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000
FXAK69 PAFG 212155
AFDAFG

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
155 PM AKDT TUE MAY 21 2013

.DISCUSSION...
AN UPPER LEVEL RIDGE OVER THE EASTERN INTERIOR IS PROGGED TO
BREAK DOWN INTO A LIGHT SOUTH TO SOUTHWEST FLOW BY WEDNESDAY.
UPPER RIDGING IS EXPECTED TO BEGIN REBUILDING OVER THE
INTERIOR FRIDAY AND OVER THE REMAINDER OF NORTHERN ALASKA
FROM THE BROOKS RANGE SOUTHWARD BY SATURDAY. THIS TREND
IS INDICATED BY THE OPERATIONAL GFS/ECMWF AND THEIR
ENSEMBLE MEANS.

A LOW PRESSURE CENTER ALOFT NEAR THE PRIBILOFS WILL MOVE
TO ST LAWRENCE ISLAND BY WEDNESDAY AFTERNOON AND TO THE
GULF OF ANADYR BY THURSDAY AFTERNOON AS IT MERGES WITH
ANOTHER UPPER LOW MOVING EASTWARD FROM THE NORTHERN
KAMCHATKA PENINSULA. GFS/ECMWF SIMILAR ON THE FORECAST
POSITION FOR FRIDAY AFTERNOON...MOVING THE LOW CENTER
TO NEAR WRANGEL ISLAND.

AT THE SURFACE...A 998 MB LOW JUST WEST OF THE PRIBILOFS WILL
MOVE TO ABOUT 100 MILES WEST OF WRANGEL ISLAND BY WEDNESDAY
AFTERNOON...FILLING TO AROUND 1002 MB. A TROUGH WILL EXTEND
FROM THE LOW WEST SOUTHWESTWARD TO A WEAK LOW EAST OF THE
KAMCHATKA PENINSULA. THE TWO LOW CENTERS ARE EXPECTED
TO COMBINE INTO A SINGLE 1008 MB CENTER OVER THE GULF OF
ANADYR BY THURSDAY AFTERNOON. RAIN OR MIXED RAIN AND SNOW
WILL CONTINUE OVER MOST OF THE WEST COAST TONIGHT...BECOMING
MAINLY RAIN THURSDAY. PRECIPITATION WILL BE LESS WIDESPREAD
THURSDAY NIGHT. OVER THE WESTERN BROOKS RANGE AND ARCTIC
SLOPE...THE PRECIPITATION WILL MOST LIKELY BE MIXED RAIN
AND SNOW.


&&

.FIRE WEATHER...
DRY CONDITIONS CONTINUING OVER THE EASTERN INTERIOR
INTO EARLY NEXT WEEK. HIGH TEMPERATURES OVER MANY PARTS
OF THE EASTERN INTERIOR FRIDAY THROUGH TUESDAY LIKELY TO
EXCEED 70 DEGREES. LOW AFTERNOON HUMIDITIES...BELOW 30
PERCENT IN MANY PARTS OF THE EASTERN INTERIOR...LIKELY TO
CONTINUE THROUGH NEXT TUESDAY. SOME SITES WILL HAVE
MIN RH BELOW 20 PERCENT. EASTERN INTERIOR WINDS ARE
EXPECTED TO REMAIN LIGHT...SO NO RED FLAG CONDITIONS
ARE EXPECTED.

&&

.HYDROLOGY...
FLOOD WARNING CONTINUES FOR THE YUKON RIVER AT FORT YUKON
AND A FLOOD WATCH REMAINS IN EFFECT DOWNSTREAM TO TANANA
AS BREAKUP ON THE YUKON RIVER PROGRESSES. A NASA/GSFC RAPID
RESPONSE MODIS IMAGE TAKEN MAY 20 SHOWS AN EXTENSIVE FLOODED
AREA ON THE YUKON RIVER EXTENDING FROM UPSTREAM OF THE ICE JAM
ALMOST TO CIRCLE. AT ITS WIDEST POINT...ABOUT 12 TO 20 MILES
UPSTREAM FROM FORT YUKON...THE FLOODED AREA APPEARS TO BE AS
MUCH AS 7 OR 8 MILES WIDE.


&&

.AFG WATCHES/WARNINGS/ADVISORIES...
FLOOD WARNING FOR AKZ220.
FLOOD WATCH FOR AKZ221.
BRISK WIND ADVISORY FOR PKZ200-PKZ210-PKZ215-PKZ220.

&&

$$

RF MAY 13