Small Craft Advisory 53, NWS Fairbanks, AK

NORTHERN ALASKA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE FAIRBANKS AK
1058 AM AKDT FRI JUL 18 2014

UPDATED COASTAL HAZARD SECTION

.DISCUSSION...

UPPER AIR...
UPPER LOW CENTER 225 MILES NORTH NORTHWEST OF BARROW IS PROGGED
BY CURRENT MODELS TO TAKE A WOBBLY PATH TO 300 MILES NORTH OF
BARROW BY SUN AFTERNOON AND TO 600 MILES NORTH OF BARROW BY MON
AFTERNOON.

THE FIRST OF SEVERAL SHORT WAVE TROUGHS EXTENDS FROM THE
UPPER LOW TO BARROW AND SOUTHWESTWARD TO DALL POINT. THIS TROUGH
WILL GRADUALLY SMOOTH OUT AS IT MOVES TO NEAR THE ALCAN BORDER BY
SAT AFTERNOON.

A LOW AMPLITUDE SHORT WAVE IS NOW OVER THE WESTERN
ARCTIC OCEAN ABOUT 300 MILES WEST NORTHWEST OF WRANGEL ISLAND.
THIS WAVE WILL BE INCREASING IN AMPLITUDE AND MOVE RAPIDLY
SOUTHEASTWARD TO THE ALASKA WEST COAST BY SUN MORNING. BY MON
MORNING THE SHORT WAVE WILL DROP SOUTHEASTWARD AND DEEPEN THE LONG
WAVE TROUGH WHICH WILL EXTEND FROM THE ARCTIC UPPER LOW TO THE
EASTERN NORTH GULF COAST. THE LONG WAVE TROUGH WILL WEAKEN BY LATE
SUN NIGHT AS THE TROUGH AXIS MOVES EAST TO THE ALCAN BORDER.

UPPER LEVEL RIDGING WILL REBUILD OVER THE SOUTHERN PARTS OF
NORTHERN ALASKA MON AFTER THE LONG WAVE TROUGH EXITS TO THE EAST.
THIS RIDGE WILL LIKELY MOVE EASTWARD INTO THE YUKON TERRITORY BY
TUE.

A MORE VIGOROUS SHORT WAVE IS EXPECTED TO MOVE TO THE CHUKCHI SEA
AND THE CHUKOTSK PENINSULA BY MON. MODEL POSITIONS FOR 00Z TUE
VARY...WITH THE GFS/NAM RUNS MOVING THE WAVE EASTWARD FASTER THAN
THE ECMWF AND CANADA MODELS. BY 12Z TUE THE DIFFERENCES BETWEEN
THE GFS AND ECMWF/CANADA RUNS BECOME LARGER. AT THIS TIME PREFER
THE SLOWER CANADA/ECMWF RUNS WHICH ARE FAIRLY CLOSE TOGETHER...MEAN
POSITION OF THESE TWO RUNS WOULD PUT THE NEW CLOSED LOW CENTER
OVER THE CHUKOTSK PENINSULA. YESTERDAYS 00Z RUN OF THE GFS
ENSEMBLE MEAN MOVES THE SHORT WAVE SLOWER THAN THE CURRENT
OPERATIONAL RUN AND IS MORE IN LINE WITH THE ECMWF AND CANADA
MODEL RUNS. THE OPERATIONAL ECMWF AGREES WELL WITH THE ENSEMBLE
MEAN PROG.

SURFACE...
993 MB LOW ABOUT 225 MILES NORTH NORTHWEST OF BARROW IS VERTICALLY
STACKED WITH THE UPPER LOW WILL MOVE TO 300 MILES NORTH OF BARROW
BY SAT AFTERNOON...THEN WEAKEN TO A 1000 MB LOW CENTER 600 MILES
NORTH OF BARROW BY SUN AFTERNOON.

A NEW 1006 MB LOW IS PROGGED TO DEVELOP IN RUSSIA ABOUT 450 MILES
SOUTH OF THE NEW SIBERIAN ISLANDS THIS AFTERNOON...MOVING TO THE
CHUKCHI SEA OR CHUKOTSK PENINSULA LATE SUN NIGHT...CENTRAL PRESSURE
995-1000 MB BY THAT TIME.

A SLOWLY MOVING FRONT EXTENDS FROM THE DEADHORSE AREA SOUTHWESTWARD
TO THE LOWER YUKON VALLEY. A BAND OF RAIN ASSOCIATED WITH THE
FRONT WILL BE MOVING SLOWLY EASTWARD THROUGH TONIGHT...RAIN COULD
SPREAD EASTWARD TO THE MIDDLE TANANA VALLEY BY TONIGHT. RAIN OR
SHOWERS OVER THE SOUTHEAST INTERIOR SAT AS THE FRONT CONTINUES
EASTWARD AND WEAKENS. SOME LOCALLY HEAVY RAIN POSSIBLE IN THE
WESTERN PARTS OF DENALI PARK TONIGHT THROUGH SUN NIGHT.

RAIN DEVELOPING OVER NORTHWEST ALASKA SUN WITH THE NEXT INCOMING
SURFACE SYSTEM. RAIN SPREADING ACROSS THE ARCTIC COAST/BROOKS
RANGE/NORTHERN INTERIOR SUN NIGHT AND MON.

ALONG AND NEAR THE COAST FROM BARROW TO WAINWRIGHT...WEST WINDS
15-20 KT TODAY AND 10-15 KT TONIGHT THROUGH SAT NIGHT COULD BRING
THE ICE EDGE CLOSER TO SHORE.

COASTAL HAZARD POTENTIAL...
SOUTHWEST WINDS 25-35 KT EXPECTED OVER NORTON SOUND SAT WILL
PRODUCE SLIGHTLY ELEVATED SEA LEVELS IN NORTON SOUND...1 TO 3 FEET
ABOVE NORMAL WITH THE HIGHEST ELEVATION OF SEA LEVEL OVER EASTERN
NORTON SOUND AND IN NORTON BAY.

SOUTHWEST WINDS 20-25 KT OVER NORTON SOUND LATE SUN
AFTERNOON THROUGH MON EVENING WILL ELEVATE SEA LEVELS
1.5 TO 2.5 FEET ABOVE NORMAL.

EXPECTED WINDS AND SEA LEVEL INCREASES WILL NOT BE HIGH
ENOUGH TO CREATE HIGH SURF OR COASTAL FLOODING ISSUES.

&&

.FIRE WEATHER...
ISOLATED AFTERNOON/EVENING THUNDERSTORMS IN PARTS OF THE
SOUTHEASTERN INTERIOR TODAY AND SAT...MIN RH ABOVE 30
PERCENT. TEMPERATURES REBOUNDING TO SEASONAL NORMALS
NEXT WEEK BUT THE AIR MASS IS LIKELY TO REMAIN RELATIVELY
MOIST WITH MIN RH STAYING ABOVE 30 PERCENT.

&&

.HYDROLOGY...
SOME LIGHT RAIN FELL OVERNIGHT OVER THE NORTHERN NULATO HILLS AND
EASTERN SEWARD PENINSULA...BUT SHOULD NO HYDROLOGICAL IMPACT.
SMALL STREAM FLOOD ADVISORY FOR THESE AREAS IS SCHEDULED TO EXPIRE
AT 215 PM THIS AFTERNOON.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY FOR PKZ200-PKZ210-PKZ220-PKZ225-PKZ230.
&&

JUL 14