427
FXUS02 KWBC 131802
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
201 PM EDT SUN JUL 13 2008
VALID 12Z WED JUL 16 2008 - 12Z SUN JUL 20 2008
...NOAM AND SURROUNDING OCEANS MODEL PREFERENCES AND SENSIBLE
WEATHER HIGHLIGHTS...
THE MODELS AND ENSEMBLES STILL OFFER REASONABLY SIMILAR LARGER
SCALE MID-UPPER LEVEL FLOW PATTERN FOR MUCH OF THE UPCOMING WEEK
FROM THE OCEANS THROUGH NORTH AMERICA...BUT DIFFER SIGNIFICANTLY
WITH MID-SMALLER SCALE DETAILS. THE MEAN MEDIUM RANGE PATTERN
ALOFT IS BLOCKY AT HIGHER LATITUDES AS COMPRISED OF TWO DEEP
CLOSED LOWS CENTERED NEAR AK AND THE ARCTIC AND A LESS ORGANIZED
E-CENTRAL CANADA LOW/TROF POSITION...ALL SANDWICHED AROUND AN
AMPLIFIED NW CANADA RIDGE. A DIET OF MORE TRANSIENT SMALLER SCALE
SYSTEMS RIDE UNDERENATH AND INLAND FROM THE PACIFIC INTO A MEAN NW
US/SW CAN MID-UPPER LEVEL TROF BEFORE EJECTING EWD ACROSS SRN
CANADA AND THE US NRN TIER STATES. SLOW MOVING BOUNDARIES NEAR
THE SRN EDGE OF THESE WESTERLIES WILL BE A PRIME LOCATION FOR
SIGNIFICANT AFTERNOON/OVERNIGHT CONVECTION AND AN ACCOMPANING
HEAVY RAINFALL THREAT AS PER IMPULSE PASSAGE AND LOWER LEVEL
INFLUX. THIS SEEMS ESPECIALLY EVIDENT FROM THE N-CENTRAL PLAINS
AND UPPER MIDWEST INTO THE GREAT LAKES. SUMMERTIME VORTS ARE
EMBEDDED FARTHER SOUTH WITHIN/AROUND MUCH WEAKER FLOW WITHIN
HOTTER/MORE CAPPED MID-LATITUDE MEAN RIDGING. LOCALLY HEAVY
RAINFALL ENHANCING FEATURES AND POOLED DEEP MOISTURE SEEM BEST
DEFINED UNDERNEATH THIS RIDGE OVER THE SERN US/FL. THERE IS ALSO
A LINGERING MONSOONAL FETCH UP THROUGH MEXICO INTO THE SW US AND
THE S-CNTRL GREAT BASIN/ROCKIES AROUND THE WRN PERIPHERY OF THE
RIDGE...COMPLETING THE OVERALL RING OF FIRE PATTERN OVER THE US.
HPC FINAL GUIDANCE THU-SUN WAS PRIMARILY DERIVED FROM A SOLUTION
IN LINE WITH THE LARGE SCALE FLOW OF THE 00 UTC GFS ENSEMBLE MEAN.
THE GEFS IS MAINLY CLUSTERED WITHIN THE FULL ENVELOPE OF ALL
MODEL AND ENSEMBLE SOLUTIONS AND INCREASINGLY FILTERS THE
SEEMINGLY LESS PREDICTABLE SMALLER SCALE FEATURES OVER TIME AS
SOLUTION SPREAD AND UNCERTAINTY GROWS. THIS SOLUTION ALSO
MAINTAINS CLOSE CONTINUITY WITH PRIOR HPC GUIDANCE.
ROTH/SCHICHTEL
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page