High Wind in Alaska, May 20 to 21, 2006

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 AM ADT SAT MAY 20 2006

.DISCUSSION...

ANALYSIS...SIGNIFICANT UPPER RIDGE EXTENDS FROM NORTH PACIFIC
NORTHWARD ACROSS ALEUTIANS AND BERING SEA TO EASTERN RUSSIA. A
CLOSED LOW SOUTHEAST OF KODIAK ISLAND IS TRACKING OFF TO THE
SOUTHEAST. TROUGH AXIS EXTENDS FROM THIS LOW NORTHWARD ACROSS
WESTERN ALASKA. THERE ARE LOTS OF CLOUDS JUST AHEAD OF THIS AXIS
ALONG WITH AREAS OF RAIN OR SHOWERS ACROSS THE SOUTHERN MAINLAND.
THERE IS A VERY TIGHT SURFACE PRESSURE GRADIENT BETWEEN THE HIGH
IN THE ALEUTIANS AND LOW IN THE SOUTHERN GULF. THERE IS ALSO COLD
ADVECTION OCCURRING ON THE BACK SIDE OF THE TROUGH AXIS OVER THE
EASTERN BERING/AKPENN. THE COMBINATION OF THESE FACTORS IS
PRODUCING STRONG WINDS THROUGH THIS REGION. A HIGH WIND WARNING IS
CURRENTLY IN EFFECT FOR ZONE 181 WHERE GUSTS HAVE REACHED 81 MPH AT
KING COVE. SUBSIDENCE MAY HAVE BEEN ENHANCED IN THIS AREA ON BACK
SIDE OF A VORT-MAX THAT MOVED THROUGH SATURDAY AFTERNOON.

MODEL ANALYSIS...MODELS INITIALIZED WELL AND SHOW GOOD RUN-TO-RUN
CONSISTENCY IN THE SHORT-TERM. BEYOND DAY 3 MODELS ARE INCONSISTENT
IN HANDLING OF RIDGE OVER THE BERING SO CONFIDENCE LEVEL IS LOW.
THERE ARE ALSO SOME DIFFERENCES NOTED WITH LOW TRACKING UP WEST SIDE
OF RIDGE TOWARD WESTERN ALEUTIANS MON. WILL GO WITH THE GFS SOLUTION
FOR NOW.

SHORT-TERM FORECAST...EXPECT SLOWLY IMPROVING CONDITIONS OVER THE
SOUTHERN MAINLAND TODAY AS RIDGE SLOWLY BUILDS IN FROM THE WEST.
HOWEVER VORT-MAXES DROPPING DOWN FROM NORTH ACROSS KUSKOKWIM AND
BRISTOL BAY WILL BE ENOUGH TO SET OFF SOME SHOWERS...ESPECIALLY
ALONG THE WESTERN SLOPES OF THE ALASKA AND ALEUTIAN RANGES. PRESSURE
GRADIENT WILL SLACKEN A BIT TODAY AS LOW MOVES AWAY FROM AREA...BUT
WINDS WILL REMAIN STRONG THROUGH MONDAY WITH COLD ADVECTION...UPPER
JET MOVING SOUTHWARD ACROSS WESTERN ALASKA/AKPENN...AND SUBSIDENCE
ON BACK SIDE OF VORT-MAXES. BY TUESDAY PRESSURE GRADIENT REALLY
LOOSENS UP AND WINDS WILL DROP SIGNIFICANTLY. HIGH WIND WARNING FOR
ZONE 181 CURRENTLY SET TO EXPIRE AT 5AM - MAY HAVE TO CONTINUE THIS
A BIT LONGER - WILL KEEP AN EYE ON OBSERVATIONS AND MAKE A LAST
MINUTE DECISION. WILL CONTINUE TO DRY OUT ACROSS SOUTHERN MAINLAND
MONDAY AND TUESDAY IN DRY NORTHERLY FLOW. DOWNSLOPING OFF THE ALASKA
RANGE AND TALKEETNAS WILL RESULT IN MUCH WARMER TEMPERATURES IN MANY
LOCALES AS WE HEAD INTO MID WEEK. WITH A FAIRLY TIGHT NORTH-SOUTH
SURFACE PRESSURE GRADIENT THERE MAY BE ENOUGH WIND TO PRODUCE RED
FLAG CONDITIONS...ESPECIALLY FOR THE SUSITNA AND MATANUSKA. WILL HAVE
TO CONSIDER ISSUING A FIRE WEATHER WATCH FOR MONDAY AND TUESDAY FOR
THESE AREAS. OUT WEST EXPECT FOG AND STRATUS TO GRADUALLY INCREASE
UNDER RIDGE AS SUBSIDENCE INVERSION DEEPENS. WARM ADVECTION WEST OF
RIDGE WILL ALSO CREATE FOG AND STRATUS. ONLY CHANCE OF PRECIP IS FOR
THE WESTERN ALEUTIANS.

EXTENDED FORECAST...AS MENTIONED ABOVE HAVE LOW CONFIDENCE IN
EXTENDED FORECAST PERIOD. LATEST GFS TRANSITIONS RIDGE FROM BERING
TO OVER MAINLAND ALASKA BY THE END OF THE WEEK. PREVIOUS RUN
MAINTAINED RIDGE OVER BERING. IN ANY CASE LOOK FOR MAINLY DRY AND
WARMER CONDITIONS FROM CENTRAL BERING TO SOUTHERN MAINLAND. SOME
AFTERNOON/EVENING CONVECTION POSSIBLE...PARTICULARLY ALONG MOUNTAINS
WHERE MELTING SNOW WILL PROVIDE MOISTURE. MOVEMENT OF RIDGE WOULD
ALLOW A NEW SYSTEM TO MOVE TO THE WESTERN ALEUTIANS BY WEEKS END.
WILL NUDGE A BIT TOWARD THE NEW SOLUTION BY INTRODUCING A CHANCE OF
RAIN LATE IN THE WEEK FOR THE CENTRAL TO WESTERN ALEUTIANS.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...FLOOD WATCH ZONE 155 FOR KWETHLUK ON THE KUSKOKWIM RIVER.
MARINE...GALES 130 132 150 155 165 175 176.
FIRE WEATHER...NONE.

SEB MAY 06

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
522 PM ADT SAT MAY 20 2006

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0456 PM     HIGH SUST WINDS  KING COVE               55.06N 162.30W
05/20/2006  M74 MPH                             AK   AWOS

            HIGH WIND WARNING WAS IN EFFECT.

&&

EZ