Prognostic Meteorological Discussion
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000 FXUS02 KWBC 221550 PMDEPD EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1149 AM EDT WED OCT 22 2014 VALID 12Z SAT OCT 25 2014 - 12Z WED OCT 29 2014 ...OVERVIEW AND PREFERENCES... THE TREND IN MEAN FLOW TOWARD A LESS AMPLIFIED PATTERN ACROSS THE CONUS NORMALLY SUGGESTS LOWER PREDICTABILITY IN FCST DETAILS. TODAY THERE ARE ADDED UNCERTAINTIES PRESENTED BY THE EXTRATROPICAL EVOLUTION OF T.S. ANA/PSBL INTERACTION WITH A MID-LATITUDE PACIFIC SYSTEM NEAR THE START OF NEXT WEEK PLUS UNKNOWN IMPACT FROM TODAY`S MODEL GUIDANCE RECEIVING LESS THAN THE NORMAL COMPLEMENT OF SATELLITE DATA. FOR SPECIFICS OF THE FCST THE 06Z GFS/00Z ECMWF PROVIDED THE MOST REASONABLE OPERATIONAL INPUT EARLY IN THE PERIOD WITH NEARLY EVEN WEIGHTING OF THE 06Z GEFS/00Z ECMWF MEANS INCLUDED WITH THE MODEL FCSTS BY DAY 5 MON. THE ENSEMBLE MEANS OFFER THE BEST WAY TO DOWNPLAY LOWER CONFIDENCE MODEL DETAILS BY DAYS 6-7 TUE-WED. ...GUIDANCE EVALUATION... ALTHOUGH IT IS NOT OUTSIDE THE FULL ENSEMBLE SPREAD... BY SUN-WED THE 00Z GFS SEEMS TO HAVE ONE OF THE LESS LIKELY PACIFIC/WRN NOAM SOLNS ALOFT RESULTING IN ONE OF THE FARTHEST SWD TRACKS FOR THE EXTRATROPICAL REFLECTION OF ANA. THERE IS PLENTY OF UNCERTAINTY IN THE SPECIFICS OF UPSTREAM FLOW AND HOW ANA MAY INTERACT WITH A SEPARATE SYSTEM TO ITS N BY DAY 4 SUN... BUT A TRACK WITHIN THE REALM OF THE 06Z GFS/00Z ECMWF AND THEIR RESPECTIVE ENSEMBLE MEANS WOULD APPEAR MORE PLAUSIBLE AT THIS TIME. WITH SOME DIFFS IN STRENGTH/POSN THE D+8 MULTI-DAY MEANS ARE SUGGESTING A CORE OF POSITIVE HGT ANOMALIES TO THE S/SW OF ALASKA. TELECONNECTIONS RELATIVE TO THIS FEATURE FAVOR A POSITIVELY TILTED TROUGH NEARING THE PAC NW COAST. THE 06Z GEFS/00Z ECMWF MEANS LEAD INTO THIS PATTERN FAIRLY WELL TO PROVIDE A LITTLE MORE CONFIDENCE IN THESE MEANS VERSUS OTHER PIECES OF GUIDANCE. LATEST CONSENSUS HAS TRENDED SOMEWHAT SLOWER WITH THE UPR TROUGH FCST TO PROGRESS EWD FROM THE ERN PAC AND GRADUALLY LOSE AMPLITUDE AS IT HEADS INTO THE DOWNSTREAM RIDGE. THIS TREND IS ACCEPTED GIVEN STRONG 00Z/06Z CLUSTERING THAT REFLECTS THIS TREND AND THE POSSIBILITY THAT ANA`S EVOLUTION COULD LEAD TO MORE AMPLIFICATION ALOFT THAN REFLECTED IN CURRENT SOLNS. RECENT DAYS OF GUIDANCE HAVE REFLECTED SOME DIFFICULTY IN RESOLVING HOW ENERGY EMBEDDED WITHIN THE CONUS TROUGH WILL BE DISTRIBUTED SO FURTHER CHANGES IN SFC WAVE/FRONTAL SPEED DETAILS ARE LIKELY. A SOLN CLOSE TO AN AVG OF THE 06Z GFS/00Z ECMWF APPEARS REASONABLE FOR AT LEAST SAT-SUN. PREFER NEARLY HALF WEIGHTING OF ENSEMBLE MEANS BY MON AND THEN THE MEANS EXCLUSIVELY THEREAFTER. ELSEWHERE... A CONSENSUS LOOKS GOOD FOR ENERGY FCST TO CLOSE OFF AN UPR LOW NEAR OR JUST N OF NRN NEW ENGLAND BY SUN WITH RAPID PROGRESSION INTO THE CANADIAN MARITIMES. MEANWHILE THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES ON T.D. NINE WHICH IS EXPECTED TO TRACK FROM THE BAY OF CAMPECHE INTO THE NWRN CARIBBEAN. RIDGING ALOFT BUILDING IN FROM THE EAST MAY SUPPORT A MORE NWD DRIFT BY DAYS 6-7 BUT SO FAR GFS RUNS HAVE TENDED TO BE ON THE STRONGER/NWD SIDE OF THE GUIDANCE SPREAD AT THIS TIME FRAME. ...SENSIBLE WEATHER HIGHLIGHTS... VIGOROUS TROUGH/SFC SYSTEM NEARING THE WEST COAST AS OF EARLY SAT WILL BRING SOME AREAS OF LOCALLY HVY RNFL TO THE NRN-CNTRL WEST COAST SAT WITH LESSER MSTR SPREADING INLAND THROUGH THE NRN HALF OF THE WEST OVER THE FOLLOWING 1-2 DAYS. AS THIS FEATURE CONTINUES EWD AN AREA FROM THE CNTRL/S-CNTRL PLAINS NEWD INTO THE GRTLKS SHOULD BE FAVORED FOR ORGANIZED RNFL DURING A PERIOD CNTRD AROUND TUE. ONE OR MORE BANDS OF HEAVIER PCPN IS PSBL WITHIN THIS AREA DEPENDING ON PRECISE EVOLUTION SFC/ALOFT. CONTINUE TO EXPECT WELL ABOVE NORMAL TEMPS AHEAD OF THE SFC FRONT WITH ONE OR MORE DAYS OF PLUS 10-20F ANOMALIES FROM THE INTERIOR WEST/ROCKIES THROUGH THE PLAINS AND INTO THE GRTLKS. AFTER A BRIEF DRYING TREND IN THE NORTHWEST ON MON... MSTR AND POTENTIAL FOR SOME HVY RNFL WILL RETURN TO THE PAC NW AHEAD OF THE EXTRATROPICAL EVOLUTION OF ANA OR ITS MERGER WITH A MID-LATITUDE PAC SYSTEM. NEAR THE EAST COAST... EXPECT UNSETTLED WEATHER OVER THE NORTHEAST DURING THE WEEKEND WITH ENERGY ALOFT/SFC FRONT CROSSING THE REGION. FLOW ALOFT MAY BEGIN TO BRING SOME DEGREE OF MSTR TOWARD THE FL PENINSULA LATE IN THE PERIOD. RAUSCH $$

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