Prognostic Meteorological Discussion
Issued by NWS

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4

000
FXUS02 KWBC 050608
PMDEPD

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
107 AM EST THU MAR 05 2015

VALID 12Z SUN MAR 08 2015 - 12Z THU MAR 12 2015

...GUIDANCE/UNCERTAINTY EVALUATION AND SENSIBLE WEATHER
HIGHLIGHTS...

GUIDANCE THAT HAD BEEN IN DECENT AGREEMENT OVERALL HAS DIVERGED
SIGNIFICANTLY WITH THE 12 UTC CYCLE CONCERNING THE TIMING OF THE
ORGANIZED SYSTEM NEARING THE WEST COAST IN ABOUT A WEEK. 12 UTC
ECMWF ENSEMBLES TRENDED MORE PROGRESSIVE AND  THE 12 UTC GEFS MUCH
SLOWER...OPPOSITE OF RESPECTIVE MODEL BIASES. THE INITIAL UPPER
LOW IS WELL SEPARATED FROM THE WESTERLIES AND PACIFIC WATER VAPOR
LOOPS FAVOR SLOW MOVING/HIGH AMPLITUDE FLOW. ACCORDINGLY AND GIVEN
UNCERTAINTY...THE WPC SOLUTION BLENDING THE 12 UTC NAEFS AND OLDER
00 UTC ECMWF ENSEMBLES PRODUCES A NET SOLUTION LEANING 2/3RD OF
THE WAY ON THE SLOWER SIDE OF THE FULL ENVELOPE OF SOLUTIONS. THIS
ONLY ALLOWS LIMITED MOISTURE REACH THE WEST COAST LATE IN THE
PERIOD AHEAD OF THE APPROACHING ERN PAC SYSTEM.

A SLOWER MID-LATITUDE SYSTEM PROGRESSION ACROSS THE PACIFIC
MID-LATITUDES ALLOWS MORE ROOM FOR NERN PACIFIC/ALASKAN ENERGY TO
BREAK INLAND AND SEWD OVER WRN CANADA AND THE US NRN TIER...BUT
PROBABLY NOT AS ROBUST AS THE 12/18 UTC GFS. THE NEWER 00 UTC GFS
HAS LESS AMPLITUDE MORE IN LINE WITH THE WPC BLEND.
SYSTEM SPECIFICS REMAIN HIGHLY UNCERTAIN...BUT EXPECT SOME LIGHT
SNOWS WITH A SERIES OF FRONTAL SYSTEMS CROSSING THE UPPER
MIDWEST/GREAT LAKES/NEW ENGLAND.

UNDERNEATH...FORECAST SPREAD DECREASED OVER THE LAST FEW GUIDANCE
CYCLES...BUT THERE REMAINS QUITE A BIT OF UNCERTAINTY WITH THE
DETAILS OF THE EJECTION OF ENERGY OVER THE US SRN TIER ASSOCIATED
WITH A COMPACT UPPER LOW INITIALLY ALONG THE WRN US-MEXICO
BORDER...LENDING A COMPOSITE SOLUTION PREFERENCE. THERE IS STILL
AMPLE POTENTIAL FOR ONE OR MORE PERIODS OF ENHANCED RNFL OVER THE
GULF COAST/SOUTHEAST...WITH THE POSSIBILITY THAT SOME OF THIS
MOISTURE COULD EXTEND FARTHER NWD DURING A PORTION OF THE PERIOD.

SCHICHTEL

$$




USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.