FXUS02 KWBC 081801
PMDEPD
 
EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
200 PM EDT WED SEP 08 2004
 
VALID 12Z SAT SEP 11 2004 - 12Z WED SEP 15 2004
 
FINAL DISCUSSION...

MEDIUM RANGE MODEL MEANS SHOW AN AMPLIFIACTION OF THE FLOW WITH
INCREASING HT FALLS INTO THE PAC NW WITH AN AMPLIFYING TROF AND
INCREASINGLY STRONG NEG HT ANOMALIES AND DOWNSTREAM HT RISES OVER 
ERN NOAM. AGAIN TDA VERY GOOD AGREEMENT BETWEEN GFS AND ECMWF.

MODELS OVERALL GO FROM A SEMIZONAL WESTERLY FLOW WITH A LIFT OUT
OF AN ERN TROF...REMAINS OF HURCN FRANCES...TO A MORE AMPLIFIED
WRLY FLOW AS A LEAD SHORTWAVE COMES INTO THE PAC NW AND SHEARS OUT
NEWD AS PAC FLOW DIVES SEWD REINFORCING A WEST COAST TROF WITH
CONTD RISE OF ERN CONUS AND ERN CANADAIN HTS. GFS THE MOST
AMPLIFIED WITH THIS SOULTION WITH GOOD RUN TO RUN CONTINUITY.
OTHER MODELS NOGAPS/CANADIAN/UKMET AND GFS ENS MEANS ARE MODERATLY
AMPLIFIED. THE 12Z ECMWF HAS UNDERGONE A CONTINUITY CHANGE WITH A
TREND OF PAST 3 DAYS TOWARD DE AMPLIFICATION AND MORE ZONAL FLOW
UNTIL LATE IN THE PERIOD WHEN IT COMES BACK INTO AGREEMENT WITH
THE GFS HIGHLY AMPLIFIED WRN TROF. LATER 00Z ECMWF IS MORE
AMPLIFIED WITH ITS PATTERN AND A BETTER MATCH TOWARD A CONSENSUS. 
HPC PREFERENCE IS TOWARD THE GFS ENS MEAN WHICH IS A MODERATED
VERSION OF THE OP GFS WHICH HAS SHOWN RECENT LOW HT BIAS AND A
CONSENSUS OF THE OTHER MODELS EXCEPT THE 12Z ECMWF.   

LATEST 12Z GFS LESS AMPLIFIED THAN PRIOR 06Z AND 12Z AND A BIT
LESS THAN THE ENS MEAN. LITTLE SFC RELECTION DIFFERENCE FROM PRIOR
PROGS 


VERY WIDE SPREAD OF SOLUTIONS CONT WITH HANDLING HURCN IVAN
RANGING FROM THE CAROLINAS TO YUCATAN AT LONGER RANGES.
LATE MORNING AND AFTN RUNS OF GLOBAL MODELS(12Z RUNS OF
UKMET/NOGAPS/CANADIAN)SEEM TO BE GRADUALLY CONVERGING ON A
SOLUTION COMING ACROSS CUBA INTO THE EASTERN GULF OF MEXICO 
AFFECTING FLORIDA/NERN GULF COAST AND THE SOUTHEASTERN U.S. 
SEE NHC ADVISORIES/WARNINGS/DISCUSSIONS.


REGIONAL HIGHLIGHTS...

..EAST..
HIGH PRESSURE INITIALLY OVER NEW ENGLAND AND THE OHIO VALLEY
GRADUALLY MOVES OFFSHORE WITH THE APPROACH OF THE FRONTAL BNDRY
THROUGH THE GREAT LAKES AND EVENTUALLY OFF THE NEW ENGLAND COAST
BY DAY 5/MON. EXTRAPOLATED HURCN IVAN INTO SWRN GA MAY SPREAD HVY
RAINS THRU GA/SC AND SRN APPLCHNS BY WED. LOW CONFIDENCE.

...NORTHWEST..
A SERIES OF POTENT FRONTS MOVES IN OFF THE PACIFIC KEEPING TEMPS
SLIGHTLY COOLER THAN NORMAL ALONG WITH HIGHER POPS DURING THE
LATTER PORTION OF THE PERIOD.

..FL/GULF COAST/SOUTHEAST..
LATEST TPC TRACK TAKES HURCN IVAN ACROSS WRN CUBA AND CLOSE TO AND
ALONG SWRN FL COAST BY THE BEGINNING OF NEXT WEEK. HPC
EXTRAPOLATION IS DUE NWD INTO SWRN GA BY DAY 7 WED. DIFFICULT
FORECAST WITH VERY WIDE SPREAD OF MODEL SOLUTIONS AT DAY 3 SAT AND
ONWARD YIELDING LOW CONFIDENCE.BUT A TREND TOWARD A CONVERGENCE OF
SOLUTIONS TOWARD THE EASTERN GULF OF MEXICO BY MOST 12Z MODEL
RUNS. REFER TO LATEST TPC ADVISORIES/WARNINGS.
ROSENSTEIN

GRAPHICS AVAILABLE AT WWW.HPC.NCEP.NOAA.GOV
$$