High Surf Advisory 3, NWS Fairbanks, AK

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
143 AM AKDT WED AUG 3 2011

.DISCUSSION...
CURRENT 500 MB AND MSLP PROGS FROM THE 03/00Z CYCLE SHOW
LITTLE DIFFERENCE OUT THROUGH 00Z FRI. THE MOST IMPORTANT
FEATURES THIS MORNING ARE A SHORT WAVE ALOFT AND A 984 MB
SURFACE LOW NEAR THE GULF OF ANADYR. BY 12Z THU...THE
SHORT WAVE IS PROGGED BECOME A MINIMAL CLOSED LOW SOUTHEAST
OF ST LAWRENCE ISLAND WHILE THE SURFACE LOW DEEPENS TO
AROUND 980 MB OVER OUTER NORTON SOUND.

BEYOND 12Z THU...MODEL FORECASTS FOR THE UPPER LOW
AND SURFACE LOW POSITIONS BEGIN TO DIVERGE. OPERATIONAL
GFS POSITION FOR 12Z FRI PLACES THE SYSTEM FARTHER TO
THE NORTHWEST THAN THE ECMWF/GEM AND GEFS ENSEMBLE MEAN...
THE LATTER 3 MODELS LOOK PRETTY CLOSE IN POSITION FOR 12Z
FRI PLACING THE LOW CENTER OVER THE WEST CENTRAL SEWARD
PENINSULA. THE NAM IS RUNNING A BIT SLOWER. I PREFER
THE CONSENSUS OF ECMWF/GEM/GEFS ENSEMBLE MEAN FOR THE
12Z FRI POSITION...CENTRAL PRESSURE FILLING TO AROUND
990-992 MB.

RAIN OVER ST LAWRENCE ISLAND WILL SPREAD EASTWARD
ACROSS ALL WEST COAST AREAS TODAY...AND TO THE WESTERN
INTERIOR TONIGHT WHILE RAIN OR SHOWERS CONTINUES OVER
THE WEST COAST AREAS. RAIN OR SHOWERS CONTINUING OVER
THE WEST COAST AND WESTERN INTERIOR THU...BECOMING
MAINLY SHOWERS THU NIGHT.

THE EASTERN INTERIOR WILL REMAIN DRY THROUGH THU NIGHT
UNDER SOUTHERLY FLOW ALOFT. PRECIPITATION MAY ADVANCE INTO
THE EASTERN INTERIOR FRI AND FRI NIGHT AS THE SHORT WAVE
TROUGH DAM CURVES NORTHEASTWARD...SLOWLY DAMPENING OUT BUT
BRINGING DOWNSLOPE FLOW TO ITS CONCLUSION. GEFS AND ECMWF
ENSEMBLE MEANS INDICATE THE MOST PROBABLE POSITION FOR THE
MAIN UPPER VORTEX FOR 00Z SUN WILL BE OVER THE SEWARD
PENINSULA...WITH AN EXPANSIVE CYCLONIC CIRCULATION OVER
THE CWA. BOTH ENSEMBLE MEANS INDICATING THE VORTEX MOVING
NORTHWARD WHILE SLOWLY WEAKENING DURING THE EXTENDED PERIOD.

SOUTHERLY WINDS IN ADVANCE OF THE SURFACE LOW WILL
BRING TIDAL LEVELS UP ABOUT 2 FEET ABOVE NORMAL ALONG
THE NORTH SHORE OF NORTON SOUND...ACCOMPANIED BY
MODERATE SURF...SEAS TO 6-7 FT NEAR SHORE WEST OF
CAPE DARBY.

NORTHERLY GALES ON THE BACK SIDE OF THE LOW WILL
GENERATE HIGH SEAS OVER MUCH OF PKZ210. HIGH WAVES
BREAKING ONSHORE ALONG THE NORTH SHORT OF ST LAWRENCE
ISLAND WILL CAUSE BEACH EROSION TONIGHT AND THU.
A HIGH SURF ADVISORY WILL BE ISSUED FOR THE NORTH
SHORT OF ST LAWRENCE ISLAND.

WITH EVENTUAL NORTHWARD MOVEMENT OF THE SURFACE LOW...
A PERIOD OF WEST WINDS TO AROUND 30 KT COULD BRING
GENERATE SEAS TO 7-8 FT OFFSHORE OF THE EASTERN
NORTON SOUND COAST THU NIGHT...WAVES ARE LIKELY TO DAMPEN
OUT SOME AS THEY BREAK ONSHORE. TIDAL LEVELS COULD
RISE TO 2-3 FEET ABOVE NORMAL ALONG THE EASTERN SHORE
OF NORTON SOUND LATE THU NIGHT THROUGH FRI.

COASTAL HAZARD POTENTIAL DAYS 3 AND 4...SEE MAIN
DISCUSSION ABOVE.

&&

.FIRE WEATHER...
NIL.

&&

.HYDROLOGY...
HEAVIEST RAINFALL AMOUNTS REPORTED DURING THE LAST 2R HRS...

ATIGUN PASS       1.5 INCHES
GOBBLERS KNOB     1.1 INCHES
COLDFOOT          0.8 INCH

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
HIGH SURF ADVISORY FOR AKZ213.

SMALL CRAFT ADVISORY FOR PKZ200-PKZ215-PKZ220-PKZ235-PKZ240-
PKZ245.

GALE WARNING FOR PKZ200-PKZ210.
&&

RF AUG 11