Small Craft Advisory 116, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
436 PM AKST THU FEB 5 2015

.ANALYSIS AND UPPER LEVELS...
THE UPPER LEVEL RIDGE REMAINS OVER THE NORTHERN BERING SEA WHILE
AN UPPER LEVEL TROUGH IS DIGGING SOUTHWESTWARD OVER THE YUKON AND
INTO THE GULF OF ALASKA. THIS IS BRINGING A STRONGER GRADIENT IN
THE UPPER LEVEL FLOW OVER MAINLAND ALASKA BETWEEN THE RIDGE AND
TROUGH.
AT THE SURFACE THE PRESSURE IS VERY TIGHT ALONG THE NORTH GULF
COAST WITH HIGH PRESSURE OVER THE INTERIOR OF THE STATE AND LOWER
PRESSURE IN THE GULF. SOUTHWEST ALASKA IS ALSO SEEING A TIGHT
PRESSURE GRADIENT BUT NOT AS STRONG AS THE OVER THE NORTH GULF
COAST.

&&

.MODEL DISCUSSION...
AS HAS BEEN THE CASE THE PAST FEW DAYS THE MODELS ARE VERY GOOD
SYNOPTIC AGREEMENT WITH THE BIGGEST ISSUE BEING HOW TO RESOLVE
WHAT WILL BE A COMPLEX LOW IN THE GULF FRI NIGHT THROUGH SUNDAY.
THE MODELS ALL HAVE THE SAME IDEA THAT THE MAIN LOW IN THE COMPLEX
WILL DEVELOP IN THE EASTERN GULF FRIDAY EVENING AND MOVE TO JUST
SOUTHEAST OF KODIAK ISLAND SATURDAY AFTERNOON. HOWEVER THE NAM IS
BRINGING MUCH STRONGER WINDS INTO THE COAST MARINE AREAS WITH A
TIGHTER GRADIENT THAN THE OTHER MODELS. IT ALSO SHOWING A
STRONGER SECONDARY LOW TRAILING THE FIRST ON SATURDAY AND SUNDAY.
THE OTHER MODELS ARE HINTING AT THIS FEATURE BUT THE NAM IS THE
STRONGEST ONE. THE AREAS WHERE THE DIFFERENCES IN MODELS WILL
HAVE THE MOST IMPACT IS KODIAK ISLAND AND THE NORTH GULF COAST
MARINE WATERS.

&&

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

STRONG NORTH WINDS SET IN THIS MORNING ACROSS THE VALDEZ AND THE
PALMER AREAS AS THE NOSE OF AN UPPER LEVEL JET STREAK MOVED TOWARD
THESE AREAS. THIS JET STREAK WILL MOVE TO THE WEST AS IT IS
ANCHORED TO THE EAST SIDE OF THE RETROGRADING HIGH OVER THE BERING
SEA...SETTING UP A VERY DEEP LAYER OF COLD ADVECTION ACROSS
SOUTHCENTRAL. WINDS HAVE DEVELOPED OVER THE REGION ACROSS THE COOK
INLET REGION...WITH HIGH WIND WARNINGS IN EFFECT FOR THE MATANUSKA
VALLEY AND THE VALDEZ AREAS. DISTURBANCES OF VARYING STRENGTH WILL
MOVE SOUTH ACROSS THE AREA THROUGH SATURDAY...WITH THE STRENGTH OF
THESE DISTURBANCES DETERMINING HOW STRONG THE RESULTING WINDS WILL
BE. THE STRONGEST SUCH DISTURBANCE MOVE SOUTH JUST TO THE WEST OF
THE SUSITNA VALLEY AND COOK INLET REGIONS DURING THE DAY ON FRIDAY
INTO FRIDAY EVENING...WITH THE STRONGEST WINDS EXPECTED THROUGH
THE COOK INLET REGION DURING THIS TIME.

DANGEROUSLY LOW WIND CHILLS WILL CONTINUE TO PLAGUE THOMPSON PASS
AS WELL AS LOCALIZED AREAS OF THE COPPER RIVER BASIN THROUGH
SATURDAY MORNING.

TRENDS WILL NEED TO BE MONITORED IN CASE OF POTENTIAL BLIZZARD
CONDITIONS DEVELOPING SATURDAY AND BEYOND IN THE KODIAK AREA.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
THE CLEAR AND DRY CONDITIONS WILL REMAIN HEADING INTO THE WEEKEND.
THE NORTHERLY WINDS WILL STRENGTHEN WITH AN UPPER LEVEL TROUGH
PASSAGE BY LATE FRIDAY NIGHT. THIS WILL RESULT IN COLDER TEMPERATURES
THROUGHOUT SOUTHWEST ALASKA WITH THE ADVECTION OF ARCTIC AIRMASS.
A WIND CHILL ADVISORY WAS ISSUED FOR THE KUSKOKWIM DELTA BEGINNING
MIDNIGHT FRIDAY NIGHT TO NOON SUNDAY. THE LOWER KUSKOKWIM VALLEY
WIND CHILLS WILL BE JUST BELOW WIND CHILL ADVISORY CRITERIA DUE TO
THE INVERSION ALOFT HELPING TO PREVENT THE STRONGER WINDS FROM
MIXING DOWN TO THE SURFACE HEADING INTO THE WEEKEND.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
THE NORTH PACIFIC LOW LOCATED SOUTH OF ADAK WILL CONTINUE TO TRACK
WESTWARD TOWARDS SHEMYA BEFORE DISSIPATING BY SATURDAY. THE
MOISTURE AND PRECIPITATION WITH THIS LOW WILL SPILL OVER IN THE
WESTERN BERING SEA. THE TEMPERATURES ARE IN THE UPPER 30S TO LOWER
40S AND THE PREDOMINANT PRECIPITATION WILL FALL AS RAIN. THE REST
OF THE BERING SEA WILL HAVE GALE FORCE NORTHERLY WINDS AS THE
GRADIENT WILL CONTINUE TO STRENGTHEN AS AN UPPER LEVEL TROUGH
BRINGS MORE COLDER AIR INTO THE EASTERN ALEUTIANS/ALEUTIAN CHAIN
BY SATURDAY. THIS WILL RESULT IN GUSTY GALE FORCE GAP WINDS ALONG
THE EASTERN ALEUTIANS THROUGH THE WEEKEND.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...OFFSHORE FLOW CONTINUES
WITH THE VERY COLD INTERIOR AIR BEING FORCED THROUGH MOUNTAIN
PASSES AND GAPS MAKING STRONG CHILLY WINDS A CONTINUING CONCERN
THROUGH THE WEEKEND. THE ALREADY STRONG CROSS MOUNTAIN PRESSURE GRADIENT
ALONG THE NORTH GULF COAST WILL INCREASE FURTHER SATURDAY NIGHT
AND SUNDAY AS A FRONT AND ACCOMPANYING LOWER PRESSURE ROTATE
NORTH. THIS WILL INCREASE NORTH WINDS AGAIN THROUGH THOMPSON PASS
AND DRAINING DOWN TOWARDS VALDEZ AS WELL AS THE OUTFLOW ACROSS THE
COPPER RIVER DELTA.

ANOTHER CONCERN DURING THE WEEKEND WILL BE THE SURFACE LOW
APPROACHING KODIAK ISLAND SUBSTANTIALLY INCREASING COLD NORTHERLY
WINDS AS WELL AS BRINGING A GOOD SUPPLY OF MOISTURE. WITH THE
ATMOSPHERE AS COLD AS IT PRESENTLY IS AND ONLY SLIGHT MODIFICATION
EXPECTED PRECIPITATION WILL DEFINITELY FALL IN THE FORM OF SNOW
AND BLOWING SNOW COULD BE A SIGNIFICANT CONCERN.

AS WE MOVE INTO NEXT WEEK A PATTERN SHIFT IS LOOKING LIKELY.
MONDAY AND TUESDAY A STRONG UPPER LEVEL RIDGE WILL BUILD OVER THE
WEST COAST OF CANADA AND ACROSS SOUTHEAST ALASKA. THIS WILL TURN
THE PREVAILING FLOW MORE SOUTHERLY AND BRINGING A WARMER...
MOISTER AIR MASS ACROSS THE GULF AND INTO SOUTHCENTRAL ALASKA MID
TO LATE WEEK IN THE FORM OF A SERIES OF FRONTAL SYSTEMS. INITIALLY
THESE FRONTS WILL BATTLE THE OFFSHORE FLOW AND ENTRENCHED COLD AIR
MASS BUT EVENTUALLY IT IS LOOKING LIKE THE WARMER SOUTHERLY FLOW
WILL WIN OUT AND MIXED PRECIPITATION TYPES WILL BECOME AN ISSUE
AGAIN TOWARDS THE END OF THE WEEK.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WIND WARNING 111 AND 131. WIND CHILL ADVISORIES 131 141
155.
MARINE...STORMS 127. GALE 126 128 130 131 132 136 137 138 139 140
150 155 160 165 179 180 181 185 411 412 413 414.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...EZ
SOUTHCENTRAL ALASKA...CC
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...PD
LONG TERM...JR

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1202 AM AKST FRI FEB 06 2015

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

0855 PM     NON-TSTM WND GST PALMER                  61.60N 149.11W
02/05/2015  M75.00 MPH                          AK   ASOS

            75 MPH WIND GUST AT PALMER MUNICIPAL AIRPORT.

1021 PM     NON-TSTM WND GST THOMPSON PASS           61.14N 145.75W
02/05/2015  M96.00 MPH                          AK   DEPT OF HIGHWAYS

&&

JPW

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1219 AM AKST FRI FEB 06 2015

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

0816 PM     NON-TSTM WND GST SSE VALDEZ              61.08N 146.30W
02/05/2015  M86 MPH                             AK   AWOS

&&

JPW