HPC Discussion for our Official-Casters
Posted by JAC on 9/22/2010, 10:11 am
http://www.hpc.ncep.noaa.gov/preepd/preepd.html


PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
822 AM EDT WED SEP 22 2010

VALID 12Z SUN SEP 26 2010 - 12Z WED SEP 29 2010

THE GENERAL FLOW PATTERN FEATURES AN EXTRATROPICAL TRANSITIONING
TYPHOON MALAKAS HELPING TO DEEPEN TROUGHING IN THE WESTERN
PACIFIC...WHICH IN TURN LEADS TO AMPLIFIED TROUGHING DOWNSTREAM
NEAR 140W...BUILDING RIDGING ACROSS THE ROCKIES/GREAT BASIN...AND
DEEPENING TROUGHING OVER THE EASTERN HALF OF THE LOWER 48 UNITED
STATES.  DAY-TO-DAY AND RUN-TO-RUN CONSISTENCY HAS BEEN
FLEETING...THOUGH THE ECMWF AND ITS ENSEMBLE MEAN HAVE SHOWN THE
BEST CONTINUITY OVER THE PAST FEW DAYS.  PROBLEMS LIE WITH HOW
MUCH ENERGY DIVES OUT OF SOUTHWESTERN/CENTRAL CANADA AND THROUGH
THE UPPER MIDWEST TO CUT OFF FROM THE WESTERLIES BY SUNDAY...AND
WHETHER OR NOT SHORTWAVE ENERGY NEARING THE GREAT LAKES ON
MONDAY/TUESDAY WILL BE STRONG ENOUGH TO LURE THE SYSTEM MORE
NORTHEASTWARD.  THE SOLUTIONS OVER THE PAST SEVERAL DAYS HAVE
CONVERGED... SOMEWHAT... BUT STILL VARY QUITE A BIT CONSIDERING
THE MOST RECENT 90 00Z MULTI-MODEL ENSEMBLE MEMBERS.  00Z
GFS/ECMWF/GEFS MEAN ARE ON THE WEST SIDE OF THE 00Z GUIDANCE
SPREAD WITH THE CANADIAN/UKMET TO THE EAST.  GIVEN THE SWINGS IN
THE GUIDANCE AND CONTINUITY THAT LEANS TO A FARTHER EAST
SOLUTION... LEANED ON THE 00Z ECMWF AND ITS ENSEMBLE MEAN
SOLUTIONS THROUGH THE PERIOD.  CONFIDENCE REMAINS LOWER THAN
NORMAL IN THE DETAILS OF THE FORECAST FROM NEXT MONDAY ONWARD.

DOWN SOUTH...THE DETERMINISTIC AND ENSEMBLE GUIDANCE CONTINUE TO
ADVERTISE A SYSTEM LIFTING OUT OF THE WESTERN CARIBBEAN /INVEST
95L/ TO THE NORTH ACROSS EITHER THE YUCATAN CHANNEL OR WESTERN
CUBA BY MID NEXT WEEK.  THE 00Z CANADIAN WAS BY FAR THE
STRONGEST/LARGEST WITH THIS SYSTEM...AND WAS DISCOUNTED.
CONSIDERING THE TRENDS ACROSS THE MIDWEST/EAST...IT APPEARS THAT
THIS SYSTEM WOULD BE HEADED NORTH TO NORTHEAST INTO THE SOUTHEAST
GULF OF MEXICO/WESTERN FLORIDA STRAITS TOWARDS THE NORTHEAST GULF
COAST/FLORIDA IN 7-10 DAYS.  THE DETAILS WILL BE COORDINATED WITH
NHC AT 16Z.  STAY TUNED.

ROTH/FRACASSO
a
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Cut the Madness - JAC, 9/22/2010, 7:23 am
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