Gale Warning 265, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
140 PM AKDT MON MAR 15 2010

.ANALYSIS AND UPPER LEVELS...
TWO LARGE UPPER LEVEL TROUGHS DOMINATE THE WEATHER SCENE OVER THE
REGION THIS MORNING. ONE TROUGH EXTENDS OUT OF AN EASTERN RUSSIA LOW
AND INTO THE WESTERN BERING WHILE THE SECOND TROUGH FEATURING A
CLOSED LOW AT 300 MB ENCOMPASSES MUCH OF THE GULF OF ALASKA AND SOUTH
CENTRAL ALASKA. PINCHED IN BETWEEN THESE TWO FEATURES IS A THIN RIDGE
THAT IS STEADILY BECOMING MORE ELONGATED AS THE WESTERN TROUGH
PRESSES EASTWARD TOWARDS THE NEARLY STATIONARY GULF LOW.

AT THE SURFACE...STACKED BENEATH THE UPPER LEVEL GULF LOW IS A 992 MB
SURFACE LOW RINGED BY NUMEROUS SHORTWAVES WITH EMBEDDED MESOSCALE
VORTICIES AS SEEN ON THE INFRARED SATELLITE IMAGERY. THESE SHORTWAVES
ARE BRINGING ISOLATED SNOW SHOWERS TO AREAS OF THE GULF COAST...WITH
THE HEAVIEST PRECIPITATION CONCENTRATED ALONG THE UPSLOPE REGIONS OF
COASTAL MOUNTAIN RANGES. A NARROW RIDGE ORIGINATING FROM A HIGH
PRESSURE SYSTEM CENTERED OVER BARROW DIVES SOUTH ACROSS THE EASTERN
BERING/WESTERN ALASKA. FURTHER WEST...A WEAKENING 980 MB TRIPLE POINT
LOW IS SLOWLY WORKING NORTHEASTWARD ALONG THE KAMCHATKA PENINSULA.

.MODEL DISCUSSION...
MODELS OVERALL ARE IN GOOD AGREEMENT THROUGH LATE IN THE WEEK...WITH
NEGLIGIBLE DIFFERENCES IN THE STRUCTURE OF THE KAMCHATKA LOW AS IT
DISSIPATES MID WEEK. PLACEMENT DIFFERENCES ARISE ON THURSDAY WITH
REGARDS TO A NEW LOW TRACKING INTO THE WESTERN GULF. LIKEWISE THE
MODELS ARE NOT QUITE REACHING A CONSENSUS ON THE TIMING OF
PRECIPITATION ASSOCIATED WITH THIS LOW...BUT DO AGREE ON THE GENERAL
VICINITY THAT WILL BE IMPACTED BY THE STORM.

.SHORT TERM FORECAST...

.SOUTH CENTRAL ALASKA...SHORTWAVES ROTATING AROUND THE LOW IN THE
CENTRAL GULF WILL CONTINUE TO BRING PERIODS OF SNOW AND RAIN TO
PRINCE WILLIAM SOUND AND UPSLOPE REGIONS OF THE KENAI AND ALASKA
MOUNTAIN RANGES...BUT THE WEATHER IN THE ANCHORAGE BOWL AND OTHER
DOWNSLOPED REGIONS OF SOUTH CENTRAL ALASKA WILL OSCILLATE BETWEEN
MOSTLY SUNNY AND MOSTLY CLOUDY SKIES AS THESE DISTURBANCES PASS
THROUGH. ONSHORE FLOW WILL HELP USHER IN MORE SEASONABLE TEMPERATURES
ACROSS SOUTHERN ALASKA THIS WEEK. THIS LOW WILL PERSIST IN THE GULF
THROUGH WEDNESDAY MORNING BEFORE WEAKENING AND DRIFTING WESTWARD. A
NEW LOW ROTATES INTO THE WESTERN GULF ON THURSDAY AND
FRIDAY...BRINGING WITH IT A RENEWED SHOT OF PRECIPITATION TO COASTAL
COMMUNITIES IN SOUTH CENTRAL ALASKA.

.SOUTHWEST ALASKA...HIGH PRESSURE WILL REMAIN STEADFAST OVER
SOUTHWESTERN ALASKA THROUGH THE MIDDLE PART OF THE WEEK. TEMPERATURES
SHOULD REBOUND THROUGH THE WEEK AS NORTHERLY WINDS WEAKEN AND TURN
SOUTHERLY AS THE RIDGE SCOOTS FURTHER EAST. THE NEXT ROUND OF
PRECIPITATION WONT IMPACT THE AREA UNTIL LATE THURSDAY OR EARLY
FRIDAY AS A LOW TRACKS INTO THE WESTERN GULF TO NEAR KODIAK ISLAND ON
THURSDAY NIGHT.

.BERING SEA AND ALEUTIANS...WINDS ASSOCIATED WITH THE CURRENT LOW IN
THE BERING SEA SHOULD DIMINISH TODAY AS THE SYSTEM WEAKENS AND TRACKS
FURTHER NORTH. A NEW LOW TRACKING OUT OF THE SEA OF OKHOTSK FOLLOWS A
SIMILAR PATH STARTING ON WEDNESDAY. A WARM FRONT LIFTING EAST AND
NORTH WITH THIS LOW WILL DELIVER A WIDE SWATH OF PRECIPITATION AND
GALE FORCE WINDS TO THE BERING SEA AND ALEUTIANS BETWEEN WEDNESDAY
AND FRIDAY.

.LONG TERM FORECAST...LITTLE CHANGE TO THE OVERALL PATTERN IS
EXPECTED THROUGH THE WEEKEND AND INTO EARLY NEXT WEEK. A LOW WILL
SKIRT THE ALEUTIANS OVER THE WEEKEND WHILE WARM ONSHORE FLOW
DOMINATES ACROSS SOUTHWEST AND SOUTH CENTRAL ALASKA.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE WARNING...170 172 175 176.
FIRE WEATHER...NONE.

KS MAR 10