449 FXUS63 KLSX 260556 AFDLSX AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE ST LOUIS MO 1256 AM CDT WED JUN 26 2013 .UPDATE... ISSUED AT 1255 AM CDT WED JUN 26 2013 QUICK UPDATE TO THE FORECAST TO ACCOUNT FOR LATEST RADAR TRENDS. AREA OF SHOWERS AND THUNDERSTORMS DEVELOPING ACROSS NORTH CENTRAL MISSOURI WILL MOVE EAST/SOUTHEAST THE REMAINDER OF THE NIGHT AFFECTING THE NORTHERN CWA. ISSUED AT 953 PM CDT TUE JUN 25 2013 THUNDERSTORMS CONTINUE TO DEVELOP ACROSS IL JUST NE OF OUR FORECAST AREA ALONG AN OLD OUTFLOW BOUNDARY. STILL EXPECTING THUNDERSTORMS TO DEVELOP ACROSS IA AHEAD OF A WEAK SHORTWAVE AND ON THE NOSE OF A SWLY LOW LEVEL JET...THEN GROW INTO AN MCS WHICH SHOULD EVENTUALLY DROP SEWD INTO NERN MO AND W CNTRL IL LATE TGT/EARLY WED MRNG. LOW TEMPERATURES TGT WILL BE QUITE MILD DUE TO SOUTHERLY SFC WINDS AND HIGH SFC DEW POINTS. GKS && .SHORT TERM...(THROUGH LATE TONIGHT) ISSUED AT 344 PM CDT TUE JUN 25 2013 SEVERAL THINGS TO DEAL WITH IN THE SHORT TERM TONIGHT. FIRST...STORMS DEVELOPING IN WARM SECTOR AHEAD OF MCV THAT IS SLIDING EAST THROUGH MO FROM MCS THAT WAS OVER WESTERN MO THIS MORNING...AS WELL AS VARIOUS OLD OUTFLOW BOUNDARIES. THIS ACTIVITY SHOULD DIMINISH MOST LOCATIONS BY EARLY THIS EVENING...THOUGH SOME LINGERING ACTIVITY OVER NORTHEAST MO/WEST CENTRAL IL AS MCV SLIDES EAST. THEN MODELS CONTINUE TO SHOW NEXT MCS DEVELOPING OVER IOWA. FORECAST CORFIDI VECTORS HAVE THIS MCS SLIDE SOUTHEAST TOWARDS FORECAST AREA...MAYBE EVEN MORE SOUTHERLY. SO SHOULD MOVE INTO NORTHERN PORTIONS OF FORECAST AREA BY 06Z. LATEST HRRR RUN IS EVEN FURTHER WEST WITH INITIAL DEVELOPMENT IN SOUTHERN IOWA...SO HAVE RAISED POPS A BIT FURTHER WEST. THERE IS A SLIGHT RISK OF SEVERE WEATHER...WITH THE MAIN THREATS BEING LARGE HAIL AND DAMAGING WINDS. AS FOR TEMPS...TO REMAIN RATHER MILD WITH LOWS IN THE LOW TO MID 70S OVERNIGHT. BYRD .LONG TERM...(WEDNESDAY THROUGH NEXT TUESDAY) ISSUED AT 344 PM CDT TUE JUN 25 2013 COMPLEX SCENARIO ON TAP FOR WEDNESDAY WITH LOTS OF UNCERTAINTY TO SPECIFIC FORECAST DETAILS. THE MAIN COMPLICATING FACTOR IS THE OVERNIGHT MCS EXPECTED TO IMPACT WESTERN IL AND PORTIONS OF ERN MO AND WHERE IT WILL BE LOCATED AT DAYBREAK. A CONSENSUS OF MODEL SOLUTIONS HAVE THE DECAYING MCS IN CENTERED THRU IL AT DAYBREAK WITH THE TRAILING FLANK OR BOUNDARY LOCATED ALONG THE MS RIVER IN ERN MO. THE VEERED NATURE OF THE TROPOSPHERIC WINDS AND WLY LLJ WOULD SUGGEST THIS SYSTEM SHOULD CONTINUE TO MOVE SEWD IN A DECAYING STATE THROUGH THE MORNING WITH POTENTIAL FOR SOME STORMS ON THE TRAILING BOUNDARY. STRONG HEATING SHOULD COMMENCE DURING THE DAY WITHIN THE WARM SECTOR AHEAD OF THE ENCROACHING COLD FRONT...AS WELL AS WEST OR SOUTHWEST OF ANY REMNANT BOUNDARIES. THE HEATING WILL BE MORE LIMITED WITH EASTWARD EXTENT DUE TO RESIDUAL CLOUDINESS FROM THE MORNING...BUT THE WARM SECTOR IS EXPECTED TO BECOME VERY UNSTABLE AND WEAKLY CAPPED WITH SBCAPE AOA 4000 J/KG. SCATTERED THUNDERSTORMS ARE EXPECTED TO REDEVELOP IN THE AFTERNOON WITHIN THE CONFLUENT ZONE AHEAD OF THE COLD FRONT AND WITH ANY RESIDUAL BOUNDARIES...PRIMARILY FROM EAST CENTRAL/SE MO INTO SOUTH CENTRAL AND SW IL. DEEP LAYER SHEAR OF 30-40 KTS AND THE AMOUNT OF INSTABILITY WOULD FAVOR SUPERCELL AND MULTICELL MODES. THE MORNING CONVECTION AND/OR RESIDUAL CLOUDS PRESENT SOME PROBLEMS WITH RESPECT TO THE MAGNITUDE OF HEAT. I HAVE COOLED TEMPS SLIGHTLY FROM ST LOUIS EASTWARD AND THIS IS HIGHLY DEPENDENT ON MORNING CLOUDS. GIVEN THE UNCERTAINTIES I HAVE DEFER ED ON ANY HEAT ADVISORIES WITH HEAT INDICES FORECAST IN THE 100-105 RANGE. STORMS SHOULD BE CLOSE TO EXITING THE CWA OR WILL HAVE EXITED THE CWA BY 00Z THURSDAY. EVEN IN THE WAKE OF THE INITIAL COLD FRONT/BOUNDARY...THURSDAY LOOKS LIKE ANOTHER SEASONABLY HOT DAY. IN FACT...IT IS NOT TOTALLY OUT OF THE QUESTION IT COULD BE HOTTER THAN WEDNESDAY BUT WITH LESSER HUMIDITY. THE ANTICIPATED NORTHWEST FLOW SHORTWAVE AND SECONDARY COLD FRONT WILL MOVE THROUGH THE AREA LATE THURSDAY NIGHT INTO EARLY FRIDAY WITH A PROMINENT WSW LLJ AHEAD OF IT. THIS SHOULD FUEL ANOTHER MCS WHICH WILL IMPACT PORTIONS OF THE CWA. THE MODELS DIVERGE ON THE MCS TRACK WITH THE GREATEST PROBABILITY ATTM APPEARING TO BE THROUGH CENTRAL MO. MUCH COOLER AIR WILL THEN SPREAD INTO THE AREA IN THE WAKE OF THE FRONT FOR FRIDAY AND SET THE STAGE FOR A PROLONGED PERIOD OF BELOW AVERAGE TEMPERATURES INTO THE EXTENDED RANGES. THE EXTENDED RANGES WILL FEATURE AN AMPLIFIED BLOCKY UPPER AIR REGIME FROM THE ERN PACIFIC ACROSS THE CONUS INTO THE WRN ATLANTIC...WITH A STRONG UPPER HIGH/RIDGE CENTERED IN THE WRN U.S. AND DEEP TROF IN THE ERN U.S. A SERIES OF SHORT WAVES WILL DROP SSEWD DOWN THE BACKSIDE OF THE UPPER TROF AND IMPACT THE AREA ON SUNDAY AND TUESDAY REINFORCING THE "COOLER" AIR AND BRINGING A CHANCE OF SHOWERS AND THUNDERSTORMS. GLASS && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 1147 PM CDT TUE JUN 25 2013 THUNDERSTORMS HAVE BEGUN TO DEVELOP OVER NORTHWEST MISSOURI AND HAVE SHOWN SOME EASTWARD MOVEMENT. CURRENT MOTION WOULD PLACE IT AT KUIN AROUND 10Z. CURRENTLY EXPECT THESE STORMS TO STAY NORTH OF KCOU...THOUGH WILL NEED TO MONITOR TO SEE IT DEVELOPMENT IS FARTHER SOUTH THAN EXPECTED. THESE STORMS COULD ALSO AFFECT THE ST. LOUIS METRO TAFS...WITH STORMS REMAINING IN THE AREA INTO WEDNESDAY AFTERNOON. STORMS THROUGH SUNRISE COULD POSE A THREAT OF GUSTY WINDS...SMALL HAIL AND MVFR/IFR CONDITIONS. STRONGER THREAT FOR SEVERE THUNDERSTORMS WILL OCCUR ON WEDNESDAY AFTERNOON AS STORMS REGENERATE MAINLY SOUTH AND EAST OF THE ST. LOUIS METRO AREA. SPECIFICS FOR KSTL...THERE CONTINUES TO BE A THREAT FOR THUNDERSTORMS TOWARD SUNRISE THAT WILL CONTINUE INTO EARLY AFTERNOON. TIMING IS STILL UNCERTAIN...SO WILL KEEP VCTS FOR NOW. OTHERWISE EXPECT MAINLY DRY AND VFR CONDITIONS. BRITT && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX