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Extended Forecast Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1559Z Oct 24, 2014)
 
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Geographic Boundaries -  Map 1: Color  Black/White       Map 2: Color  Black/White


EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1159 AM EDT FRI OCT 24 2014

VALID 12Z MON OCT 27 2014 - 12Z FRI OCT 31 2014

...THE POTENT EXTRATROPICAL LOW ASSOCIATED WITH TROPICAL STORM ANA
THREATENS BC AND THE NWRN US...

WPC MEDIUM RANGE GUIDANCE HAS BEEN PRIMARILY DERIVED FROM A BLEND
OF REASONABLY COMPATABLE GUIDANCE FROM THE 06 UTC GFS/GEFS MEAN
AND 00 UTC ECMWF/ECMWF ENSEMBLE MEAN MON INTO THU...BEFORE
TRANSITIONING TO MODESTLY HIGHER WEIGHTING OF THE 00 UTC ECMWF
ALONG WITH GFS/ECMWF ENSEMBLES LATER THU INTO NEXT FRI AT THE
EXPENSE OF THE DETERMINISTIC 06 UTC GFS. GUIDANCE BEGINS TO DIFFER
MORE IN ERNEST WITH THE SYSTEM AND THE TRANSLATION SPEED OF A
TRAILING COLD FRONT AND PROGRESSIVE MODEST PCPN IN THIS DAY 6/7
TIME FRAME AND THE WPC SOLUTION IS ON THE STRONGER/MORE AMPLIFIED
SIDE OF THE FULL ENVELOPE OF MODEL AND ENSEMBLE SOLUTIONS...BUT
NOT AS STRONG AND COLD AS THE 00 UTC ECMWF THAT STILL DOES NOT
HAVE SUFFICIENT ENSEMBLE SUPPORT. THE 06 UTC GFS HAS TRENDED
TOWARD THE WPC SOLUTION SIGNIFICANTLY COMPARED TO THE 00 UTC GFS
RUN.  THIS IS ALSO ESPECIALLY EVIDENT WITH THE LESS PROGRESSIVE
NATURE OF AMPLE ERN PACIFIC MID-UPPER LEVEL TROUGHING INLAND INTO
THE WRN US LATER NEXT WEEK WITH DELAYED HEIGHT FALLS ONSHORE IN
THE 06 UTC GFS MORE IN LINE WITH THE ECMWF/ECMWF ENSEMBLES.

THE LATEST MODELS AND ENSEMBLES ARE IN BETTER AGREEMENT WITH THE
APPROACH AND INLAND PUNCH INTO NORTH AMERICA OF THE POTENT
EXTRATROPICAL LOW ASSOCIATED WITH CURRENT PACIFIC TROPICAL STORM
ANA NOW LOCATED WELL NW OF THE HAWAIIAN ISLANDS. ANA HAS BEEN
AROUND FOR A WHILE AND IS FORECAST BY THE CENTRAL PACIFIC
HURRICANE CENTER TO APPROACH VANCOUVER ISLAND WITH 45 KT SUSTAINED
WINDS AND 55 KNOT AND HIGHER TERRAIN ENHANCED GUSTS BY TUESDAY. AN
ASSOCIATED AND WELL ORGANIZED HEAVY WIND/WAVE AND PCPN THREAT
EXISTS INTO BC AND WITH FRONTAL SURGE DOWN AND ACROSS THE NWRN
US...INCLUDING INLAND ELEVATION HEAVY SNOW POTENTIAL OVER THE NRN
ROCKIES INTO MIDWEEK CONSIDERING AVAILABLE MOISTURE AS CURRENTLY
FED INTO THE TROPICAL SYSTEM AS PER LATEST BLENDED TPW LOOPS. THIS
STRONG LOW IS FORECAST TO TRACK INTO THE NRN PLAINS AND UPPER
MIDWEST THU AND THROUGH THE GREAT LAKES INTO THE NORTHEAST IN
ABOUT A WEEK. THIS OFFERS A THREAT FOR ENHANCED COLD ADVECTION
LAKE EFFECT PCPN BY THEN IN THE WAKE OF THIS FEATURE.

SCHICHTEL