Prognostic Meteorological Discussion
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2
000
FXAK02 KWNH 231758
PMDAK

ALASKA EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
158 PM EDT WED JUL 23 2014

VALID 12Z SUN JUL 27 2014 - 12Z THU JUL 31 2014


AFTER A PERIOD OF RELYING ON THE GLOBAL ENSEMBLE MEANS AS SYNOPTIC
GUIDANCE ACROSS THE ALASKA REGION AT THE MEDIUM RANGE, THE 00Z/23
DATA CYCLE AFFORDED A WINDOW OF OPPORTUNITY FOR A SUBSTANTIAL
INCORPORATION OF DETERMINISTIC MASS FIELDS. THE 00Z/23 ECMWF WAS
CORRELATED CLOSELY ENOUGH WITH THE MEANS TO MERIT ITS USE AS A
TEMPLATE FOR AT LEAST THE FRONTS AND PRESSURES THROUGH DAY 6. BY
DAYS 7 AND 8, THE DEEP CYCLONE INDICATED BY THAT MODEL OVER THE
ARCTIC OCEAN STANDS IN SHARP CONTRAST TO THE LAST TWO CYCLES OF
ENSEMBLE MEANS, SO QUICKLY SWITCHED TO THE 00Z/23 ECENS MEAN FOR
THAT PORTION OF THE FORECAST.

THE INCORPORATION OF THE OPERATIONAL ECMWF PROVIDES SHARPER
GRADIENTS AND WIND SHIFTS, THOUGH THE BLOCKY NATURE OF THE FLOW
SAPS ANY REAL CYCLOGENETIC ADVECTIONS AND FORCING. MOST OF THE
OPEN FLOW REMAINS ALONG THE NORTH SLOPE, WHERE THE PASSAGE OF A
WAVE MID PERIOD SHOULD ALLOW COOL HIGH PRESSURE TO BUILD INTO THAT
REGION AND A PORTION OF THE EASTERN INTERIOR. THE CYCLONIC FLOW
LIFTING ACROSS THE OUTER ALEUTIANS AND INTO THE BERING SEA IS THE
SURFACE SLICE OF A STACKED VORTEX; SO EVEN THERE, THE LACK OF
TRULY NOVEL ADVECTIONS SHOULD LIMIT THE SYSTEM`S SENSIBLE WEATHER
THREATS.


CISCO

$$





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.