000 FXUS63 KEAX 201734 AFDEAX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 1234 PM CDT THU SEP 20 2007 ...UPDATED AVIATION DISCUSSION... .DISCUSSION... /ISSUED 341 AM CDT THU SEP 20 2007/ THE FRONT THAT STALLED ACROSS NORTHERN MISSOURI WEDNESDAY...FROM KANSAS CITY TO MACON...HAS SLOWLY SETTLED SOUTH TO RESIDE ALONG A LINE ROUGHLY FROM COLUMBIA THROUGH HARRISONVILLE. TO OUR WEST THE TROUGH IS RELOADING AS A CUTOFF LOW DIGS ITS WAY SOUTH OVER CALIFORNIA. THIS HAS KEPT THE SOUTHWEST FLOW ANCHORED ACROSS THE CENTRAL PLAINS...THOUGH FOR MISSOURI AND EASTERN KANSAS RIDGING ACTION HAS LEFT US UNDER A FAIRLY WEAK FLOW ALOFT AS THE STRONGER WESTERLIES HAVE BEEN SHIFTED NORTH. CONVECTION THAT LINGERED INTO THE OVERNIGHT HOURS FROM YESTERDAY HAS COME TO AN END ACROSS OUR PORTION OF EASTERN KANSAS AND MISSOURI THIS MORNING. HOWEVER...A LITTLE FARTHER WEST ISOLATED THUNDERSTORMS CONTINUE TO PERCOLATE ALONG THANKS TO THE WARM AIR ADVECTION DUE TO THE SHORTWAVE RIDGING THAT IS MOVING INTO THE PLAINS. FARTHER EAST...BACK OVER MISSOURI...THE PROFILER NETWORK SHOWS US THAT THE SKIES ABOVE US ARE A MUCH LESS CONDUSIVE ENVIRONMENT FOR THESE STORMS AS H8 WINDS VEER QUICKLY AROUND TO THE NORTH. THEREFORE... WHILE THERE MIGHT BE SUFFICIENT MOISTURE IN THE UNCAPPED AIRMASS ACROSS THE FORECAST AREA FOR SOME SHOWERS OR THUNDERSTORMS... THOUGHTS ARE THAT ANY CONVECTION TODAY WILL NEED TO WAIT FOR THE AFTERNOON HEATING TO GET GOING. ADD TO THIS THAT THERE IS NO UPPER LEVEL SUPPORT IN THE WEAK WINDS ALOFT. THEREFORE...HAVE TRIMMED TODAYS POPS BACK LEAVING ONLY ISOLATED THUNDERSTORM CHANCES IN THE AFTERNOON HOURS. FRIDAY WILL SEE ANOTHER SMALL CHANCE OF THUNDERSTORM ACTIVITY MOVE BACK INTO REGION AS A COLD FRONT SWEEPS SOUTH THROUGH THE NORTHERN PLAINS. THIS FRONT WILL BE THE END RESULT OF A SHORTWAVE...CURRENTLY IN ALBERTA...MOVING EAST THROUGH SOUTHERN CANADA. GFS AND NAM-WRF HAVING A BIT OF A DISAGREEMENT ON HOW FAR THE SOUTH THE FRONT WILL MOVE THROUGH THE PLAINS FRIDAY AND SATURDAY. GFS HAS BEEN THE MUCH MORE CONSISTENT MODEL...HANGING THE FRONT JUST SOUTH OF THE IOWA BORDER FRIDAY NIGHT...WHILE THE NAM-WRF PLUNGES IT ALL THE WAY INTO FAR SOUTHERN MISSOURI. THE SOLUTION OFFERED BY THE GFS IS PREFERRED AS THE NAM-WRF LOOKS FAR TOO AGGRESSIVE GIVEN THE EASTWARD MOVEMENT OF THE FRONTS UPPER LEVEL SUPPORT...AND THE SHORTWAVE RIDGING THAT WILL BE OCCURRING ACROSS THE PLAINS. KEPT SOME SLIGHT CHANCE POPS IN THE FRIDAY AFTERNOON/EVENING HOURS ACROSS FAR NORTHERN MISSOURI DUE TO THE LACK OF CAP AS THE FRONT MOVES IN. BUT...THE LACK OF ANY KIND OF UPPER LEVEL SUPPORT SPEAKS TO...AT BEST...AN ISOLATED POTENTIAL FOR THUNDERSTORMS DURING AND JUST AFTER THE PEEK HEATING HOURS OF THE AFTERNOON. SO...AS WE LOSE THE STEEP LOW LEVEL LAPSE RATES DURING THE EVENING...SO WILL WE LOSE OUR CHANCE OF STORMS. OTHERWISE...KEPT TEMPERATURES RANGING NEAR MAV GUIDANCE NUMBERS AS THOSE OFFERED BY THE MET SEEMED A BIT COOL. CUTTER && .AVIATION... AFTERNOON CU BEGINNING TO BUBBLE AS OF TAF ISSUANCE TIME AND WILL LIKELY SEE A FEW STORMS POP UP LATER THIS AFTERNOON WITHIN WEAKLY CAPPED AIR MASS. HANDLED THIS WITH CB GROUPING IN THE TAFS AS COVERAGE WILL LIKELY BE VERY SPOTTY. OTHERWISE...MAY SEE SOME LIGHT HINDRANCE TO VIS TOWARDS THE MORNING HOURS...MORE SO NEAR THE MORE PROTECTED KSTJ AS STEADY SFC WINDS WILL KEEP BR THINNER NEAR KMCI AND KMKC. DEROCHE && .EAX WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. $$