Small Craft Advisory 927, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 AM AKST SAT NOV 14 2009

.ANALYSIS AND UPPER LEVELS...
IN THE UPPER-LVLS A LARGE TROF ENVELOPS THE ENTIRE AOR...FROM THE
WESTERN BERING TO SOUTHCENTRAL AND THE GULF OF AK. VARIOUS SHORTWAVES
ARE ROTATING THROUGH THE FLOW PARTICULARLY OVER THE ALEUTIANS AND SW
AK ENHANCING SNOW SHOWER ACTIVITY. AN UPPER-LOW IS CENTERED OVER
CENTRAL/INTERIOR AK. AT THE SURFACE THIS MORNING...A STORM FORCE LOW
IS MOVING ASHORE NEAR CAPE SUCKLING WITH ASSOCIATED MODERATE TO HEAVY
SNOW OVER PRINCE WILLIAM SOUND INTO THE COPPER RIVER BASIN. STRONG
WINDS ASSOCIATED WITH THIS LOW BRINGING BLIZZARD CONDITIONS AROUND
VALDEZ AND THOMPSON PASS. BROAD NORTHWESTERLY FLOW IS PREDOMINANT FOR
MUCH OF THE BERING AND ALEUTIANS IN THE COLD-ADVECTION FLOW.

.MODEL DISCUSSION...
MODELS ARE ACCEPTABLY CAPTURING THE MAJOR FEATURES IN THE AOR. THE
LOW MOVING ASHORE THIS MORNING WILL WEAKEN...AND A RESIDUAL TROF OF
LOW PRESSURE WILL REMAIN OVER THE GULF INTO EARLY NEXT WEEK. A FRONT
WILL MOVE INTO THE WESTERN BERING AND ALEUTIANS SUNDAY NIGHT AND
WEAKEN AS IT ADVANCES TO THE EAST. THE GFS WAS EMPLOYED FOR THE
MORNING FORECAST PACKAGE IN THE SHORT TERM...WITH A TREND TOWARDS THE
EC IN THE LONGER TERM.

.SHORT TERM FORECAST...
.SOUTHCENTRAL...
THE STORM FORCE LOW MOVES ONSHORE WITH SNOW TAPERING TO SNOW SHOWERS
FROM SOUTH TO NORTH FOR PRINCE WILLIAM SOUND UP TO THE COPPER RIVER
BASIN...AND THE BLIZZARD CONDITIONS AROUND VALDEZ AND THOMPSON PASS
ENDING BY MIDDAY. THE RELAXING OF THE PRESSURE GRADIENT WILL HELP THE
STRONG NORTH-WEST WINDS PARTICULARLY NEAR SEWARD AND WHITTIER TO
SUBSIDE AS SATURDAY WEARS ON. THE REMAINDER OF SOUTHCENTRAL FROM THE
MAT-SU VALLEY DOWN TO THE ANCHORAGE BOWL REMAINING GENERALLY COLD AND
DRY INTO EARLY NEXT WEEK. IN THE ABSENCE OF DEEP MOISTURE...THE
UPPER-TROF OVER THE REGION WILL YIELD MAINLY CLOUDY CONDITIONS WITH A
FEW FLURRIES OR BRIEF SNOW SHOWERS AS THE NEW WEEK ENTERS.

.SOUTHWEST...
PERIODS OF LIGHT SNOW AS SHORTWAVES ROTATE THROUGH BRISTOL BAY AND
THE KUSKOWIM DELTA...PARTICULARLY ALONG UPSLOPE AREAS. CORE OF
COLD-ADVECTION AND UPPER-DYNAMICS WILL BE OVER THE BERING AND EASTERN
ALEUTIANS...AND THUS PRECIPITATION LOOKS TO BE LIGHT.

.BERING SEA/ALEUTIANS...
SNOW SHOWERS ENHANCED BY COLD-ADVECTION AND STRONGER UPPER-LVL
DYNAMICS OVER THE CENTRAL THROUGH EASTERN ALEUTIANS AND PRIBILOFFS.
BROAD NORTHWESTERLY FLOW GIVING WAY OVER FAR WESTERN REACHES OF THE
ALEUTIANS AND BERING SUNDAY NIGHT INTO MONDAY AS NEXT FRONT
APPROACHES.

.LONG TERM FORECAST...
COLD-DRY FOR MUCH OF THE MAINLAND INTO NEXT WEEK AS UPPER-TROF
CONTINUES TO DIG SOUTHEAST THROUGH THE N PAC AND GULF. A BREAKDOWN IN
THE PATTERN OVER THE WESTERN AOR LOOKS TO ALLOW MORE DEEP SYSTEMS TO
AFFECT THE ALEUTIANS...THOUGH CHALLENGES WILL FOCUS ON THE DETAILS OF
WHERE EXACTLY THESE SYSTEMS WILL MOVE.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WARNING...135
MARINE...STORM...351 352 120
         GALE...411 412 413 414 121 125 130 132 138 140 150 155 160
                165 170 171 172 175 176 179 180 185
         HEAVY FREEZING SPRAY...412 414 160 179 180 185

JAM NOV 09