Small Craft Advisory 167, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
526 AM AKST SUN FEB 22 2015

.ANALYSIS AND UPPER LEVELS...
THE HIGH PRESSURE AT THE SURFACE REMAINS CENTERED OVER BRITISH
COLUMBIA WITH THE ASSOCIATED RIDGE EXTENDING INTO THE YUKON
TERRITORY. THE LOW IN THE NORTHERN BERING SEA CONTINUES TO TRACK
NORTH TOWARDS THE KAMCHATKA PENINSULA PRODUCING SOUTHERLY SMALL
CRAFT WINDS THROUGH THE EASTERN AND NORTHERN BERING SEA THIS
MORNING. ON THE BACKSIDE OF THIS LOW PRESSURE SYSTEM...THE REST OF
THE BERING SEA HAS WEST TO NORTHWESTERLY WINDS WITH SCATTERED SNOW
SHOWERS. THE SURFACE OBSERVATIONS ALONG THE EASTERN ALEUTIANS AND
THROUGH THE SOUTHWEST ALASKA REGION REMAIN IN THE UPPER 30S. IN
BETWEEN THESE TWO SYNOPTIC FEATURES...THERE IS A STRONG 130 KNOT
SOUTH TO NORTH MERIDIONAL JET STREAK RUNNING THROUGH THE WESTERN
GULF...KENAI PENINSULA AND THE COPPER RIVER BASIN. THIS WILL
CONTINUE TO BRING WARM MOIST AIR THROUGHOUT THE SOUTHCENTRAL
REGION. THE RADAR IMAGERY IS SHOWING SHOWERY PRECIPITATION THROUGH
THE NORTHERN GULF COAST LINE...COOK INLET AND SPREADING
NORTHWARD. THE FLOW IN THE LOWER LEVELS REMAINS SOUTHERLY
THROUGHOUT THE REGION. THE TEMPERATURES REMAIN WELL ABOVE FREEZING
ALONG THE NORTHERN GULF COAST LINE AND THE INTERIOR...EXCEPT FOR
LOWER 30S IN THE COPPER RIVER BASIN.

&&

.MODEL DISCUSSION...
THE MODELS REMAIN IN GOOD AGREEMENT WITH THE LOW PRESSURE SYSTEM
IN THE NORTHERN BERING SEA AS IT TRACKS TOWARDS THE KAMCHATKA
PENINSULA BY SUNDAY NIGHT. THE GULF WILL REMAIN IN SOUTHERLY
FLOW THROUGH MONDAY. THE NAM CONTINUES TO BE MORE AGGRESSIVE IN
DRYING OUT THE ANCHORAGE BOWL QUICKER THAN THE OTHER MODELS. THE
GEM-REG/EC WERE THE PREFERRED MODELS OF CHOICE. THE FORECAST
CONFIDENCE REMAINS ABOVE AVERAGE HEADING INTO MONDAY.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
ANOTHER WARM SYSTEM WILL WORK ITS WAY ACROSS SOUTH CENTRAL ALASKA
TODAY. THIS SYSTEM IS NOT AS MOIST AS THE ONE ON SATURDAY
(YESTERDAY) AND RAINFALL IS EXPECTED TO BE SHOWERY FOR INLAND
AREAS RATHER THAN FULL-ON CONTINUOUS RAIN. THERE WILL BE A BRIEF
BREAK LATER TODAY BEFORE THE NEXT SYSTEM MOVES IN LATER TONIGHT.
PRECIPITATION WITH THE NEXT SYSTEM WILL START AS RAIN...BUT MAY
TRANSITION TO SNOW LATER IN THE DAY ON MONDAY AS COLDER AIR
BEGINS TO WORK ITS WAY INTO THE AREA. UNFORTUNATELY ACCUMULATIONS
(IF ANY) ARE EXPECTED TO BE ON THE LIGHT SIDE IF THE NUMERICAL
MODELS HOLD TO THEIR CURRENT SOLUTIONS.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
UNSEASONABLY WARM TEMPERATURES AND WET CONDITIONS SHOULD PERSIST
THROUGH THE WEEKEND OVER MUCH OF THE SOUTHCENTRAL AREA...AS
SOUTHERLY FLOW ASSOCIATED WITH THE LOW OVER THE BERING CONTINUES
TO FEED IN WARM MOIST AIR FROM THE NORTH PACIFIC OVER THE AREA.
MOST LOCATIONS CONTINUE TO REPORT RAIN AS THE DOMINANT
PRECIPITATION TYPE...AND EVEN THE TYPICAL "COLD" SPOTS IN THE
KUSKOKWIM VALLEY AND ALONG THE NORTH COAST OF THE DELTA ARE ABOVE
FREEZING AT THE SURFACE. PRECIPITATION WILL BECOME MORE SHOWERY
OVERNIGHT TONIGHT AS THE WAVE PUSHES FURTHER NORTHWARD...HOWEVER
THE SHOWERS WILL BE SHORT-LIVED AS ANOTHER ROUND OF STEADY RAIN
MOVES IN SUNDAY MORNING WITH THE NEXT WAVE TRACKING IN FROM THE
NORTH PACIFIC. GUSTY WINDS OVER THE MAINLAND WILL CONTINUE TO
DIMINISH THROUGH THIS EVENING...AS THE GRADIENT OVER THE AREA
BEGINS TO SLACKEN. ONCE THE LOW OVER THE BERING TRACKS FURTHER
NORTHWEST AND THE UPPER LEVEL TROUGH OVER THE BERING MOVES IN
PLACE OVER THE SOUTHWEST MAINLAND MONDAY MORNING...SOME COLDER AIR
(BY NO MEANS ARCTIC) WILL BEGIN TO FILTER INTO THE SOUTHWEST COAST
AND COOL OFF PARTS OF THE SOUTHWEST MAINLAND.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
A LARGE LOW PRESSURE COMPLEX OVER THE EASTERN HALF OF THE BERING
CONTINUES TO PUMP DEEP WARM AIR INTO THE STATE. MEANWHILE...ON
THE BACKSIDE THIS SYSTEM...COLDER AIR BEGINS TO MIGRATE OFF THE
KAMCHATKA PENINSULA AND FILTER INTO MUCH OF THE BERING SEA
TONIGHT...WHICH WILL HELP TO CREATE A FAIRLY WIDE SWATH OF GUSTY
WINDS DOWN THROUGH THE CENTRAL ALEUTIANS. A ROBUST UPPER LEVEL LOW
OVER NORTHEASTERN RUSSIA WILL BEGIN TO TRACK SOUTHEAST OVERNIGHT
TONIGHT. A SERIES OF EMBEDDED WAVES WILL SWING OFF OF THIS
SYSTEM...DEVELOPING A SURFACE LOW OVER THE WESTERN BERING LATE
SUNDAY AND TRACKING TOWARD THE PRIBILOFS ON MONDAY. THIS LOW WILL
HELP KEEP THE PATTERN MORE PROGRESSIVE (WEST TO EAST FLOW) THAN
IT HAS BEEN THE PAST WEEK...AND WILL HELP PUSH SOME OF THAT
COLDER AIR TOWARD THE MAINLAND BY MONDAY. THIS SHOULD START TO
TURN SOME OF THE LINGERING SHOWERS FROM RAIN TO SNOW OVER THE
EASTERN ALEUTIANS. BUT LIMITED MOISTURE WILL MAKE FOR ALMOST NIL
ACCUMULATIONS.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...ON TUESDAY THE NEXT
PACIFIC FRONTAL SYSTEM WILL TRACK INTO THE SOUTHWESTERN GULF WHILE
A COLD UPPER LEVEL TROUGH TO ITS NORTH SWINGS ONSHORE INTO WESTERN
ALASKA. TODAYS MODEL RUNS HAVE SHIFTED THE TRACK OF THE LOW A BIT
FURTHER SOUTH AS IT CROSSES THE GULF SUCH THAT THE FRONT NOW STAYS
MAINLY OFFSHORE PRIMARILY IMPACTING KODIAK ISLAND AND THE GULF
COAST WITH RAIN AND BREEZY CONDITIONS AS IT CROSSES TUESDAY AND
WEDNESDAY. SNOW SHOWERS ALONG THE WEST COAST FROM THE
SIGNIFICANTLY COLDER TROUGH TO THE NORTH WILL TAPER OFF THROUGH
THE DAY TUESDAY AS THE TROUGH SWINGS NORTHEAST WITH DRIER WEATHER
PREVAILING MIDWEEK AS UPPER LEVEL RIDGING BUILDS OVER MAINLAND
ALASKA.

IN THE MEANTIME...THE NORTH PACIFIC STORM TRACK WILL BEGIN
SHIFTING BACK A BIT FURTHER NORTH AS A RATHER COLD AIR MASS SWINGS
FROM THE SEA OF OKHOTSK OUT INTO THE WESTERN NORTH PACIFIC. THE
STRONG THERMAL CONTRAST WILL HELP TO SPIN UP A SERIES OF STRONG
FRONTAL SYSTEMS THROUGH THE UPCOMING WEEK AND WEEKEND. THESE
FRONTAL SYSTEMS WILL TRACK UP ACROSS THE WESTERN ALEUTIANS AND
INTO THE BERING SEA WHERE THEY WILL ADDITIONALLY BE ABLE TO TAP
INTO COLD SIBERIAN AIR.

THE UPPER LEVEL RIDGING OVER THE GULF OF ALASKA AND MAINLAND WILL
CONTINUE TO AMPLIFY THURSDAY AND FRIDAY. A FRONTAL SYSTEM RIDING
UP THE WESTERN UPSTREAM SIDE OF THE RIDGE WILL LIFT NORTH TOWARDS
THE ALASKA PENINSULA ON FRIDAY...OVER SW ALASKA FRIDAY NIGHT THEN
SPREAD INTO SOUTH CENTRAL ALASKA ON SATURDAY. WHILE THIS SYSTEM
ITSELF DOES NOT LOOK ALL THAT STRONG...IT DOES HAVE A LONG
SOUTHERLY FETCH TO TAP INTO AND DRAW ADDITIONAL WARM AND MOIST AIR
UP INTO THE REGION ON THE LEADING EASTWARD SIDE OF ITSELF FRIDAY
NIGHT AND SATURDAY.

ADDITIONALLY MODELS ARE SHOWING A STRONG WESTERLY UPPER LEVEL
TROUGH MOVING OVER NORTHERN AND CENTRAL INTERIOR ALASKA WHICH
COMES INTO PHASE WITH THE FRONTAL SYSTEM SATURDAY NIGHT. THE
RESULT THE RAPID WEST THEN SOUTHWESTWARD ACCELERATION OF THE
SYSTEM WILL BREAK DOWN THE UPPER LEVEL RIDGE AND A STRONGER UPPER
RIDGE WILL BUILD TO THE WEST BEHIND IT. THIS PATTERN WILL BEAR
CLOSE WATCHING AS IT HAS THE POTENTIAL TO SPIN THE SURFACE LOW UP
AGAIN VERY RAPIDLY AS IT TRACKS ALONG THE NORTH AND EASTERN GULF
COAST WHILE A STRONG SURFACE HIGH BUILDS INLAND. THIS TIGHT
OFFSHORE PRESSURE IN ADDITION TO A STRONG NORTHERLY JET BRINGS THE
POTENTIAL FOR RATHER STRONG NORTHERLY OUTFLOW WINDS OVER SOUTH
CENTRAL ALASKA AND THE NORTHERN GULF COAST NEXT SUNDAY AND MONDAY.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE 178.
         HEAVY FREEZING SPRAY 185 411 412.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...PD
SOUTHCENTRAL ALASKA...BL
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...MSO
LONG TERM...JER

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE ANCHORAGE AK
906 AM AKST SUN FEB 22 2015

AKZ101-111-121-125-131-141-145-230300-
ANCHORAGE-MATANUSKA VALLEY-WESTERN KENAI PENINSULA-
WESTERN PRINCE WILLIAM SOUND-NORTHEAST PRINCE WILLIAM SOUND-
COPPER RIVER BASIN-SUSITNA VALLEY-
INCLUDING THE CITIES OF...ANCHORAGE...EAGLE RIVER...INDIAN...
EKLUTNA...PALMER...WASILLA...SUTTON...CHICKALOON...KENAI...
SOLDOTNA...HOMER...COOPER LANDING...WHITTIER...SEWARD...
GIRDWOOD...MOOSE PASS...VALDEZ...THOMPSON PASS...GLENNALLEN...
EUREKA...MCCARTHY...PAXSON...SLANA...TALKEETNA...WILLOW...
CANTWELL
906 AM AKST SUN FEB 22 2015

...SLICK ROADS AND WALKWAYS EXPECTED THROUGH MONDAY...

WHILE AIR TEMPERATURES ARE NEAR OR ABOVE FREEZING ACROSS
SOUTHCENTRAL ALASKA...RAIN FALLING ON FROZEN OR ICE-COVERED ROADS
AND SIDEWALKS WILL CONTINUE TO MAKE FOR HAZARDOUS TRAVELING
CONDITIONS THROUGH MONDAY...ESPECIALLY ON SIDE STREETS.

CAUTION IS ADVISED WHEN OUTDOORS ACROSS SOUTHCENTRAL ALASKA.

FOR THE LATEST WEATHER FORECAST PLEASE VISIT
WEATHER.GOV/ANCHORAGE.

FOR THE LATEST ROAD CONDITIONS IN YOUR AREA PLEASE VISIT
511.ALASKA.GOV.