860
FXUS63 KEAX 050040
AFDEAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
740 PM CDT SAT JUL 4 2009
DISCUSSION
DID A MINOR UPDATE TO REVISE WHERE SHOWERS AND ISOLATED
THUNDERSTORMS WILL BE OCCURRING EARLY THIS EVENING IN CENTRAL
MISSOURI. ALSO WATCHING SOME LIGHT SPRINKLES AND DRIZZLE WITH THE
THICKER CLOUD DECK HEADING SOUTH OUT OF IOWA AND NEBRASKA AT THIS
TIME. WILL NOT PUT A MENTION OF RAIN IN NORTHERN AREAS AT THIS
POINT AS PRECIPITATION SHOULD BE VERY LIGHT...AND MAY DECREASE WITH
EVENING COOLING...BUT WILL KEEP AN EYE ON IT.
PC
PREV DISCUSSION
/400 PM CDT SAT JUL 4 2009/
THIS AFTN-TONIGHT...
SFC LOW AND WEAK SFC COLD FRONT NOW PRESSING THROUGH THE CWA THIS
AFTN. SFC THETA-E CONVERGENCE STRONGEST ACROSS NORTH CENTRAL
MISSOURI IN VICINITY OF SFC LOW. HENCE...WITH MEETING LOWER
CONVECTIVE TEMPS ISO-SCT SHRA/TSRA HAVE DEVELOPED. FURTHER
SOUTH...WHILE INSTABILITY HAS CLIMBED BETWEEN 500-1000 J/KG ALONG
WEAK FRONT...CONVERGENCE MUCH WEAKER. THUS WHILE IT WILL BE FEASIBLE
FOR DEVELOPMENT ESPECIALLY ALONG THE SOUTHEAST...FEEL IT WOULD BE
MUCH MORE ISOLATED IN NATURE. ONLY CONCERN ACROSS THE NE CWA WOULD
BE POSITIONING OF SFC LOW AND WEAK SFC WARM FRONT SOUTH OF
CHILLICOTHE AND KIRKSVILLE. WITH ENOUGH POTENTIAL GIVEN BREAKS OF
SUNSHINE...LOW LCLS IN EXTREME NORTHERN MO AND POCKETS OF CAPE IN
THE LOWEST 5K FT...A FUNNEL OR TWO COULD BE POSSIBLE IN STRONGER
SHOWERS TIED TO THE FRONT. HOWEVER...FEEL THE LIKELIHOOD OF THIS
OCCURRENCE IS VERY LOW.
FOR TONIGHT...MODELS ARE ALL IN RELATIVE AGREEMENT IN BRINGING
MASSIVE AREA OF MVFR/IFR STRATUS SOUTHWARD INTO THE CWA BEHIND SFC
FRONT. WEAK CAA ALOFT WILL ALLOW TEMPERATURES TO DROP RATHER QUICKLY
THIS EVENING...WITH OVERNIGHT LOWS FALLING INTO THE LOWER 60S IN
MOST AREAS. GIVEN THE SATURATED GROUNDS...EXPECTED LOW CIGS AND
LIGHT MIXING OFF THE SFC...SEE POTENTIAL FOR THE DEVELOPMENT OF
DRIZZLE AND OR LIFR STRATUS/FOG. BOUNDARY LAYER WINDS REMAIN A BIT
MORE STOUT THAN I WOULD LIKE TO SEE FOR WIDESPREAD DENSE FOG IN ALL
AREAS AND SLIGHTLY DRIER AIR MAY ADVECT SOUTHWARD...HOWEVER WATER
TEMPS REMAIN NEAR 80F THIS AFTN WHICH WOULD SETUP AROUND A 15-20
DEGREE DIFFERENTIAL FOR SFC TO WATER TEMPS. WITH RIVER VALLEYS
LIKELY DECOUPLING AFTER MIDNIGHT...SUFFICIENT CONDITIONS MAY EXIST
FOR STEAM FOG. THUS WILL INCLUDE PATCHY FOG WORDING ATTM.
31
MONDAY-SATURDAY...
NORTHWEST FLOW WILL BE IN PLACE ACROSS THE REGION THROUGH TUESDAY.
MODELS PROG ILL-DEFINED SHORTWAVES TO TRANSLATE THROUGH THE FLOW
ACROSS THE UPPER MIDWEST. IT IS POSSIBLE THAT THUNDERSTORM ACTIVITY
WILL DEVELOP NORTH OF MISSOURI...WHICH WOULD MOVE INTO THE AREA.
HOWEVER THE MODELS NOW HOLD THE SURFACE BOUNDARY WELL NORTH OF THE
AREA. SO WITH SHORTWAVE GENERALLY STAYING NORTHEAST OF THE FORECAST
AREA AND THE SURFACE BOUNDARY ALSO PROGGED TO STAY NORTH...WILL DROP
POPS BACK DOWN BELOW THE SLIGHT CHANCE CATEGORY.
RIDGE BUILDS IN ACROSS THE REGION BY WEDNESDAY...BRINGING STEADILY
WARMING TEMPS TO THE AREA THROUGH AT LEAST FRIDAY. APPEARS AT LEAST
A MODEST CAP WILL ALSO BUILD IN ACROSS THE REGION...SO WILL KEEP
WEDNESDAY THROUGH FRIDAY DRY. MAX TEMPS ON FRIDAY ARE TRICKY AT THIS
POINT. VERY WARM TEMPS ALOFT AND REGION JUST AHEAD OF AN APPROACHING
FRONT...COULD PUSH TEMPS EVEN WARMER THAN CURRENTLY
FORECAST...ESPECIALLY ACROSS THE WESTERN CWA.
GFS/ECMWF SHOW A SOMEWHAT STRONGER SHORTWAVE MOVING ACROSS THE UPPER
MIDWEST LATE IN THE WEEK. THERE REMAINS A SIGNIFICANT AMOUNT OF
UNCERTAINTY IN THE STRENGTH/POSITION OF THE SHORTWAVE...AND OF THE
STRENGTH OF THE RIDGE/CAPE AT THAT TIME. FOR NOW WILL BRING IN
SLIGHT CHANCE POPS ACROSS FAR NORTHERN MISSOURI ON FRIDAY...
SPREADING ACROSS THE REST OF THE FORECAST AREA FRIDAY NIGHT INTO
SATURDAY. THIS MAY MEAN CURRENTLY FORECAST MAX TEMPS ON FRIDAY MAY
BE A LITTLE TOO WARM...ESPECIALLY ACROSS FAR NORTHERN-NORTHEAST
MISSOURI. WILL THEN COOL TEMPS DOWN SOMEWHAT FOR SATURDAY. THAT
BEING SAID...IF RIDGE HOLDS TIGHT...TEMPS ON SATURDAY MAY NEED TO BE
BUMPED UP.
33
AVIATION
/641 PM CDT SAT JUL 4 2009/
FOR THE 00Z TAFS...LOOKING AT SATELLITE AND UPSTREAM
OBSERVATIONS...SHOW THE GENERAL TREND FOR A LOWERING TO MVFR THEN
IFR CEILINGS TONIGHT LOOKS GOOD. WILL ALSO ADD MVFR VSBYS EARLIER
DUE TO POTENTIAL HAZE FROM FIREWORKS AS WELL AS PREVAILING LOW LEVEL
MOISTURE FROM EARLIER RAINS. IMPACT OF A FEW EARLY EVENING SHOWERS
IN THE KANSAS CITY AREA WILL BE MINIMAL AT THE TAF SITES. SUNDAY
SHOULD BRING IMPROVING CONDITIONS TO THE CIGS THROUGH THE MORNING AS
850 FRONT DROPS SOUTH OF THE REGION BY LATE MORNING.
PC
EAX WATCHES/WARNINGS/ADVISORIES
MO...NONE.
KS...NONE.
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