Small Craft Advisory 206, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
546 AM AKST SAT MAR 7 2015

.ANALYSIS AND UPPER LEVELS...

A PROGRESSIVE UPPER LEVEL RIDGE OVER MAINLAND AK IS EXITING THE
STATE THIS MORNING. WEAK RIDGING IS OVER THE WESTERN
BERING...BETWEEN AN UPPER LOW NORTH OF KAMCHATKA AND A TROUGH
OVER THE BERING STRAIT. A 130 KT JET OVER THE SOUTHERN BERING
AIMED AT BRISTOL BAY IS SLOWLY WEAKENING IN PLACE.

AT THE SURFACE...A LOW IS OVER WESTERN AK. THE ASSOCIATED FRONT
IS DRAPED ALONG THE AKPEN EXTENDING INTO THE SUSITNA VALLEY.
THE JET IS DRIVING SIGNIFICANT SW FLOW WHICH IS SPREADING RAIN
INTO THE BRISTOL BAY AREA...AND SNOW NORTH OF LAKE ILIAMNA AND
INTO THE EASTERN KUSKOKWIM VALLEY. BEHIND THE FRONT COLDER AIR IS
FILTERING INTO THE KUSKOKWIM DELTA WITH SNOW SHOWERS. ALONG THE
EASTERN SIDE OF THE AK RANGE THE SW FLOW CONTINUES TO BRING HEAVY
SNOW FROM TALKEETNA NORTH...WITH MAINLY RAIN OVER THE ANCHORAGE
BOWL AND HILLSIDE...KENAI PENINSULA...AND GULF COAST AREAS.

&&

.MODEL DISCUSSION...

ONCE AGAIN THE MODELS SHOW EXCELLENT POSITIONAL AGREEMENT IN
BRINGING THE REMAINS OF THE FRONT TO THE ALCAN BORDER THIS
EVENING. THE ASSOCIATED LOW MOVES ACROSS NORTHERN AK AND EXITS
INTO CANADA SUN MORNING. CYCLONIC CIRCULATION REMAINS OVER
MAINLAND AK INTO MON WHEN HIGH PRESSURE MOVES IN. THE NEXT FRONT
OF SIGNIFICANCE FROM A NORTH PACIFIC LOW WILL AFFECT THE WESTERN
ALEUTIANS SAT THROUGH MON. THE WARMER GFS/EC SOLUTION...WHICH
BETTER REPRESENTED THE PRECIPITATION TYPES CURRENTLY AFFECTING
THE FORECAST AREA...CONTINUES TO BE USED IN THE FORECAST.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...

WARM AIR AT THE SURFACE HAS PUSHED UP COOK INLET AND KEPT
PRECIPITATION ALL RAIN FOR THE KENAI PENINSULA AND MOST OF THE
ANCHORAGE AREA. THE FREEZING LEVEL IN ANCHORAGE WAS AROUND 1500
FT OVERNIGHT AND THE SNOW LEVEL IS PROBABLY AROUND THE 1200 TO
1500 FT LEVEL EARLY THIS MORNING. WHERE IT IS SNOWING IT IS
ACCUMULATING SIGNIFICANTLY. HENCE THE SNOW ADVISORY CONTINUES FOR
THE HILLSIDE IN SPITE OF MOST OF ANCHORAGE REMAINING IN RAIN THAT
HAS BEEN HEAVY ENOUGH TO SET A NEW PRECIPITATION RECORD BY 6 AM.

TO THE NORTH THERE IS SNOW IN THE MAT-SU VALLEY WITH THE
PRECIPITATION TYPE CHANGEOVER BEING BETWEEN PALMER AND THE WASILLA
AIRPORT. OVER A FOOT OF SNOW HAS ALREADY FALLEN FROM TALKEETNA
NORTH AND SNOW WILL TAPER OFF IN THE SUSITNA VALLEY FROM THE
SOUTHWEST THIS AFTERNOON. VALDEZ TURNED TO ALL SNOW AND IT IS
SNOWING HEAVILY AT THIS TIME. IT IS EXPECTED TO TURN BACK TO RAIN
IN TOWN BY THE AFTERNOON BUT WILL REMAIN SNOW TOWARD THE
PASS...WHICH COULD SEE AN ADDITIONAL FOOT OF SNOW TODAY. THE
COPPER RIVER BASIN IS EXPERIENCING GUSTY SOUTH WINDS WHICH ARE
DOWNSLOPING MOST OF THE SNOW IN THE LOWER ELEVATIONS. THE UPSLOPE
TOWARD THE ALASKA RANGE IS PRODUCING HEAVY SNOWFALL AND THERE IS A
SNOW ADVISORY FOR NORTH OF GLENNALLEN FOR THIS.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (TODAY THROUGH MON MORNING)...

THE MAJORITY OF THE UPPER LEVEL ENERGY AND JET SUPPORT ASSOCIATED
WITH THE UPPER LEVEL LOW HAS SHIFTED EASTWARD TOWARD SOUTHCENTRAL
ALASKA. THIS HAS RESULTED IN PRECIPITATION RAPIDLY COMING TO AN
END ACROSS THE EASTERN KUSKOKWIM DELTA AND EASTERN BRISTOL BAY
AREA THIS MORNING. SNOW SHOWERS (RAIN SHOWERS IN PART OF THE
BRISTOL BAY AREA) WILL CONTINUE THROUGH THE DAY AS A MIX OF STEEP
NORTHWEST FLOW ALOFT USHERING IN COLDER AIR ALOFT AND ONSHORE
FLOW PREVENTS SIGNIFICANT MODIFICATION OF THE AIR MASS. A SECOND
UPPER LEVEL LOW WILL PUSH ACROSS THE SOUTHWEST MAINLAND ON SUNDAY
AND BRING ANOTHER DECENT SHOT OF SNOWFALL TO THE REGION.
HOWEVER...BY THIS TIME TEMPERATURES WILL BE MUCH COOLER AND THE
ATMOSPHERE WILL NOT BE ABLE TO SUPPORT A LOT OF MOISTURE WHICH
WILL LEAD TO PRETTY BENIGN NEW SNOWFALL AMOUNTS (AN INCH OR TWO).

WIND CHILLS MAY START TO BECOME AN ISSUE SUNDAY NIGHT AS
TEMPERATURES ARE EXPECTED TO PLUMMET BELOW ZERO. IT WILL TAKE
SOME TIME FOR THE WINDS OVER THE DELTA TO DIMINISH WHICH COULD
CREATE WIND CHILL VALUES IN THE TWENTY- TO THIRTY-BELOW RANGE.
WINDS WILL THEN BEGIN TO RELAX ON MONDAY AND BRING AN END TO ANY
POTENTIAL WIND CHILL ISSUES. A MUCH COLDER AIR MASS WILL BE
SITUATED OVER SOUTHWEST ALASKA BY THE BEGINNING OF THE WEEK
BRINGING WELL BELOW AVERAGE TEMPERATURES TO THE REGION.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (TODAY THROUGH MON MORNING)...

A COLD FRONT EXTENDS FROM A LOW IN THE NORTHERN BERING SEA DOWN
ACROSS SOUTHWEST ALASKA AND THEN TOWARD DUTCH HARBOR. THE EASTERN
ALEUTIANS AND ALASKA PENINSULA WILL SEE TEMPERATURES NEAR STEADY
IN THE MORNING HOURS WITH TEMPERATURES SLOWLY DROPPING DURING THE
DAY. PRECIPITATION FROM MUCH OF THE BERING SEA HAS COME TO AN END
THIS MORNING WITH DRIER AIR BEING ENTRAINED INTO THE LOW IN THE
NORTHERN BERING SEA. AN AREA OF LOW PRESSURE IN THE NORTHERN
PACIFIC WILL MOVE SOUTH OF SHEMYA ON SUNDAY BRINGING ANOTHER ROUND
OF GUSTY WINDS (IN THE 50 TO 60 MPH RANGE) AS WELL AS A MIX OF
RAIN AND SNOW TO THE WESTERN AND CENTRAL ALEUTIANS. WITH A STOUT
RIDGE DEVELOPING OVER THE NORTHERN TWO-THIRDS OF THE BERING
SEA...THE LOW WILL STRUGGLE TO MAKE MUCH NORTHERN PROGRESS.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...
SKIES OVER THE SOUTHERN MAINLAND WILL BEGIN TO CLEAR BY LATE THIS
WEEKEND AS OFFSHORE FLOW TAKES OVER. OUTFLOW WINDS ALSO DEVELOP
THROUGHOUT THE NORTH GULF COAST ON SUNDAY EVENING AS A WEAK LOW
WILL DEVELOP IN THE VICINITY OF PRINCE WILLIAM SOUND. THESE WINDS
WILL CONTINUE INTO THE MIDDLE OF NEXT WEEK AS THE LOW MOVES INTO
THE EASTERN GULF...LEAVING A TIGHT AND PERSISTENT PRESSURE
GRADIENT IN ITS WAKE.

OVER THE BERING...A NORTH PACIFIC LOW ENTERING THE WESTERN
ALEUTIANS ON SUNDAY WILL SLOWLY MOVE EASTWARD INTO THE EASTERN
ALEUTIANS...BUT RIDGING OVER THE EASTERN BERING WILL PREVENT IT
FROM TRACKING ANY FURTHER TO THE EAST. IMPACTS FROM THIS LOW
WILL CONTINUE PRIMARILY OVER THE ALEUTIANS...WITH RAIN/SNOW AND
GALE FORCE WINDS. THIS SYSTEM WILL EVENTUALLY RETREAT BACK TO THE
NORTH PACIFIC ON TUESDAY AND BECOME ABSORBED IN A COMPLEX LOW THAT
IS EXPECTED TO APPROACH THE GULF LATE NEXT WEEK.

THIS COMPLEX LOW REMAINS A CHALLENGE IN THE LONG TERM FORECAST AS
THE MODELS ALL CONTINUE TO PAINT A SIGNIFICANTLY DIFFERENT PICTURE
FOR MOST OF THE STATE. THE GFS HAS CONSISTENTLY BEEN MUCH DEEPER
AND FURTHER WEST WITH THIS SYSTEM BY BRINGING A WARM...DEEP...AND
MOIST LOW TOWARDS THE KENAI PENINSULA. THE EC ON THE OTHER HAND
REMAINS NOTABLY WEAKER AND FURTHER EAST...BRING A MAJORITY OF THE
PRECIPITATION AND WARM AIR TO THE PANHANDLE WITH RIDGING OVER THE
SOUTH MAINLAND. THE LONG TERM FORECAST CONTINUES TO USE WPC
GUIDANCE HEAVILY DURING THIS PERIOD WHICH IS MORE SIMILAR TO THE
EC SOLUTION...AND KEEPS BELOW NORMAL TEMPERATURES AND LOW CHANCES
OF PRECIPITATION FOR THE SOUTH MAINLAND THROUGH NEXT WEEK.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WINTER STORM WARNING...145
         WINTER STORM ADVISORY...101 111 141
MARINE...GALES...119 120 121 130 131 139 177-181 185
         HVY FRZG SPRY...179 180 185
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...DS
SOUTHCENTRAL ALASKA...EZ
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...MC
LONG TERM...DEK/CC

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
949 AM AKST SAT MAR 07 2015

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0700 AM     SNOW             7 S TALKEETNA           62.24N 150.09W
03/07/2015  M6.5 INCH                           AK   COCORAHS

&&

DEK

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1154 AM AKST SAT MAR 07 2015

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1149 AM     SNOW             41 NNE TALKEETNA        62.88N 149.59W
03/07/2015  M14.5 INCH                          AK   TRAINED SPOTTER

            MEASURED SNOWFALL SINCE LATE AFTERNOON 06 MAR.

&&

JPW

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1200 PM AKST SAT MAR 07 2015

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1149 AM     SNOW             TRAPPER CREEK           62.24N 150.42W
03/07/2015  M12.0 INCH                          AK   TRAINED SPOTTER

            SINCE 630 PM LAST NIGHT.

&&

JPW

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1218 PM AKST SAT MAR 07 2015

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1149 AM     SNOW             PAXSON                  63.09N 145.61W
03/07/2015  M9.5 INCH                           AK   DEPT OF HIGHWAYS

            9.5 INCHES OF SNOW SINCE LAST NIGHT.

&&

JPW