Small Craft Advisory 121, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
534 AM AKST SUN FEB 8 2015

.ANALYSIS AND UPPER LEVELS...
HIGH PRESSURE REMAINS OVER NORTHEASTERN RUSSIA WITH A LOW NOW
JUST SOUTH OF THE ALASKA PENINSULA. BETWEEN THESE TWO FEATURES
STRONG NORTHEASTERLY FLOW MOVES THROUGH THE SOUTHWEST AND BERING
SEA. THIS FLOW HAS ALSO ADVECTED SOME COLD AIR FROM MAINLAND
ALASKA OUT OVER THE BERING. THE SURFACE LOW IS CLOSER TOWARDS
SOUTHERN KODIAK ISLAND AND WITH THE NORTHEAST WINDS IS BRINGING
NEW SNOW TO THE ISLAND. THE SNOW COMBINED WITH THE WINDS IS
PRODUCING BLIZZARD CONDITIONS.

&&

.MODEL DISCUSSION...
THE MODELS ARE HAVING A LOT OF PROBLEMS WITH THE LOW NEAR KODIAK
ISLAND. SATELLITE SHOWS A PLETHORA OF LOWS THROUGHOUT THE GULF AND
ALL OF THE MODELS ARE HAVING ISSUES RESOLVING THESE SMALL
CIRCULATIONS WHICH IS PART OF THE REASON WHY THEY ARE ALSO
STRUGGLING WITH THE MAIN LOW. THERE IS ADDITIONAL DISCREPANCY ON
THE HANDLING OF THE MAIN CORE OF SNOW ALONG THE GULF COAST AND FOR
KODIAK ISLAND. THE NAM HAS BEEN DOING THE BEST WITH THE COMPLEX
LOW PLACEMENT BUT IS ALSO THE BIGGEST OUTLIER WITH PRECIPITATION
FIELDS.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
AS THE LOW NEAR KODIAK MOVES FURTHER SOUTHWEST AND WEAKENS...THE
PRESSURE GRADIENTS ACROSS THE SOUTHCENTRAL WILL CONTINUE TO DROP
WHICH WILL KEEP WINDS IN THE AREA ON A DOWNWARD TREND. UPPER LEVEL
FLOW WILL ALSO BE CHANGING TO BECOME MORE SOUTHERLY WHICH WILL
BRING BACK SNOW TO THE GULF COAST TODAY. THE SOUTHERLY FLOW WILL
ALSO BRING IN MORE CLOUD COVER FOR MUCH OF THE SOUTHCENTRAL WHICH
WILL HELP TO MODERATE THE TEMPERATURES. FOR KODIAK THE HEAVIEST
BAND OF SNOW IS EXPECTED TO SHIFT TO THE WEST DURING THE MORNING
WHICH WILL END BLIZZARD CONDITIONS.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA
THE SURFACE LOW NEAR KODIAK ISLAND BEGINS TO FILL AND WEAKEN
SLOWLY THROUGH THE AFTERNOON. WINDS SHOULD TAPER DOWN EARLY T0DAY
ACROSS THE KUSKOKWIM VALLEY AND BRISTOL BAY AND THEREFORE THE
ADVISORY TIMES WILL BE ADJUSTED TO EXPIRE AT NOON. THE KUSKOKWIM
DELTA ADVISORY WILL BE KEPT INTACT AS HIGH PRESSURE TO THE NORTH
WILL KEEP A TIGHTER GRADIENT OVER THIS AREA. SNOW SHOWERS ALONG
THE ALASKA PENINSULA ARE EXPECTED TO CONTINUE THROUGH MONDAY AS
LOW PRESSURE REMAINS JUST TO THE SOUTH. A STORM SYSTEM DEVELOPING
IN THE NORTH PACIFIC WILL MOVE UP TO THE ALASKA PENINSULA LATER ON
MONDAY. THIS SYSTEM PUSHES A WARM FRONT BRINGING A MIX OF
PRECIPITATION MONDAY NIGHT INTO TUESDAY. MAX GALE WINDS ARE
EXPECTED WITH THIS SYSTEM ALONG THE SOUTH SIDE OF THE ALASKA
PENINSULA. THIS RAPIDLY DEVELOPING STORM SYSTEM SHOULD BE
MONITORED FOR UPDATES AS STORM FORCE WINDS MAY BE POSSIBLE MONDAY
NIGHT.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS

WEAK INSTABILITY SNOW SHOWERS CONTINUE ACROSS THE BERING THROUGH
TUESDAY NIGHT. GUSTY WINDS ACROSS THE BERING WILL BE STRONGEST
ALONG THE CENTRAL AND SOUTHWESTERN WATERS TODAY AS A STRONG 850MB
JET DIVES TOWARD THE CENTRAL ALEUTIANS THIS AFTERNOON. WINDS
TAPER DOWN SLIGHTLY TONIGHT WITH THE NEXT STORM SYSTEM MOVING INTO
THE EASTERN ALEUTIANS MONDAY AFTERNOON. EXPECT MAX GALES WITH THIS
STORM SYSTEM WITH THE POSSIBILITY OF STORM FORCE WINDS TO DEVELOP
MONDAY NIGHT. THERE IS STILL A BIT OF UNCERTAINTY ON THE TRACK AND
STRENGTH OF THIS SYSTEM AS IT IS RAPIDLY DEVELOPING.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...A RATHER LARGE VERTICALLY
STACKED LOW CENTERED WELL SOUTH OF THE EASTERN ALEUTIANS WILL
SLOW AS IT DRIFTS EAST TUESDAY TO BECOME STATIONARY SOUTH OF THE
ALASKA PENINSULA AND WESTERN GULF WHERE IT WILL REMAIN THROUGH
LATE WEEK. AN UPPER LEVEL RIDGE OUT OF AHEAD OF THE LOW WILL
AMPLIFY OVER THE EASTERN PACIFIC AND GULF OF ALASKA ON MONDAY
THEN SHIFT EAST OVER SOUTHEAST AND SOUTHCENTRAL ALASKA TUESDAY
BEFORE SETTING UP RESIDENCE A AS CONTINENTAL SCALE BLOCKING RIDGE
STRETCHING ACROSS THE WESTERN US AND WESTERN CANADA. THESE TWO
VERY LARGE SCALE FEATURES WILL STEER WARMER MOISTER AIR AND A
SERIES OF LOW PRESSURE SYSTEMS UP INTO THE GULF THROUGH THE WEEK.

WHILE MODEL DIFFERENCES IN THE TIMING AND STRENGTH OF THE
INDIVIDUAL LOW PRESSURE WAVES HAVE INCREASED SINCE YESTERDAY THERE
IS STILL GOOD CONSISTENCY IN THE LARGE SCALE FLOW PATTERN...SO
CONFIDENCE REMAINS HIGH IN THE PATTERN SHIFT OCCURRING AND THE
TREND OF INCREASING TEMPERATURES AND INCREASING PRECIPITATION
THROUGH THE WEEK...ESPECIALLY ALONG THE COAST. WITH COLD AIR WELL
ENTRENCHED INLAND FREEZING RAIN CONTINUES TO BE A CONCERN AS DOES
ALL OTHER PRECIPITATION TYPES HOWEVER THE SPECIFIC TRACK OF THE
INDIVIDUAL LOWS (WHICH CONFIDENCE IS LOWER ON) WILL BE KEY IN
DETERMINING WHICH AREAS GET WHAT PRECIPITATION TYPES. STRONG WINDS
ESPECIALLY IN THE MARINE AREAS WILL ALSO LIKELY BE A SIGNIFICANT
IMPACT THROUGH THE WEEK WITH MANY OF THE FRONTAL WAVES.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...BLIZZARD 171 WIND CHILL 152 155 161
MARINE...

STORM 130 138

GALES 120 120 127 128 137 139 150 155 170 172-177 179 180 181 185

HEAVY FREEZING SPRAY 121 126 127 128 130 138 139 140 141 165 170
179 180 185

NONE. FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...DK
SOUTHCENTRAL ALASKA...DK
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...KH
LONG TERM...JR