Area Forecast Discussion
Issued by NWS Anchorage, AK

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
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 271302
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
502 AM AKDT FRI MAR 27 2015

.ANALYSIS AND UPPER LEVELS...
THE MAIN SYNOPTIC FEATURE INFLUENCING THE WEATHER ACROSS THE
REGION THIS MORNING IS A BROAD COMPLEX LOW EMBEDDED IN A
SPRAWLING LONGWAVE TROUGH THAT CONTINUES TO ENCOMPASS MUCH OF THE
NORTHERN PACIFIC. THIS COMPLEX LOW REMAINS QUASI STATIONARY NEAR
THE ALASKA PENINSULA AS A SERIES OF WAVES ROUND ITS EASTERN
PERIPHERY AND TRACK INTO THE GULF TOWARDS THE SOUTHERN MAINLAND.
THE FIRST OF THESE WAVES HAS ALREADY PUSHED INLAND AND WEAKENED
OVER SOUTHCENTRAL ALASKA...WITH RAIN CONTINUING ALONG THE COAST
AS STRONG CROSS BARRIER FLOW ACROSS THE CHUGACH MOUNTAINS KEEPS
INLAND AREAS MOSTLY DRY. A FEW SHOWERS HAVE ALSO PUSHED INTO THE
BRISTOL BAY REGION AS ANOTHER DISTURBANCE BRUSHES THE SOUTHWEST
COAST. MEANWHILE...A DECAYING FRONTAL BOUNDARY OVER THE CENTRAL
BERING CONTINUES TO BRING RAIN TO THE EASTERN ALEUTIANS AND
PERIODS OF SNOW TO THE PRIBILOF ISLANDS.

&&

.MODEL DISCUSSION...
MODELS REMAIN IN GOOD SYNOPTIC AGREEMENT IN THE SHORT TERM BUT
CONTINUE TO STRUGGLE WITH THE DETAILS OF INDIVIDUAL WAVES AS THEY
ORIGINATE OVER THE NORTH PACIFIC AND TRACK NORTHWARD TOWARDS THE
GULF. THE MOST SIGNIFICANT OF THESE FEATURES WILL DEVELOP THIS
MORNING BENEATH THE LEFT EXIT REGION OF A STRONG UPPER LEVEL JET
SOUTH OF 50N LATITUDE AND THEN MOVE INTO THE GULF FRIDAY NIGHT
INTO SATURDAY. THERE IS STILL A LARGE AMOUNT OF SPREAD WITH
RESPECT TO THE EVENTUAL TRACK OF THIS LOW...WITH THE GFS/NAM
SOLUTIONS TAKING IT INTO THE CENTRAL GULF WHEREAS THE CANADIAN
(GEM) GLOBAL MODEL IS CLOSER TO KODIAK ISLAND. UTILIZED THE EC FOR
THE FORECAST AS IT REPRESENTS SOMEWHAT OF A MIDDLE GROUND SOLUTION
AND HAS ALSO SHOWN GOOD CONSISTENCY FOR THE PAST SEVERAL DAYS.
ALSO USED THE GEM REGIONAL IN THE FIRST 36 HOURS FOR ENHANCED
DETAIL OF WINDS OVER THE BERING AND SOUTHWEST MAINLAND.

&&

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

WINDS ACROSS SOUTHCENTRAL ALASKA HAVE TURNED SOUTHEAST OVERNIGHT
BEHIND AN UPPER LEVEL WAVE THAT HAS MOVED NORTHWEST OF THE AREA.
THE GUSTY WINDS THROUGH CHANNELED TERRAIN SHOULD DIMINISH THIS
MORNING AS THE PRESSURE GRADIENT EASES. THERE WILL BE RAIN
SHOWERS THAT ARE MIXED WITH SNOW OVER HIGHER TERRAIN TODAY BUT
MOST OF THE PRECIPITATION WILL FALL OVER THE COASTAL AREAS. THE
LEE SIDE OF THE MOUNTAINS WILL STILL ONLY SEE SOME ISOLATED
SHOWERS.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
THE MAIN LOW THAT HAS BEEN IMPACTING THE AREA IS THE LOW SOUTH OF
THE EASTERN ALEUTIANS. THIS LOW IS BRINGING IN MOIST SOUTHEAST FLOW
FROM THE NORTH PACIFIC THAT IS PRODUCING SHOWERS ACROSS THE
SOUTHWEST. THE LOW IS WEAKENING AND AS IT DOES THE SHOWERS WILL
DIMINISH. BY TONIGHT IT WILL BE ABSORBED BY ANOTHER LOW
APPROACHING FROM THE SOUTH AND THIS NEW LOW WILL MOVE INTO THE
GULF BRINGING IN DRIER NORTHEASTERLY FLOW TO THE SOUTHWEST.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
NORTHERLY FLOW DOMINATES THE AREA KEEPING SHOWERS WIDESPREAD FOR
THE ALEUTIANS. HOWEVER...TONIGHT HIGH PRESSURE WILL BUILD IN OVER
THE WESTERN ALEUTIANS WHICH WILL DIMINISH THE SHOWERS. THEN ON
SATURDAY NIGHT A FRONT WILL PUSH IN OVER THE WESTERN ALEUTIANS
BRINGING PRECIP BACK. THE CENTRAL AND EASTERN ALEUTIANS WILL STAY
UNDER THE NORTHERLY FLOW.

&&

.LONG TERM FORECAST (SUNDAY THROUGH THURSDAY)...

NEXT SUNDAY THROUGH MIDWEEK WILL BE A PERSISTENT PATTERN WITH
BROAD TROUGHING OVER THE EASTERN BERING AND THE GULF OF ALASKA
WITH THE MAIN CENTER IN THE VICINITY OF THE WESTERN GULF. RAIN
SHOWERS WILL DEVELOP AROUND THE CORE OF THE LOW WITH SCATTERED
SHOWERS ALONG THE COASTS. INLAND LOCATIONS CONTINUE TO STAY MAINLY
DRY DURING THIS TIME DUE TO DOWNSLOPING OVER THE MOUNTAINS WITH
SOUTHEASTERLY FLOW. TO THE WEST OVER THE BERING...A COLDER AIR
MASS BEGINS TO ADVECT SOUTHWARD ON SUNDAY. MODELS ARE STARTING TO
COME INTO AGREEMENT WITH THIS COLDER AIR SLOWLY SHIFTING EASTWARD
THROUGH THE END OF THE WEEK. DUE TO THIS NEWLY ANTICIPATED PATTERN
SHIFT...CONFIDENCE IS LOW IN THE LONG RANGE FORECAST WEDNESDAY
THROUGH FRIDAY.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALES 119 120 131 132 137 150 175 179
         HEAVY FREEZING SPRAY 179.
FIRE WEATHER...NONE.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...CB
SOUTHCENTRAL ALASKA...EZ
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...DK
LONG TERM...KH



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