Area Forecast Discussion
Issued by NWS Anchorage, AK

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

000
FXAK68 PAFC 261314
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
514 AM AKDT SAT JUL 26 2014

.ANALYSIS AND UPPER LEVELS...

HIGH AMPLITUDE RIDGE OVER THE NORTH PACIFIC...BERING...AND
EASTERN RUSSIA EXTENDS FROM 40 N TO 70 N. IT IS ADJACENT TO AN
EVEN LARGER TROUGH EXTENDING FROM 40 N TO THE NORTH POLE WITH AN
EMBEDDED LOW OVER THE NORTHERN HALF OF AK AND A CLOSED CIRCULATION
OVER THE POLE ITSELF. A SMALLER LOW IS ALSO OVER THE SOUTHERN
GULF OF AK. AT THE SURFACE...HIGH PRESSURE IS CENTERED OVER THE
CENTRAL ALEUTIANS WITH A WEAK LOW OVER THE EASTERN GULF.

&&

.MODEL DISCUSSION...

MODELS ARE IN AGREEMENT THAT THE UPPER BERING RIDGE WILL CONTINUE
TO BUILD NORTH...REACHING 85 N BY TUE EVENING. WHILE THIS IS
HAPPENING A PIECE OF ENERGY FROM THE CUT-OFF LOW OVER NORTHERN AK
WILL SLIDE SOUTH AND ENHANCE THE SOUTHERN END OF THE TROUGH OVER
THE GULF BY MON. THIS WILL BE FOLLOWED BY A WAVE MOVING AROUND THE
UPPER NORTH POLE LOW WHICH REINFORCES THE NORTHERN AK LOW MON
AFTERNOON. FINALLY THIS REINFORCED LOW WILL THEN SLIDE SOUTH AND
STRENGTHEN THE GULF LOW ON TUE.

AT THE SURFACE ALL OF THIS WILL BE REFLECTED BY TROUGHS MOVING
ACROSS THE TALKEETNAS TODAY...ALONG THE ALASKA AND ALEUTIAN RANGES
TONIGHT INTO SUN...AND THEN ACROSS SOUTHCENTRAL MON INTO TUE.
FINALLY THE FRONT ASSOCIATED WITH THE NORTHERN AK LOW ON ITS WAY
TO THE GULF WILL MOVE ACROSS SOUTHWEST AK MON THROUGH TUE.

TO ADD ADDITIONAL COMPLEXITY...SEVERAL WAVES WILL ALSO MOVE
AROUND THE GULF LOW SUN THROUGH TUE...AND A WEATHER FRONT WILL
ENTER THE WESTERN ALEUTIANS AND BERING SAT NIGHT AND REACH THE
CENTRAL ALEUTIANS BY TUE.

THE FORECAST UTILIZES THE GFS AND EC WHICH ARE CONSISTENT IN
TIMING OF THE WAVES.

&&

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...

SHOWERS WILL BE LIMITED TO EAST OF THE KENAI RANGE AND FROM THE
TALKEETNAS EAST. ISOLATED THUNDERSTORMS ARE EXPECTED THIS
AFTERNOON AND EVENING NEAR THE TALKEETNAS. SHOWERS WILL CONTINUE
OVER THESE AREAS ON SUN. RAIN WILL REDEVELOP MON...ESPECIALLY WEST
OF THE TALKEETNAS. ON TUE RAIN WILL BE ENHANCED FROM THE EAST WITH
A WAVE MOVING AROUND THE GULF LOW.

SOUTHWEST ALASKA...

EXCEPT FOR A FEW SHOWERS NEAR THE COAST TODAY...THE REGION WILL
BE DRY UNTIL RAIN BEGINS MON AND LASTS THROUGH TUE.

BERING SEA/ALEUTIANS...

LOW CLOUDS FOG AND DRIZZLE WILL BE WIDESPREAD BENEATH THE HIGH.
RAIN AND WIND WILL ARRIVE OVER THE WESTERN ALEUTIANS TONIGHT AND
REACH THE CENTRAL ALEUTIANS TUE.

&&

LONG TERM FORECAST...

HIGH AMPLITUDE RIDGING CENTERED OVER THE BERING SEA WILL BE
DOMINANT BEGINNING THE EXTENDED PERIOD ON TUESDAY...WITH A CLASSIC
OMEGA BLOCK PATTERN ACROSS ALASKA REGION. THE DOMINANT FEATURE
ACROSS SOUTHERN ALASKA TUESDAY WILL BE A SPRAWLING UPPER LOW IN
THE GULF OF ALASKA...WITH A NORTHERLY SHORTWAVE TROUGH MOVING
ACROSS SOUTHWEST ALASKA. BY MIDWEEK...EMBEDDED VORTICITY MAXIMA
ROTATING AROUND THE GULF LOW WILL BEGIN TO IMPINGE UPON SOUTHERN
ALASKA...WITH THE THREAT FOR STRONG EASTERLY WAVES TRACKING WEST
ACROSS THE SOUTHERN PART OF THE STATE. TIMING DIFFERENCES AMONG
THE VARIOUS GLOBAL MODELS ARE RATHER LARGE...BUT THEY ALL HINT AT
A SIMILAR SYNOPTIC PATTERN AND EVOLUTION. STAY TUNED...

BY LATE WEEK...THE PATTERN WILL NOT CHANGE DRAMATICALLY...WITH
THE ECMWF AND GFS ENSEMBLE DEPICTING A CONTINUED HIGH LATITUDE
RIDGING PATTERN OVER THE BERING AND A PERSISTENT LOW IN THE GULF.
THIS PATTERN TENDS TO FAVOR TEMPERATURES NEAR CLIMATOLOGY...WITH
INDIVIDUAL DAYS STRONGLY MODULATED BY INDIVIDUAL SHORTWAVE LENGTH
FEATURES.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...NONE.
FIRE WEATHER...NONE.
&&

$$

JUL 14


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