FXUS63 KEAX 270529
AFDEAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
1129 PM CST THU NOV 26 2009
...UPDATED AVIATION DISCUSSION...
.DISCUSSION...
SHORT TERM (TONIGHT-SATURDAY NIGHT)...
LAST OF THE CLOUDS CONTINUING TO ERODE QUICKLY TOWARD THE EAST THIS
AFTERNOON...BUT GUSTY NORTHWEST WINDS AND COLD ADVECTION HAVE
MAINTAINED A SEASONABLY CHILLY DAY DESPITE THE SUNSHINE. MAIN SHORT
TERM WEATHER FOCUS WILL CENTER AROUND A PRONOUNCED WARMUP FOR
TOMORROW AND SATURDAY...BUT WILL HAVE TO CONTEND WITH ONE MORE NIGHT
OF AT OR BELOW FREEZING TEMPERATURES FIRST.
19Z SURFACE ANALYSIS SHOWED AN ELONGATED SURFACE RIDGE EXTENDING UP
THE ENTIRE LENGTH OF THE EASTERN PLAINS JUXTAPOSED BENEATH THE
INFLECTION POINT OF THE 500MB HEIGHT FIELD. WITH DEWPOINTS IN THE
MID 20S...TEMPERATURES SHOULD FALL QUICKLY OVERNIGHT AS DECOUPLING
AND RADIATIONAL COOLING ARE MAXIMIZED WITHIN THE PASSING SURFACE
RIDGE AXIS. STILL...THE FALL SHOULD BE LIMITED BY A LEAST A LIGHT
SOUTHWEST WIND OVERNIGHT...AND THE ENSUING WARM ADVECTION ALOFT
AFTER MIDNIGHT. THUS...THE PROSPECTS OF A HARD FREEZE IN THE KANSAS
CITY METRO APPEAR LOW. AS OUTLINED IN THE CLIMATE SECTION
BELOW...THE CURRENT FORECAST WOULD LOCK IN 2009 AS THE LATEST ON
RECORD THAT THE FIRST HARD FREEZE (TEMPS 28 OR LOWER) HAS OCCURRED
-- PUSHING THIS YEARS OCCURRENCE INTO DECEMBER.
ACTUALLY A CHALLENGING TEMPERATURE FORECAST FOR TOMORROW. ON THE
NOSE OF AN UNSEASONABLY STRONG WESTERLY DOWNSLOPE COMPONENT...THE
TOP OF THE INVERSION AT ONLY 900MB IS PROGGED TO WARM TO AN AMAZING
17C ALONG THE KS/MO BORDER BY AFTERNOON. THIS WOULD NORMALLY YIELD
SURFACE TEMPERATURES WELL INTO THE 70S. UNFORTUNATELY...IT IS LATE
NOVEMBER AND WITH A BACKED SURFACE COMPONENT TO THE WIND...WE WILL
LIKELY ONLY REALIZE ABOUT 50% POTENTIAL MIXING DEPTH. HAVE STILL
GONE ABOVE ALL OBJECTIVE GUIDANCE WITH HIGHS IN THE MID 60S ALONG
THE KS/MO BORDER...TAILING BACK INTO THE MID 50S OVER NE MO.
THE WARM NOSE WILL SHIFT INTO THE SRN CWA FOR SATURDAY WITH LOW-MID
60S LIKELY ALONG AND SOUTH OF THE MISSOURI RIVER...AND STILL
SEASONABLY MILD READINGS IN THE UPPER 50S ALONG THE IOWA BORDER.
BOOKBINDER
MEDIUM RANGE (SUNDAY-THURSDAY)...
VARIOUS SUITE OF MEDIUM RANGE MODELS HAVE OBTAINED MUCH BETTER
AGREEMENT AND CONTINUITY THROUGH THE MAJORITY OF THE MEDIUM RANGE
PERIOD. THE GENERAL MODEL TREND OVER THE PAST SEVERAL DAYS
ADVERTISING DISTINCT POSITIVE TILT SPLIT FLOW ACROSS THE CNTRL AND
WRN CONUS...ALONG WITH A FRONTAL BOUNDARY SINKING WELL SOUTH THROUGH
THE FORECAST AREA HAS ONLY BECOME REINFORCED AND ACCENTUATED WITH
THE LAST COUPLE MODEL RUNS. FORTUNATELY...THESE TRENDS CORROBORATE
WITH PREVIOUS CONCEPTUAL THINKING AND MANUAL FORECASTS GIVEN THE
OVERALL BASE EL NINO STATE AND ENHANCED SUBTROPICAL JET
COMPONENT...FAVORING LANDFALLING PACIFIC SYSTEMS SPLITTING TOWARDS
THE SOUTHERN STREAM ATTRACTOR. A BLEND OF THE OPERATIONAL 12Z GFS
AND 00Z ECMWF WAS ACHIEVABLE TODAY WITH MORE CONFIDENCE...TO PROVIDE
BETTER DETAIL WITHIN THE MEDIUM RANGE PERIOD.
COLD FRONT WILL HAVE PASSED INTO SRN MISSOURI BY SUNDAY
AFTERNOON...AS STRONG POSITIVE TILT RIDGING IN THE WAKE OF THE NRN
STREAM WAVE DISASSOCIATING FROM THE SRN STREAM CUTOFF WAVE FORCES
RATHER AGGRESSIVE SFC PRESSURE RISES OVER THE NRN AND CNTRL PLAINS.
EFFECTIVE ELEVATED BAROCLINIC ZONE (WHILE LAGGING THE SFC FRONT
SLIGHTLY) SHOULD ALSO BECOME QUICKLY DISPLACED TO THE SOUTH OF THE
CWA SUNDAY AFTERNOON...WHILE STRONGER THETA-E ADVECTION BECOMES
ORIENTED ALONG THIS BAROCLINICITY FROM THE I-44 TO I-40 CORRIDORS.
SUFFICIENT RESIDUAL MOISTURE AND FRONTOGENETICAL FORCING IN THE
H7-H5 LAYER MAY STILL EXIST POST FRONTAL TO GENERATE LIGHT
PRECIPITATION...THUS HAVE RETAINED POPS FOR THE SRN TIER OF THE
FORECAST AREA INTO SUNDAY EVENING. PARTIAL THICKNESSES FROM MEDIUM
RANGE MODELS ALSO SUGGEST RAIN CHANGING TO SNOW ON THE NRN PERIPHERY
OF THE PRECIPITATION SHIELD...AND CONCEPTUAL THINKING WOULD POINT TO
THIS SCENARIO AS WELL...WITH A TIGHT NRN EDGE TO QPF AND A RAPID
SHIFT SOUTHWARD OF PRECIPITATION ECHOES AS DRIER AIR AND STRONGER
DOWNGLIDE FILTER EQUATORWARD TOWARDS THE TIGHTENING BAROCLINICITY
ALONG THE SRN STREAM JET AXIS.
OTHERWISE...WITH THE IMMEDIATE AREA CAUGHT BETWEEN ACTIVITY WELL
REMOVED IN BOTH THE NRN AND SRN STREAMS...AND CONTROLLED BY SFC HIGH
PRESSURE OF PACIFIC ORIGIN...HAVE ADVERTISED A DRY FORECAST WITH
TEMPERATURES NO MORE THAN 1 STANDARD DEVIATION REMOVED FROM
CLIMATOLOGY. MAY NEED TO INCREASE TEMPERATURES TUESDAY AS MODELS
HAVE SOME INDICATION OF WARMER AIR DOWNSLOPING OFF THE HIGHER
TERRAIN INTO WRN MISSOURI...THOUGH ENOUGH SPREAD AMONG ENSEMBLE
GUIDANCE PRECLUDES PUSHING HIGHS ABOVE THE WARMEST MEMBER AT THIS
POINT. TOWARDS AND JUST BEYOND THE END OF THIS FORECAST
PERIOD...THERE IS MOUNTING EVIDENCE OF A COLDER AND MORE CONTINENTAL
ORIGINATING AIRMASS ADVECTING INTO THE NRN AND CNTRL PLAINS. WHILE
UPSTREAM SFC PRESSURE ARE NOT FORECAST TO BECOME ABNORMALLY HIGH FOR
DECEMBER...AND A LARGE AMOUNT OF AIRMASS MODIFICATION CAN BE
EXPECTED WITH THE DEARTH SNOW COVER EXISTING ALL THE WAY THROUGH THE
PRAIRIES OF CANADA...CERTAINLY THIS MAY BE THE FIRST TASTE OF WINTER
TEMPERATURES FOR THE REGION THIS SEASON.
21
&&
.AVIATION...
FOR THE 06Z TAFS...SOUTHERLY WINDS HAVE SPREAD ACROSS THE REGION LATE
THIS EVENING. SURFACE WINDS WILL STAY OUT OF THE SOUTH OVER THE NEXT
24 HOURS. DAYTIME MIXING SHOULD ALLOW SOME GUSTY WINDS TO MIX DOWN.
HAVE KEPT GUSTS IN THE TEENS AS DEPTH OF THE MIXING IS QUESTIONABLE
AT THIS TIME...BUT GUSTS INTO THE LOW TO MID 20S MAY BE POSSIBLE.
CUTTER
&&
.CLIMATE...
THE CURRENT FORECAST LOW TEMPERATURES FOR THE NEXT 5 DAYS MAKE IT
UNLIKELY THAT A HARD FREEZE (TEMPERATURES AT OR BELOW 28 DEGREES)
WILL OCCUR DURING THE MONTH OF NOVEMBER. HERE ARE THE TOP 5 LATEST
OCCURRENCES OF 28 DEGREE LOW TEMPERATURES IN KANSAS CITY:
RANK DATE YEAR
----- ------ ------
? ?????? 2009
1 NOV 29 1905
2 NOV 27 1944
3 NOV 26 1902
4 NOV 26 1958
5 NOV 25 1928
FOR ADDITIONAL INFORMATION...PLEASE VISIT OUR WEBSITE AT
WWW.WEATHER.GOV/KC.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
