Gale Warning 728, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
445 AM AKST SAT NOV 15 2014

.ANALYSIS AND UPPER LEVELS...

WITH A STRONG BLOCKING RIDGE CONTINUING OVER THE YUKON...VERY
LITTLE SIGNIFICANT OVERALL CHANGE HAS OCCURRED IN THE LAST 24
HOURS. THIS RIDGING CONTINUES TO STRETCH FROM THE THE YUKON...INTO
THE CENTRAL INTERIOR AND SOUTHCENTRAL. SUBSIDENCE UNDER IT HAS
ALLOWED FOR PERSISTENT FOG AND STRATUS IN THE COPPER RIVER BASIN
TO START YESTERDAY MORNING TO CONTINUE OVERNIGHT. OTHERWISE SKIES
REMAIN MOSTLY CLEAR WITH LIGHT WINDS. THE NORTH PACIFIC LOW IS
STILL CENTERED ABOUT 300 MILES SOUTH OF DUTCH HARBOR...AND IS
SLOWLY FILLING AS IT CRAWLS NORTHWARD. A FRONT THAT MOVED THROUGH
THE WESTERN ALEUTIANS YESTERDAY HAS BECOME ABSORBED INTO THE NORTH
PACIFIC LOW...BRINGING RAIN SHOWERS AND GUSTY SOUTHEASTERLY WINDS
TO THE REGION. ANOTHER WAVE SOUTH OF THE GULF CAN BE SEEN PROGRESSING
TO THE NORTHWEST TOWARDS THE AKPENN. THIS SYSTEM WILL CONTINUE ON
THIS TRACK TODAY...RESULTING IN ANOTHER ROUND OF RAIN AND INCREASED
WINDS TO THE WESTERN GULF...SOUTHWEST MAINLAND...AND THE WATERS OF
BRISTOL BAY.

&&

.MODEL DISCUSSION...

AS IS OFTEN THE CASE IN BLOCKING PATTERNS SUCH AS THIS...SYNOPTIC
MODEL AGREEMENT THROUGH THE SHORT TERM REMAINS VERY GOOD. THERE
CONTINUES TO BE SLIGHT DISAGREEMENT WITH THE NORTHWARD TRACK OF
THE UPPER LOW MOVING INTO THE GULF ON SUNDAY (WITH THE LAST 2 RUNS
OF THE NAM BEING THE QUICKEST). THE EC WAS PRIMARILY USED FOR THE
LOW TRACK OF THIS SYSTEM...THOUGH THE NAM WAS STILL UTILIZED ALONG
THE GULF COAST ON SUNDAY TO BETTER CAPTURE THE SMALL SCALE FEATURES.
THE NAM IS ALSO SLIGHT OUTLIER ON SUNDAY WITH THE TRACK OF A NORTH
PACIFIC LOW INTO THE CENTRAL ALEUTIANS...SO THE GFS AND EC WERE
USED INTO MONDAY. OVERALL THESE DISCREPANCIES ARE FAIRLY SMALL...AND
AS A RESULT FORECAST CONFIDENCE REMAINS GOOD EARLY NEXT WEEK.

&&

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

DRY CONDITIONS WILL PERSISTS ACROSS MUCH OF SOUTHCENTRAL ALASKA
THROUGH SUNDAY MORNING WITH A STOUT RIDGE OF HIGH PRESSURE
CENTERED OVER WESTERN CANADA THAT EXTENDS WESTWARD OVER MUCH OF
THE ALASKA MAINLAND. PATCHY FOG WILL ONCE AGAIN BE A CONCERN THIS
MORNING FOR THE ANCHORAGE BOWL...MAT-SU VALLEY AND THE COPPER
RIVER BASIN...AND AGAIN SATURDAY MORNING WITH CLEAR SKIES ALLOWING
FOR SIGNIFICANT RADIATIONAL COOLING DURING THE OVERNIGHT AND EARLY
MORNING HOURS. THIS WILL BE COUPLED WITH ABNORMALLY WARM 925 MB
AND 850 MB TEMPERATURES...WHICH WILL AID IN CREATING A SUBSTANTIAL
SURFACE BASED INVERSION. BY MIDDAY ON SUNDAY...AN UPPER LEVEL
DISTURBANCE AND A WEAK SURFACE TROUGH WILL BRING RAIN AND SNOW CHANCES
BACK TO THE NORTHERN GULF COAST...PARTS OF THE MAT-SU VALLEY AND
THE ANCHORAGE BOWL. A BRIEF SHOT OF FREEZING RAIN IS POSSIBLE
DURING THE ONSET OF PRECIPITATION WITH BELOW FREEZING SURFACE
TEMPERATURES AND 850 MB TEMPERATURES ABOVE FREEZING. HOWEVER...BASED
ON THE ORIENTATION OF THE SURFACE AND 850 MB PRESSURE GRADIENT...IT
APPEARS THAT DOWNSLOPING SHOULD PREVENT THE MAJORITY OF THE
PRECIPITATION FROM REACHING THE GROUND IN ANCHORAGE. OUT BY KODIAK
ISLAND...STEADY RAINFALL IS EXPECTED TO CONTINUE AS THE WARM
CONVEYOR BELT ASSOCIATED WITH THE LOW IN THE BERING SEA AND AN
UPPER LEVEL DISTURBANCE PUSHES ACROSS THE KODIAK ISLAND AND THE
ALASKA PENINSULA.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 THROUGH 3)...

A VERY PERSISTENT PATTERN WILL REMAIN IN PLACE THROUGH THE
MONDAY...WITH NUMEROUS FAST MOVING DISTURBANCES TRACKING OVER THE
REGION. THIS WILL KEEP AN ACTIVE PATTERN OVER THE AREA...WITH
THREATS FOR RAIN MAINLY IMPACTING COASTAL AND MOUNTAIN
LOCATIONS...WITH SPOTTY SHOWERY ACTIVITY ELSEWHERE. A STRONGER LOW
WILL TRACK INLAND LATE THIS AFTERNOON AND TONIGHT...WITH LOCALLY
STRONG GAP WINDS DEVELOPING ALONG AND NEAR THE ALASKA RANGE.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 THROUGH 3)...

A MULTITUDE OF FAST MOVING LOWS WILL TRACK ACROSS THE EASTERN AND
CENTRAL BERING THROUGH SUNDAY BEFORE A LARGER AND STRONGER LOW
MOVES IN MONDAY. RAIN AND RAIN SHOWERS WILL IMPACT THE ENTIRE
BERING SEA AND ALEUTIANS.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...

THE HIGH LATITUDE BLOCKING PATTERN LOOKS TO HOLD STRONG THROUGH
THE EXTENDED FORECAST AS HIGH PRESSURE CONTINUES OVER WESTERN
CANADA/ALASKA MAINLAND AND A COMPLEX LOW PRESSURE SYSTEM RESIDES
OVER THE BERING SEA. A SERIES OF UPPER LEVEL DISTURBANCES ROTATING
ALONG THE PERIPHERY OF THE LOW IN THE BERING SEA WILL IMPACT
SOUTHCENTRAL ALASKA THROUGH THE FORECAST PERIOD...WHICH WILL IN
TURN KEEP RAIN/SNOW CHANCES POSSIBLE. GREATEST CHANCES FOR
PRECIPITATION WILL BE ALONG THE NORTHERN GULF COAST AS THE RIDGE
OVER THE MAINLAND PREVENTS THESE DISTURBANCES FROM TRAVERSING TOO
FAR INLAND. MODELS BEGIN TO DIVERGE SIGNIFICANTLY BY MID TO LATE
NEXT WEEK WITH THE EVOLUTION OF THE LOW IN THE BERING SEA AND HOW
IT HANDLES THE INTERACTION OF MULTIPLE SHORTWAVES EITHER PHASING
WITH OR ROTATING AROUND THE LOW. HOWEVER...THE MODELS DO SHOW A
SIMILAR PATTERN OF A STRENGTHENING OF BOTH THE SURFACE AND UPPER
LEVEL LOW FEATURES. AS THESE STRENGTHENED FEATURES IMPACT THE
RIDGE BY LATE NEXT WEEK THE MODELS ARE HINTING AT AN EASTWARD
DISPLACEMENT OF THE RIDGE. THERE IS STILL QUITE A BIT OF UNCERTAINTY
DUE TO THE LACK OF MODEL AGREEMENT AT THIS TIME...BUT IT STILL
APPEARS THAT THE BLOCKING PATTERN SHOULD HOLD TOGETHER THROUGH THE
FORECAST PERIOD.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...STORM...131.
          GALE...119 120 130 132 136 137 138 139 150.
FIRE WEATHER...NONE.

&&

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

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1231 PM AKST SAT NOV 15 2014

AKZ181-160945-
ALASKA PENINSULA-
INCLUDING THE CITIES OF...COLD BAY...SAND POINT
1231 PM AKST SAT NOV 15 2014

...A DUSTING OF ASH FALL IS POSSIBLE UNTIL 6 PM AKST NEAR PAVLOF VOLCANO...

PAVLOF VOLCANO AT 55.25N 161.53W IS CURRENTLY ERUPTING AND
PRODUCING AN ASH PLUME. A PILOT HAS REPORTED AN ASH PLUME TO
30,000 FEET ABOVE THE VOLCANO. A DUSTING OF ASH FALL IS POSSIBLE
IN THE IMMEDIATE VICINITY OF THE VOLCANO AND TO THE NORTHWEST OF
THE VOLCANO.

AVOID EXCESSIVE EXPOSURE TO ASH WHICH IS AN EYE AND RESPIRATORY
IRRITANT. THOSE WITH RESPIRATORY SENSITIVITIES SHOULD TAKE EXTRA
PRECAUTION TO MINIMIZE EXPOSURE.

SPECIAL WEATHER STATEMENT...CORRECTED
NATIONAL WEATHER SERVICE ANCHORAGE AK
1231 PM AKST SAT NOV 15 2014

AKZ181-160945-
ALASKA PENINSULA-
INCLUDING THE CITIES OF...COLD BAY...SAND POINT
1231 PM AKST SAT NOV 15 2014

...A DUSTING OF ASH FALL IS POSSIBLE UNTIL 6 PM SATURDAY AKST
NEAR PAVLOF VOLCANO...

PAVLOF VOLCANO AT 55.25N 161.53W IS CURRENTLY ERUPTING AND
PRODUCING AN ASH PLUME. A PILOT HAS REPORTED AN ASH PLUME TO
30,000 FEET ABOVE THE VOLCANO. A DUSTING OF ASH FALL IS POSSIBLE
IN THE IMMEDIATE VICINITY OF THE VOLCANO AND TO THE NORTHWEST OF
THE VOLCANO.

AVOID EXCESSIVE EXPOSURE TO ASH WHICH IS AN EYE AND RESPIRATORY
IRRITANT. THOSE WITH RESPIRATORY SENSITIVITIES SHOULD TAKE EXTRA
PRECAUTION TO MINIMIZE EXPOSURE.