Small Craft Advisory 84, NWS Fairbanks, AK

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
248 AM AKDT MON SEP 3 2012

.DISCUSSION...
UPPER AIR...
AN ACTIVE PROGRESSIVE PATTERN WILL CONTINUE AS A PARADE OF
SHORT WAVE RIDGES AND TROUGHS CONTINUES TO MARCH ACROSS THE
NORTHERN ALASKA FORECAST AREA. THE NEXT SHORT WAVE IN THE
SERIES WILL SWEEP ACROSS NORTHERN ALASKA TODAY INTO TONIGHT.
ANOTHER SHORT WAVE WILL MOVE NORTHWARD ACROSS THE NORTHERN
ALASKA MAINLAND TUESDAY EVENING INTO WEDNESDAY. THE SHORT
WAVES AND THEIR ASSOCIATED SURFACE SYSTEMS WILL PRODUCE
WIDESPREAD RAIN OVER THE WESTERN INTERIOR AND WEST COAST...
AND STRONG SOUTHERLY CHINOOK WINDS IN AND NEAR ALASKA
RANGE PASSES.

SURFACE...
A 982 MB LOW OVER KUSKOKWIM BAY AT 10 PM SUNDAY WILL MOVE
TO NEAR THE BERING STRAIT BY 10 AM TUESDAY FILLING TO AROUND 990
MB...THEN BECOMING ABSORBED BY THE CIRCULATION AROUND THE NEXT
INCOMING LOW. A 992 MB LOW EAST OF KOMANDORSKI ISLAND IN THE
WESTERN ALEUTIANS AT 10 PM SUNDAY WILL DEEPEN RAPIDLY AS IT TRACKS
EASTWARD THROUGH TUESDAY. CURRENT MODELS IN GOOD AGREEMENT...PROGGED
POSITION FOR 4 PM TUESDAY WILL BE NEAR OR JUST EAST OF THE
PRIBILOF ISLANDS WITH CENTRAL PRESSURE ABOUT 975 MB. THE LOW WILL
REACH ITS LOWEST CENTRAL PRESSURE...AROUND 970 MB...LATE MONDAY
NIGHT. THE LOW WILL CURVE NORTHWARD UP THE WEST TUESDAY NIGHT AND
WEDNESDAY...FILLING TO AROUND 985 MB OVER THE SEWARD PENINSULA BY
4 PM WEDNESDAY.

SIGNIFICANT RAINFALL...
THE TWO SHORT WAVE TROUGHS AND THE ASSOCIATED SURFACE SYSTEMS
WILL PRODUCE WIDESPREAD RAIN OVER THE WESTERN INTERIOR...WEST
COAST...AND PARTS OF THE CENTRAL INTERIOR THROUGH WEDNESDAY. OVER
THE WEST COAST AND WESTERN INTERIOR...TOTAL RAINFALL AMOUNTS OF 1
TO 2 INCHES THROUGH WEDNESDAY ARE EXPECTED OVER MOST AREAS. SOME
LOCALLY HEAVIER AMOUNTS WILL BE POSSIBLE. RAIN WILL BE LIKELY OVER
THE WESTERN ARCTIC ZONES TONIGHT THROUGH WEDNESDAY...BUT AMOUNTS
WILL BE LESS...MOSTLY IN THE RANGE FROM 0.25 TO 0.75 INCH. THE
EASTERN INTERIOR WILL BE MAINLY DRY DUE TO STRONG SOUTHERLY FLOW
ACROSS THE ALASKA RANGE BEING PREDOMINANT. A FEW SPRINKLES OR
SHOWERS MAY BE POSSIBLE WITH THE PASSAGE OF THE FIRST SHORT
WAVE...BUT THESE WOULD BE OF RELATIVELY SHORT DURATION AS SOUTHERLY
WINDS AND DOWNSLOPE INCREASE AGAIN IN ADVANCE OF THE SECOND SHORT
WAVE.

WINDS IN AND NEAR ALASKA RANGE PASSES...
ADVISORY LEVEL WINDS ARE EXPECTED TO DEVELOP DURING THE NEXT
6 HOURS...CONTINUING THROUGH MOST OF MONDAY NIGHT. MAXIMUM
GUSTS WILL BE LIKELY IN THE 50-60 MPH RANGE. A PERIOD
OF LIGHTER WINDS IS EXPECTED FROM EARLY TUESDAY MORNING
THROUGH MOST OF TUESDAY AFTERNOON. STRONG WINDS WILL REDEVELOP
TUESDAY EVENING...WITH MAXIMUM GUSTS OF AT LEAST 60 MPH LIKELY
IN THE WIND PRONE AREAS.

MEDIUM RANGE FORECAST DISCUSSION...
A STRONG LOW NEAR THE SOUTHERN ALEUTIANS THIS MORNING WILL TRACK
ACROSS THE SOUTHERN BERING SEA EARLY THIS WEEK MOVING INTO THE SW
MAINLAND TUE NIGHT. THE LOW WILL BEGIN TO WEAKEN AND LIFT NE BY
THE START OF THE MEDIUM RANGE WED EVENING. A STRONG CHINOOK EVENT
FOR THE AK RANGE SHOULD BE WINDING DOWN BY WED EVENING AS THE FLOW
ALOFT TURNS MORE SOUTHWEST. THIS WILL ALLOW A MUCH COOLER AIR MASS
AND AREAS OF RAIN TO PUSH EAST ACROSS THE CENTRAL AND EASTERN
INTERIOR. THE PATTERN IS EXPECTED TO REMAIN COOL AND UNSETTLED
INTO NEXT WEEKEND WITH A REINFORCING SHOT OF COLD AIR TO MOVE EAST
ACROSS NORTHERN AK. BY NEXT WEEKEND 850 MB TEMPS ARE EXPECTED TO
BE BELOW 0C ACROSS NEARLY ALL OF NORTHERN AK AND AS COLD AS -10C
ALONG THE ARCTIC COAST WHERE SOME SNOW OR SNOW SHOWERS WILL BE
POSSIBLE. CB

COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE

&&

.HYDROLOGY...
WIDESPREAD RAIN AMOUNTS OF 1 TO 2 INCHES OVER THE WESTERN
INTERIOR AND WEST COAST THROUGH WEDNESDAY WILL LIKELY CAUSE
RISES ON MANY RIVERS AND STREAMS.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY FOR AKZ223-AKZ225-AKZ226-AKZ227.

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

GALE WARNING PKZ210-PKZ220-PKZ225-PKZ230.

&&

RF/CB SEP 12