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
   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
   Winter Weather
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 1932Z Oct 23, 2017)
 
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
332 PM EDT MON OCT 23 2017

VALID 12Z FRI OCT 27 2017 - 12Z TUE OCT 31 2017

MEDIUM RANGE FORECAST OVER THE HIGH LATITUDES OF THE NORTH PACIFIC
CONTINUES TO BE A CHALLENGE ON SYSTEM TIMING/TRACK/STRENGTH DUE TO
YET ANOTHER FORECAST EXTRATROPICAL TRANSITION OF WHAT IS NOW
TROPICAL STORM 27W (AND WHAT IS NOW IN THE SHORT TERM EX-LAN). THE
PATH OF LEAST RESISTANCE (OR LEAST REGRET) IS TO USE AN ENSEMBLE
CONSENSUS IN ORDER TO MINIMIZE DAY TO DAY CHANGES. THE ECMWF
ENSEMBLE MEAN IS USUALLY BETTER THAN THE GEFS MEAN IN AN AMPLIFIED
PATTERN, BUT THE INCLUSION OF A COUPLE OF FICKLE TROPICAL SYSTEMS
HAS PROVED TO BE A CHALLENGE FOR EVEN THE USUALLY STEADFAST ECMWF
EPS. NEVERTHELESS, THE 06Z GEFS AND 00Z ECMWF ENSEMBLE MEAN
OFFERED REASONABLY CLOSE SOLUTIONS THAT A BLEND OF THE TWO FORMED
A GOOD STARTING POINT. INCLUSION OF THE 12Z GFS AND 00Z ECMWF IN
THE FIRST FEW DAYS OFFERED AT LEAST SOME DETAILS THOUGH CONFIDENCE
IS RATHER LOW IN SPECIFICS THROUGH THE PERIOD.

FIRST SYSTEM SHOULD CREEP OUT OF THE NORTH PACIFIC THIS WEEKEND
INTO THE EASTERN ALEUTIANS/AKPEN AND PERHAPS THE GULF THEREAFTER,
BUT THE ENSEMBLES HAVE NOT LATCHED ONTO CONSISTENT TIMING WITH
THIS STORM (LIKELY DUE TO A COMBINATION OF THE UPSTREAM FLOW AND
UNCERTAIN EVOLUTION IN THE BERING FRI-SAT). AGAIN, ENSEMBLE
CONSENSUS FORMED THE BASIS TO THE FRONTS.

FARTHER UPSTREAM, AN UPPER TROUGH IS FORECAST TO PUSH THROUGH THE
WESTERN BERING AT THE END OF THE WEEK AND FIGHT DOWNSTREAM
BUILDING RIDGING ALONG 140W INTO W CANADA. THAT SHOULD SLOW DOWN
THE PATTERN BUT EMBEDDED SYSTEMS (SEE ABOVE) HAVE MADE THAT AN
UNSTEADY TREND. CURRENT TROPICAL STORM 27W IS FORECAST TO RECURVE
JUST EAST OF 130E AND SE OF JAPAN LATER THIS WEEK BUT THE
MODEL/ENSEMBLES DO SO AT VERY DIFFERENT LONGITUDES. THE GFS WAS
FARTHER WEST THAN THE CANADIAN/ECMWF AND THUS WAS SLOWER TO BRING
IT INTO THE WESTERLY FLOW AND ACROSS THE NORTH PACIFIC. DESPITE
THAT, THE GFS MANAGED TO CATCH UP TO THE ECMWF AND THE ENSEMBLE
CONSENSUS AND BRING THAT SYSTEM INTO THE WESTERN ALEUTIANS BY NEXT
TUESDAY.

PATTERN SHOULD SUPPORT INITIAL PRECIPITATION ALONG SOUTHCENTRAL
INTO THE PANHANDLE WITH THE LEAD SYSTEM (EX-LAN) FOLLOWED BY SOME
CLEARING THANKS TO UPPER RIDGING. GIVEN THE TIMING OF THE NEXT
SYSTEM OUT OF THE NORTH PACIFIC, MORE RAIN/SNOW IS EXPECTED BY
NEXT WEEK AS THE FRONT LIFTS INTO THE GULF.


FRACASSO