Issued by NWS Springfield, MO
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000 FXUS63 KSGF 081741 AFDSGF AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPRINGFIELD MO 1141 AM CST SAT NOV 8 2008 ...UPDATE TO AVIATION... .UPDATE... AN EXPANSIVE AREA OF LOWER CEILINGS ON THE BACKSIDE OF AN UPPER LEVEL LOW CENTERED OVER MICHIGAN CONTINUES TO MOVE INTO EAST KANSAS AND MISSOURI. SATELLITE IMAGERY DOES NOT SHOW MANY BREAKS IN THIS DECK. THUS HAVE INCREASED CLOUD COVER AND LOWERED TEMPERATURES TODAY WITH HIGHS REACHING NEAR 40 DEGREES. THE WARMEST READINGS ARE EXPECTED ALONG THE ARKANSAS BORDER AND IN PORTIONS OF SOUTHEAST KANSAS WHERE A FEW BREAKS IN THE CLOUDS REMAIN POSSIBLE. ALSO HAVE ADJUSTED WINDS WITH TIGHT PRESSURE GRADIENT PRODUCING A NORTHWEST WIND NEAR 15 MPH WITH STRONGER GUSTS. THE WIND WILL WEAKEN NEAR SUNSET AS THE PRESSURE GRADIENT RELAXES WITH THE UPPER LEVEL LOW TRACKING INTO CANADA. ANGLE && .DISCUSSION... A COLD AIR ADVECTION REGIME IS WELL ESTABLISHED ACROSS THE EASTERN PLAINS AND MISSOURI OZARKS REGION. TEMPERATURES HAVE RESPONDED TO THE ENTRANCE OF THE NORTHERN PLAINS AIRMASS BY FALLING INTO THE 30S THIS MORNING. THIS AIRMASS WILL CONTINUE TO SPREAD IN AS THE REGION REMAINS POSITIONED ON THE BACK SIDE OF A LARGE SYNOPTIC LOW PRESSURE SYSTEM. ASSOCIATED WITH THE SYNOPTIC LOW...REMAINS A LOW CLOUD DECK THATS CIRCULATING AROUND THIS FEATURE. THIS INTRUDING STRATUS DECK...ALONG WITH CONTINUED COLD AIR ADVECTION WILL LIMIT TEMPERATURES FROM WARMING OUT OF THE 40S TODAY. AS A MATTER FACT...CENTRAL MISSOURI WILL ONLY WARM INTO THE LOWER 40S THIS AFTERNOON. BY SUNDAY NIGHT...A PACIFIC DISTURBANCE THAT CAN BE SEEN ON THE MOISTURE CHANNEL...WILL APPROACH FROM THE WEST. THIS DISTURBANCE WILL CAUSE A STRONG WARM AIR ADVECTION PATTERN TO DEVELOP ACROSS THE SOUTHERN AND EASTERN PLAINS. ISENTROPIC ANALYSIS OF SEVERAL LOW LEVEL POTENTIAL TEMPERATURES SURFACES SUGGEST 45-55 KNOTS OF PARCEL MOVEMENT INTO SOUTHERN MISSOURI. MEANWHILE A ZONE OF BAROCLINICITY WILL EXIST ALLOWING FOR LIFT TO INTERACT WITH THE INCREASING MOISTURE. PERHAPS THE GREATEST CHALLENGE IN THIS MORNINGS FORECAST WAS DETERMINING WHEN THE RAIN WILL BEGIN. THE ECMWF IS SHOWING A TENDENCY TO PHASE THE NORTHERN AND SOUTHERN STREAMS...SUGGESTING A SLOWER SOLUTION...AND A MUCH DIFFERENT STRUCTURE TO THE SYSTEM AS A WHOLE. ALL OTHER MODELS DO NOT SHOW THIS PHASING...WHICH ALLOWS MOISTURE AND LIFT TO SPREAD ACROSS PORTIONS OF THE CWA BY LATE SUNDAY NIGHT. I DIDN`T WANT TO...BUT I`M GOING TO HAVE TO FOLLOW THE MAV POP GUIDANCE CLOSELY FOR SUNDAY NIGHT. THE THOUGHT OF FOLLOWING MODEL CONSENSUS AS OPPOSED TO THE ECMWF WOULD ALSO SUGGEST AGGRESSIVE POPS FOR MONDAYS PERIOD AS RAIN SPREADS ACROSS ALL OF SOUTHERN AND CENTRAL MISSOURI. DECENT AREAL COVERAGE OF SHOWERS...ESPECIALLY IN THE EASTERN OZARKS...WILL CONTINUE INTO MONDAY NIGHT. REGARDING ANY FROZEN PRECIP CHANCES...IT JUST DOESN`T LOOK LIKE IT WILL BE COLD ENOUGH FOR SLEET OR SNOW. WEDNESDAY INTO NEXT WEEKEND LOOKS COOL AND DRY. THE GFS SHOWS MORE OF A ZONAL PATTERN SETTING UP DURING THIS TIME FRAME...WITH A DEVELOPING SOUTHERN STREAM SHORT WAVE TROUGH TOWARD THE WEEKEND. THIS SOUTHERN STREAM WAVE WOULD IMPACT AREAS ALONG AND SOUTH OF INTERSTATE 20 WITH SHOWERS AND THUNDERSTORMS...WHILE COOL AND BENIGN CONDITIONS PERSIST IN THE OZARKS. CRAMER && .AVIATION... STRATUS DECK WITH PREDOMINATELY MVFR CEILINGS CONTINUES TO MOVE SOUTHEAST THROUGH EAST KANSAS AND SOUTHWEST MISSOURI ON THE BACKSIDE OF A STRONG UPPER LEVEL LOW CENTERED OVER MICHIGAN. MVFR CEILINGS ARE EXPECTED TO CONTINUE UNTIL NEAR 00Z AT KSGF. UTILIZING CLIMATOLOGY THROUGH THE CEILING TREND TOOL...CEILINGS ARE EXPECTED TO QUICKLY ERODE AFTER 00Z WITH SKIES BECOMING CLEAR. VISIBLE SATELLITE AND KFSK OBSERVATION CONFIRMS THAT UPSTREAM OF KJLN THAT THERE ARE A FEW BREAKS IN THE STATUS DECK WHERE CEILINGS RAISE TO VFR. HAVE OPTED TO COVER THIS WITH A TEMPO GROUP. CEILINGS ARE EXPECTED TO QUICKLY ERODE NEAR 22Z AT KJLN. NORTHWEST SURFACE WINDS WILL REMAIN OVER 15 KNOTS AND GUSTY THROUGH THE AFTERNOON AT BOTH AERODROMES. NEAR SUNSET...THE PRESSURE GRADIENT WILL BEGIN TO RELAX AND WIND SPEEDS WILL WEAKEN. ANGLE && .SGF WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. && $$
