Re: 92L - Very Interesting Preliminary NCEP Forecast Discussion
Posted by DTB_2009 on 8/25/2009, 10:31 am
PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
906 AM EDT TUE AUG 25 2009

VALID 12Z SAT AUG 29 2009 - 12Z TUE SEP 01 2009

TELECONNECTIONS FOR A NEGATIVELY ANOMALY IN THE NORTHEAST PACIFIC
WHICH FADES LATE IN THE PERIOD FAVORS RIDGING IN WESTERN NORTH
AMERICA AND DOWNSTREAM TROUGHING ACROSS EASTERN CANADA/THE
NORTHEAST/GREAT LAKES WHICH WEAKENS EARLY NEXT WEEK.  RIDGING
ACROSS WESTERN CANADA IS SO AMPLIFIED THAT THERE IS ROOM FOR
ENERGY TO UNDERCUT IT ABOUT 20 DEGREES UNDER ITS APEX...IN THE MID
40S LATITUDE.  THE MODELS AGREE WITH THESE IDEAS.   THERE ARE
DIFFERENCES CONCERNING THE STRENGTH OF THE GREAT LAKES/NORTHEAST
TROUGHING WITH THE 00Z UKMET THE MOST AMPLIFIED AND THE 00Z/06Z
GFS THE QUICKEST TO LIFT THE CORE OF THE ENERGY NORTHWARD.  SINCE
THE 00Z ECMWF/00Z CANADIAN SPLIT THE DIFFERENCE...THEY ARE
PREFERRED.

THE PROBLEM OF THE DAY CONTINUES TO BE A DEVELOPING TROPICAL
DISTURBANCE...NOW NEAR 21.5N 61.5W...WHICH CONTINUES TO EXHIBIT
DIFFERENCES AND DAY-TO-DAY CHANGES WITHIN THE MEDIUM RANGE
GUIDANCE.  ALL THE GLOBAL GUIDANCE HAVE TRENDED WESTWARD WITH ITS
TRACK SINCE THIS TIME YESTERDAY WHILE THEIR FORWARD MOTION HAS
SHOWN GOOD CONTINUITY.  HOWEVER...THE 00Z MULTI-MODEL ENSEMBLE
GUIDANCE SHOWS THE ECMWF MEMBERS MORE WEST/INLAND THAN THE
CANADIAN/GEFS MEMBERS WHICH ARE OFFSHORE.  THE NON-ETA 03Z SREF
MEMBERS ALSO PREFER AN OFFSHORE TRACK WHILE THE ETA MEMBERS HEAD
THE POSSIBLE TROPICAL CYCLONE TOWARDS THE CAROLINAS.  CHOSE TO
SPLIT THE DIFFERENCE IN THE ENSEMBLE SPREAD AND TRACK THE SYSTEM
CLOSE TO THE EASTERN SEABOARD...WHICH LED TO ADDITIONAL
ACCELERATION FROM THE NIGHT SHIFT PROGS. THIS PREFERRED SOLUTION
MIRRORS A SLIGHTLY SLOWER VERSION OF THE 06Z DGEX WITH THIS
CYCLONE.  HEAVY RAINFALL SHOULD SPREAD TO THE LEFT OF ITS TRACK
ALONG THE MID-ATLANTIC COAST THROUGH SOUTHERN AND EASTERN NEW
ENGLAND...IF THIS TRACK VERIFIES.  THE COORDINATION CALL WITH TPC
AT 16Z SHOULD BE INTERESTING TODAY...AND COULD LEAD TO CHANGES IN
THIS PREFERENCE.

ROTH/JAMES
89
In this thread:
92L Could Spinup Late Today or Early Wednesday. - JAC, 8/25/2009, 6:58 am
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