FXUS63 KEAX 062020
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
320 PM CDT SUN JUL 6 2008

.DISCUSSION...

SHORT TERM...TONIGHT THROUGH TUESDAY...

HOT WEATHER REMAINS IN PLACE THROUGH TUESDAY AS PROFILERS AND OTHER
OBSERVATIONS SHOW SOUTH-SOUTHWEST FLOW CONTINUES TO USHER IN WARMEST
AIR OF THE SUMMER SO FAR. 850 MB TEMPERATURES INCREASING TO 22 DEG C
TOMORROW...WITH AMPLE SUN WILL LOOK FOR AN EVEN WARMER DAY TOMORROW.
ALTHOUGH NEAR ADVISORY CRITERIA...DO NOT PLAN TO ISSUE ADVISORY AT
THIS TIME. FURTHER COORDINATION WITH PUBLIC HEALTH OFFICIALS MAY BE
NEEDED AS CRITERIA FOR CITIZEN GROUP ACTION INCLUDES HEAT INDEX
VALUE OF 95 DEG F AT 11 AM. FOR TOMORROW...WE WILL BE CLOSE TO
THAT...AND AT OR JUST ABOVE AT NOON TOMORROW.

HUMIDITIES ALSO REMAIN HIGH WITH PWATS ALMOST 1.5 INCHES. MEANWHILE
UPPER TROUGH OVER FOUR CORNERS TRANSLATING SLOWLY EAST AND NORTHERN
STREAM TROUGH WILL PHASE IN AND DRAG A COOL FRONT THROUGH ON
TUESDAY.

MODELS HAVE SLOWED THIS SYSTEM A LITTLE...WHICH SEEM REASONABLE
GIVEN THE CAP AND UPPER RIDGE OVER MOST OF MISSOURI. GRIDS STILL
SEEM A LITTLE FAST...BUT WILL LET NEXT SHIFTS DECIDE WHETHER TO SLOW
DOWN EVEN MORE. FOR NOW HAVE FRONT IN THE NORTHWEST AROUND NOON ON
TUESDAY AND DRAPING ACROSS MORE EAST WEST ORIENTATION BY
MIDNIGHT...PROVIDING FOCUS FOR STORMS. FREEZING LEVEL ON MODEL
SOUNDINGS STILL AROUND 15K FEET...SO ANY HAIL WILL LIKELY BE ON THE
SMALL SIDE. WIND PROFILES RATHER UNIDIRECTIONAL AND CAPES FAIRLY
MODEST...SO SEVERE THREAT OVERALL WILL BE FAIRLY LIMITED WITH THIS
FRONT.

AS THE FRONT SAGS SOUTH OF CWA WE WILL SEE COOLER TEMPERATURES BY
WEDNESDAY MORNING. ADOLPHSON

MEDIUM RANGE (WEDNESDAY THROUGH SUNDAY)...

MEDIUM RANGE FORECAST WILL BE BASED PRIMARILY OFF THE 00Z ECMWF
SOLUTION...WITH ADJUSTMENTS MADE FOR EXPECTED MESOSCALE PROCESSES IN
ADDITION TO TYPICAL BIASES AND GENERAL CONCEPTUAL MODELING. WHILE
THE 12Z OPERATIONAL GFS HAS GOOD AGREEMENT WITH OTHER MEDIUM RANGE
MODEL SUITES EARLY IN THE PERIOD...AND OFFERS SOME BETTER RESOLVED
FEATURES AND PREFERRED FORECASTS...THIS MODEL SIGNIFICANTLY DEVIATES
IN DEVELOPING A DEEP PROGRESSIVE TROUGH THROUGH SRN CANADA LATER IN
THE PERIOD. SUCH A DEEP PROGRESSIVE PATTERN IS NOT SUPPORTED BY ANY
ENSEMBLE MEMBER...AND DOES NOT FIT ANY TELECONNECTION OR EXPECTED
DIAGNOSTIC PATTERN BASED ON UPSTREAM AND DOWNSTREAM FEATURES. THUS
PAST THURSDAY...ANY FEATURE ADVERTISED BY THE OPERATIONAL GFS WAS
COMPLETELY IGNORED.

INITIAL FORECAST CONCERN WILL BE THE EXTENT OF THE SOUTHWARD
PROGRESSION TO A COLD FRONT WEDNESDAY...AND ASSOCIATED PRECIP
CHANCES NEAR THIS BOUNDARY. FEEL CONVECTIVE COLD POOL GENERATION
WILL PUSH THE EFFECTIVE BOUNDARY SOMEWHAT FURTHER SOUTH THAN THE
ECMWF CURRENTLY INDICATES...AND IN THIS CASE...PREFER THE GFS H8
THETA-E GRADIENT AS THE MOST LIKELY BOUNDARY POSITION TOWARDS
CNTRL/SRN MISSOURI. HAVE HELD SOME SLIGHT CHANCE POPS ACROSS THE FAR
SRN CWA IN THE EVENT THAT PREEXISTING CONVECTION IS NOT PARTICULARLY
EXTENSIVE (PERIODICALLY HINTED AT BY MODELS)...AND SOUTHWARD FRONTAL
PUSH IS NOT AS AGGRESSIVE THROUGH THE FORECAST AREA.

MAIN UNCERTAINTY HEADING INTO THE FRIDAY TIME FRAME WILL BE THE
EXISTENCE AND PLACEMENT OF AT LEAST ONE WEAK DISTURBANCE EMANATING
FROM THE TROPICS IN EASTERLY FLOW...AND ROUNDING THE WRN PERIPHERY
OF THE SEMI-PERMANENT SUBTROPICAL RIDGE...INTO A WEAKNESS IN THE
HEIGHT FIELD ACROSS THE CNTRL CONUS. WHILE ALL SIGNS ARE FAVORABLE
FOR SUCH A DISTURBANCE(S) TO OCCUR...MODELS TYPICAL HANDLE THE
TIMING AND PLACEMENT OF SUCH FEATURES QUITE POORLY. THUS WITH SUCH
LARGE UNCERTAINTY IN ANY GIVEN TIME PERIOD...HAVE RELUCTANTLY BROAD
BRUSHED SLIGHT CHANCE POPS THROUGH A FAIRLY LONG PERIOD...MAINLY
FOCUSED TOWARDS CNTRL MISSOURI. OVERALL FEELING IS MANY LOCATIONS
ALONG AND SOUTH OF THE MISSOURI RIVER WILL SEE AT LEAST ONE PERIOD
OF RAIN IN THE WED-FRI TIME FRAME (MOST LIKELY THURSDAY)...BUT THE
INABILITY TO PINPOINT ANY GIVEN PREFERRED TIME FRAME PRECLUDES A
HIGHER MENTION AT THIS TIME.

REGARDING TEMPERATURES...HAVE HEDGED BETWEEN MEX AND ENSEMBLE MEAN
GUIDANCE POST FRONTAL THROUGH THURSDAY...THOUGH MAY NEED TO CHOP OFF
A FEW MORE DEGREES IF SUCH A TROPICAL WAVE LEADS TO MORE EXTENSIVE
CLOUD COVER AND PRECIPITATION...AND CONSEQUENTLY BECOMES A DETRIMENT
TO DIURNAL TEMPERATURE RISES. BEYOND THURSDAY...WITH EXPECTED STRONG
HEIGHT RISES ALOFT THROUGH THE MISSISSIPPI RIVER VALLEY AHEAD OF
HEIGHT FALLS ACROSS THE PACIFIC NW...HAVE ADVERTISED TEMPERATURES AT
THE UPPER END OF ENSEMBLE MEAN GUIDANCE (SLIGHTLY ABOVE
AVERAGE)...MORE CLOSELY REFLECTING A PATTERN INDICATED BY THE
OPERATIONAL ECMWF.


21

&&

.AVIATION...

FOR 18Z TAFS...VFR CONDITIONS WILL PREVAIL AT TERMINALS NEXT 24
HOURS. THUNDERSTORMS WILL MOVE THROUGH NORTHWEST MISSOURI...BUT WILL
STAY NORTH OF TERMINALS...THROUGH TOMORROW. WINDS WILL REMAIN FROM
THE SOUTHWEST AROUND 10 MPH. ADOLPHSON

&&


.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
$$