Small Craft Advisory 801, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
200 PM AKDT FRI NOV 4 2011

.MODEL DISCUSSION...IN THE SHORT TERM MODELS ARE IN GOOD AGREEMENT.
PLACEMENT AND INTENSITY OF THE LOW MOVING ACROSS THE BERING FROM THE
WEST IS CONSISTENT BETWEEN MODELS AND FROM RUN TO RUN. MOVING INTO
THE MID TERM MODELS ARE STILL DOING WELL BUT HAVE SOME
DIFFERENCES...SPECIFICALLY WITH THE NEW LOW IN THE NORTH PACIFIC THAT
WILL TRACK JUST SOUTH OF THE ALEUTIANS FROM WEST TO EAST SUNDAY
THROUGH MONDAY. THE GFS IS SLIGHTLY FASTER AND MORE NORTH THAN THE EC
OR NAM WHILE THE EC BECOMES SLIGHTLY SOUTH OF THE NAM MONDAY MORNING.
FOR THE WEST WE WENT WITH THE EC AND IN THE EAST WE WENT WITH THE NAM
OVER THE LAND FOR DETAIL AND THE EC OVER THE WATER.

.ANALYSIS AND UPPER LEVELS...THE LOW COMPLEX OVER THE SOUTHERN PART
OF THE STATE CONTINUES TO WEAKEN AND DRIFT EAST WHICH HAS CAUSED
PRECIPITATION OVER MOST OF THE AREA TO SLOW DOWN. BEHIND THIS LOW
COLD AIR ADVECTION MOVES ACROSS THE SOUTH CENTRAL. FURTHER TO THE
WEST A RIDGE IS BUILDING IN OVER THE EASTERN ALEUTIANS FROM THE
CENTRAL ALEUTIANS. THIS RIDGE WILL MOVE EAST ACROSS THE STATE AND OUT
OF THE REGION BY SUNDAY AFTERNOON. BEHIND THE RIDGE A STRENGTHENING
LOW IN THE WESTERN BERING BEGINS TO MOVE ACROSS THE BERING AND WILL
MAKE ITS WAY TO THE MAINLAND NEAR BETHEL SATURDAY NIGHT.

.SHORT TERM FORECAST...
FOR THE EAST...WIDESPREAD VERY LIGHT SNOW IS FALLING AROUND
SOUTHCENTRAL THIS AFTERNOON. COLD AIR ADVECTING EAST ACROSS THE
ALASKA RANGE WILL BRING SOUTHCENTRAL ANOTHER BRIEF SHOT OF MEASURABLE
SNOW THIS EVENING...MOSTLY UP AGAINST THE MOUNTAINS...BEFORE A
SHORTWAVE RIDGE BUILDS FROM SOUTHWEST AK. THE COLD ADVECTION AND
DEPARTING SURFACE LOW WILL STRENGTHEN THE PRESSURE GRADIENT ALONG THE
GULF COAST...BRINGING GUSTY WINDS BACK TO THE TYPICAL AREAS LATE
TONIGHT. THIS WILL HAVE LITTLE IMPACT EXCEPT WHERE SNOW IS
TRANSPORTABLE LIKE THOMPSON PASS AN ADVISORY FOR BLOWING SNOW MIGHT
BE WARRANTED OVERNIGHT AND SATURDAY MORNING.

A MORE SIGNIFICANT WEATHER SYSTEM WILL APPROACH SATURDAY. A LOW WILL
DEVELOP ALONG THE OCCLUSION NEAR THE SOUTHERN TIP OF THE KENAI
PENINSULA...HELPING TO ENHANCE THE PRECIPITATION AROUND SOUTHCENTRAL.
THE QUICK MOVING SYSTEM WILL DROP SIGNIFICANT SNOW FROM KACHEMAK BAY
UP TO THE SUSITNA VALLEY OVER A SHORT PERIOD OF TIME. THE CURRENT
THINKING IS THAT THE SPEED OF THE SYSTEM WILL LIMIT THE SNOWFALL
TOTALS TO BELOW ADVISORY CRITERIA. SNOW TAPERS OFF RAPIDLY SUNDAY
MORNING ALTHOUGH THE UPPER TROUGH AXIS REMAINS NEAR BRISTOL BAY...SO
MORE SNOW IS LIKELY BY THE END OF THE WEEKEND WITH THE MOIST
SOUTHWESTERLY FLOW PREVAILING. NOT UNTIL MONDAY WILL THE TROUGH MOVE
THROUGH SOUTHCENTRAL AND COLDER AND DRIER AIR SETTLES OVER THE
REGION.

FOR THE WEST...WINDS HAVE STARTED TO TAPER DOWN THROUGHOUT MUCH OF
THE ALEUTIANS AND SOUTHWEST ALASKA AS THE LOW OVER THE STATE PUSHES
FURTHER EAST. THEY WILL PICK BACK UP AS THE FRONT ASSOCIATED WITH THE
LOW IN THE WESTERN BERING MOVES ACROSS THE ALEUTIANS. RAIN AND SNOW
SHOWERS ARE ALSO EXPECTED IN THE ALEUTIANS AS THE FRONT PASSES WITH
THE PREDOMINANT CONDITION BEING RAIN DUE TO THE WARM AIR BEING
ADVECTED IN AHEAD OF THE LOW. AS THE LOW AND ASSOCIATED FRONT REACH
SOUTHWEST ALASKA AND WINDS PICK UP ALONG THE COAST THE QUESTION IS
WHAT KIND OF PRECIPITATION WILL BE EXPECTED. IN THE SOUTHERN AREAS IT
LOOKS TO BE MOSTLY RAIN...HOWEVER IN AREAS NEAR BETHEL WE ARE LOOKING
AT SNOW WITH STRONG WINDS INDICATING THE POSSIBILITY FOR BLIZZARD
CONDITIONS. CURRENTLY WE HAVE A BLIZZARD WATCH OUT FOR THE AREA
STARTING SATURDAY MORNING.

EARLY NEXT WEEK...A STRONG IMPULSE MOVES OUT OF SOUTHEAST ASIA AND A
LOW PRESSURE SYSTEM DEVELOPS OVER THE NORTH PACIFIC. THIS SYSTEM
CONTINUES TO STRENGTHEN AS IT MOVES INTO THE BERING SEA
TUESDAY...BRINGING WIDESPREAD STORM FORCE WINDS TO THE REGION. THE
STRONG SOUTHWESTERLY FETCH HAS THE POTENTIAL TO CAUSE HIGH SURF
LEADING TO SIGNIFICANT BEACH EROSION AND POSSIBLE COASTAL FLOODING
FROM BRISTOL BAY TO NORTON SOUND. THIS STORM WILL HAVE OUR ATTENTION
THROUGH THE WEEKEND AS THE MODELS NAIL DOWN THE EXACT STRENGTH AND
PATH.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WATCH...155
MARINE...STORM...185
         GALES...129 130 132 138 127 150 155 160 165 180 170 171 172
         175 176 179
FIRE WEATHER...NONE

DWK/AB NOV 11