFDEAX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 534 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 12 TAFS...VFR CONDITIONS ARE EXPECTED THROUGH MUCH OF THE VALID PERIOD. A SCATTERED VFR DECK WILL EXPAND EASTWARD FROM KANSAS THIS MORNING AND PERSIST AND GRADUALLY THICKEN THROUGH THE DAY. BY THIS EVENING BASES SHOULD LOWER AND CIGS SHOULD EVENTUALLY BECOME OVERCAST. STEEP MID-LEVEL LAPSE RATES SHOULD DEVELOP LATER THIS AFTERNOON AS AN UPPER LEVEL SYSTEM STARTS TO INFLUENCE THE AREA. AS ATMOSPHERE BEGINS TO SATURATE LAT THIS AFTERNOON/THIS EVENING MORE VERTICAL DEVELOPMENT IS LIKELY TO CLOUDS. HOWEVER WITH LACK OF ANY FOCUS UNTIL A COLD FRONT ENCROACHES UPON THE AREA TUESDAY MORNING THUNDERSTORM CHANCES AT ANY PARTICULAR POINT LOOK SMALL SO WILL NOT MENTION ANYTHING WITH THIS ISSUANCE. AS CIGS LOWER TOWARDS THE 06Z TIME FRAME SOME -RA OR DRIZZLE IS EXPECTED. WITH DECENT DEPTH TO SATURATION FELT IT MORE LIKELY TO BE -RAIN. REGARDLESS...AT THIS TIME WILL MENTION MVFR CIGS/VSBYS UNTIL CONFIDENCE INCREASES THAT IFR CONDITIONS WOULD PREVAIL. CDB && .EAX WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. && $$
