656 FXUS63 KLSX 230746 AFDLSX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ST LOUIS MO 246 AM CDT SUN JUN 23 2013 .SYNOPSIS... ISSUED AT 245 AM CDT SUN JUN 23 2013 UPPER LEVEL PATTERN HAS GOTTEN A BIT MUDDLED AS CONVECTION FROM YESTERDAY LEFT A MESOSCALE CONVECTIVE VORTEX IN CENTRAL ILLINOIS...AND THEN THERE IS THE UPPER LOW THAT CONTINUES TO RETROGRADE FROM TENNESSEE TO THE NORTHWEST. THIS HAS ALLOWED THE UPPER LEVEL HIGH/RIDGE TO BE NEARLY BROKEN IN TWO WITH THIS OBVIOUS WEAKNESS EXTENDING THROUGH THE CENTER OF THE CWA. AT THE SURFACE...NUMEROUS BOUNDARIES REMAIN FROM CONVECTION...INCLUDING ONE THAT IS MOVING WEST ACROSS THE METRO AT THIS MOMENT...SHIFTING THE WIND FROM SOUTHWEST TO SOUTHEAST. TEMPERATURES GENERALLY ARE IN THE 70S. && .SHORT TERM...(TODAY THROUGH MONDAY) ISSUED AT 245 AM CDT SUN JUN 23 2013 AFTER YESTERDAYS RENDITION OF CONVECTION-GONE-WILD...MY CONFIDENCE IN ANY ONE MODEL SOLUTION IS QUITE LOW. THAT BEING SAID...I BELIEVE THERE ARE A FEW FEATURES THAT CAN BE FOCUSED ON FOR TRIGGERING THUNDERSTORMS TODAY. THE FIRST IS THE MCV/RETROGRADING LOW TO OUR SOUTHEAST WHICH COULD INTERCEPT THE BROAD MOIST LOW LEVEL FLOW TO DEVELOP ISOLATED/SCATTERED THUNDERSTORMS FROM NEAR THE ST. LOUIS METROPOLITAN AREA EASTWARD INTO CENTRAL ILLINOIS THIS MORNING. THEN LATER THIS MORNING AND INTO THE AFTERNOON...OUTFLOW FROM CENTRAL/NORTHERN PLAINS IN COMBINATION WITH AN APPROACHING SHORTWAVE TROF ACROSS THE PLAINS WILL AID THUNDERSTORM DEVELOPMENT FROM THE WEST. THEN IN BETWEEN...DIURNAL INSTABILITY COULD LEAD TO ADDITIONAL ISOLATED/SCATTERED CONVECTION. MANY OF THE CONVECTION ALLOWING MODELS SHOW SOME FLAVOR OF THIS SCENARIO...WITH MORNING STORMS FROM ST. LOUIS AND POINTS EAST...THEN THUNDERSTORMS DEVELOPING BY AFTERNOON TO OUR WEST...AND GROWING UPSCALE INTO AN MCS THAT MOVES ACROSS AT LEAST THE NORTHERN CWA. GIVEN THE AMOUNT OF INSTABILITY...SEVERE STORMS WILL BE POSSIBLE WITH WIND BEING THE PRIMARY THREAT. TEMPERATURES MAY BE KEPT IN CHECK BY CLOUD COVER TODAY...SO HAVE SPLIT THE MOS GUIDANCE WITH UPPER 80S TO LOWER 90S FORECAST. REMNANTS OF MCS AND RESIDUAL BOUNDARIES COULD RESULT IN ADDITIONAL THUNDERSTORM DEVELOPMENT ON MONDAY...AS THE UPPER LEVEL RIDGE AXIS TRIES TO BUILD NORTH ACROSS THE CWA. HIGH TEMPERATURES WILL INCREASE WITH HIGHS IN THE LOWER TO MIDDLE 90S. CVKING .LONG TERM...(TUESDAY THROUGH SATURDAY) ISSUED AT 245 AM CDT SUN JUN 23 2013 HOT AND HUMID CONDITIONS EXPECTED TUESDAY THROUGH THURSDAY AS UPPER LEVEL RIDGE BUILDS BACK TO THE WEST AND 850MB TEMPERATURES SOAR ACROSS THE CWA. ONLY LOW CHANCE POPS MAINTAINED AS TIMING OF ANY NORTHWEST SHORTWAVES AND EVENTUAL COLD FRONT ARE STILL TO BE PINNED DOWN. COOLER AIR LOOKS TO ARRIVE BY NEXT WEEKEND THOUGH WITH HIGHS ONLY IN THE 80S AS HIGH PRESSURE RIDGE BUILDS SOUTH ACROSS THE MIDWEST. CVKING && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 1117 PM CDT SAT JUN 22 2013 EARLIER CONVECTION THAT PUSHED THROUGH PORTIONS OF THE REGION TODAY HAS NEARLY COMPLETELY DISSIPATED OVER SOUTHEAST MISSOURI. STILL THINKING TONIGHT SHOULD BE DRY AS INSTABILITY THAT HELPED FUEL STORMS TODAY HAS DIMINISHED. SOUTHERLY WINDS WILL INCREASE BY LATE MORNING TOMORROW WITH ISO-SCT THUNDERSTORMS STILL POSSIBLE FOR THE METRO TAFS. KEPT VCTS MENTION TOMORROW AFTERNOON AS 500-700 HPA TEMPS ACTUALLY COOL TOMORROW COMPARED TO TODAY. HOWEVER...MID/UPPER LEVEL FLOW IS MORE CONFLUENT. SO THINKING COVERAGE MAY BE LESS THAN TODAYS ACTIVITY. MORE ORGANIZED CONVECTION LOOKS TO FORM TO THE NORTHWEST SATURDAY EVENING OVER THE MID-MO RIVER VALLEY WHICH WOULD LIKELY TRACK ESE. TAF SITE WITH BEST CHANCE OF SEEING THIS CONVECTION WOULD BE KUIN SO HAVE ADDED A VCTS GROUP BEGINNING AT 0400 UTC SUNDAY. SPECIFICS FOR KSTL... EARLIER CONVECTION THAT PUSHED THROUGH PORTIONS OF THE REGION TODAY HAS NEARLY COMPLETELY DISSIPATED OVER SOUTHEAST MISSOURI. STILL THINKING THAT REST OF TONIGHT SHOULD REMAIN DRY AS INSTABILITY THAT HELPED FUEL STORMS TODAY HAS DIMINISHED. SOUTHERLY WINDS WILL INCREASE BY LATE MORNING TOMORROW WITH ISO-SCT THUNDERSTORMS STILL POSSIBLE FOR THE METRO TAFS. KEPT VCTS MENTION TOMORROW AFTERNOON AS 500-700 HPA TEMPS ACTUALLY COOL TOMORROW COMPARED TO TODAY. HOWEVER...MID/UPPER LEVEL FLOW IS MORE CONFLUENT SO THINKING COVERAGE MAY BE LESS THAN TODAYS ACTIVITY. MORE ORGANIZED CONVECTION LOOKS TO FORM TO THE NORTHWEST SATURDAY EVENING OVER THE MID-MO RIVER VALLEY WHICH WOULD LIKELY TRACK ESE. THIS ACTIVITY MAY CLIP KSTL VERY LATE TOMORROW NIGHT/EARLY MONDAY MORNING BUT HAVE NO MENTION AS OF NOW DUE TO HIGH UNCERTAINTY ON FORMATION/EVOLUTION OF POSSIBLE CONVECTIVE COMPLEX. GOSSELIN && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX