236
FXUS02 KWBC 041813
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
112 PM EST WED NOV 04 2009
VALID 12Z SAT NOV 07 2009 - 12Z WED NOV 11 2009
FAST STRONG SEMIZONAL PACIFIC FLOW CONTS THIS PERIOD. TYPICAL
SHORTWAVE AMPLITUDE AND TIMING PROBLEMS CONTINUE WITH A STEADY
TREND TO DE AMPLIFY ENERGY COMING INTO THE WEST COAST LATE SAT AND
SUN. THIS BEGAN WITH YTDAS 12Z RUNS AND DEAMPLIFICATION CONTS INTO
THE 00Z RUNS TDA. THE CHANGES ARE AGREED UPON BY MODELS. DAYS 3
AND 4 SAT/SUN ARE WELL ENOUGH TO BLEND ECMWF AND GFS AND OVER
CONUS THIS WOULD INCLUDE DAY 5 MON. MODEL MEANS AND INDIVIDUAL
ENSEMBLE HT CONTOURS SHOW GOOD AGREEMENT THRU DAY 5 BUT HAVE A
VAST INCREASE IN SPREAD WITH POOR RUN TO RUN CONTINUITY AND
INDICATE VERY LOW CONFIDENCE IN ANY SOLUTION. WITH THIS IN MIND
HAVE GONE AGAIN TOWARDS AND INCREASING AMOUNT OF ENSEMBLE MEANS
FOR DAYS 6 AND 7 TUES/WED FROM THE EPAC AND DOWNSTREAM OVER CONUS.
NO CHANGES TO AFTN FINALS FROM MORNING UPDATED PRELIMS.
HIGH PRESSURE COVERS ERN CONUS DAYS 3-5 SAT-MON WITH WARM
ADVECTION FLOW THRU THE CENTRAL AND SRN PLAINS/LOWER MS VALLEY.
WESTWARD PAC HIGH PRESSURE BUILDS INTO THE WEST AND GREAT BASIN
SUNDAY AND MONDAY. BROAD AREA OF BRISK EASTERLY FLOW CONTS THIS
PERIOD FROM SC/GA SOUTHWARD AND ACROSS THE GULF OF MEXICO. MODELS
CONT TO GENERATE A LARGE BROAD AREA OF LOW PRESSURE OVER CENTRAL
AMERICA WITH THE POTENTIAL FOR A COUPLE OF SEPARATE AREAS OF LOW
PRESSURE IN THE EPAC AND GULFMEX. CHI 200/850 VELOCITY POTENTIAL
CHARTS AND A FAVORABLE MJO WITH WEST PHASE 850MB WIND ANOMALIES
CONT TO SPIN UP LOW LEVEL VORTICITY IN THIS REGION. LOWER WRN
GULFMEX REGION CONTS TO BE A FAVORABLE AREA WITH ITS CONCAVE COAST
TO ALLOW FOR LOW LEVEL CYCLOGENESIS OR AT LEAST INVERTED TROF
DEVELOPMENT ALONG A STATIONARY FRONTAL BOUNDARY. THIS CONTS TO BE
AGREED UPON BY MODELS AND SHOULD SPREAD SOME HEAVY RAIN INTO THE
CENTRAL GULF COAST REGION SUN INTO WED. SOUTHWARD T.D. ELEVEN HAS
FORMED AND SHOULD SLOWLY MOVE NWD DURING THE PERIOD TOWARDS THE
YUCATAN CHANNEL. BY DAYS 6 AND 7 PREFER BROAD CYCLONIC MEAN MID
LEVEL FLOW INTO WRN CONUS WITH SOME ERN CONUS RIDGING WITH AS
MENTIONED ABOVE LOW CONFIDENCE.
ROSENSTEIN
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