Prognostic Meteorological Discussion
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000
FXHW01 KWNH 311219
PMDHI

HAWAII EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
818 AM EDT THU JUL 31 2014

VALID 00Z FRI AUG 01 2014 - 00Z FRI AUG 08 2014

THE 31/00Z ECENS AND GEFS MEANS AND THEIR DETERMINISTIC RUNS
MAINTAINED DECENT CONTINUITY THROUGH 6/12Z---WITH A TREND FOR MORE
EASTWARD PROGRESSION OF A MODERATE/STRONGER SHORTWAVE THROUGH THE
ALASKA PANHANDLE.

THE NORTHEASTWARD MIGRATION OF A CLOSED H5-TO-SFC LOW THROUGH THE
CENTRAL GULF OF ALASKA INTO DAY 5-6 HAS TAKEN A SLIGHT
TWIST...WITH THE 31/00Z GFS DETERMINISTIC TAKING THE SYSTEM INTO
NORTHERN BRITISH COLUMBIA AT A FASTER PACE THAN THE DETERMINISTIC
ECMWF BY THE END OF DAY 7. FROM A CONTINUITY PERSPECTIVE, THOUGHT
THE GFS HAS BEEN A BETTER INDICATOR OF MEDIUM RANGE SURFACE
FEATURES IN THE GULF OF ALASKA VS THE ECMWF.

IN THE SUBTROPICS, THE 31/00Z GEFS/ECENS MEANS AND THEIR
DETERMINISTIC RUNS DO NOT WAVER MUCH AT ALL WITH THE SURFACE RIDGE
STRENGTH AND CENTRAL PRESSURE LOCATION INVOF 35-40N 140W BETWEEN
DAYS 4-6. WHAT WILL BE A KEY FEATURE EMERGING IN THE LATTER HALF
OF THE MEDIUM RANGE IN THE EASTERN GULF OF ALASKA APPEARS TO HAVE
A SIGNIFICANT IMPACT ON THE SUBTROPICAL RIDGE AXIS AND NORTHWARD
TRANSPORT OF TROPICAL MOISTURE FROM THE DEEP TROPICS.

BLENDING THE 31/00Z GFS/ECMWF DETERMINISTIC RUNS CONTINUES TO
INDICATE A DISTURBANCE INVOF ~146W @ 7/00Z AND ~149W @ 7/12Z---THE
LATE DAY 6-EARLY DAY 7 TIME FRAME. THIS BLEND YIELDS A SLIGHTLY
SLOWER TREND VERSUS 24 HOURS AGO---AND THE 30/00Z CYCLE. BUT A 1
DEGREE EASTWARD ADJUSTMENT IS NOT A BAD STARTING POINT FOR A
FEATURE THAT HAS ALSO TRENDED A DEGREE OR TWO NORTH AND WEST IN
THE LAST 24 HOURS.

PLEASE MONITOR INFORMATION FROM THE CENTRAL PACIFIC HURRICANE
CENTER AND NATIONAL HURRICANE CENTER CONCERNING TROPICAL WEATHER
DEVELOPMENTS IMPACTING HAWAI`I.

VOJTESAK

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