THE WEATHER PREDICTION CENTER

COLLEGE PARK, MD


ALASKA EXTENDED FORECAST DISCUSSION




ALASKA EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
154 PM EDT MON JUL 28 2014

VALID 12Z FRI AUG 01 2014 - 12Z TUE AUG 05 2014

LATEST GUIDANCE CONTINUES TO FOCUS FLOW AROUND AN OMEGA BLOCK THAT
LASTS MUCH OF THE WEEK OVER MID-UPPER LATITUDES IN THE VICINITY OF
ALASKA...ALBEIT WITH A GRADUALLY GROWING TREND FOR SOME BREAKDOWN
NEXT WEEK.  NOTHING LASTS FOREVER...BUT WOULD PREFER TO HOLD ONTO
THE BLOCK AS MUCH AS FEASIBLE GIVEN THE NATURE OF SUCH SYSTEMS.
THIS BLOCK IS PRIMARILY COMPRISED OF SLOW MOVING AND UNSETTLING
CLOSED MEAN LOWS CENTERED OFF THE TIP OF THE WRN ALEUTIANS AND
OVER THE GULF OF ALASKA THAT BOOKEND AN AMPLIFIED RIDGE EXTENDING
NORTHWARD THROUGH THE CENTRAL ALEUTIANS TO ACROSS THE BERING SEA.
THIS PATTERN FAVORS WRAPPING SOME PCPN UP INTO THE WRN ALEUTIANS
AND INTO COASTAL SRN AND SERN ALASKA AS HARD TO PREDICT IMPULSES
ALOFT ROTATE SOME ACTIVITY EVEN WITH LESS FAVORABLE LOWER LEVEL
FLOW. LASTING RIDGE AMPLITUDE UP INTO THE BERING SEA MEANWHILE
FAVORS DOWNSTREAM COOLING WITH ARCTIC STREAM TROUGHING AND SOME
PCPN DIGGING THROUGH THE NORTH SLOPE INTO THE INTERIOR EVEN THOUGH
CONTINUITY/DETAILS REMAIN LESS CLEAR/PREDICTABLE IN GUIDANCE.

ACCORDINGLY...THE WPC ALASKAN PRODUCT SUITE WAS PRIMARILY DERIVED
FROM A BLEND OF THE 06 UTC GFS/GFS ENSEMBLE MEAN ALONG WITH THE 00
UTC ECMWF ENSEMBLE MEAN.  THESE GUIDANCE CHOICES FOR THE MOST PART
ARE SLIGHTLY SLOWER WITH BLOCK BREAKDOWN THAN A FULL ENVELOPE OF
GUIDANCE SOLUTIONS COMPOSITE.

SCHICHTEL





Last Updated: 154 PM EDT MON JUL 28 2014