605
FXUS02 KWBC 111918
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
316 PM EDT FRI JUL 11 2008
VALID 12Z MON JUL 14 2008 - 12Z FRI JUL 18 2008
..FINAL MEDIUM RANGE FORECAST DISCUSSION
MODELS/ENSEMBLES SHOW THE LONGWAVE PATTERN FEATURING VERY BROADLY
CYCLONIC FLOW ACROSS THE NRN STATES AND SRN CANADA...WITH ANOTHER
TROF ATTEMPTING TO FORM NEAR VANCOUVER/BC AND THE PACIFIC NW COAST
NEXT WEEK. HURCN BERTHA WILL REMAIN IN A WEAK FLOW PATTERN FOR THE
FORESEEABLE FUTURE WELL OFF THE E COAST. TS BERTHA POSITIONS DAY 5
AND BEYOND MAY NEED TO BE ADJUSTED S....SEE BULLETINS FROM THE
TPC.
THE AREA ALONG AND OFF THE PACIFIC NW COAST REMAINS THE MAIN BONE
OF CONTENTION AMONG THE
MODELS ESPECIALLY DAYS 5-7. LATEST ENSEMBLE DATA REASONABLY
SUPPORT A DECENT TROF NEAR 50N/130W BY DAYS 5-6.
THE NEW 12Z/11 GFS HAS QUESTIONABLE CONTINUITY AS IT HAS STRONGLY
BACKED OFF FROM ITS CLOSED LOW NEAR 50N/130W FOR THU DAY 6 IN ITS
06Z/11 RUN. THE 12Z/11 ECMWF HAS TRENDED IN THE OPPOSITE DIRECTION
AT FHR 132. AFTER TUE DAY 4 THE NEW GFS BECOMES TOO FAST FOR MY
LIKING DRIVING A FRONT ACROSS SERN CANADA AND THE ADJACENT NERN
STATES....AFTER HAVING GREAT CONTINUITY THRU THE FIRST 60 HOURS.
THE 12Z/11 CANADIAN/UKMET/ECMWF UNDERSCORE THE DIFFICULTY IN
TRYING TO NAIL DOWN HOW MUCH ENERGY LINGERS OVER BC VERSUS HOW
MUCH SHEARS OUT ACROSS CANADA TUE-THU. ALL THE NEW 12Z GUIDANCE
TOGETHER SUPPORTS OUR STAYING ON THE SLIGHTLY MORE AMPLIFIED
ENVELOPE OF SOLUTIONS CONCERNING THE PACIFIC NW TROF....AND IN THE
MIDDLE OF THE ENVELOPE OF MODEL AND ENSEMBLE SOLUTIONS ELSEWHERE.
..REGIONAL HIGHLIGHTS
..SLOWLY WEAKENING FRONT ACROSS THE SERN STATES
A DECENT FRONT FOR THIS TIME OF YEAR WILL PUSH WELL S INTO THE
GULF STATES...PERHAPS EVEN THE NRN FL PANHANDLE...HELPING TO FOCUS
MOISTURE SHOWERS AND TSTMS. THE ECMWF AND CANADIAN MODELS PINCH
OFF AN UPPER LOW W OF FL FROM AN UPPER TROF ALONG THE SE COAST
DAYS 5-6...AND THIS FEATURE...SHOULD IT MATERIALIZE....HAS THE
POTENTIAL TO INCREASE LOCALLY HEAVY RAINFALL ACROSS THE NRN HALF
OF THE FL PENINSULA TOWARDS THE END OF NEXT WEEK.
..SW MONSOON AREA.
WITH NO MECHANISM TO INTERRUPT IT...MONSOONAL MOISTURE NOW IN
PLACE SHOULD CONTINUE TO FIRE UP EACH DAY DURING THE TIME OF THE
DIURNAL MAXIMUM SOUTH OF 40 DEGREES LATITUDE. NEAR AND ABOVE
LATITUDE 40N...MORE WESTERLY FLOW SHOULD KEEP CONDS DRIER ACROSS
THE NRN ROCKIES AND NRN HIGH PLAINS. WESTERLY COMPONENTS ALOFT
ASSOCIATED WITH A TROF ALONG THE W COAST WILL ALSO HELP KEEP
MONSOONAL MOISTURE FROM SPREADING TOO FAR W INTO SE PORTIONS OF
CA...NV...AND UT.
..FRONT PUSHING INTO THE UPPER MS VLY/WRN GRT LAKES
BEGINNING ON TUE AND CONTINUING THE REMAINDER OF THE WEEK...A WAVY
FRONTAL SYS AND ITS MESO-GENERATED BOUNDARIES WILL BE A FOCUS FOR
CONVECTION. INITIALLY...MOST OF THE ACTIVITY SHOULD BE N-W OF THE
AREAS THAT HAVE RECENTLY EXPERIENCED THE GREATEST FLOODING. WITH
TIME...HOWEVER...OUTFLOW BOUNDARIES COULD PUSH THE MAIN FOCUS DOWN
INTO VULNERABLE IA/WI THE LATTER HALF OF NEXT WEEK.
FLOOD
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