Small Craft Advisory 128, NWS Anchorage, AK

SOUTH CENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
400 PM AKST MON FEB 10 2014

.ANALYSIS AND UPPER LEVELS...
A RIDGE OF HIGH PRESSURE EXTENDS FROM RUSSIA INTO THE WEST CENTRAL
BERING SEA AND ACROSS NORTHERN ALASKA TO A HIGH OVER THE EASTERN
BROOKS RANGE. LOW PRESSURE PERSISTS OVER THE GULF OF ALASKA WITH A
LOBE OF THE LOW PRESSURE WORKING ITS WAY WEST ALONG THE NORTH GULF
COAST TODAY PRODUCING SNOW SHOWERS FROM PRINCE WILLIAM SOUND WEST TO
THE LOWER COOK INLET TO KODIAK ISLAND. THE TIGHT PRESSURE GRADIENT
COUPLED WITH DENSE COLD AIR OVER THE INTERIOR IS RESULTING IN STRONG
OUTFLOW GAP WINDS...ESPECIALLY IN THE MATANUSKA VALLEY AND THROUGH
THOMPSON PASS IN THE CHUGACH MOUNTAINS. AN UPPER LEVEL TROUGH EXTENDS
FROM THE CANADIAN ARCTIC TO AN UPPER LOW OVER THE KENAI PENINSULA.
THE TROUGH WILL MOVE SOUTHEAST TO BRITISH COLUMBIA AS THE UPPER LOW
MOVES TO THE SOUTHWEST EVENTUALLY INTO THE NORTH PACIFIC TONIGHT.

.MODEL DISCUSSION...
MODELS REMAIN IN GENERALLY GOOD AGREEMENT WITH RESPECT TO THE OVERALL
SYNOPTIC PATTERN INTO FRIDAY. SMALL DIFFERENCES SHOW UP WITH RESPECT
TO THE LOW MOVING INTO THE WESTERN BERING SEA FRIDAY AS THE GFS IS A
TAD FASTER THAN THE ECMWF BRINGING THE LOW INTO THE WESTERN BERING
SEA AND WESTERN ALEUTIANS. AT THIS POINT WE ARE LEANING TO A ECMWF
AND NAM SOLUTION ALTHOUGH THEY ARE BOTH TRENDING TO THE GFS SOLUTION.
THE RUN TO RUN CONSISTENCY IS GOOD INTO THE COMING WEEKEND WITH THE
GFS BEING THE MOST CONSISTENT AT THIS TIME.

.SHORT TERM FORECAST...
SOUTH CENTRAL ALASKA...
THE OFFSHORE FLOW WILL CONTINUE FOR THE NEXT FEW DAYS AS HIGH
PRESSURE REMAINS OVER THE BERING AND THE UPPER LOW CURRENTLY OVER
SOUTH CENTRAL DIVES QUICKLY SOUTHWARD ALONG THE ALASKA PENINSULA AND
INTO THE NORTHERN PACIFIC. GUSTY NORTH WINDS WILL BEGIN TO SUBSIDE BY
THIS EVENING AS THE SURFACE PRESSURE GRADIENT WEAKENS. OFFSHORE FLOW
WILL CONTINUE TO RESULT IN CLEAR AND COLD CONDITIONS INTO THE MIDDLE
OF THE WEEK BEFORE THE NEXT CHANCE FOR SNOW ARRIVES WITH THE UPPER
LOW DROPPING OVER THE SOUTHWEST MAINLAND THURSDAY. WE WILL CONTINUE
THE RED FLAG WARNING FOR THE MATANUSKA VALLEY INTO THE EVENING DUE TO
THE DRY WINDY CONDITIONS AND LACK OF SNOW COVER. A SURFACE LOW
DEVELOPS AND STRENGTHENS ALONG THE NORTH GULF COAST AND PRINCE
WILLIAM SOUND WEDNESDAY AND THURSDAY THAT WILL BE MONITORED CLOSELY.
THIS COULD RESULT IN SETTING UP A CLASSIC COLD ADVECTION SNOW EVENT
FOR THE NORTHERN COOK INLET. SNOW SHOWERS ALONG THE NORTH GULF COAST
WILL END FROM EAST TO WEST THROUGH THIS EVENING. THE SNOW SHOWERS
OVER KODIAK ISLAND WILL PERSIST OVERNIGHT AS THE EAST FLOW ADVECTS
MOISTURE INTO THE ISLAND. THEY WILL TAPER OFF IN THE MORNING AS THE
UPPER LOW MOVES SOUTH AND THE SURFACE TROUGH MOVES OFF TO THE
SOUTHWEST.

SOUTHWEST ALASKA...
WINDS WILL SLOWLY DIMINISH THROUGH TOMORROW BUT STILL REMAIN GUSTY AT
TIMES. COLDER ARCTIC AIR WILL MOVE INTO THE WESTERN INTERIOR TO THE
KUSKOKWIM DELTA AND BRISTOL BAY WEDNESDAY. ANOTHER UPPER LOW WILL
THEN DROP SOUTH FROM THE ARCTIC INTO SOUTHWEST ALASKA BY THURSDAY AND
HELP TO REINFORCE THE COLD AIR IN PLACE OVER MUCH OF THE STATE.
THE COLDER SHOT OF ARCTIC AIR BY THE MIDDLE OF THE WEEK WILL LIKELY
SEND TEMPERATURES WELL BELOW NORMAL ALONG WITH SOME VERY COLD WIND
CHILLS.

BERING SEA AND ALEUTIANS...
A WEAK DISTURBANCE ALOFT PULLING ARCTIC AIR OVER THE RELATIVELY WARM
WATERS WILL SUPPORT SNOW SHOWERS TO THE EASTERN ALEUTIANS AND ALASKA
PENINSULA INTO TONIGHT ALONG WITH A CONTINUATION OF GUSTY NORTHERLY
WINDS. A BREAK IN THE SNOW SHOWERS WILL COME ON TUESDAY BEFORE
ANOTHER ARCTIC SHOT AND SNOW SHOWERS RETURN BY MID-WEEK.

.LONG TERM FORECAST...
A COLD UPPER LEVEL LOW WILL BECOME ENTRENCHED OVER THE MAINLAND INTO
THE MIDDLE OF NEXT WEEK. THE EXACT LOCATION OF THE UPPER AND SURFACE
LOW WILL DETERMINE WHERE THE PRECIPITATION THREAT AREAS WILL BE.
OVERALL EXPECT CONDITIONS TO REMAIN ON THE COLD SIDE AND THE BEST
CHANCES FOR PRECIPITATION WILL BE ALONG THE NORTH GULF COAST TO
KODIAK ISLAND AND POTENTIALLY INLAND ACROSS THE COPPER RIVER BASIN
AND SOUTH CENTRAL ALASKA. CONVERSELY UPPER LEVEL RIDGING OVER THE
WESTERN ALEUTIANS AND BERING SEA COUPLED WITH A SERIES OF STORMS
MOVING THROUGH WILL KEEP THAT REGION ON THE WARMER SIDE WITH FREQUENT
EPISODES OF PRECIPITATION.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALE 127 128 130 138 155 165 170 172 173 174 175 176 179
              414
         HEAVY FREEZING SPRAY 126 127 128 129 130 138 139 140 150 160
                              165 180 181 185 414
FIRE WEATHER...RED FLAG WARNING ZONE 111

SAM FEB 14