Gale Warning 450, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
100 AM ADT FRI MAY 19 2006

.DISCUSSION...

ANALYSIS...WATER VAPOR IMAGERY SHOWS MOISTURE TRANSPORT IN BROAD
SOUTHWEST FLOW FROM EASTERN BERING ACROSS MAINLAND ALASKA OUT AHEAD
OF UPPER TROUGH AXIS OVER THE CENTRAL BERING. AT THE SURFACE THERE
IS A 993 MB LOW JUST WEST OF CAPE NEWENHAM WITH OCCLUDED FRONT
EXTENDING SOUTHEASTWARD ACROSS BRISTOL BAY TO TRIPLE POINT NEAR
SOUTHERN END OF KODIAK ISLAND. RADAR SHOWS RAIN SPREADING ACROSS
SOUTHWEST ALASKA AND NORTHWARD ACROSS COOK INLET/KENAI
PENINSULA/PRINCE WILLIAM SOUND AS FRONT APPROACHES. SURFACE RIDGE
EXTENDS FROM HIGH OVER NORTH PACIFIC ACROSS GULF INTO SOUTHCENTRAL.
THE PRESSURE GRADIENT ACROSS SOUTHCENTRAL HAS TIGHTENED AHEAD OF
FRONT RESULTING IN GUSTY WINDS ACROSS MUCH OF THE AREA. WEAK COLD
ADVECTION IS OCCURRING OVER THE CENTRAL BERING BEHIND THE SURFACE
LOW RESULTING IN GUSTY WINDS TO 30 KT.

MODEL ANALYSIS...MODELS SHOW GOOD RUN-TO-RUN CONSISTENCY AND HAVE
A GOOD HANDLE ON CURRENT SYNOPTIC FEATURES. THEREFORE...HAVE HIGH
CONFIDENCE IN TODAYS FORECAST.

SHORT-TERM FORECAST...LOW NEAR CAPE NEWENHAM WILL WEAKEN AS IT
MOVES INLAND THIS MORNING WHILE TRIPLE POINT WILL DEVELOP OVER
KODIAK ISLAND. AFTER A BRIEF BREAK IN THE STEADY RAIN OVER
SOUTHWEST ALASKA ANOTHER BATCH WILL MOVE IN EARLY THIS MORNING WITH
SURFACE LOW AND AHEAD OF UPPER TROUGH SETTING UP A VERY WET DAY.
BEST CHANCE OF RAIN OVER SOUTHECENTRAL WILL BE DURING OVERNIGHT
HOURS INTO EARLY MORNING. THEN UPPER FLOW WILL BACK TO THE SOUTH
TO SOUTHEAST DURING THE MORNING HOURS AS UPPER TROUGH APPROACHES
CREATING DOWNSLOPING IN THE USUAL LOCATIONS. AS TRIPLE POINT
DEVELOPS THIS AFTERNOON FLOW WILL BACK TOWARD THE NORTH AND THINGS
WILL DRY OUT EVEN MORE OVER SOUTHCENTRAL. HOWEVER NORTH GULF COAST
RIDING WILL BE REINFORCED WITH DEVELOPMENT OF TRIPLE POINT LOW TO
SOUTH SO EXPECT GUSTY WINDS ONCE AGAIN THIS AFTERNOON AND EVENING
ACROSS SOUTHCENTRAL. MEANWHILE RIDGE WILL BUILD OVER THE CENTRAL
BERING HELPING TO REALLY TIGHTEN THE SURFACE PRESSURE GRADIENT OVER
THE EASTERN BERING SEA LATER TODAY. COMBINED WITH COLD ADVECTION
THIS WILL RESULT IN GALE FORCE WINDS EASTERN BERING AND BRISTOL BAY
THROUGH AKPENN INTO NORTH PACIFIC THIS AFTERNOON THROUGH SUNDAY.
EXPECT STORM FORCE GUSTS THROUGH CHANNELED AREAS IN THE AKPENN.
BUILDING RIDGE ALSO RESULTS IN DEVELOPMENT OF UPPER JET WHICH HELPS
TO AMPLIFY TROUGH AND PUSH TRIPLE POINT QUICKLY SOUTHEASTWARD ACROSS
GULF SATURDAY NIGHT. MOST AREAS WILL DRY OUT SUNDAY WITH THE
EXCEPTION OF WEST SIDE OF ALASKA/ALEUTIAN RANGES WHERE NORTHWESTERLY
FLOW WILL BANK CLOUDS UP AGAINST MOUNTAINS. LOOKS LIKE SETTING UP
A BLOCK AS WE HEAD INTO THE BEGINNING OF THE NEW WEEK WITH HIGH
CENTERED OVER BERING SO LITTLE CHANGE FROM SUNDAY...PERHAPS A LITTLE
DRIER ACROSS SOUTHERN MAINLAND.

EXTENDED FORECAST...PERSISTENCE FOR DAYS 4 THROUGH 7 OF THE FORECAST.
HIGH PRESSURE SITTING OVER THE BERING WILL DEVELOP SUBSIDENCE
INVERSION RESULTING IN STRATUS AND FOG ACROSS THE BERING. DOWNSTREAM
OF THE RIDGE OVER SOUTHERN MAINLAND MAY SEE A FEW WEAK SHORT-WAVES
DROP DOWN FROM THE NORTH RESULTING IN A CHANCE OF SHOWERS. OTHERWISE
LOOKS PRETTY DRY WITH SEASONABLE TEMPERATURES.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...FLOOD WARNING ZONE 155 FOR LOWER AND UPPER KALSKAG.
         FLOOD WATCH ZONE 155 FOR KWETHLUK.
MARINE...GALES 150 155 160 165 180.
FIRE WEATHER...NONE.

SEB MAY 06