295
FXUS02 KWBC 211842
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
242 PM EDT MON JUL 21 2008
VALID 12Z THU JUL 24 2008 - 12Z MON JUL 28 2008
PRELIMINARY UPDATE...
GLOBAL MODEL/ENSEMBLE GUIDANCE MAINTAINS GOOD CONTINUITY WITH THE
PREVAILING AMPLIFIED LARGE SCALE PATTERN FEATURING A STRONG
CENTRAL NORTH AMERICAN RIDGE SANDWICHED BETWEEN MEAN TROFS OVER
THE NERN PAC/NWRN NOAM AND OVER ERN NOAM. WITHIN EACH MEAN TROF
EXPECT ONE SYSTEM IN PLACE AT THE START OF THE PERIOD TO BE
REPLACED BY A SECOND DURING THE WEEKEND. EARLY IN THE PERIOD THE
GFS IS A SHARP/AMPLIFIED OUTLIER WITH THE TROF OVER THE EAST...
AND THEN BY SUN OR MON THE GFS/CANADIAN BECOME MORE AMPLIFIED THAN
MOST OTHER MODEL AND ENSEMBLE GUIDANCE AS THE ERN TROF RELOADS.
FARTHER WEST... BY DAYS 5-7 SAT-MON THE GFS LOWERS NWRN CONUS/WRN
CANADA HGTS A LITTLE MORE THAN THE ECMWF AND NEARLY IDENTICAL 00Z
GEFS AND EUROPEAN CENTRE ENSEMBLE MEANS. THE UKMET MAY ALSO BRING
A LITTLE TOO MUCH ENERGY INTO THE MEAN RIDGE BY LATE DAY 5. THE
CANADIAN BECOMES OUT OF PHASE WITH REMAINING GUIDANCE OVER THE ERN
PAC AND VICINITY BY DAYS 6-7. CONSULT LATEST TPC
ADVISORIES/DISCUSSIONS FOR LATEST INFO REGARDING T.S. DOLLY WHICH
IS FCST TO BE INLAND OVER THE RIO GRANDE VALLEY AS THE MEDIUM
RANGE PERIOD STARTS EARLY THU. CONSENSUS APPROACH FOR HANDLING
THE WELL AGREED UPON MEAN PATTERN LEADS TO USING A SOLN CLOSE TO
THE 00Z ECMWF FOR DAYS 3-4 THU-FRI... AND A 00Z ECMWF/GEFS MEAN
BLEND TO ACCOUNT FOR INCREASING DETAIL UNCERTAINTY BY DAYS 5-7
SAT-MON.
FINAL...
THE 12Z GFS AND GEM GLOBAL ARE BROADLY SUPPORTIVE OF THE BLEND
USED IN THE PRELIMINARY PACKAGE...WITH THE MANUAL FRONTS AND
PRESSURES LINING UP WELL WITH THE LATEST GEFS MEAN...SO MADE NO
CHANGES FOR THE FINAL ISSUANCE. DOLLY IS STILL EXPECTED TO AFFECT
AT SOUTHERN TEXAS EARLY THIS PERIOD...AND WILL LIKELY CONTRIBUTE
MOISTURE TO THE MONSOON AREAS OF THE DESERT SOUTHWEST ONCE IT IS
WELL INLAND AND DISSIPATED AS AN ORGANIZED CIRCULATION.
CISCO/RAUSCH
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