National Weather Service National Headquarters

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXAK68 PAFC 232126
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
130 PM AKDT THU MAY 23 2013

.ANALYSIS AND UPPER LEVELS...
A LONGWAVE TROUGH CENTERED OVER THE BERING SEA CONTINUES TO DOMINATE
THE REGION. MOST OF THE STATE IS EXPERIENCING WEAK SOUTHWEST FLOW
ALOFT...WITH EMBEDDED WEAK DISTURBANCES MOVING THROUGH THE PATTERN. A
RIDGE OF HIGH PRESSURE OVER THE WESTERN COAST OF NORTH AMERICA IS
GAINING STRENGTH AND SHOWING SIGNS OF BUILDING NORTHWESTWARD INTO
ALASKA. FAIRLY WEAK SURFACE PRESSURE GRADIENTS OVER THE GULF REGION
ARE ALLOWING WIDESPREAD LOW CLOUDS AND FOG TO LINGER OVER COASTAL
AREAS INCLUDING COOK INLET...THOUGH A GRADUALLY TRENT TOWARD OFFSHORE
FLOW IS BEGINNING TO CLEAR OUT MOST INLAND AREAS. A SHORTWAVE OVER
THE ALASKA PENINSULA IS SLIDING TO THE SOUTHEAST...AND IS BRINGING
SCATTERED SHOWERS TO THE BRISTOL BAY ZONE THIS MORNING. FURTHER
WEST...A PACIFIC LOW AROUND 993 MB IS TRACKING NORTHWARD TOWARD THE
BERING SEA. WINDS FROM THE CENTRAL ALEUTIANS TO AKPEN HAVE BEGUN TO
EXPERIENCE LIGHT SOUTHEASTERLY WINDS...THE FIRST HARBINGER OF THE
APPROACHING SYSTEM.

.MODEL DISCUSSION...AVAILABLE ATMOSPHERIC MODELS ALL SHOW A SIMILAR
OVERALL TREND. THIS IS CHARACTERIZED BY A LONGWAVE TROUGH REMAINING
OVER THE BERING SEA AND EXTENDING DOWN INTO THE SOUTHERN GULF...WITH
A WARM RIDGE OF HIGH PRESSURE BUILDING FROM CANADA INTO MAINLAND
ALASKA. THIS WILL BRING IN THE WARMEST TEMPERATURES OF THE YEAR SO
FAR TO MOST MAINLAND LOCATIONS...AND A TRANSITION TO DIURNAL
CONVECTIVE ACTIVITY MAINLY OVER THE MOUNTAIN RANGES IN THE DOMAIN.
THE MODELS ALL HAVE SOME SLIGHT DIFFERENCES IN THE EVOLUTION OF
INDIVIDUAL WEAK STORM SYSTEMS OVER THE NEXT WEEK...BUT THE ECMWF WAS
CHOSEN AS THE MODEL OF THE DAY TODAY BASED ON BETTER RUN-TO-RUN
CONSISTENCY THAN THE OTHER MODELS.

.SHORT TERM FORECAST...
SOUTHCENTRAL AND SOUTHWEST ALASKA...LIGHT FLOW WITH PERSISTENT LOW
CLOUDINESS WILL GRADUALLY BECOME MORE OFFSHORE BY TOMORROW. THIS WILL
ALLOW A STEADY DECREASE IN CLOUD-COVER AND INCREASE IN TEMPERATURES
OVER THE NEXT FEW DAYS. SEA BREEZES WILL DEVELOP LATER THIS AFTERNOON
AROUND COOK INLET AND PRINCE WILLIAM SOUND...AND LIKELY CONTINUE EACH
AFTERNOON/EVENING THROUGH EARLY NEXT WEEK. HIGHER ELEVATIONS ALONG
AND EAST OF THE TALKEETNA MOUNTAINS WILL BEGIN TO EXPERIENCE A
TYPICAL SUMMER PATTERN OF DIURNAL CONVECTION BEGINNING
FRIDAY...THOUGH MOST SHOWERS WILL STRUGGLE TO MOVE AWAY FROM THE
MOUNTAINS GIVEN THE MARGINAL OVERALL INSTABILITY. BY SUNDAY..A WEAK
SHORTWAVE WILL MOVE IN FROM THE EAST AND BRING INCREASED CLOUDS TO
THE COPPER BASIN AND PRINCE WILLIAM SOUND.

BERING SEA AND ALEUTIANS...THE MOST SIGNIFICANT WEATHER FEATURE OVER
THE COMING DAYS WILL DEFINITELY BE THE MOVEMENT OF THE PACIFIC LOW
AND ASSOCIATED FRONT INTO THE SOUTHERN BERING BY SUNDAY MORNING. THE
STRONGEST PARTS OF THE STORM WILL MOVE OVER THE EASTERN ALEUTIANS AND
ALASKA PENINSULA. HOWEVER...THIS STORM LOOKS WEAKER THAN THE STORM
EARLIER THIS WEEK...WITH MINIMUM GALE-FORCE WINDS AND RAINFALL THE
LARGEST IMPACT EXPECTED AT THIS TIME. BY SUNDAY AFTERNOON...THE LOW
WILL BECOME STATIONARY IN THE SOUTHERN BERING AND WEAKEN IN PLACE
THROUGH THE START OF NEXT WEEK.

.LONG TERM FORECAST...
THE EMERGING SUMMERY WEATHER PATTERN APPEARS THAT IT WILL HOLD
THROUGH AT LEAST THE MIDDLE OF NEXT WEEK. EXPECT MAINLAND LOCATIONS
TO SEE AT OR ABOVE NORMAL TEMPERATURES AND MOSTLY SUNNY SKIES THROUGH
THE WEEKEND. OUT WEST..TEMPERATURES WILL WARM TO NEAR-NORMAL...THOUGH
WIDESPREAD LOW CLOUDINESS WILL CONTINUE TO PLAGUE THE REGION.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALE 155 170 172
FIRE WEATHER...NONE

DIXON MAY 13