142
FXUS02 KWBC 031855
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
249 PM EDT TUE JUN 03 2008
VALID 12Z FRI JUN 06 2008 - 12Z TUE JUN 10 2008
THE GENERAL FLOW PATTERN FEATURES TWO POSITIVE ANOMALIES NEAR
NORTH AMERICA...ONE MOVING BY 45N 150W AND ANOTHER DEVELOPING NEAR
NEW YORK CITY. THIS FAVORS TROUGHING/A POSSIBLE CLOSED CYCLONE IN
THE PACIFIC NORTHWEST AS WELL AS TROUGHING EAST OF THE ATLANTIC
CANADA. IN THE WEST...THIS FAVORS A MORE 00Z OR 12Z CANADIAN/12Z
UKMET SOLUTION WHILE OUT EAST...A NON-00Z CANADIAN SOLUTION IS
PREFERRED NEAR THE EASTERN RIDGE. THIS LED TO A MODEL CHOICE OF
THE 06Z GFS/00Z ECMWF COMPROMISE EARLY ON...BEFORE THE PREFERENCE
SWITCHED TO THE 06Z GFS/06Z NCEP ENSEMBLE MEAN BLEND LATE. NO
CHANGES HAVE BEEN MADE IN THE AFTERNOON PRESSURES.
EASTERN PACIFIC/WEST COAST...
THE MODEL THAT MOST RESEMBLES THE PREFERRED IDEA BEST IN THIS
REGION IS THE 00Z CANADIAN...WHILE THE 12Z CANADIAN AND UKMET ARE
JUST SLOWER VERSIONS OF OUR PREFERENCE. THERE IS A HIGH DEGREE OF
SPREAD CONCERNING THE CLOSED CYCLONE WHICH MOVES DOWN THE COAST OF
NORTH AMERICA...WITH THE ECMWF AND 12Z GFS THE LEAST AGGRESSIVE
/THOUGH THE ECMWF IS TRENDING QUICKER/ AND THE 00Z/06Z GFS THE
MOST AGGRESSIVE. A LOOK AT THE 00Z ENSEMBLE MEMBERS FROM THE
GEFS/CANADIAN/ECMWF ENSEMBLES SHOW THAT THE 06Z GFS SOLUTION IS
POSSIBLE WHEN LOOKING AT THE 5640 METER HEIGHT LINE SPAGHETTIS AT
500 HPA. OVER THE PAST FEW MONTHS...THE MORE EXTREME TROUGH/UPPER
LOW SOLUTIONS IN THE WEST HAVE VERIFIED. HOWEVER...WITH SO MUCH
SPREAD SEEN IN THE OPERATIONAL GUIDANCE...WILL TREND TOWARDS THIS
IDEA BY BLENDING THE 06Z GFS WITH THE 06Z NCEP ENSEMBLE
MEAN...SIMILAR TO THE 00Z CANADIAN...AND MAINTAINED EXCELLENT
CONTINUITY FROM DAY TO DAY.
NORTHERN PLAINS/EASTERN CANADA/EAST...
THE NCEP ENSEMBLE MEAN HAS TRENDED TOWARDS YESTERDAYS QUICKER
GUIDANCE CONCERNING THE CYCLONE PROGRESSING FROM THE UPPER
MISSISSIPPI VALLEY INTO THE FAR NORTHERN ATLANTIC. WHILE THERE
ARE STILL PROBLEMS CONCERNING EXACT CYCLONE TRACK AND PROGRESSION
OF THE BACKDOOR COLD FRONT/LIFTING WARM FRONT IN THE EAST...A
COMPROMISE BETWEEN THE 06Z GFS/00Z ECMWF SOLUTIONS APPEARS BEST
CONSIDERING THE TREND SEEN IN THE NCEP ENSEMBLE MEAN...LEADS TO
EXCELLENT CONTINUITY...AND TAKES ADVANTAGE OF THE BETTER
VERIFICATION NORMALLY SEEN IN THE ECMWF EARLY IN THE MEDIUM RANGE
PERIOD. THIS SOLUTION IS ONLY SLIGHTLY SLOWER THAN SEEN ON
YESTERDAYS MANUAL PROGS. IN THE WARM SECTOR ACROSS THE UPPER OHIO
VALLEY AND MID-ATLANTIC STATES UNDER THE DOMINATION OF A WARM CORE
RIDGE...WIDESPREAD 90S ARE EXPECTED EACH AFTERNOON...WITH THE
FIRST 100 DEGREE TEMPERATURES OF THE WARM SEASON POSSIBLE IN
ISOLATED LOCATIONS.
PRECIPITATION AREAS OF CONCERN...
THE LOWER OHIO VALLEY WILL INITIALLY SEE THE CONVECTIVE ACTION
THIS PERIOD NEAR A SPLIT IN THE UPPER FLOW PATTERN ALONG A
PROGRESSIVE COLD FRONT. THE NEXT FRONTAL WAVE IN THE SERIES THIS
WEEKEND COULD BRING HEAVY RAINS TO THE UPPER MISSISSIPPI VALLEY
AND GREAT LAKES. DOWN SOUTH...THE MODELS ARE DELAYING THE ONSET
OF THE WET SEASON IN FLORIDA UNTIL AT LEAST JUNE 7...WHICH WOULD
MAINTAIN HIGHER THAN NORMAL FIRE DANGER ACROSS THE FLORIDA
PENINSULA DURING THE REMAINDER OF THE FIRST WEEK OF JUNE.
ROTH
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page