214
FXUS63 KEAX 210557
AFDEAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
1157 PM CST FRI NOV 20 2009
..UPDATED AVIATION DISCUSSION
DISCUSSION
MAIN CONCERN THROUGH THE SHORT TERM WILL BE WITH FOG POTENTIAL
TONIGHT INTO TOMORROW MORNING. WEAK SFC RIDGE REMAINS STATIONED
ACROSS THE CWA THIS AFTERNOON AND WILL LIKELY REMAIN IN PLACE THROUGH
THIS EVENING. THIS WILL LIKELY LEAD TO CONTINUED LIGHT AND VARIABLE
SFC WINDS THROUGH AT LEAST THE EARLY PART OF TONIGHT. BROAD TROUGH
WILL ENGULF THE WESTERN CONUS TONIGHT LEADING TO PRESSURE FALLS ALONG
THE LEE OF THE ROCKIES. THIS WILL BRING ABOUT A MORE SOUTHERLY LLVL
FLOW REGIME BY LATE TONIGHT INTO THE MORNING HOURS. COMPLICATED
FORECAST DEALING WITH THE POSSIBILITY OF DENSE FOG OVERNIGHT AS A
COMBINATION OF RADIATIONAL AND ADVECTION PROCESSES WILL LIKELY BE AT
WORK. CLOUD COVER ACROSS THE SOUTHERN COUNTIES HAS ALL BUT DISSIPATED
ATTM WITH THE BULK OF THE REMAINING ACTIVITY CONFINED TO THE SOUTHERN
PLAINS AND OZARKS. BELIEVE THE MAJORITY OF THE CWA WILL REMAIN FAIRLY
CLEAR THROUGH THIS EVENING AND EARLY NIGHTTIME HOURS ALLOWING FOR
EFFICIENT RADIATIONAL COOLING TO COMMENCE. THIS WILL ALLOW THE
BOUNDARY LAYER TO COME CLOSE TO SATURATION AND PERHAPS RESULT IN
AREAS OF FOG FORMATION BY MIDNIGHT. HOWEVER LATER TONIGHT...A WEAK
WARM FRONT WILL LIFT NORTHWARD INTO THE SOUTHERN CWA ALLOWING LLVL
MOISTURE AND CLOUD COVER TO MAKE A DECENT SURGE NORTHWARD. THIS
SHOULD BRING ABOUT ADDITIONAL FOG DEVELOPMENT ACROSS THESE AREAS
TOWARDS THE EARLY MORNING HOURS. HOWEVER AS THIS OCCURS...SFC FLOW
WILL LIKELY INCREASE A BIT AS THE SFC RIDGE BECOMES BETTER
ESTABLISHED ACROSS THE OHIO VALLEY AND PRESSURE CONTINUE TO FALL
ACROSS THE HIGH PLAINS. THEREFORE...UNCERTAINTY EXISTS AS TO THE
EXTENT AND DENSITY OF FOG WHERE RADIATIONAL PROCESSES DOMINATE. WILL
INCLUDE AREAS OF FOG ACROSS THE ENTIRE CWA OVERNIGHT AND LEAVE IT TO
LATER SHIFTS TO HOIST ANY ADVISORIES AS MORE CONFIDENCE IN
LOCATION...TIMING...AND DENSITY IS GAINED. FOG WILL LIKELY LINGER
THROUGH THE MID MORNING HOURS BEFORE GRADUALLY BURNING OFF.
BY TOMORROW...LEE SIDE TROUGHING WILL LEAD TO INCREASED SOUTHERLY
LLVL FLOW AND SLIGHTLY WARMER TEMPS ACROSS MOST AREAS. SFC FRONT WILL
SLIDE INTO EASTERN NEBRASKA/CENTRAL KANSAS BY SATURDAY NIGHT INTO
SUNDAY MORNING BEFORE STALLING AS NEXT SHORT WAVE TROUGH DIVES INTO
THE ROCKIES AND FURTHER PRESSURE FALLS TAKE SHAPE ACROSS THE HIGH
PLAINS. THIS WAVE WILL THEN PUSH INTO THE PLAINS ON SUNDAY LIKELY
BRINGING THE WEAK SFC BOUNDARY CLOSER TO THE CWA AND BRING AT LEAST A
SLIGHT CHC OF SHOWERS TO THE NORTHWESTERN COUNTIES DURING THE DAY.
DEROCHE
MEDIUM RANGE (MONDAY THROUGH FRIDAY)...
FOR NEXT WORK WEEK THE PRIMARY WEATHER ISSUE WILL BE THE DEVELOPMENT
OF A PROGRESSIVE TROUGH THAT WILL POSSIBLY BRING SOME PRECIPITATION
TO THE CENTRAL PLAINS. MID RANGE MODELS ARE CURRENTLY ADVERTISING A
SERIES OF SHORTWAVES TO MOVE THROUGH THE PLAINS OVER THE WEEKEND AND
NEXT WEEK WITH A MODESTLY LARGE TROUGH DEVELOPING IN RESPONSE ACROSS
THE CENTRAL PLAINS MONDAY/TUESDAY. MODELS HAVE BE CONSISTENT IN
ADVERTISING ITS DEVELOPMENT...BUT THE TIMING IS A BIT OF AN ISSUE.
LATEST RUN OF THE THE GFS CONTINUES TO BE THE OUTLIER AS IT IS THE
FASTEST SOLUTION. GEM/ECMWF/UKMET ALL HAVE THE SYSTEM MOVING MORE
SLOWLY THROUGH THE PLAINS...WHICH SEEMS REASONABLE DUE TO THE
STRENGTH OF THE JET ROUNDING ITS BASE.
SO...WHILE TIMING PREFERENCE IS HEDGED TOWARDS THE ECMWF/UKMET/GEM
COMBINATION...THE TRACK OF THE TROUGH ACROSS THE PLAINS IS FAIRLY
CHAOTIC. THE GFS IS ADVERTISING THE INITIAL TROUGH DIGGING STRAIGHT
THROUGH THE NORTHERN PLAINS INTO MISSOURI...WITH A SECONDARY WAVE
DIGGING INTO ITS BACK SIDE AND RELOADING THE TROUGH FOR THURSDAY.
THE GEM AND ECMWF KEEP THE FEATURE MORE AS ONE COHERENT SHORT LIVED
CUTOFF LOW AS IT MOVES INTO AND THEN BACK OUT OFF THE PLAINS. HAVE
OPTED NOT TO ADJUST THE FORECAST TOO MUCH DUE TO THE VERITY AND THE
LACK OF CONFIDENCE IN THE CURRENT SET OF SOLUTIONS. CHANCE POPS FOR
PORTIONS OF THE FORECAST AREA MONDAY THROUGH TUESDAY SEEMS TO STILL
BE A GOOD IDEA...THOUGH DETAILS ARE STILL A BIT VAGUE. GENERAL TREND
WOULD AT LEAST INDICATE THAT...GIVEN THE SOURCE REGION OF OF THE AIR
MASS BEHIND THE TROUGH...IT SHOULD BE TOO WARM FOR ANY FROZEN
PRECIPITATION. SO...FOR NOW HAVE SIMPLY KEPT OUR GOING PRECIPITATION
AS RAIN. OTHERWISE...REMAINDER OF THE WORK WEEK CURRENTLY LOOKS DRY
AS SOME FORM OF RIDGING WILL BEGIN TO BUILD IN FROM THE WEST...
PUSHING THE NORTHWEST FLOW BEHIND THE TROUGH OFF TO THE EAST.
CUTTER
AVIATION
FOR THE 06Z TAFS...OVERALL...THERE WERE ONLY MINOR CHANGES MADE TO
THE PREVIOUS FORECASTS. CONCERN FOR OVERNIGHT DENSE FOG REMAINS IN
PLAY FOR KSTJ AND TO A LESSER DEGREE KMCI. TERMINAL CURRENTLY
REPORTS LIFR CONDITIONS AND VLIFR IS CERTAINLY POSSIBLE AFTER 11Z. A
SURFACE RIDGE AXIS FROM EAST CENTRAL KS THROUGH KMCI TO SOUTH OF
KIRK WILL BE THE DEMARCATION LINE BETWEEN DENSE FOG NORTH OF THIS
AXIS AND MVFR STRATUS/FOG TO THE SOUTH. THIS SURFACE RIDGE AXIS IS
EXPECTED TO MOVE LITTLE OVERNIGHT SO KMCI WILL BE ON THE BORDERLINE
AND HENCE COULD GO EITHER WAY WITH YEA/NAY ON DENSE FOG. WILL LIKELY
BE NEEDING A FEW AMENDMENTS FOR KMCI.
THE DENSE FOG SHOULD BE SLOW TO DISSIPATE SATURDAY MORNING AND COULD
LAST FOR THE ENTIRE MORNING. ONCE THE FOG LIFTS/DISSIPATES AM STILL
EXPECTING TO SEE CONSIDERABLE MVFR CEILINGS FOR THE REST OF THE DAY
AS LOW LEVEL WARM AIR ADVECTION/ISENTROPIC LIFT PULLS UP THE
EXTENSIVE LOW CLOUD FIELD NOW COVERING OK/SOUTH CENTRAL KS/SOUTHERN
MO.
MJ
EAX WATCHES/WARNINGS/ADVISORIES
MO...NONE.
KS...NONE.
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