Small Craft Advisory 26, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
440 AM AKST SAT JAN 10 2015

.ANALYSIS AND UPPER LEVELS...

THE LARGE SCALE PATTERN FEATURES CONTINUED BLOCKING OVER EASTERN
SIBERIA...AND A POWERFUL 200 KT PACIFIC JET STREAM MOVING EAST OF
THE DATELINE...SOUTH OF 40N. TWO LEFTOVER REMNANT UPPER LOWS EXIST
ACROSS THE REGION THIS MORNING...ONE NEAR SAINT MATTHEW
ISLAND...AND ANOTHER OVER THE SOUTHEAST GULF OF ALASKA. EXTENSIVE
LEFTOVER CLOUDS REMAIN OVER MUCH OF SOUTHCENTRAL...AND THEY WILL
LIKELY REMAIN IN SOME FASHION AS THE FLOW ALOFT REMAINS WEAK
TODAY. OUT WEST...ONSHORE FLOW BEHIND A WEAK COLD FRONT HAS SPREAD
EXTENSIVE LOW CLOUDS AND FOG...AND THIS WILL PERSIST THROUGH TODAY
BEFORE THE PRESSURE GRADIENT STRENGTHENS TONIGHT AND TOMORROW AS
A FRONT LIFTS NORTH.

WITH TIME...THE GENERAL BLOCKING REGIME OVER EASTERN SIBERIA WILL
SHUNT POLAR AIR OUTBREAKS INTO THE CANADIAN ARCTIC...WITH CONTINUED
ENHANCEMENT OF THE WESTERN NORTH AMERICAN RIDGE INTO SOUTHERN
ALASKA THROUGH THE FORECAST PERIOD. WITH A TRAIN OF ROSSBY WAVES
FORMING ALONG THE POWERFUL PACIFIC JET STREAM THEN INTERACTING
WITH THE AFOREMENTIONED RIDGE...A SERIES OF STRONG TO POWERFUL
PACIFIC CYCLONES WILL TRACK INTO THE SOUTHERN BERING AND GULF OF
ALASKA THROUGH THE END OF NEXT WEEK. THIS WILL KEEP SOUTHERN
ALASKA WELL ABOVE NORMAL THROUGH THE FORECAST PERIOD AS WARM
FRONTS TRACK TOWARD SOUTHERN ALASKA. THERE REMAINS NO END IN SIGHT
TO THE SIGNIFICANT WARM ANOMALIES AS THE RECORD BREAKING WARMTH
THIS WINTER MARCHES ON.

&&

.MODEL DISCUSSION...

THE SUITE OF NUMERICAL GUIDANCE ARE IN EXCELLENT AGREEMENT WITH
THE SHORT TERM FORECAST...AND ARE IN VERY GOOD AGREEMENT WITH THE
LARGE SCALE SYNOPTIC PATTERN HEADING INTO LATE NEXT WEEK. THE
SMALLER SCALE DIFFERENCES WITH THE TRACK AND EXACT STRENGTH OF A
SERIES OF LOWS MOVING INTO THE SOUTHERN GULF OF ALASKA AND BERING
SEA GROWS RAPIDLY AFTER 48 HOURS. OVERALL...THE ECMWF HAS BEEN THE
MOST CONSISTENT...SO THAT MODEL SOLUTION WAS FAVORED
OVERALL...WITH SOME NAM WITHIN THE FIRST 48 HOURS TO CAPTURE LOCAL
WINDS AND PRESSURE GRADIENTS.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (SATURDAY AND SUNDAY)...
THE LOW IN THE SOUTHEAST GULF WILL SLOWLY DRIFT TOWARD THE WEST
THROUGH TONIGHT. KEEPING A CHANCE OF SHOWERS MAINLY FOR THE
COASTAL AREAS AND THE COPPER RIVER BASIN. THIS LOW WILL WEAKEN AND
DRIFT NORTH ON SUNDAY NIGHT AS A MUCH STRONGER NORTHEAST PACIFIC
SYSTEM DRIVES TOWARD THE GULF FROM THE SOUTH. AS THIS LOW
APPROACHES THE SURFACE GRADIENT WILL TIGHTEN UP...INCREASING THE
WINDS OVER THE NORTHERN GULF. INLAND AREAS FROM THE WESTERN KENAI
NORTH TO THE SOUTH END OF DENALI PARK WILL BE BASICALLY DRY
THROUGH SUNDAY NIGHT WITH A WEAK INLAND RIDGE.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (SATURDAY AND SUNDAY)...
UPPER LEVEL RIDGING BUILDING OVER SOUTHWEST ALASKA WILL CONTINUE
TO BRING WARMING TEMPERATURES ALOFT ABOVE A COOLER NEAR-SURFACE
LAYER. AS LOWER-LEVEL WINDS INCREASE THE FOG SHOULD BEGIN TO
DIMINISH IN COVERAGE...THOUGH SHELTERED AREAS WILL LIKELY SEE FOG
STICK AROUND THROUGH TONIGHT. TEMPERATURES WILL REMAIN WELL ABOVE
NORMAL...THOUGH CONDITIONS WILL REMAIN PRECIPITATION-FREE MOST
AREAS THROUGH SUNDAY.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (SATURDAY AND SUNDAY)...
A STRENGTHENING LOW SOUTH OF THE THE WESTERN ALEUTIANS WILL PUSH A
FRONT NORTH THROUGH THE ALEUTIANS TONIGHT INTO SUNDAY...BRINGING
WINDS UP TO LOW-END GALE FORCE...WITH HIGHER GUSTS THROUGH TERRAIN
GAPS ESPECIALLY NEAR DUTCH HARBOR. CONTINUED SEASONABLY WARM
TEMPERATURES WILL ACCOMPANY THIS SYSTEM RESULTING IN ALL RAIN
ACROSS MOST OF THE BERING.

&&

.LONG TERM FORECAST (MONDAY THROUGH SATURDAY)...
WTIH LITTLE CHANGE IN THE FORECAST PATTERN EARLY NEXT WEEK...THERE
IS INCREASING CONFIDENCE THAT A SLOWLY MOVING DEEP LOW SOUTH OF
THE AKPENN WILL BRING GALE FORCE WINDS TO THE GULF STARTING
MONDAY EVENING AND CONTINUING INTO TUESDAY. HEAVY RAIN ALSO
APPEARS LIKELY FROM THIS SYSTEM FOR KODIAK ISLAND AND WESTERN
GULF COAST. PRECIPITATION WILL THEN SPREAD TOWARDS THE SOUTHWEST
MAINLAND AND INTERIOR SOUTHCENTRAL BY EARLY TUESDAY...HOWEVER WARM
AIR ALOFT MOST LIKELY BE SUFFICIENT FOR THIS TO FALL IN THE FORM
OF RAIN (WITH A POSSIBILITY OF FREEZING RAIN).

SAME BASIC PATTERN CONTINUES WITH THE STRONG JET STREAM REMAINING
CENTERED AROUND 35N AND BLOCKING RIDGE OVER THE WEST COAST OF
NORTH AMERICA EXTENDING ACROSS NORTHERN ALASKA WITH LITTLE CHANGE
EXPECTED IN THESE LARGE SCALE FEATURES FOR THE NEXT WEEK. THE
RESULTS WILL BE A CONTINUING SERIES OF STRONG LOW PRESSURE
SYSTEMS DEVELOPING IN THE NORTH PACIFIC AND TRACKING TO THE EAST
WITH MUCH OF THE ENERGY STAYING SOUTH OF THE AREA. SEVERAL OF THE
LOWS WILL TURN NORTH AND MOVE INTO THE GULF OF ALASKA AS THEY FILL
THEN DISSIPATE. GIVEN THAT THESE SYSTEMS WILL ALL BE WEAKENING AS
THEY LIFT NORTH THEY WILL PRIMARILY BRING PRECIPITATION TO
COASTAL AREAS AND OCCASIONALLY FURTHER INLAND WITH TEMPERATURES
CONTINUING ABOVE NORMAL.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE 172 174 175 176 177 178.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...JA
SOUTHCENTRAL ALASKA...BL
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...CC
LONG TERM...DEK/JR