Prognostic Meteorological Discussion
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000
FXHW01 KWNH 271227
PMDHI

HAWAII EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
726 AM EST SAT DEC 27 2014

VALID 00Z SUN DEC 28 2014 - 00Z SUN JAN 04 2015

THOUGHT THE 27/00Z ECENS/ECMWF SOLUTION MORE CLOSELY FOLLOWS THE
EVOLVING PATTERN IN THE MID-LATITUDE AND SUBTROPICAL CENTRAL
PACIFIC EASTWARD TO THE US MAINLAND. THE PRIMARY REASON IS HOW
MUCH FASTER THE 27/00Z GEFS/GFS IS---INCORPORATING SEVERAL KEY
FEATURES INTO THE FLOW PATTERN---PARTICULARLY IN THE GULF OF
ALASKA AND OVER THE DESERT SOUTHWEST (AZ/NV/SOCAL) BY DAY 5 (NEXT
THURSDAY). AT THE VERY LEAST, THE 27/06Z DETERMINISTIC GFS HAS
SLOWED DOWN THE PROGRESSION OF A CLOSED 500MB LOW INVOF 35N 150W
AROUND THE 1/12Z TIME FRAME. THE DETERMINISTIC 27/00Z ECMWF WOULD
HAVE THIS SAME FEATURE CLOSER TO 30N 155W AT 1/12Z.

PREFER THE DETERMINISTIC ECMWF HERE. THAT IS---IF---THE FORECAST
WAS TO LEAN ONE WAY OR THE OTHER WITH A DETERMINISTIC OUTCOME AT
THE DAY 4-5 TIME SCALE. THOUGHT IS THAT IT MAY PROVIDE A BETTER
REPRESENTATION OF THE CLOUD COVER AND LOW-LEVEL WIND FIELDS FOR
THE MID-LEVEL TROUGH PASSAGE IN 30/00Z-1/00Z TIME FRAME.

THE KEY FRAME OF REFERENCE---FOR THE HAWAI`I FORECAST---REMAINS
TIED TO A MID-LEVEL TROUGH MIGRATION ACROSS HAWAI`I BETWEEN 31/00Z
AND 1/00Z. THE CONSOLIDATION OF THIS TROUGH BETWEEN 150W-160W AND
A DOWNSTREAM MIGRATION OF THIS ENERGY REALLY IS THE FUNDAMENTAL
DIFFERENCE---THAT WOULD LEAN MY PREFERENCE AWAY FROM THE GEFS/GFS
SOLUTION---BEYOND THE 1/00Z TIME FRAME. THE EMERGENCE OF A CLOSED
500MB LOW SCENARIO---A FEATURE OF BOTH 27/00Z MEANS
(ECENS/GEFS)---ADDS SOME CONFIDENCE THAT ANOTHER MID-LEVEL TROUGH
WILL BEGIN TO AFFECT THE FORECAST AREA ON TUESDAY AND SPREADS
THESE SENSIBLE WEATHER IMPACTS EASTWARD ACROSS THE ENTIRE ISLAND
CHAIN ON WEDNESDAY.

FOR THE DAY 6-7...RECOMMEND USING THE 27/00Z ECENS MEAN FOR ITS
CONSISTENT FORECAST APPROACH IN THE EASTERN THIRD OF THE PACIFIC.

VOJTESAK

$$




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