Prognostic Meteorological Discussion
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FXHW01 KWNH 281218
PMDHI

HAWAII EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
717 AM EST SUN DEC 28 2014

VALID 00Z MON DEC 29 2014 - 00Z MON JAN 05 2015

FOR HAWAI`I AND MUCH OF THE PACIFIC, THE 28/00Z ECENS/ECMWF IS THE
PREFERRED SOLUTION. ITS DETERMINISTIC OUTPUT COULD BE UTILIZED
INTO DAY 6 (3/12Z) AND HAS BEEN A CONSISTENT CHOICE WITH RESPECT
TO THE EXPECTED FLOW PATTERN IN THE SUBTROPICAL AND MID-LATITUDE
PACIFIC. FOR DAY 6 AND BEYOND, THE 28/00Z IS A SOLID CHOICE ACROSS
THE ENTIRE PACIFIC.

THE PRIMARY FEATURE OF THE FLOW THIS PERIOD WILL BE THE
PROGRESSION OF MIGRATORY SYSTEMS ACROSS THE CENTRAL
PACIFIC---ORIGINATING ALONG A RESURGENT WESTERN PACIFIC JET AXIS
EMERGING OFF THE EAST CENTRAL ASIA.

THE TROUGH THAT HAS BEEN ON TRACK TO PASS ACROSS HAWAI`I IN THE
31/00Z TO 1/00Z TIME FRAME WILL BE `FOLLOWED UP` BY ANOTHER
MID-LATITUDE TROUGH IN THE 2/12Z TO 3/12Z TIME FRAME.

BOTH FRONTAL PASSAGES APPEAR TO BE RELATED TO THE SAME COMPLEX
LONG WAVE TROUGH/RIDGE INTERACTIONS OCCURRING OVER THE
HIGH-LATITUDE WESTERN HEMISPHERE. IN PARTICULAR, THE RETROGRESSION
OF THE PATTERN OVER ALASKA AND THE BERING SEA IS ALLOWING A
PROGRESSIVE WEST-TO-EAST PATTERN ALONG 45N-50N TO `UNDERCUT` THE
HIGH LATITUDE RIDGE..

IN THIS MEDIUM RANGE FORECAST PERIOD (2/12Z TO 4/12Z)---A BROAD
TROUGH AND CYCLONIC FLOW ALOFT INVOF THE KAMCHATKA PENINSULA WILL
BE THE ANCHOR POINT FOR AN ACTIVE WESTERLY PACIFIC FLOW AND
CYCLOGENESIS NEAR THE DATELINE. IT`S THE CHARACTER OF THE CENTRAL
PACIFIC `WAVE TRAIN` (IN MY OPINION) THAT FAVORED THE 28/00Z ECENS
SOLUTION LONGER TERM VERSUS THE 28/00Z GEFS.

THOUGHT THE AMPLITUDE OF THE UPPER-LEVEL RIDGE AND THE
RETROGRESSION OF THE FLOW OVER THE GULF OF ALASKA---IN THE GEFS
SOLUTION---RELIES TOO MUCH ON THE FORMATION AND THEN INCORPORATION
OF A 500MB CUTOFF LOW INTO THE MID-LATITUDE FLOW. ITS NORTHWARD
MIGRATION ALONG 155W IN THE DAY 5-6 PERIOD LOOKS OUT OF PLACE.
OTHER FACTORS---OVER THE YUKON AND WEST CENTRAL CANADA---APPEAR TO
ME--TO BE `DRIVING THINGS` IN THE NORTHEAST PACIFIC WITH RESPECT
TO THE RETROGRADING RIDGE.

IT WILL BE WORTH WATCHING...BUT FELT THE 28/00Z GEFS/GFS WAS
`OKAY` GUIDANCE FOR HAWAI`I UNTIL 2/00Z. BUT THEN, IT BEGINS TO
INFLUENCE THE MID-LATITUDE FLOW AND THE EASTERN ALEUTIANS-WESTERN
GULF OF ALASKA WITH ERRONEOUS MID-LEVEL ENERGY TRANSFER.

VOJTESAK

$$





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