Prognostic Meteorological Discussion
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FXHW01 KWNH 311230
PMDHI

HAWAII EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
729 AM EST SAT JAN 31 2015

VALID 00Z SUN FEB 01 2015 - 00Z SUN FEB 08 2015

THE 31/00Z ECENS/GEFS MEANS AND DETERMINISTIC RUNS HAVE NOT
WAVERED ON THEIR DEPICTION OF THE SYNOPTIC-SCALE PATTERN THROUGH
F84 (3/12Z)---AND THE EMERGENCE OF A DEEPENING SURFACE CYCLONE
INVOF ~30N 155W (A SUB 996MB SFC LOW).


MEDIUM RANGE ASSESSMENT/UNCERTAINTY...
FUNDAMENTALLY,THE ECENS/GEFS DIFFER SIGNIFICANTLY AFTER 5/12Z
(MID-POINT DAY 5) AS THE DAY 3---30N 155W SURFACE CYCLONE
INTENSIFIES AND MIGRATES DOWNWIND OF THE UPPER-LEVEL TROUGH. THE
FUNDAMENTAL DIFFERENCE IS---EROSION AND BREAKDOWN OF THE
DOWNSTREAM NORTH AMERICAN RIDGE. FOR REASONS OF SEMI-UNKNOWN
ORIGIN...THE 31/00Z GEFS/GFS DEFLECTS THE DEEP CYCLONE (NOW A SUB
968 MB LOW) BY 5/12Z SO FAR AWAY FROM THE GULF OF ALASKA AND THE
UPPER-LEVEL RIDGE---TO RULE OUT THE ENTIRE PACKAGE.

RECOMMEND SETTLING ON THE MORE CONSISTENT ECENS AND DETERMINISTIC
ECMWF (LAST THREE RUNS) DURING THIS 1-7DAY FORECAST CYCLE. ITS
SUGGESTION THAT A RATHER BROAD AND FAST-MOVING 200MB WESTERLY JET
WILL BECOME WELL-ESTABLISHED ACROSS THE WESTERN PACIFIC---AND
COVERING THE 35N-40N LATITUDES TO ROUGHLY 150W-160W. THAT FLOW
SHOULD ANCHOR A SERIES OF MODERATELY-INTENSE SURFACE WAVES NORTH
AND WEST OF HAWAI`I THROUGH THE PERIOD. THE SEQUENCING AND
EVOLUTION---HANDLED WITH BETTER SUCCESS.

VOJTESAK


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