FXUS63 KSGF 271153
AFDSGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPRINGFIELD MO
553 AM CST FRI NOV 27 2009

...UPDATE TO AVIATION...

.DISCUSSION...

IT WAS A COLD NOVEMBER NIGHT ACROSS EXTREME SOUTHEAST KANSAS AND THE 
MISSOURI OZARKS.  AN AIRMASS OF CANADIAN ORIGIN HAD NOT ONLY SPREAD 
ACROSS THE OZARKS...BUT HAD SHIFTED AS FAR SOUTH AS THE SOUTHERN 
GULF OF MEXICO.  LIGHT WINDS...CLEAR SKIES...AND A DRY CONTINENTAL 
AIRMASS CAUSED TEMPERATURES TO FALL INTO THE MIDDLE 20S IN MOST 
LOCATIONS.  

AS HIGH PRESSURE CONTINUES TO SHIFT TO THE EAST TODAY...SURFACE 
WINDS WILL INCREASE FROM THE SOUTH.  THESE SOUTHERLY WINDS IN 
CONJUNCTION WITH FULL SUNSHINE WILL BOOST TEMPERATURES THIS 
AFTERNOON...RANGING FROM THE UPPER 50S IN THE EASTERN OZARKS...TO 
THE MIDDLE 60S ACROSS THE OSAGE PLAINS.  SIMILAR CONDITIONS ARE 
EXPECTED ON SATURDAY...WITH EVEN WARMER READINGS...AS ALL LOCATIONS 
SHOULD WARM INTO THE MID AND UPPER 60S.  

THIS WARMTH WILL CONCLUDE SUNDAY IN THE FORM OF A COLD FRONT.  THE 
WRF SOLUTION HAS SLOWED DOWN THE TIMING OF THE FRONT...SHIFTING IT 
ACROSS THE INTERSTATE 44 CORRIDOR AROUND NOON...AND THROUGH THE REST 
OF SOUTHERN MISSOURI BY MID AFTERNOON.  THEREFORE I HAVE ELECTED TO 
INCREASE MAX TEMPS FOR SUNDAY...ESPECIALLY IN AREAS OF SOUTHERN 
MISSOURI. 

SUNDAYS FRONTAL PASSAGE WILL ALSO CREATE SOME MODEST 
LIFT...POTENTIALLY CAUSING LIGHT RAIN TO DEVELOP IN SOME AREAS.  I 
HAVE DECIDED TO CUT BACK ON POPS FOR BOTH SUNDAY AND SUNDAY 
NIGHT...DUE TO THE POSSIBILITY THAT MODELS MAY BE SURGING MOISTURE 
NORTHWARD TOO QUICKLY.  HERE IS WHY I THINK MOISTURE WILL BE LACKING 
COME SUNDAY.  CURRENTLY...A 1026MB SURFACE HIGH RESIDES OVER FAR 
SOUTHERN TEXAS NEAR CORPUS CHRISTI.  THIS FEATURE HAD FORCED A VERY 
DRY AIRMASS WELL INTO THE GULF OF MEXICO...AND AS FAR SOUTH AS THE 
YUCATAN PENINSULA.  AS 40 DEW POINTS OVERSPREAD THE WESTERN GULF ON 
NORTHERLY TRAJECTORIES THROUGH TODAY...MODELS SHOW AND INCREASE IN 
MOISTURE LEVELS ACROSS THIS SAME REGION...WHICH DOESN'T MAKE SENSE.

CONSIDERING THAT OUR FRONTAL PASSAGE IS SET FOR SUNDAY...THE WESTERN 
GULF WILL ONLY HAVE ABOUT 36 HOURS TO RECHARGE AND TRANSPORT.  
MEANWHILE...LIFT ASSOCIATED WITH SUNDAYS COLD FRONT APPEARS QUITE 
MODEST AT BEST.  THE DRIER MET GUIDANCE WAS LIKELY THE SOLUTION TO 
LEAN THE FORECAST WITH...HOWEVER...THE MAV WASN'T TOO FAR OFF.  
THEREFORE SUNDAY AND SUNDAY NIGHTS POP GRIDS WERE INITIATED WITH THE 
MAV...WHICH ILLUSTRATES A NICE DOWNWARD TREND FROM PREVIOUS 
FORECASTS.  

AN UPPER LEVEL TROUGH WILL ACCOMPANY THIS COLD FRONT...AND SHIFT 
EAST OF THE REGION BY MONDAY MORNING.  ANY RESIDUAL LIGHT 
PRECIPITATION THAT WOULD FALL SUNDAY NIGHT WOULD MOST LIKELY OCCUR 
OVER THE EASTERN OZARKS.  

A MOSTLY DRY AND COOL FORECAST IS ON TAP FOR THE MONDAY THROUGH 
WEDNESDAY TIME FRAME.  BOTH THE ECMWF AND GFS SUGGEST THAT A CUTOFF 
LOW WILL GRADUALLY SHIFT SOUTH OF THE OZARKS REGION.  THIS FEATURE 
MAY CAUSE PRECIPITATION TO OCCUR TOWARD THE WEDNESDAY NIGHT - FRIDAY 
TIME FRAME.  GIVEN THE CURRENT MODEL TRACK OF THIS LOW...MOST OF THE 
ACTIVE WEATHER WOULD BE CONFINED TO THE INTERSTATE 40 CORRIDOR AND 
TO THE SOUTH.  THE TRENDS ON THIS UPPER LOW IS SOMETHING TO MONITOR 
OVER THE NEXT FEW DAYS.  ANY NORTHWARD SHIFT IN IT'S POTENTIAL TRACK 
COULD MAKE FOR INCREASED PRECIP CHANCES FOR SOUTHERN MISSOURI IN THE 
EXTENDED.

CRAMER

&&

.AVIATION...

FOR THE 27/1200Z KSGF/KBBG/KJLN A DRY AIR MASS WILL ALLOW VFR
CONDITIONS TO CONTINUE THROUGH THIS TAF PERIOD. S-SW WINDS WILL
INCREASE AS THE PRESSURE GRADIENT TIGHTENS UP SOMEWHAT WITH THE
SLOW APPROACH OF A FRONT FROM THE NORTHWEST AND HIGH PRESSURE
ALONG THE GULF COAST. GUSTS WILL BE SOMEWHAT LIMITED BY THE
SHALLOWNESS OF THE DAYTIME MIXED LAYER. PROGGED SOUNDINGS SUPPORT
LOW LEVEL WIND SHEAR IN ALL TAFS AFTER 28/00Z AS BOUNDARY LAYER
DECOUPLES. DSA

&&

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

$$