Area Forecast Discussion
Issued by NWS Fairbanks, AK

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FXAK69 PAFG 262305
AFDAFG

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
305 PM AKDT TUE MAY 26 2015

.DISCUSSION...
ALOFT...STRONG RIDGE OF HIGH PRESSURE OVER WESTERN CANADA WILL
EXPAND OVER EASTERN INTERIOR THROUGH THU WHILE A 517 DM LOW OVER
THE WESTERN BERING SE DRIFTS NORTH AND WEAKENS INTO A TROUGH FROM
WRANGELL ISLAND TO CORDOVA 4PM THU. THE TROUGH WILL MOVE NORTHEAST
AND BY 4PM FRI WILL FORM A 567 DM LOW OVER THE CENTRAL
INTERIOR...LATER SECTION ON MODELS REGARDING THIS. LOW OVER THE
NORTHERN GULF OF ALASKA MOVING EAST THROUGH WED...A SHORT WAVE
TROUGH OVER THE NORTH GULF COAST WILL ROTATE NORTHWEST OVER THE
EASTERN ALASKA RANGE TONIGHT AND THEN DISSIPATE WED. BY 4PM THU A
517 DM LOW MOVES NORTH INTO THE SOUTHERN BERING SEA.

SURFACE...THERMAL TROUGH FROM KOTZEBUE TO FAIRBANKS TO NORTHWAY
PERSISTING FROM TANANA TO NORTHWAY ON WED THOUGH DISSIPATING
FARTHER WEST. ON THURSDAY THE TROUGH WILL SHIFT NORTH TO LIE FROM
FORT YUKON TO EAGLE. 986 MB LOW OVER THE CENTRAL BERING WITH A
FRONTAL SYSTEM FROM SAINT MATTHEW ISLAND TO NUNIVAK ISLAND TO
BRISTOL BAY. THE LOW WILL CURVE NORTHWEST AND DISSIPATE BY LATE
WED WHILE THE WEATHER FRONT MOVES TO THE BERING STRAIT TO NOME TO
BETHEL 4PM WED...THEN TO CAPE LISBURNE TO AMBLER TO TANANA AND
DIFFUSE 4PM THU. TROUGH FROM BARROW TO ANAKTUVUK PASS WILL MOVE
EAST TO PRUDHOE BAY BY 10 PM WED AND INTO CANADA BY 10 AM THU.
1034 MB HIGH OVER THE BEAUFORT SEA WILL DRIFT EAST WHILE A 1027
MB HIGH FORMS NORTHWEST OF BARROW TONIGHT AND DRIFTS EAST BUILDING
TO 1032 MB THU. 975 MB LOW MOVING NORTH INTO THE SOUTHERN BERING
SEA 4PM THU MOVING SLOWLY NORTH AND WEAKENING TO 989 MB 4PM FRI.

MODELS...AGREE FAIRLY WELL THROUGH THU. THEN THERE IS HIGH
VARIANCE AMONG THE ECMWF...GFS..NAM...AND CANADIAN ON WHERE THE
UPPER LOW IS LOCATED WHICH MOVES INTO THE INTERIOR ON
FRI...SPAWNED BY THE TROUGH MOVING OVER WESTERN ALASKA THU. AT
THIS POINT WILL FAVOR THE ECMWF ENSEMBLE SOLUTION WITH A WEAKER
CENTER THAN THE OPERATIONAL MODELS AND LOCATED CLOSER TO CANADA
AT 4PM FRI. IN MEDIUM TERM THE ECMWF AND GFS ARE SIMILAR IN
BRINGING A SHORT WAVE ENERGY SOUTH FROM THE HIGH CANADIAN
ARCTIC...OVER THE EASTERN PORTION OF ALASKA SUCH THAT THERE IS A
STRONG EAST-WEST TROUGH OVER THE INTERIOR SUN PM. THIS SCENARIO
IS OUTSIDE OF TYPICAL PATTERNS FOR THIS TIME OF YEAR AND IS VIEWED
WITH SUSPICION DESPITE THE RELATIVE AGREEMENT AMONG THE MODELS.
HISTORICALLY THE MODELS FORECAST THIS DEVELOPMENT DURING THE WARM
SEASON MORE OFTEN THAN IT OCCURS.

NORTH SLOPE...HIGH PRESSURE OFFSHORE WILL CONTINUE THE STRATUS AND
DIURNAL FOG ALONG THE COASTAL AREAS...PROBABLY THROUGH FRI.
SCATTERED SHOWERS MOVING INTO THE BROOKS RANGE WED NIGHT THROUGH
THU NIGHT AS THE UPPER TROUGH OUT WEST BECOMES AN UPPER LOW OVER
THE NORTHERN INTERIOR. EXPECT THE HEAVIEST RAIN TO OCCUR OVER THE
SOUTH SLOPES THOUGH.

WESTERN ALASKA...EXPECT ISOLATED THUNDERSTORMS TODAY FROM GALENA
NORTHWEST OVER LAND AREAS AS THERE WAS SOME ACTIVITY TO THE
SOUTHEAST MON EVE AND THAT AREA OF INSTABILITY HAS DRIFTED
NORTHWEST TODAY. RAIN MOVING ACROSS SOUTHERN COASTAL AREAS LATER
TONIGHT AND WED WITH INCOMING WEATHER FRONT...BREAKING INTO
SCATTERED SHOWERS INLAND COASTAL AREAS WED AFTERNOON AND DRIFTING
NORTHEAST AND INLAND WED NIGHT AND THU.

CENTRAL AND EASTERN INTERIOR...SHOWERS ACROSS THE SOUTHERN
INTERIOR THIS EVENING ASSOCIATED WITH THERMAL TROUGH AND LEFTOVER
MOISTURE FROM A PREVIOUS WEATHER FRONT. LATER TONIGHT THROUGH WED
AM SOUTHEAST OF DELTA THE SHORT WAVE MOVING ACROSS WILL PRODUCE
MORE GENERAL LIGHT RAIN. WED AFTERNOON EXPECT CONVECTION AGAIN
OVER SOUTHERN INTERIOR WITH ISOLATED THUNDERSTORMS. AS RIDGE
BUILDS OVER THE EASTERN INTERIOR THU EXPECT LITTLE IN THE WAY OF
SHOWERS OTHER THAN THE FAR WESTERN CENTRAL INTERIOR AND THE LOWER
KOYUKUK VALLEY WHERE THE WEATHER FROM FROM WESTERN AK WILL BE
MOVING INTO THE AREA. AS THIS FEATURE DISSIPATES BUT ITS SUPPORT
ALOFT CONTINUES AS AN UPPER LOW OVER THE INTERIOR FRI...WILL CARRY
A CHANCE OF SHOWERS FOR MOST ZONES THOUGH STILL A GOOD DEAL OF
UNCERTAINTY ON LOCATION AND STRENGTH OF LOW AT THIS TIME.

&&

.FIRE WEATHER...MINIMUM RH VALUES HAVE INCREASED SIGNIFICANTLY
OVER MUCH OF THE CENTRAL AND EASTERN INTERIOR WITH NUMEROUS
SHOWERS AND WETTING RAIN EXPECTED OVER THE SOUTHEAST INTERIOR
TONIGHT AND WEDNESDAY MORNING. SCATTERED TO NUMEROUS SHOWERS ARE
EXPECTED OVER THE EASTERN INTERIOR THIS EVENING. ISOLATED
THUNDERSTORMS THAT DEVELOP THIS AFTERNOON AND EVENING WILL
DIMINISH OVERNIGHT. SCATTERED SHOWERS WILL CONTINUE INTO WEDNESDAY
WITH ISOLATED THUNDERSTORMS DEVELOPING OVER THE FORTYMILE COUNTRY
SOUTH OF EAGLE.

&&

.HYDROLOGY...NONE.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
GALE WARNING FOR PKZ210.

BRISK WIND ADVISORY FOR PKZ225-PKZ230-PKZ245.
&&

FIRE WEATHER...CCC

$$

JL MAY 15


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