High Wind in Alaska, October 10, 2009

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
422 AM AKDT SAT OCT 10 2009

.DISCUSSION...
THE MODELS REMAIN IN EXCELLENT AGREEMENT ON THE EVOLUTION OF THE
WEATHER PATTERN DURING THE NEXT 3 DAYS. A LARGE UPPER LEVEL RIDGE
OF HIGH PRESSURE REMINISCENT OF THE STRONG RIDGES THAT WERE
OBSERVED MUCH OF JULY WILL REMAIN IN PLACE ACROSS THE EASTERN
INTERIOR INTO EARLY NEXT WEEK BEFORE SLOWLY WEAKENING. A POWERFUL
STORM SYSTEM NEAR THE PRIBILOF ISLANDS EARLY THIS MORNING WILL
GRADUALLY FILL AND LIFT TO THE GULF OF ANADYR BY 00Z MON.

INTERIOR...A STRONG RIDGE WITH 500 MB HEIGHTS AND 850 MB TEMPS
EASILY IN THE 90TH PERCENTILE...AND IN SOME CASES CLOSE TO RECORD
LEVELS FOR THIS TIME OF YEAR. THE 12Z PAFA SOUNDING HAD A 850 MB
TEMP OF +12C (ONLY 3C SHY OF RECORD LEVELS) AND A REMARKABLY HIGH
FREEZING LEVEL OF 11.5K FT AGL THE RIDGE AXIS WILL GENERALLY
EXTEND FROM NEAR YAKUTAT NORTH INTO THE BEAUFORT SEA. FOR AREAS IN
THE INTERIOR WITH NO SNOW COVER THIS WILL PUSH TEMPS TO NEAR
RECORD LEVELS. AREAS WITH SNOW COVER WILL BE CONSIDERABLY COOLER.
THE ONLY CONCERN THE NEXT FEW DAYS WILL BE FOR BOUTS OF STRONGER
WIND IN THE PASSES OF THE AK RANGE AS THE RIDGE AXIS REMAINS EAST
OF ALL BUT THE EXTREME EASTERN AK RANGE.

WEST COAST...THE MOST SIGNIFICANT WEATHER WILL BE FOUND ALONG THE
WEST COAST. A 964 MB LOW NEAR THE PRIBILOF ISLANDS GRADUALLY FILLS
AND LIFTS TO THE GULF OF ANADYR BY SUNDAY EVENING. THE MAIN
CONCERN WILL BE FOR THE POTENTIAL OF COASTAL FLOODING ALONG PARTS
OF THE SOUTHERN SEWARD PENINSULA COAST. INITIALLY THE WIND
DIRECTION WILL BE OUT OF THE EAST...WHICH WILL ALLOW THE SEAS TO
BUILD...BUT WILL NOT PRODUCE ANY STORM SURGE. AS THE LOW BEGINS
TO LIFT OUT AND THE WIND VEERS INTO THE S/SE LATE TONIGHT AND
SUNDAY A STORM SURGE OF UP TO 3 FEET CAN BE EXPECTED. THIS WILL
LIKELY LEAD TO SIGNIFICANT BEACH EROSION AND AREAS OF MINOR
FLOODING ALONG LOW LYING AREAS. THE WIND AND SEAS WILL BEGIN TO
GRADUALLY DIMINISH BY SUNDAY EVENING AS THE LOW PULLS AWAY AND WEAKENS.
THE LOW IS ALSO SPREADING RAIN NORTH ALONG MOST OF THE WEST COAST
EARLY THIS MORNING THAT SHOULD TAPER BACK TO SCATTERED SHOWERS
THIS AFTERNOON/EVENING. TEMPERATURES WILL BE WARM ENOUGH TO KEEP
THE PRECIPITATION IN THE FORM OF RAIN ALONG ALL OF THE WEST
COAST.

NORTH SLOPE...THE LARGE RIDGE OF HIGH PRESSURE WILL EXTEND NORTH
INTO THE BEAUFORT SEA WITH AN UNSEASONABLY WARM AIRMASS ALOFT FOR
THE NEXT FEW DAYS ALONG ALL OF THE ARCTIC COAST...AND MOST NOTABLY
FROM BARROW EAST. THE PRESSURE GRADIENT TIGHTENS SOME TODAY ALONG
THE CHUKCHI SEA COAST AS THE LOW LIFTS NNW THROUGH THE BERING SEA
AND EVENTUALLY SPREADS EAST ALONG THE BEAUFORT SEA COAST.  AREAS OF
STRATUS/FOG ARE EXPECTED TO DEVELOP TODAY INTO SUNDAY. THE WIND
GRADUALLY BECOMES MORE OFFSHORE LATE SUNDAY INTO MONDAY BUT WITH
THE WARM AIR OVER THE COOLER WATERS IT MAY BE TOUGH TO GET RID OF
THE LOWER STRATUS IN MANY AREAS ALONG THE IMMEDIATE COAST.

MID-RANGE...THE MODELS ARE IN GOOD AGREEMENT INTO THE MIDDLE OF NEXT
WEEK AND THEN MODEL SPREAD INCREASES.  A STRONG CLOSED 500 MB HIGH
CENTERED ACROSS THE EASTERN INTERIOR REMAINS IN TACT INTO THE MIDDLE
OF THE WEEK. THE GENERAL CONSENSUS OF THE MODELS IS THAT THE HIGH
SLOWLY SLIDES TO THE EAST AND WEAKENS LATE IN THE WEEK.  THIS WOULD
LEAD TO A LOWER HEIGHT PATTERN AND MORE SEASONABLE TEMPERATURES
ACROSS THE INTERIOR.  MODEL SPREAD REALLY INCREASES ALONG THE WEST
COAST WITH THE LATEST OPERATIONAL RUN OF ECMWF BUILDING A
MODERATE RIDGE WHILE THE GFS HAS A CLOSED LOW. NEEDLESS TO SAY
FORECAST CONFIDENCE DIMINISHES BY LATE IN THE WEEK.

COASTAL HAZARD POTENTIAL DAYS 3 AND 4...WINDS AND SEAS WILL
CONTINUE TO GRADUALLY DIMINISH ALONG THE WEST COAST SUN NIGHT AND
MON.

&&

.HYDROLOGY...NONE.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...

COASTAL FLOOD WARNING FOR AKZ211.

WIND ADVISORY FOR AKZ215-AKZ225-AKZ226-AKZ227.

HIGH SURF ADVISORY FOR AKZ212.

SMALL CRAFT ADVISORY FOR PKZ225-PKZ230-PKZ235.

GALE WARNING FOR PKZ200-PKZ210-PKZ215-PKZ220-PKZ225.

STORM WARNING FOR PKZ210.

&&

CB OCT 09