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 25 26 27 28 29 30

000
FXAK68 PAFC 261250
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
450 AM AKDT TUE MAY 26 2015

.ANALYSIS AND UPPER LEVELS...

THE MASSIVE UPPER LEVEL LOW THAT COVERS MOST OF AK...WESTERN
CANADA...AND THE EASTERN BERING IS SHOWING SIGNS OF WEAKNESS THIS
MORNING. A CLOSED UPPER LOW OVER KODIAK ISLAND IS IN THE PROCESS
OF SLICING THROUGH THE BASE OF THE RIDGE ON ITS WAY TO SE AK.
ANOTHER CLOSED LOW IS OVER THE WESTERN BERING. AT THE
SURFACE...HIGH PRESSURE IS OVER MOST OF MAINLAND AK...EXCEPT FOR A
THERMALLY INDUCED TROUGH OF LOW PRESSURE IN THE YUKON THAT EXTENDS
INTO AK NORTHEAST OF THE AK RANGE. THIS THERMAL LOW WAS THE FOCUS
OF THUNDERSTORM ACTIVITY YESTERDAY. ANOTHER LOW IS OVER THE
WESTERN BERING WITH AN ASSOCIATED FRONT CROSSING THE EASTERN
ALEUTIANS INTO THE AKPEN.

&&

.MODEL DISCUSSION...

MODELS ARE IN AGREEMENT THAT THE UPPER LOW OVER KODIAK WILL RACE
TO SOUTHEAST AK BY WED AFTERNOON...THE THERMAL TROUGH WILL REMAIN
ALONG THE NORTHERN EDGE OF THE ALASKA RANGE...AND THE SURFACE AND
UPPER RIDGES WILL REBUILD THROUGH WED OVER THE REST OF MAINLAND
AK. IN THE WEST...THE BERING LOW WILL SPIN NORTHWEST AND DISSIPATE
LATER ON WED WHILE THE ASSOCIATED FRONT REACHES THE WESTERN ALASKA
COAST THIS AFTERNOON AND DISSIPATES TONIGHT. THE EC WAS USED IN
THE SHORT TERM OUT WEST AND A GEM/NAM BLEND WAS USED TO CAPTURE
DETAIL IN THE WIND AND MOISTURE FIELDS IN THE EAST.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA...
AN UPPER LEVEL LOW WILL SLIDE EASTWARD ACROSS THE GULF TODAY AND
INTO THE PANHANDLE LATE TONIGHT. MOISTURE FROM THIS SYSTEM IS
PUSHING MOISTURE INTO THE COPPER RIVER BASIN AND NORTHERN SUSITNA
VALLEY. SHOWERS WILL DEVELOP OVER THESE AREAS TODAY AND CONTINUE
INTO TONIGHT...THEN MOVE EASTWARD LATE TONIGHT AND WEDNESDAY. SOME
MOISTURE AND A BIT OF INSTABILITY WILL LINGER OVER THE REMAINDER
OF SOUTH CENTRAL INTO THIS EVENING PRODUCING SOME SHOWERS...MAINLY
OVER THE MOUNTAINS. HIGH PRESSURE AT THE SURFACE WILL BUILD OVER
THE GULF AND SOUTH CENTRAL ALASKA FROM THE SOUTHWEST AS THE UPPER
LOW MOVES EAST BRINGING WITH IT A DRYING TREND. AROUND COOK INLET
SOME UP-INLET FLOW (FROM THE SOUTHWEST) WILL KEEP TEMPERATURES
COOL TODAY...WITH A WARMING TREND THEN DEVELOPING.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...

A WEAKENING LOW MOVING INTO THE GULF OF ALASKA WILL CONTINUE TO
SUPPORT SHOWERS OVER PORTIONS OF BRISTOL BAY AND THE LOWER
KUSKOKWIM DELTA...ESPECIALLY OVER THE HIGHER TERRAIN...BUT
INCREASING STABILITY AND DRYING AIR WILL LIMIT THE COVERAGE AND
INTENSITY. THE NEXT MAJOR WEATHER FEATURE ACROSS SOUTHWEST WILL
BE A FRONT MOVING IN FROM THE BERING. THIS FEATURE WILL BRING
INCREASING SOUTHEAST WINDS...AS WELL AS RAIN TO COASTAL LOCATIONS
INTO WEDNESDAY BEFORE WEAKENING WEDNESDAY NIGHT. INTERIOR
LOCATIONS WILL GENERALLY REMAIN DRIER AND WARMER.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...

THE BERING SEA REMAINS UNDER THE INFLUENCE OF THE PACIFIC STORM
TRACK...WITH A STOUT FRONTAL ZONE RACING ACROSS THE BERING SEA
THIS MORNING. THIS FRONT WILL MOVE FROM THE PRIBILOF ISLANDS AND
CENTRAL ALEUTIANS TO THE EASTERN ALEUTIANS AND EASTERN BERING SEA
BY THIS EVENING. GUSTY SOUTHERLY WINDS WILL MAINLY IMPACT THOSE
LOCATIONS...WITH A PERIOD OF MODERATE RAIN AS THE FRONT MOVES
THROUGH. THE FRONT WILL THEN STALL OVER THE EASTERN ALEUTIANS EAST
OF DUTCH HARBOR...WITH RAIN LASTING INTO WEDNESDAY. THE NEXT MAJOR
WEATHER IMPACT WILL BE A STRONG GALE FORCE LOW MOVING INTO THE
WESTERN BERING ON WEDNESDAY NIGHT AND THURSDAY...BRINGING RAIN AND
NEAR STORM FORCE WIND GUSTS TO PORTIONS OF THE WESTERN ALEUTIANS.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...
THE OVERALL PATTERN REMAINS UNCHANGED...WITH A PERSISTENT RIDGE
DOMINATING MUCH OF THE SOUTHERN MAINLAND AND GULF THROUGH THE END
OF THE WEEK...AND A SERIES OF NORTH PACIFIC LOWS TRACKING THROUGH
THE ALEUTIANS AND BERING SEA THROUGH EARLY NEXT WEEK. DRIER
CONDITIONS ARE EXPECTED OVER MUCH OF THE SOUTHERN MAINLAND AS THE
RIDGE BUILDS OVER THE AREA THROUGH THE WEEK. THIS IS ALSO EXPECTED
TO BRING SOME OF THE WARMEST TEMPERATURES SO FAR THIS SEASON TO
THE COPPER RIVER BASIN...MATSU VALLEY...AND PARTS OF THE SOUTHWEST
MAINLAND WITH TEMPERATURES CLIMBING INTO THE 70S. THE STRENGTH OF
THIS RIDGE WILL KEEP THE RAINY AND WINDY CONDITIONS CONFINED
MOSTLY TO THE BERING SEA AND ALEUTIANS THROUGH EARLY NEXT WEEK.
HOWEVER...MODELS ARE HINTING AT THE POTENTIAL FOR CONVECTIVE
SHOWERS TO DEVELOP OVER PARTS OF THE SOUTHCENTRAL MAINLAND LATER
IN THE WEEK...AS INSTABILITY INCREASES OVER THE AREA WITH THE
PASSING OF AN UPPER LEVEL TROUGH THURSDAY AFTERNOON/EVENING.
MODELS REMAIN IN FAIR AGREEMENT WITH THESE FEATURES/PATTERN OVER
THE SOUTHERN MAINLAND AND GULF...KEEPING FORECAST CONFIDENCE OVER
THE EASTERN DOMAIN SLIGHTLY ABOVE AVERAGE.

FURTHER WEST...THE ALEUTIANS AND BERING SEA WILL SEE LITTLE TO NO
BREAK FROM WET AND WINDY CONDITIONS THROUGH MUCH OF THE WEEK. THE
ABOVE MENTIONED NORTH PACIFIC LOW WILL STRENGTHEN AS IT TRACKS
THROUGH THE WESTERN/CENTRAL ALEUTIANS THURSDAY...BEFORE RECURVING
TO THE NORTHWEST OVER THE WESTERN BERING FRIDAY. THE ASSOCIATED
FRONTAL SYSTEM WILL BRING GUSTY WINDS AND RAIN TO THE
WESTERN/CENTRAL ALEUTIANS THURSDAY...THEN WEAKEN AS IT TRACKS
EASTWARD OVER THE ALEUTIAN CHAIN THROUGH THE END OF THE WEEK. AS
THE INITIAL FRONTAL SYSTEM DISSIPATES OVER THE EASTERN ALEUTIANS
AND ALASKA PENINSULA SUNDAY...ANOTHER FRONTAL SYSTEM BEGINS TO
TRACK OVER THE WESTERN ALEUTIANS/BERING FROM THE WEST. THIS
SYSTEM WILL BRING ANOTHER ROUND OF RAIN AND GUSTY WINDS TO THE
WESTERN AND CENTRAL ALEUTIANS/BERING SUNDAY THROUGH MONDAY. MODELS
HAVE COME INTO BETTER AGREEMENT WITH THESE FEATURES OVER THE
WESTERN DOMAIN IN THE MOST RECENT MODEL RUNS. HOWEVER...THEY ARE
STILL STRUGGLING WITH THE FINER DETAILS IN BOTH TIMING AND
STRENGTH. THUS FORECAST CONFIDENCE HAS SLIGHTLY INCREASED OVER THE
WESTERN DOMAIN THROUGH MUCH OF THE LONG TERM...BUT STILL REMAINS
BELOW AVERAGE.

&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALES 170 179 185.
FIRE WEATHER...NONE.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...DS
SOUTHCENTRAL ALASKA...BL
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...JA
LONG TERM...TP


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