High Wind Watch 12, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
500 AM AKDT FRI SEP 20 2013

.MODEL DISCUSSION...
THE MODELS ARE IN BETTER AGREEMENT WITH THE NORTH PACIFIC LOW IN THE
EASTERN GULF OF ALASKA. THIS LOW TRACKS TOWARDS YAKUTAT THIS
AFTERNOON AND MOVES INLAND IN THE EVENING. THE MODELS ARE HANDLING
THE BERING SEA LOW PRESSURE SYSTEM BETTER WITH THE LOW TRACKING
PARALLEL WITH THE ALEUTIAN CHAIN BEFORE CROSSING THE EASTERN
ALEUTIANS BY SATURDAY MORNING. THE LOW RAPIDLY INTENSIFIES BY FRIDAY
MIDDAY WHICH WILL PRODUCE GALE/STORM FORCE WINDS FOR THE CENTRAL
ALEUTIANS. THE GFS/EC MODELS ARE IN GOOD AGREEMENT BUT THE NAM IS THE
OUTLIER FOR THE TWO LOW PRESSURE SYSTEMS. THE FORECAST CONFIDENCE IS
HIGH THROUGH THE WEEKEND.

.ANALYSIS AND UPPER LEVELS...
AN AMPLIFIED UPPER LEVEL RIDGE REMAINS LOCATED OVER THE EASTERN
ALEUTIANS. THIS IS PRODUCING NORTHWEST FLOW AND DRY CONDITIONS FOR
SOUTHWEST AND SOUTHCENTRAL ALASKA. THE SATELLITE IMAGERY REFLECTS THE
DRIER STABLE CONDITIONS WITH MAINLY CLEAR SKIES. THE JET STREAK IS
CHARACTERIZED BY ZONAL FLOW THROUGH THE ALEUTIANS WITH THE JET CORE
AT 135 KNOTS. THE LOW IN THE BERING SEA HAS RAPIDLY INTENSIFIED THIS
MORNING SOUTHWEST OF PRIBILOF ISLANDS. THE SATELLITE IMAGERY IS
REFLECTING A LARGE SWATH OF MOISTURE WITH A CLOUD SHIELD STREAMING
THROUGH THE WESTERN/CENTRAL ALEUTIANS TOWARDS THE PRIBILOF ISLANDS.

.SHORT TERM FORECAST...
SOUTHCENTRAL ALASKA...
THE MAJORITY OF SOUTHCENTRAL ALASKA WILL HAVE MOSTLY SUNNY SKIES
BEFORE INCREASING OF CLOUDS BY SATURDAY MORNING. THE CLEAR SKIES
OVERNIGHT AIDED IN THE FREEZE WARNING FOR THE ANCHORAGE BOWL AND THE
MATANUSKA SUSITNA VALLEY REGION...THIS WILL REMAIN IN EFFECT FOR THE
EARLY MORNING HOURS BEFORE THE TEMPERATURES WILL BE ABOVE FREEZING
WITH THE MORNING SUNRISE. THE TEMPERATURES WILL NOT BE AS COLD FOR
SATURDAY WITH THE INCREASED CLOUD COVER AS THE NORTH PACIFIC LOW
TRACKS CLOSER TO THE EASTERN ALEUTIANS WITH THE CLOUD SHIELD
SPREADING INTO THE SOUTHCENTRAL ALASKA REGION.

SOUTHWEST ALASKA...
NORTHWEST FLOW WILL DOMINATE TODAY AS THE RIDGE MOVES EASTWARD
THROUGH THE EASTERN ALEUTIANS. THE WINDS WILL SHIFT TO A SOUTHEAST
FLOW THIS AFTERNOON WITH A WARM FRONTAL BOUNDARY APPROACHING THE
REGION. THERE WILL BE WIDESPREAD STRATUS AND RAIN ALONG THE ALASKA
PENINSULA AND THE WESTERN CAPES ASSOCIATED WITH THE WARM FRONTAL
BOUNDARY.

THE BERING SEA AND ALEUTIANS...
A LOW PRESSURE SYSTEM HAS DEVELOPED THIS MORNING JUST NORTHEAST OF
KISKA. THIS SYSTEM WILL RAPIDLY INTENSIFY THIS AFTERNOON AS IT TRACKS
SOUTH OF PRIBILOF ISLANDS. THERE WILL WIDESPREAD STRATUS AND RAIN
WITH GALE/STORM FORCE WINDS. BY SATURDAY MORNING THE LOW WILL CROSS
THE EASTERN ALEUTIANS TOWARDS THE SOUTHERN END OF KODIAK. BY SATURDAY
WITH THE PREDOMINATE NORTHWEST FLOW THERE WILL BE STRONG GAP WINDS
FOR THE EASTERN ALEUTIANS.

.LONG TERM FORECAST...
FOR NEXT WEEK A SHORTWAVE TROUGH WILL BE POSITIVE TILTED THROUGH THE
BERING SEA AS A CUTOFF LOW FORMS OVER THE WESTERN ALEUTIANS. THERE
WILL BE A STRONG MERIDONAL JET STREAK OVER THE CENTRAL ALEUTIANS WITH
A AMPLIFIED RIDGE OVER THE EASTERN ALEUTIANS WHICH WILL GRADUALLY
MOVE EASTWARD. THIS WEATHER PATTERN WILL ALLOW STORMS TO KEEP
TRACKING THROUGH THE BERING SEA BEFORE CROSSING INTO THE GULF OF
ALASKA.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...FREEZE WARNING 101 111
MARINE...GALE 130 132 136 137 138 140 150 160 175 176
         STORM 120 155 165 170 171 172
FIRE WEATHER...NONE

PLD SEP 13