Small Craft Advisory 81, NWS Fairbanks, AK

NORTHERN ALASKA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE FAIRBANKS AK
259 AM AKDT SUN SEP 2 2012

CORRECTED LINE 3 IN SIGNIFICANT RAIN PARAGRAPH

.DISCUSSION...

UPPER AIR...
A VERY ACTIVE AND PROGRESSIVE PATTERN WILL CONTINUE WITH
A SERIES OF SHORT WAVE TROUGHS AND RIDGES ALOFT TRAVERSING
THE NORTHERN ALASKA FORECAST AREA. A WEAKENING SHORT WAVE
WILL BE EXITING NORTHEAST ACROSS THE EASTERN INTERIOR THIS
MORNING. THE NEXT SHORT WAVE...WHICH WILL BE STRONGER...WILL
ARRIVE OVER THE SOUTHWEST ALASKA MAINLAND LATE SUNDAY
NIGHT...EXITING NORTH TO THE ARCTIC COAST BY TUESDAY AFTERNOON.
THIS WILL BE FOLLOWED BY A VERY STRONG SHORT WAVE ARRIVING OVER
THE SOUTHWEST ALASKA MAINLAND TUESDAY EVENING AND SWEEPING
NORTHEASTWARD ACROSS THE MAINLAND THROUGH WEDNESDAY AFTERNOON.

SURFACE...
986 MB LOW ABOUT 100 MILES SOUTHWEST OF THE PRIBILOFS AT 10 PM
SATURDAY WILL MOVE TO KUSKOKWIM BAY BY 4 AM MONDAY WITH CENTRAL
PRESSURE AROUND 982 MB. LOWEST CENTRAL PRESSURE WILL BE NEAR 980
MB THIS AFTERNOON. BY 4 AM TUESDAY THE LOW WILL OVER THE WESTERN
SEWARD PENINSULA FILLING TO AROUND 990 MB. A MUCH STRONGER LOW
WILL BE MOVING ACROSS THE SOUTHERN BERING SEA MONDAY NIGHT
AND TUESDAY...LOWEST CENTRAL PRESSURE WILL BE AROUND 972 MB
MON EVENING WITH THE CENTER AROUND 100 MILES WEST NORTHWEST OF
ADAK. BY TUESDAY EVENING...THE LOW WILL BE ABOUT 100 MILES
SOUTH OF NUNIVAK ISLAND WITH CENTRAL PRESSURE AROUND 976 MB.

SIGNIFICANT RAINFALL...
WIDESPREAD RAIN DEVELOPING ON THE WEST COAST SOUTH OF
THE SEWARD PENINSULA AND THE SOUTHERN PARTS OF THE WESTERN
INTERIOR SUNDAY AFTERNOON WITH THE APPROACH OF THE NEXT SYSTEM.
WIDESPREAD RAIN SPREADING NORTHWARD OVER MOST OF THE WEST COAST
AND WESTERN INTERIOR SUNDAY NIGHT AND CONTINUING INTO MONDAY. OVER
THE WEST COAST AND WESTERN INTERIOR THROUGH MONDAY... WIDESPREAD
RAINFALL AMOUNTS OF 0.5 TO 1 INCH EXPECTED...WITH SOME LOCAL
AMOUNTS OF UP TO 1.5 INCHES. ANOTHER EPISODE OF WIDESPREAD RAIN
SPREADING NORTHWARD ACROSS THE WEST COAST AND WESTERN INTERIOR
FROM MID DAY TUESDAY INTO TUESDAY NIGHT.

CHINOOK WINDS IN AND NEAR ALASKA RANGE PASSES...
SOUTH WINDS IN AND NEAR ALASKA RANGE PASSES WILL INCREASE
DURING THE DAY TODAY...GUSTS TO AROUND 50 MPH LIKELY IN THE
NORMALLY WINDY SPOTS TONIGHT AND MONDAY. WINDS MAY DIMINISH
SOME MONDAY NIGHT INTO TUESDAY MORNING BUT INCREASE AGAIN
TUESDAY AFTERNOON AS VERY STRONG SOUTHERLY FLOW ALOFT DEVELOPS.
STRONG WINDS LIKELY CONTINUING INTO WEDNESDAY. 700 MB WINDS
ACROSS THE ALASKA RANGE ARE PROGGED TO MAX OUT AT 60-80 KT.
MAXIMUM SURFACE GUSTS WILL ALMOST CERTAINLY REACH THE ADVISORY
LEVEL...GUSTS TO 70+ MPH WILL BE POSSIBLE IN THE MOST WIND
PRONE SPOTS.

MEDIUM RANGE FORECAST DISUSSION...
AN ACTIVE AND PROGRESSIVE PATTERN IS EXPECTED DURING THE MEDIUM
RANGE.  AT THE START OF THE MEDIUM RANGE TUE NIGHT A DEEP VERTICALLY
SFC LOW WILL BE FOUND IN THE SE BERING SEA.  THE LOW MOVES INTO THE
SW MAINLAND OF AK WED AND THEN WEAKENS AND QUICKLY EJECTS TO THE
NORTHEAST AND ENDS UP IN THE ARCTIC OCEAN BY THU MORNING.  A
MODERATE TO STRONG CHINOOK EXPECTED AHEAD OF THE LOW THAT WILL
BRING AT LEAST ADVISORY LEVEL AND POSSIBLY WARNING LEVEL WINDS TO
THE FAVORED WINDY SPOTS IN/NEAR THE AK RANGE.  THE FLOW TURNS
SOUTHWEST AS THE LOW PULLS AWAY ALLOWING AREAS OF RAIN AND A MUCH
COOLER AIR MASS TO SWEEP EAST ACROSS THE CENTRAL AND EASTERN
INTERIOR.  MODEL SPREAD THEN INCREASES LATE IN THE WEEK INTO NEXT
WEEKEND.  IT APPEARS LIKELY THAT NORTHERN AK WILL BE UNDER AN UPPER
TROUGH WITH COOL AND UNSETTLED WEATHER.  THE DETAILS OF SHORTWAVES
MOVING EAST ACROSS THE BERING AS WELL AS ENERGY THAT MAY DROP DOWN
INTO NORTHERN AK FROM THE HIGH ARCTIC REMAIN HIGHLY UNCERTAIN. CB

COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NORTH TO NORTHEAST
GALES THROUGH THE BERING STRAIT AND OVER THE NORTHWEST
CAPES MONDAY...DIMINISHING MONDAY NIGHT. NO COASTAL FLOODING
EXPECTED BUT THERE WILL BE ROUGH SEAS THROUGH THE BERING
AND OFFSHORE FROM THE NORTHWEST CAPES.

&&

.HYDROLOGY...
A FLOOD WATCH REMAINS IN EFFECT FOR THE KOYUKUK RIVER AT
ALLAKAKET AND HUGHES. THE KOYUKUK RIVER BELOW THE JOHN RIVER
CRESTED SATURDAY AFTERNOON AND IS NOW FALLING. THE KOYUKUK
RIVER AT BETTLES APPEARS TO HAVE CRESTED SATURDAY AND
SATURDAY EVENING AND WILL LIKELY STARTING TO FALL SLOWLY
TODAY.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH FOR THE KOYUKUK RIVER AT ALLAKAKET AND HUGHES.

SMALL CRAFT ADVISORY FOR PKZ220-PKZ225-PKZ230-PKZ240-PKZ245.
&&

RF/CB SEP 12