Issued by NWS Springfield, MO
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000 FXUS63 KSGF 070826 AFDSGF AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPRINGFIELD MO 226 AM CST FRI NOV 7 2008 .DISCUSSION... A VERTICALLY STACKED AND MATURE CYCLONE CONTINUES TO GRADUALLY SHIFT OVER THE UPPER MIDWEST THIS MORNING. THIS FEATURE IS CONTROLLING THE SENSIBLE WEATHER CONDITIONS OVER THE ENTIRE CONUS EAST OF THE ROCKIES. A COLDER AIRMASS BLANKETING THE REGION HAS RESULTED...CAUSING TEMPERATURES TO FALL INTO THE 30S THIS MORNING. AN ADDITIONAL SHOT OF COLDER AIR IS BEING OBSERVED OVER NEBRASKA AND SOUTH DAKOTA...WHERE TEMPERATURES ARE FALLING INTO THE 20S. THIS REGION IS ALSO FACILITATING LIGHT TO MODERATE SCATTERED SNOW SHOWERS FROM UPPER LIFT ASSOCIATED WITH AN UPPER SPEED MAX ROTATING AROUND THE WESTERN FLANK OF THE SYNOPTIC CYCLONE. THIS BELT OF LIFT WILL APPROACH SOUTHERN MISSOURI TODAY. HOWEVER...INSUFFICIENT MOISTURE CONTENT COMBINED WITH ONLY MODEST LIFT SUGGESTS INCREASING CLOUDS AND VIRGA. NO MEASURABLE PRECIPITATION IS EXPECTED THROUGH TODAY. HEADING INTO TONIGHTS PERIOD...I HAVE CONTINUED THE DOWNWARD TREND IN TEMPERATURES. THE MAV GUIDANCE IS TOO WARM FOR TONIGHT...AND LEANED FORECAST CLOSER TO THE COOLER MET. THE REASONING BEHIND GOING COOLER LIES WITHIN THE ORIGIN OF TONIGHTS AIRMASS. AGAIN...READINGS OVER NEBRASKA AND SOUTH DAKOTA ARE WELL INTO THE 20S...THEREFORE OVERNIGHT LOWS IN THE LOW 30S ACROSS THE OZARKS SEEMS REASONABLE. FOR SATURDAY AND SUNDAY...THE COOL AND DRY WEATHER WILL CONTINUE. MEANWHILE A WAVE LOCATED OVER THE PACIFIC OCEAN (VIEWED ON MOISTURE CHANNEL SAT)...WILL PROGRESS EAST AND DIG SOMEWHERE OVER THE NATIONS MID SECTION. CONFIDENCE WITH HOW THE STRUCTURE OF THIS SYSTEM EVOLVES IS QUITE LOW FOR A COUPLE OF REASONS. THE WAVE IS IN A LOCATION NOT SAMPLED BY UPPER AIR STATIONS...ALONG WITH THE FACT THAT MEDIUM RANGE MODELS ARE HANDLING THE SYSTEM COMPLETELY DIFFERENT. WHAT WE CAN SAY IS THAT RAIN CHANCES WILL INCREASE SOMETIME BETWEEN THE MONDAY - WEDNESDAY TIME FRAME. NO MATTER WHAT MODEL VERIFIES...THERE IS NO SIGNAL FOR TEMPERATURES COOL ENOUGH FOR FROZEN PRECIP...AT LEAST FOR NOW. CRAMER && .AVIATION... FOR THE 06Z TAFS...DRIER AIR CONTINUES TO BE PULLED INTO THE LARGE UPPER LOW CIRCULATING OVER WESTERN MINNESOTA THIS EVENING...AND HAS EFFECTIVELY ERODED THE CLOUD DECK ON THE SOUTHERN EDGE OF THE CYCLONIC CIRCULATION OVER OUR AREA. SO WILL GO UNLIMITED CEILINGS THROUGH MUCH OF THE NIGHT. THE LATEST MODEL GUIDANCE AND UPSTREAM SATELLITE TRENDS INDICATE SOME OF THE MOISTURE WILL WORK ITS WAY EASTWARD BACK OVER THE OZARKS THIS MORNING AND AFTERNOON...SO WILL BRING AT LEAST A SCATTERED DECK INTO THE REGION THROUGH LATE AFTERNOON. WINDS SHOULD REMAIN PREDOMINANTLY OUT OF THE WEST WITH GUSTS AROUND 20-25 KNOTS AS THE BOUNDARY LAYER MIXES DURING THE AFTERNOON. TERRY && .SGF WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. && $$
