Prognostic Meteorological Discussion
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2
000
FXAK02 KWNH 271751
PMDAK

ALASKA EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
151 PM EDT MON JUL 27 2015

VALID 12Z FRI JUL 31 2015 - 12Z TUE AUG 04 2015

THE 27/00Z ENSEMBLE GUIDANCE HAS SETTLED DOWN SOME ACROSS THE
ARCTIC AND OVER THE NORTHERN PACIFIC. AND FOR ALL THE
SMALLER-SCALE TRANSITIONAL DETAILS---THAT EMERGED ACROSS THE
BERING SEA AND WESTERN GULF OF ALASKA THE PAST 5 DAYS...THE DAY 7
FORECAST ALOFT AND AT THE SURFACE LOOKS QUITE `SEASONAL`.

THE FORECAST IS HOWEVER---A CHALLENGE BEYOND DAY 7. FOR WHAT
APPEARS `SEASONAL` NORTH OF THE 50TH PARALLEL AND FOR MUCH OF
ALASKA...IS QUITE `UNSEASONAL` IN THE CENTRAL PACIFIC---WITH A
BEVY OF TROPICAL AND SUBTROPICAL ENTITIES THAT SLOWLY CREEP
NORTHWARD INTO THE MID-LATITUDE FLOW PATTERN THROUGH TIME.

BEING THAT THESE CONCERNS---THE TRANSFER OF MOISTURE/ENERGY FROM
THE SUBTROPIC AND INTO THE MID-LATITUDES HAVE 2 `PATHWAYS` TO
CHANNEL NORTHWARD (INVOF 140W AND 170E)---IN/AROUND DAY 7---BODES
WELL TO GO WITH THE ENSEMBLE MEANS HERE. THOSE SELECTIONS WILL
ESTABLISH THE `AVERAGED` LONGER-WAVE PATTERN...ANCHOR A BROAD
CYCLONIC CIRCULATION IN THE GULF OF ALASKA...AND KEEP A WEAK
PRESSURE GRADIENT BETWEEN 40N-50N LATITUDE---SO ADJUSTMENTS CAN BE
MADE.

VOJTESAK

$$





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