Prognostic Meteorological Discussion
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2
000
FXAK02 KWNH 261924
PMDAK

ALASKA EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
323 PM EDT SUN MAR 26 2017

VALID 12Z THU MAR 30 2017 - 12Z MON APR 03 2017

THE FORECAST PERIOD STARTS WITH BROAD UPPER TROUGHING OVER MUCH OF
THE STATE WITH LARGE-SCALE RIDGING OFF TO THE WEST OVER SIBERIA
AND THE BERING SEA. MEANWHILE...MODELS CONTINUE TO SHOW A LARGE
AND DEEP UPPER LEVEL LOW APPROACHING THE CENTRAL ALEUTIANS EARLY
THURSDAY AND WEAKENING INTO MORE OF A BROAD TROUGH AS IT CROSSES
THE ISLAND CHAIN INTO BRISTOL BAY THIS WEEKEND. OPERATIONAL MODELS
AND THE ENSEMBLE MEANS ARE IN VERY GOOD AGREEMENT WITH THE OVERALL
SYNOPTIC SETUP OF THIS FEATURE INTO DAY 6/SATURDAY. DIFFERENCES
ARISE ON DAY 7 AS THE OPERATIONAL GFS WANTS TO DEVELOP A SECOND
CLOSED LOW SOUTH OF THE ALEUTIANS AND THE ECMWF/ECENS MAINTAINS
MORE OF A FASTER MOVING AMPLIFIED TROUGH. THE GEFS MEAN IS SLOWER
THAN THE ECENS WITH THIS FEATURE BUT STILL DOES HINT AT THE
POSSIBILITY OF A SECOND LOW. THIS TRANSLATES TO TIMING DIFFERENCES
DOWNSTREAM AS WELL WITH A SHORTWAVE APPROACHING THE WESTERN US AND
THE ECMWF/ECENS ARE ON THE FASTER SIDE OF THE GUIDANCE. BY DAY
8/MONDAY...THINGS APPEAR TO SORT THEMSELVES OUT BUT WITH SOME
TIMING DIFFERENCES WITH AN AMPLIFIED TROUGH WEST OF THE STATE AND
THROUGH THE ALEUTIANS AS A SECOND DEEP CLOSED LOW APPROACHES THE
WESTERNMOST ISLANDS. GIVEN THE CONTINUED UNCERTAINTY BEYOND DAY
6...WENT WITH A MAJORITY ENSEMBLE BLEND WITH SLIGHT WEIGHTING
TOWARDS THE GFS/GEFS DUE TO BETTER RUN TO RUN CONTINUITY WITH
RESPECT TO THE DOWNSTREAM FEATURE. THIS APPROACH IS CLOSE TO
PREVIOUS SHIFT CONTINUITY AS WELL.

IN TERMS OF SENSIBLE WEATHER...EXPECT HEAVY PRECIPITATION ALONG
THE EASTERN ALEUTIANS...THE SOUTHERN COAST...AND THE PANHANDLE
THURSDAY AND INTO THE WEEKEND WITH LIGHTER PRECIPITATION FARTHER
INLAND ACROSS THE WESTERN AND CENTRAL PORTIONS OF THE STATE AS THE
DEEP UPPER LOW AND ASSOCIATED INTENSE SURFACE CYCLONE REACHES THE
AREA AND WEAKENS OVER WESTERN ALASKA. VERY WINDY CONDITIONS ARE
ALSO LIKELY NEAR THE COAST...ACROSS THE ALEUTIANS...AND ESPECIALLY
OVER THE OFFSHORE WATERS WITH STORM FORCE WINDS LIKELY.
TEMPERATURES ACROSS THE SHOULD MODERATE BY THIS WEEKEND AS THE
INITIAL UPPER TROUGH OVER THE STATE RETREATS NORTH AND THE DEEP
CYCLONE APPROACHES FROM THE WEST. AREAS TO THE NORTH OF THE BROOKS
RANGE THOUGH WILL LIKELY REMAIN QUITE COLD AS AN ARCTIC FRONTAL
BOUNDARY REMAINS IN PLACE THROUGH THE FORECAST PERIOD.

SANTORELLI

$$




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