765
FXUS02 KWBC 291930
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
329 PM EDT THU MAY 29 2008
VALID 12Z SUN JUN 01 2008 - 12Z THU JUN 05 2008
..FINAL MEDIUM RANGE DISCUSSION
THE MEAN LONGWAVE PATTERN STARTS OFF WITH BROAD TROFS ALONG EACH
COAST AND A FLAT RIDGE OVER THE CENTRAL AND SRN PLAINS. OVER THE
COURSE OF THE NEXT WEEK...FAST FLOW FROM THE PACIFIC WILL DRIVE
INTO THE NWRN CONUS AND FLATTEN THE RIDGE OVER THE CENTRAL CONUS.
MODEL CONSENSUS SHOWS SOME RIDGING ALOFT OCCURRING IN THE SERN
CONUS BY THE END OF THE PERIOD.
THE NEW 12Z GFS APPEARED TO CORRECT THE ERRORS OF ITS PREVIOUS
06Z/29 RUN WHICH LOWERED HEIGHTS TOO MUCH INTO THE FLAT MEAN RIDGE
OVER THE MS VLY AROUND THE MIDDLE OF NEXT WEEK.
WE BLENDED IN 30% OF THE NEW 12Z/29 GFS RUN WITH 70% OF UPDATED
PRELIM CONTINUITY IN CREATING THE FINAL GRAPHICS. THE NEW 12Z/29
ECMWF MAKES A DEPARTURE FROM ITS 00Z CONTINUITY DAYS 5-7 IN
KEEPING MUCH MORE OF AN UPPER TROF OVER ERN CANADA...HOLDING COOL
AIR IN PLACE ACROSS THE NERN QUARTER OF THE CONUS. THIS SEEMS TOO
RADICAL A CONTINUITY CHANGE AND WE PREFER MORE THE 12Z
CANADIAN/12Z GFS/12Z UKMET SIDE OF THE ENVELOPE OF MODEL
SOLUTIONS. THE ECMWF DEFINES THE COLDER EDGE OF THE ENVELOPE OF
SOLUTIONS OVER ERN NOAM DAYS 5-7...WHILE THE GFS/CANADIAN UKMET
EDGE OF SOLUTIONS GIVE A MILDER PICTURE OVER THE NERN CONUS.
PREFER THE MILDER SIDE OF THIS ENVELOPE AS IT FOLLOWS CONTINUITY
BETTER.
REGIONAL HIGHLIGHTS
PLAINS/EAST...
AGAIN TODAY...FRONTAL AND MESOSCALE ACTIVITY WILL BE DEFINED BY A
NWD-SHIFTING SRN EDGE OF THE WESTERLIES. A BROAD WAVY BOUNDARY
ACROSS UPPER PORTIONS OF THE SRN STATES WILL PROVIDE A SYNOPTIC
SCALE FOCUS FOR SCTD TO ORGANIZED CONVECTION THE FIRST TWO DAYS OF
THE MEDIUM RANGE. BY DAY 5...LOOK FOR ACTIVITY TO BE SHIFTING
SLOWLY NWD INTO THE OH VLY/MID ATLANTIC ALONG A WARM FRONTAL ZONE
AS A TREND FOR UPPER TROFFING IN THE W AND RIDGING IN THE SE
COMMENCES. BY DAY 6...THE GRT LAKES AND SRN NEW ENG MAY SEE THE
LIONS SHARE OF ACTIVITY. PRECIPITATION CHARACTER WILL DEFINITELY
TAKE ON SUMMER CHARACTERISTICS WITH SPOTTY LOCALLY HEAVY
RAINS...AS MCS ACTIVITY PROPAGATES ESE THRU THE WARM FRONTAL ZONE.
...TROPICS
WE ARE STILL WATCHING THE BROAD ARE OF DISTURBED WEATHER OVER
CENTRAL AMERICA THAT HAS SPAWNED A TROPICAL DEPRESSION. AFTER THE
INITIAL DEPRESSION DRIFTS WWD AND WEAKENS...MODELS ARE IN NO HURRY
TO SPIN UP A NEW DEVELOPMENT. HOWEVER SHOULD ONE OCCUR...IT WOULD
MOST LIKELY BE THE AREA SOMEWHERE ESE OF THE YUCATAN PENINSULA.
PLEASE REFER TO STATEMENTS FROM THE NATIONAL HURRICANE CENTER.
..WEST/NRN HIGH PLAINS
AGAIN TODAY...SURGES OF PACIFIC ENERGY ARE EXPECTED TO ASSIST
DAILY PERIODS OF INSTABILITY SHOWERS OVER NWRN CONUS ABOVE
LATITUDE 40N. THESE SURGES OF ENERGY WILL HELP KICK OFF MCS
ACTIVITY ONCE THEY REACH THE NRN PLAINS STATES.
FLOOD
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