Skip Navigation Links weather.gov 
NOAA logo - Click to go to the NOAA homepage National Weather Service   NWS logo - Click to go to the NWS homepage
The Weather Prediction Center

 
 

 

Follow the Weather Prediction Center on Facebook Follow the Weather Prediction Center on Twitter
NCEP Quarterly Newsletter
WPC Home
Analyses and Forecasts
   National High & Low
   WPC Discussions
   Surface Analysis
   Days ½-2½ CONUS
   Days 3-7 CONUS
   Days 4-8 Alaska
   QPF
   PQPF
   Flood Outlook
   Winter Weather
   Storm Summaries
   Heat Index
   Air Quality
   Tropical Products
   Daily Weather Map
   GIS Products
Current Watches/
Warnings

Satellite and Radar Imagery
   Satellite Images
   National Radar
Product Archive
WPC Verification
   QPF
   Medium Range
   Model Diagnostics
   Event Reviews
International Desks
Development and Training
   Development
WPC Overview
   About the WPC
   Staff
   WPC History
   Accomplishments
   Other Sites
   FAQs
Meteorological Calculators
Contact Us
   About Our Site
 
USA.gov is the U.S. Government's official web portal to all federal, state, and local government web resources and services.
 
Alaska Extended Forecast Discussion
 
(Latest Discussion - Issued 1848Z Sep 02, 2014)
 
Version Selection
Versions back from latest:  0   1   2   3   4   5   6   7   8   9   10   
 
Abbreviations and acronyms used in this product
 
View Alaska Map


ALASKA EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
248 PM EDT TUE SEP 02 2014

VALID 12Z SAT SEP 06 2014 - 12Z WED SEP 10 2014

THE DOMINANT FOCUS THIS PERIOD WILL BE A STRONG NRN PACIFIC SYSTEM
THAT BEST CONSENSUS EXPECTS TO TRACK NEAR THE ALEUTIANS AND TOWARD
PORTIONS OF THE MAINLAND.  OVER THE PAST COUPLE DAYS
MODEL/ENSEMBLE GUIDANCE HAS ALL SHOWN A PRONOUNCED STRONGER TREND
WITH THIS SYSTEM THOUGH OPERATIONAL GFS/ECMWF RUNS CAUGHT ONTO
BETTER DEFINITION IN EARLIER RUNS THAN THE MEANS.  BEYOND SOME
TIMING SPREAD SEEN INTO MON... WITH THE 00Z ECMWF ON THE SLOWER
SIDE BUT STILL WITHIN THE FULL ENSEMBLE SPREAD... AMPLIFICATION OF
UPSTREAM SIBERIAN FLOW ADDS ANOTHER ELEMENT OF UNCERTAINTY BY DAYS
6-8 MON-WED.  GFS/EC CONTINUITY ALONG WITH 06Z GFS AND 00Z EC/CMC
RUNS SUGGEST THE 00Z GFS AMPLIFIES ITS NRN STREAM FLOW TOO FAR
EWD.  ENSEMBLE MEANS DO NOT AMPLIFY THIS ENERGY AS FAR WWD AS THE
06Z GFS CLUSTER BUT MERIT CONSIDERABLE WEIGHTING GIVEN THEIR
BETTER THAN AVG AGREEMENT THROUGH DAY 8 AND GOOD CONTINUITY
RELATIVE TO YDAYS WPC FCST.

AHEAD OF THIS EVOLUTION A COMBINATION OF NERN PAC AND MAINLAND
SHRTWVS SHOULD SUPPORT A SFC WAVE NEAR THE SRN/SERN COAST SAT-SUN.
 FOR THIS PART OF THE FCST THE 00Z GFS COMPARES POORLY TO OTHER
GUIDANCE ALOFT AND TO SOME DEGREE AT THE SFC OVER THE SERN
MAINLAND/PANHANDLE.

BASED ON THE ABOVE GUIDANCE COMPARISONS THE DAYS 4-8 SAT-WED FCST
EMPHASIZES THE 06Z GEFS/00Z ECMWF ENSEMBLE MEANS WITH SOME
WEIGHTING OF THE 06Z GFS INCLUDED TO ADD SOME OPERATIONAL DETAIL
IN LIGHT OF TRENDS SHOWING SOME PSBL USEFULNESS OF COMPATIBLE
RUNS.  THE 00Z ECMWF IS ALSO SUFFICIENTLY CLOSE TO CONSENSUS TO BE
INCLUDED THROUGH 12Z DAY 5 SUN.  THE 06Z GFS IS NOT AVBL AFTER DAY
7 SO DAY 8 USES THE ENSEMBLE MEANS EXCLUSIVELY.

IF ANYTHING THE NEW 12Z SOLNS LOWER CONFIDENCE IN A PARTICULAR
SCENARIO.  THE GFS PULLS OFF NRN STREAM ENERGY EVEN FARTHER WWD
THAN THE 06Z GFS/00Z ECMWF... ULTIMATELY LEADING TO AN
ALEUTIANS/BERING SEA SYSTEM CONSIDERABLY SLOWER THAN THE 00Z ECMWF
BY DAY 8 WED.  THE 12Z ECMWF REMAINS SLOW WITH THE INITIAL NRN PAC
SYSTEM AND DELAYS NRN STREAM AMPLIFICATION... RESULTING IN LEAVING
THE NRN PAC SYSTEM MUCH FARTHER SWWD THAN OTHER GUIDANCE BY NEXT
TUE.  THE 12Z CMC ENDS UP BEING SOMEWHAT OF A COMPROMISE.  

RAUSCH