Prognostic Meteorological Discussion
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FXHW01 KWNH 231221
PMDHI

HAWAII EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
720 AM EST SUN NOV 23 2014

VALID 00Z MON NOV 24 2014 - 00Z MON DEC 01 2014

THE 23/00Z DETERMINISTIC GFS/ECMWF SEEMED TO CLOSELY FOLLOW THE
SHORT-TERM LOCAL FORECASTS. THE FRONTAL PASSAGE WILL LIKELY
PRODUCE A SENSIBLE WEATHER CHANGE---WITH A MODIFIED MID-LATITUDE
PACIFIC AIRMASS SPREADING ACROSS THE ISLAND CHAIN BETWEEN 24/12Z
AND 26/00Z.

OF NOTE, THE 23/00Z ECENS/GEFS MAINTAINED GOOD MASS FIELD
CONTINUITY OVER THE EASTERN HALF OF THE PACIFIC OCEAN AFTER DAY
3---VERSUS THEIR DETERMINISTIC RUNS. SO KEEPING EXTENDED FORECAST
AT A NEARLY EQUAL BLEND SEEMS THE WAY TO GO FOR DAY 5-7 IN THE
SUBTROPICAL PACIFIC UNTIL THE DOWNSTREAM/UPSTREAM PATTERN RESOLVES
ITS CONTINUED VARIABILITY.

THE BIGGEST DIFFERENCES IN THE SUBTROPICS BETWEEN THE
DETERMINISTIC GFS/ECMWF CONCERN THE TIMING OF A SECOND
MID-LATITUDE TROUGH PROGRESSION (FROM THE ALEUTIANS) ACROSS THE
DATELINE AND EASTWARD TO 160W AROUND 29/00Z. THE GFS MAINTAINS A
DISTINCT SEPARATION OF THE MID-LATITUDE WAVE TRAIN ALONG
40N---ENOUGH OF A DISTINCTION---TO ALLOW A SECOND FRONT TO MIGRATE
INTO THE SUBTROPICS---APPROACHING KAUAI FROM THE NORTHWEST ON DAY
6 (29/12Z). THE ECMWF ANTICIPATES A CONSOLIDATION OF THE LONG WAVE
PATTERN INVOF 135W---AND IS SIGNIFICANTLY FASTER WITH THE ALEUTIAN
SYSTEM`S INCORPORATION INTO THE MID-LATITUDE FLOW PATTERN
DOWNSTREAM OFF THE WEST COAST OF THE MAINLAND. THEREFORE, IT
CARRIES A MUCH-LESS AMPLIFIED AND WEAKER SURFACE FRONT (29/12Z).

VOJTESAK

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