Saturday, June 26, 2010

Area Forecast Discussion - South Central/Southwest Missouri

FXUS63 KSGF 261150
NATIONAL WEATHER SERVICE SPRINGFIELD MO
650 AM CDT SAT JUN 26 2010

..UPDATE TO AVIATION...

DISCUSSION...
/ISSUED 245 AM CDT SAT JUN 26 2010/

IT WAS A BALMY NIGHT OVER EXTREME SOUTHEAST KANSAS AND THE
MISSOURI OZARKS. THE AREA REMAINED POSITIONED SOUTH OF THE PRIMARY
BELT OF WESTERLIES...AND WITHIN A TROPICAL LIKE AIRMASS. A LARGE
STORM COMPLEX WAS IMPACTING SECTIONS OF NORTHERN MISSOURI AND
ILLINOIS. THIS COMPLEX SHOULD PROPAGATE ALONG THE MISSISSIPPI
RIVER...KEEPING THE EASTERN OZARKS DRY THROUGH THIS MORNING.

DIURNAL HEATING COMBINED WITH THE HUMID AIRMASS WILL LIKELY RESULT
IN A FEW AFTERNOON SHOWERS AND THUNDERSTORMS. FOR SOME
REASON...BOTH THE GFS AND THE WRF SUGGEST THAT AN AREA OF CONVECTION
WILL DEVELOP ACROSS EASTERN OKLAHOMA THIS MORNING AND TRACK INTO
SOUTHWEST MISSOURI. MOS GUIDANCE WAS IMPACTED BY THIS
SOLUTION...KEEPING TEMPERATURES IN THE UPPER 80S FOR LOCATIONS NEAR
SPRINGFIELD AND JOPLIN. I'M NOT EXACTLY SURE WHAT FORCING MECHANISM
WOULD CAUSE A COMPLEX OF CONVECTION TO DEVELOP IN
OKLAHOMA...THEREFORE WE DECIDED TO INCREASE THE TEMPERATURE FORECAST
TO VALUES SIMILAR TO YESTERDAYS READINGS...LOW TO MID 90S.

I ALSO WANTED TO QUICKLY DISCUSS WHAT WE ARE OBSERVING ACROSS THE
DEEP SOUTH. THERE APPEARS TO BE TWO WEAK EXTRA-TROPICAL
CIRCULATIONS MEANDERING WITHIN AN UNORGANIZED FLOW REGIME. I'M
NOT SURE HOW MODELS ARE HANDLING THESE TWO UPPER LOWS. MY GUESS IS
THAT THEY WILL EVENTUALLY SHEAR OUT AS THEY TRANSLATE NORTHWARD AND
CLOSER TO THE MAIN BELT OF WESTERLIES. HOWEVER...GIVEN THE DEGREE
OF MOISTURE AVAILABLE ACROSS THE DEEP SOUTH AND EASTERN PLAINS...WE
WILL NEED TO KEEP CLOSE TABS ON CONVECTIVE POTENTIAL THAT THESE TWO
LOWS COULD TRIGGER. THIS IS MORE OF A SHORT TERM FORECAST CHALLENGE
THAT WE NEED TO ADDRESS THROUGH THE WEEKEND.

SUNDAYS CONDITIONS WILL BE SIMILAR TO TODAY...WITH CHANCES FOR
AFTERNOON SHOWERS AND THUNDERSTORMS. A FRONTAL SYSTEM WILL APPROACH
THE REGION BY SUNDAY NIGHT...POTENTIALLY CREATING A MORE WIDESPREAD
EPISODE OF SHOWERS AND THUNDERSTORMS THROUGH MONDAY MORNING. A FEW
LOCATIONS COULD EXPERIENCE SOME HEAVY RAIN. FULL SUMMERTIME
VEGETATION AND THE LACK OF RAINFALL THIS MONTH WILL MITIGATE
RUNOFF...ESPECIALLY IN RURAL AREAS.

FOLLOWING THIS FRONTAL PASSAGE...AN EXTENDED PERIOD OF COOLER AND
DRIER WEATHER IS EXPECTED. A DRY CONTINENTAL AIRMASS WILL SPREAD
WELL INTO THE DEEP SOUTH. SOME MODELS SUGGEST THAT DEW POINTS COULD
FALL INTO THE 50S ACROSS THE EASTERN OZARKS...CAUSING OVERNIGHT LOWS
TO FALL INTO THE 50S IN THIS SAME REGION.

DESPITE THE UPPER LEVEL RIDGE BUILDING BACK OVER THE STATE BY
WEDNESDAY AND THURSDAY...MEDIUM RANGE MODELS STILL SUGGEST THAT
SURFACE TRAJECTORIES WILL REMAIN FROM THE EAST OR NORTHEAST. THIS
WILL MITIGATE GULF MOISTURE FROM RETURNING...KEEPING HUMIDITY VALUES
AT A MUCH MORE COMFORTABLE LEVEL THROUGH ALL OF NEXT WEEK.

AS WE ADVANCE WELL INTO THE EXTENDED FORECAST...THERE COULD BE A
TROPICAL SYSTEM MAKING LAND FALL SOMEWHERE OVER THE GULF COAST. IT
IS YET TO BE DETERMINED IF THE OZARKS REGION WOULD BE IMPACTED BY
THIS FEATURE...STAY TUNED.

CRAMER

&&

AVIATION...
/ISSUED 645 AM CDT SAT JUN 26 2010/

FOR THE 26/1200Z KSGF/KJLN/KBBG TAFS...TAFS WILL GENERALLY BE VFR
THROUGH THIS TAF PERIOD. SOME MVFR FOG WILL BE POSSIBLE IN AREAS
OF SOUTHERN MO...BUT THIS WILL BE SHORT LIVED OVER THE NEXT COUPLE
OF HOURS. A WEAK DISTURBANCE MOVING NORTHEAST FROM THE OK/NORTH TX
AND AN OUTFLOW BOUNDARY MOVING SOUTH INTO CNTRL MO MAY BE THE
FOCUS FOR TSTMS LATER TODAY WITH DAYTIME HEATING...BUT PREDICTED
AREAL COVERAGE AND PLACEMENT REMAIN LOW CONFIDENCE. A TIGHTENING
PRESSURE GRADIENT AND DEEP MIXING WILL SUPPORT SOME MODERATELY
GUSTY SOUTH WINDS AFTER 26/18Z. DSA

&&

SGF WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&

$$

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