High Surf in Alaska, August 31, 2014

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
1231 PM AKDT SUN AUG 31 2014

.DISCUSSION...
CURRENT UPPER AIR PROGS ARE IN GOOD AGREEMENT OUT THROUGH 4 PM
THU. A DEEP WINTER DEPTH UPPER LOW...ABOUT 506 DAM AT 500 MB...IS
LOCATED NEAR 74N/165W...ABOUT 200 NM NORTHWEST OF BARROW. THE
UPPER LOW WILL MOVE ON A CYCLONIC LOOPING TRAJECTORY TO BE ABOUT
50 NM NORTHEAST OF BARROW BY 4 AM WED...THEN MOVING RAPIDLY
EASTWARD TO ABOUT 100 NM NORTH OF DEMARCATION POINT BY 4 PM
WED...WHILE WEAKENING SLIGHTLY TO A STILL LOW 516 DAM CENTER.

A SERIES OF SHORT WAVE TROUGHS ROTATING AROUND THE UPPER LOW WILL
SWEEP ACROSS NORTHERN ALASKA DURING THE NEXT FEW DAYS. THE NEXT
INCOMING SHORT WAVE...WHICH WILL BE RATHER STRONG...WILL ARRIVE
IN NORTHWEST ALASKA LATE TONIGHT AND MOVE RAPIDLY EASTWARD TO THE
ALCAN BORDER BY TUE AFTERNOON WHILE SMOOTHING OUT IN
AMPLITUDE...MAKING IT DIFFICULT TO PICK OUT IN THE 500 MB HEIGHT
FIELD. WITH STRONG UPPER LEVEL DYNAMICS...A 998-1000 MB SURFACE
LOW IS EXPECTED TO DEVELOP NEAR THE BERING STRAIT OR OVER THE
SEWARD PENINSULA BY MON MORNING. THE FAST UPPER LEVEL FLOW WILL
CARRY THE SURFACE SYSTEM RAPIDLY EASTWARD. BY TUE AFTERNOON THE
LOW IS EXPECTED TO DEEPEN TO ABOUT A 995 MB CENTER ABOUT 50 NM
NORTHWEST OF HUSLIA...AND TO THE BROOKS RANGE NEAR THE ALCAN
BORDER BY 4 AM TUE. THE ASSOCIATED WEATHER FRONT WILL SWEEP
EASTWARD AND STALL OUT ALONG THE ALASKA RANGE TUE AND TUE NIGHT.
STORM TOTAL PRECIPITATION IS EXPECTED TO BE 0.25 TO 1 INCH OVER
THE WEST COAST...WESTERN AND NORTHERN INTERIOR WITH LOCAL AMOUNTS
OVER AN INCH. OVER THE ARCTIC COAST AND BROOKS RANGE...RAINFALL
TOTALS OF 0.25 TO 0.5 INCH ARE EXPECTED. THE HEAVIEST EVENT
TOTAL PRECIPITATION AMOUNTS ARE EXPECTED IN THE FOLLOWING ZONES...
CENTRAL INTERIOR...0.75 TO 1+ INCHES ZONE 222...1 TO 2 INCHES.
DENALI...1 TO 2 INCHES...LOCAL AMOUNTS TO 3 INCHES POSSIBLE.
UPPER KUSKOKWIM VALLEY...1 TO 2+ INCHES.
MIDDLE TANANA VALLEY...1 TO 2 INCHES.
LESSER AMOUNTS ARE EXPECTED OVER THE REST OF THE SOUTHERN AND
EASTERN INTERIOR. IN THE ALASKA RANGE...THE SNOW LEVEL IS EXPECTED
TO BE 4000-5000 FT MON AFTERNOON AND MON NIGHT...LOWERING TO
3500-4000 FT BY TUE AFTERNOON...AND TO AROUND 2500 FT BY WED
AFTERNOON. THIS SHOULD REDUCE THE RAINFALL RUNOFF INTO SMALL
STREAMS SO SMALL STREAM FLOODING DOES NOT APPEAR TO BE A STRONG
THREAT AT THIS TIME. HOWEVER...THERE WILL BE POTENTIAL FOR
SIGNIFICANT SNOW ACCUMULATION ABOVE THE PASS LEVEL IN THE WESTERN
ALASKA RANGE. IN THE BROOKS RANGE...SNOW LEVELS ARE NOT EXPECTED
TO BE ANY HIGHER THAN 3000 FT MON AFTERNOON THROUGH WED. OVER THE
ARCTIC SLOPE...SNOW LEVELS WILL BE MOSTLY FROM THE SURFACE TO 1000
FT MON NIGHT THROUGH WED.

STRONG 850 MB WINDS ARE EXPECTED WITH THIS SHORT WAVE...AS HIGH
AS 45 TO 70 KT OVER THE SOUTHERN INTERIOR AREAS MON AND MON NIGHT.
EXPECT STRONG AND GUSTY SOUTHWEST WINDS OVER INTERIOR HIGHWAY
SUMMITS AND PASSES MON AND MON NIGHT.

ANOTHER SHORT WAVE IN THE FAST UPPER LEVEL FLOW PATTERN WILL
ARRIVE IN NORTHWEST ALASKA TUE...MOVING TO THE ALCAN BORDER BY
WED AFTERNOON. PRECIPITATION AMOUNTS WITH THIS SHORT WAVE ARE
EXPECTED TO BE MUCH LESS...AND BE LIMITED MAINLY TO THE NORTH
SLOPE AND BROOKS RANGE. A THIRD SHORT WAVE WILL ARRIVE OVER
NORTHWEST ALASKA THU MORNING...MOVING EASTWARD ACROSS THE NORTHERN
PARTS OF NORTHERN ALASKA THROUGH THU NIGHT. PRECIPITATION WITH
THIS WAVE IS AGAIN EXPECTED TO BE RELATIVELY LIGHT AND BE
RESTRICTED MAINLY TO THE ARCTIC SLOPE.

COASTAL HAZARD POTENTIAL...
SEA ELEVATIONS OF 1.5 TO A LITTLE OVER 3 FEET EXPECTED IN NORTON
SOUND LATE SUN NIGHT THROUGH LATE MON NIGHT. THE HIGHEST SEA
LEVEL RISES...A LITTLE OVER 3 FEET...WILL BE OVER EASTERN NORTON
SOUND MON AFTERNOON AND MON EVENING. SEAS COULD BE AS HIGH AS
8 FEET OFFSHORE OVER EASTERN NORTON SOUND...BUT LOWER NEAR SHORE.
WEST TO NORTHWEST WINDS TO 25 KT TUE THROUGH TUE EVENING COULD
PRODUCE ELEVATED SURF ON THE ARCTIC COAST FROM BARROW WESTWARD.
SEAS COULD BE AS HIGH AS 6-8 FEET NOT TOO FAR OFFSHORE. MAXIMUM
SEA LEVEL ELEVATIONS ARE EXPECTED TO BE ABOUT 1.5 FEET AT ICY CAPE
AND ABOUT 1 FOOT AT BARROW.

&&

.HYDROLOGY...
SEE MAIN DISCUSSION FOR EXPECTED PRECIPITATION AMOUNTS. NO SMALL
STREAM FLOOD ISSUES ARE EXPECTED IN THE ALASKA RANGE AT THIS TIME
DUE TO THE LOWERING FREEZING AND SNOW LEVELS. IN THE MIDDLE
TANANA VALLEY...FORECAST RAINFALL COULD RESULT IN THE UPPER
CHENA RIVER RISING TO ACTION STAGE BY EARLY WED MORNING.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY...PKZ200-PKZ210-PKZ230-PKZ235-PKZ240-PKZ245.
WIND ADVISORY...OVER SUMMITS IN AKZ220-AKZ221-AKZ222.

&&

RF AUG 14