Small Craft Advisory 276, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
400 PM AKDT SAT MAR 28 2009

.ANALYSIS AND UPPER LEVELS...
THE MAIN PLAYER FOR THE SHORT TERM IS AN IMPRESSIVE 967 MB LOW NEAR
DUTCH HARBOR. WATER VAPOR IMAGERY REVEALS A GOOD SURGE OF MOISTURE
FROM THE MID-LATITUDES ASSOCIATED WITH THIS SYSTEM. IN THE UPPER
LEVELS A LONGWAVE TROUGH IS CENTERED OVER THE CENTRAL BERING SEA. A
DEVELOPING UPPER LEVEL LOW IS LOCATED AT THE BASE OF THIS
TROUGH...ACTING TO FURTHER DEEPEN THE LOW NEAR DUTCH HARBOR. A SET OF
ROBUST 160 KT JET STREAKS ARE LOCATED ON EITHER SIDE OF THIS UPPER
LOW...FURTHERING DEVELOPMENT OF THE SURFACE LOW.

.MODEL DISCUSSION...
MODELS CONTINUE TO BE IN DECENT AGREEMENT REGARDING THE OVERALL
PATTERN THROUGH THE BEGINNING OF NEXT WEEK. MAIN FOCUS IS ON THE
AFOREMENTIONED LOW MOVING INLAND NEAR CAPE NEWENHAM SUNDAY MORNING.
THE GFS SOLUTION IS PREFERRED FOR GUIDANCE WITH THIS AFTERNOONS
PACKAGE SINCE IT INITIALIZED WELL BASED ON SATELLITE COMPARISON.

.SHORT TERM FORECAST...
.SOUTHCENTRAL...
CONDITIONS WILL BE DETERIORATING TONIGHT AS THE LOW BEGINS TO AFFECT
THE REGION. WINDS WILL BE INCREASING AS THE GRADIENT TIGHTENS AND
STRONG WINDS ALOFT MOVE OVERHEAD. ANTICIPATING A STRONG BARRIER JET
TO FORM ALONG THE NORTHERN GULF...BRINGING POTENTIAL STORM FORCE
WINDS OVER HIGHER ELEVATIONS...AS WELL AS FOR PORTAGE VALLEY AND
ALONG TURNAGAIN ARM. STRONG WINDS WILL BE POSSIBLE OVER
SOUTHERN AND WESTERN PORTIONS OF THE ANCHORAGE BOWL TOMORROW
AFTERNOON AND EVENING. GIVEN FAIRLY LOW DEWPOINTS...PRECIPITATION
SHOULD REMAIN SNOW EXCEPT ALONG IMMEDIATE COASTAL LOCATIONS. AS A
RESULT...A BLIZZARD WARNING HAS BEEN ISSUED FOR PORTAGE VALLEY AND
TURNAGAIN ARM TONIGHT THROUGH TOMORROW. GOOD MOISTURE ADVECTION AND
LIFT WILL BRING A ROUND OF OVERRUNNING SNOW TO THE SUSITNA VALLEY.
ACCORDINGLY A WINTER WEATHER ADVISORY FOR SNOW IS IN EFFECT...WITH
AREAS ALONG THE ALASKA RANGE AND WEST OF THE PARKS HIGHWAY EXPECTED
TO PICK UP THE HIGHEST ACCUMULATIONS. TYPICAL DOWNSLOPING AREAS WILL
REMAIN RELATIVELY DRY THROUGH TOMORROW...ALTHOUGH AS THE UPPER TROUGH
PUSHES THROUGH SUNDAY NIGHT LIGHT ACCUMULATIONS OF SNOW ACROSS
SOUTHCENTRAL CAN BE EXPECTED. CONDITIONS WILL BE IMPROVING THROUGHOUT
THE DAY MONDAY...ALTHOUGH SNOW SHOWERS WILL BE SLOW TO CLEAR THE
REGION.

.SOUTHWEST...
WINDS AND PRECIPITATION WILL BE ON THE INCREASE THROUGH TONIGHT AS
THE LOW MOVES TOWARDS CAPE NEWENHAM. DUE TO THE LOW TRACK...WARM AIR
WILL INFILTRATE THE AKPEN AND SOUTHERN PORTIONS OF BRISTOL BAY. A MIX
OF RAIN AND SNOW ARE EXPECTED FOR THESE AREAS...MAINLY KING SALMON
SOUTH. ELSEWHERE PRECIPITATION WILL REMAIN ALL SNOW. STRONG WINDS
WILL LEAD TO BLIZZARD CONDITIONS ALONG COASTAL AREAS OF THE
KUSKOKWIM DELTA AND FOR NORTHERN PORTIONS OF BRISTOL BAY. COLD AIR
WILL MOVE BACK INTO THE REGION DURING THE DAY SUNDAY...CHANGING
PRECIPITATION ACROSS SOUTHWEST BACK TO ALL SNOW. BRISK WESTERLY WINDS
AND COLD ADVECTION SHOWERS WILL PERSIST INTO THE BEGINNING OF THE
WEEK.

.BERING SEA AND ALEUTIANS...
BLIZZARD CONDITIONS ACROSS THE EASTERN ALEUTIANS AND PRIBILOFS WILL
PERSIST THROUGH TOMORROW AS COLD AIR ADVECTION CRANKS UP ON THE
BACKSIDE OF THE LOW. WESTERLY WINDS WILL BE STRONGEST ACROSS THE
EASTERN ALEUTIANS AND THE PRIBILOFS DUE TO THE TIGHTEST PRESSURE
GRADIENT. ELSEWHERE...SNOW SHOWERS WILL PERSIST AS COLD ADVECTION
LINGERS THROUGH THE END OF THE WEEKEND. A WEAK LOW WILL BEGIN TO
AFFECT THE WESTERN ALEUTIANS ON MONDAY.

.LONG TERM FORECAST...
STILL EXPECT FLOW TO BECOME INCREASINGLY ZONAL ACROSS THE SOUTHERN
PORTION OF THE STATE AS WE MOVE THROUGH THE WEEK. THE RESULT WILL BE
FAST MOVING SYSTEMS PASSING FROM THE NORTH PACIFIC INTO THE GULF OF
ALASKA. PERIODS OF UNSETTLED WEATHER WILL PERSIST ACROSS THE AREA OF
RESPONSIBILITY THROUGHOUT THE COMING WEEK.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WARNING...125 155 161 185 195
         HIGH WIND WARNING...101
         WINTER WEATHER ADVISORY...145
MARINE...STORM...120 155 165 170 179 413 414
         GALE...125 129 130 132 138 140 141 150 160 171 172 175
                180 351 352 412
         HEAVY FREEZING SPRAY...130 179 412 413 414
FIRE WEATHER...NONE

NRH MAR 09