Home > Products > Valid Products > AFD

000
FXAK69 PAFG 222342
AFDAFG

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
242 PM AKST MON DEC 22 2014

.DISCUSSION...

EVEN THOUGH QUIET WEATHER IS EXPECTED ACROSS MOST OF NORTHERN
ALASKA THROUGH WEDNESDAY MORNING...THERE ARE A FEW FORECAST
CONCERNS INCLUDING STRATUS OVER THE WESTERN TWO-THIRDS OF ALASKA
AND THE YUKON AND CHANCES FOR SNOW SHOWERS OVER PARTS OF THE
INTERIOR THROUGH WEDNESDAY AFTERNOON.

IN REGARDS TO THE 12Z DETERMINISTIC MODEL GUIDANCE...THERE IS
FAIRLY GOOD AGREEMENT AMONGST THE MODELS THROUGH 12Z WEDNESDAY.
AFTER 12Z WEDNESDAY...SIGNIFICANT DIFFERENCES BETWEEN THE ECWMF
AND THE GFS/GEFS/NAM ON THE KEY SYNOPTIC FEATURES DEVELOP AND
BECOME WORSE DURING THE EXTENDED.

ALOFT...

COLD UPPER LEVEL TROUGH EXTENDS FROM A WEAK LOW OVER THE NEW
SIBERIAN ISLANDS SOUTHEAST OVER THE CHUKOTSK AND SEWARD PENINSULAS
AND BEAUFORT SEA. THIS TROUGH WILL DEEPEN AS IT MOVES EAST OVER
THE NORTHERN HALF OF ALASKA THROUGH LATE THIS WEEK. COINCIDENT
WITH THIS TROUGH...A COLDER AIRMASS WILL BE MOVING EASTWARD. THE
COLDEST AIR AT H850...AROUND -20C...WILL BE CONTAINED TO NORTH OF
THE BROOKS RANGE AND AT THE SURFACE...A 10F TO 15F DROP IN
TEMPERATURES FROM WHAT WAS SEEN LAST NIGHT. LOCATIONS SOUTH OF
THE BROOKS RANGE WILL SEE TEMPERATURES COOLING TO NEAR NORMAL
TUESDAY AND WEDNESDAY.

AFTER 12Z WEDNESDAY...DETAILS BECOME A BIT FUZZY SINCE MODEL
SOLUTIONS GREATLY DIFFER. EVEN THOUGH THIS IS THE CASE...THERE IS
A GENERAL CONSENSUS THAT AN UPPER LEVEL RIDGE WILL BUILD NORTH
FROM THE BERING SEA AND OVER MAINLAND ALASKA FOLLOWING THE PASSAGE
OF THE AFOREMENTIONED TROUGH. CONCERNING THE AFOREMENTIONED TROUGH
AFTER 12Z WEDNESDAY...THE GFS IS MORE PROGRESSIVE WITH MOVING IT
EAST...WHILE THE ECWMF HOLDS IT BACK...KEEPING A BROAD UPPER LEVEL
TROUGH OVER WESTERN ALASKA BEFORE LIFTING IN NORTHEAST LATE THIS
WEEK.

AN UPPER LOW WILL DEVELOP EAST OF KAMCHATKA PENINSULA BY 06Z
WEDNESDAY AND GRADUALLY DRIFT EAST INTO THE BERING. SIMILAR TO
OTHER UPPER LEVEL FEATURES MENTIONED...THE GFS AND ECWMF HANDLE
THE PROGRESSION OF THIS LOW DIFFERENTLY BEYOND 12Z WEDNESDAY.
HOWEVER...BOTH MODELS DO SHOW MULTIPLE SHORTWAVES ROUNDING THE
BASE OF THIS LOW AND MOVING NORTHEAST TOWARDS THE WEST COAST.
THOUGH TIMING OF THESE SHORTWAVES IS UNCERTAIN GIVEN MODEL
DISAGREEMENT.

SURFACE...

1008MB SURFACE LOW LOCATED 140 MILES NORTHWEST OF BARROW AT 18Z IS
PROGGED TO MOVE NORTHWEST TOWARDS THE NEW SIBERIAN ISLANDS THROUGH
MIDWEEK. THE WEAK 1009MB LOW OVER PRINCE WILLIAM SOUND WILL MERGE
INTO A NORTHWARD MOVING 990MB LOW FROM THE NORTHERN PACIFIC. THE
RESULTING LOW WILL MOVE EAST AND OVER THE SOUTHEAST AK PANHANDLE.

OVER THE BERING...A STRONG LOW WILL MOVE TO NEAR SHEMYA BY 12Z
TUESDAY. AN OCCLUSION STRETCHING FROM THIS LOW WILL ROTATE EAST
OVER THE ALEUTIAN ISLANDS WEDNESDAY AND THEN NORTHEAST ALONG THE
ALASKA PENINSULA AND SOUTHWEST COAST BY 00Z THURSDAY. POSSIBLE
HAZARDS POSSIBLY ASSOCIATED WITH THIS LOW WILL BE GALE TO STORM
FORCE WINDS DEVELOPING WEDNESDAY NIGHT OVER ST LAWRENCE AND BERING
STRAIT AND A MESSY WINTRY MIX OF SNOW/FREEZING RAIN/RAIN OVER THE
SOUTHWEST...WHERE WARM AIR ADVECTION ALOFT AHEAD OF THE FRONT WILL
CREATE SOME ISSUES WITH PRECIPITATION TYPE STARTING AFTER 00Z
THURSDAY FOR ST LAWRENCE ISLAND AND THE YUKON DELTA.

MORNING AND EARLY IMAGES FROM THE SPORT MICROPHYSICS RGB
PRODUCT...SHOWS A BLANKET OF STRATUS OVER THE WESTERN TWO-THIRDS
OF ALASKA THAT IS GRADUALLY INCREASING IN AREAL EXTENT OVER
EASTERN ALASKA THIS AFTERNOON. THE PRESENCE OF STRATUS WILL
GREATLY IMPACT OVERNIGHT TEMPERATURES...KEEPING TEMPERATURES
WARMER THAN OTHERWISE WOULD BE WITHOUT STRATUS AND COLDER H850
TEMPERATURES.

IN REGARDS TO PRECIPITATION...AS THE AFOREMENTIONED UPPER LEVEL
TROUGH SHIFTS EAST OVER NORTHERN ALASKA...PERIODS OF SNOW DEVELOP
OVER THE CENTRAL/EASTERN INTERIOR AND EASTERN ARCTIC COAST TUESDAY
MORNING AND THEN GRADUALLY SHIFT EAST THROUGH THURSDAY. SNOW
ACCUMULATIONS WILL RANGE FROM A DUSTING UP TO 2 INCHES...WITH
POSSIBLE IMPACTS TO THE PUBLIC BEING HAZARDOUS ROAD CONDITIONS
ALONG THE HIGHWAYS.

COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
HEAVY FREEZING SPRAY WARNING FOR PKZ210.

&&

$$

LTH DEC 14




000
FXAK69 PAFG 222342
AFDAFG

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
242 PM AKST MON DEC 22 2014

.DISCUSSION...

EVEN THOUGH QUIET WEATHER IS EXPECTED ACROSS MOST OF NORTHERN
ALASKA THROUGH WEDNESDAY MORNING...THERE ARE A FEW FORECAST
CONCERNS INCLUDING STRATUS OVER THE WESTERN TWO-THIRDS OF ALASKA
AND THE YUKON AND CHANCES FOR SNOW SHOWERS OVER PARTS OF THE
INTERIOR THROUGH WEDNESDAY AFTERNOON.

IN REGARDS TO THE 12Z DETERMINISTIC MODEL GUIDANCE...THERE IS
FAIRLY GOOD AGREEMENT AMONGST THE MODELS THROUGH 12Z WEDNESDAY.
AFTER 12Z WEDNESDAY...SIGNIFICANT DIFFERENCES BETWEEN THE ECWMF
AND THE GFS/GEFS/NAM ON THE KEY SYNOPTIC FEATURES DEVELOP AND
BECOME WORSE DURING THE EXTENDED.

ALOFT...

COLD UPPER LEVEL TROUGH EXTENDS FROM A WEAK LOW OVER THE NEW
SIBERIAN ISLANDS SOUTHEAST OVER THE CHUKOTSK AND SEWARD PENINSULAS
AND BEAUFORT SEA. THIS TROUGH WILL DEEPEN AS IT MOVES EAST OVER
THE NORTHERN HALF OF ALASKA THROUGH LATE THIS WEEK. COINCIDENT
WITH THIS TROUGH...A COLDER AIRMASS WILL BE MOVING EASTWARD. THE
COLDEST AIR AT H850...AROUND -20C...WILL BE CONTAINED TO NORTH OF
THE BROOKS RANGE AND AT THE SURFACE...A 10F TO 15F DROP IN
TEMPERATURES FROM WHAT WAS SEEN LAST NIGHT. LOCATIONS SOUTH OF
THE BROOKS RANGE WILL SEE TEMPERATURES COOLING TO NEAR NORMAL
TUESDAY AND WEDNESDAY.

AFTER 12Z WEDNESDAY...DETAILS BECOME A BIT FUZZY SINCE MODEL
SOLUTIONS GREATLY DIFFER. EVEN THOUGH THIS IS THE CASE...THERE IS
A GENERAL CONSENSUS THAT AN UPPER LEVEL RIDGE WILL BUILD NORTH
FROM THE BERING SEA AND OVER MAINLAND ALASKA FOLLOWING THE PASSAGE
OF THE AFOREMENTIONED TROUGH. CONCERNING THE AFOREMENTIONED TROUGH
AFTER 12Z WEDNESDAY...THE GFS IS MORE PROGRESSIVE WITH MOVING IT
EAST...WHILE THE ECWMF HOLDS IT BACK...KEEPING A BROAD UPPER LEVEL
TROUGH OVER WESTERN ALASKA BEFORE LIFTING IN NORTHEAST LATE THIS
WEEK.

AN UPPER LOW WILL DEVELOP EAST OF KAMCHATKA PENINSULA BY 06Z
WEDNESDAY AND GRADUALLY DRIFT EAST INTO THE BERING. SIMILAR TO
OTHER UPPER LEVEL FEATURES MENTIONED...THE GFS AND ECWMF HANDLE
THE PROGRESSION OF THIS LOW DIFFERENTLY BEYOND 12Z WEDNESDAY.
HOWEVER...BOTH MODELS DO SHOW MULTIPLE SHORTWAVES ROUNDING THE
BASE OF THIS LOW AND MOVING NORTHEAST TOWARDS THE WEST COAST.
THOUGH TIMING OF THESE SHORTWAVES IS UNCERTAIN GIVEN MODEL
DISAGREEMENT.

SURFACE...

1008MB SURFACE LOW LOCATED 140 MILES NORTHWEST OF BARROW AT 18Z IS
PROGGED TO MOVE NORTHWEST TOWARDS THE NEW SIBERIAN ISLANDS THROUGH
MIDWEEK. THE WEAK 1009MB LOW OVER PRINCE WILLIAM SOUND WILL MERGE
INTO A NORTHWARD MOVING 990MB LOW FROM THE NORTHERN PACIFIC. THE
RESULTING LOW WILL MOVE EAST AND OVER THE SOUTHEAST AK PANHANDLE.

OVER THE BERING...A STRONG LOW WILL MOVE TO NEAR SHEMYA BY 12Z
TUESDAY. AN OCCLUSION STRETCHING FROM THIS LOW WILL ROTATE EAST
OVER THE ALEUTIAN ISLANDS WEDNESDAY AND THEN NORTHEAST ALONG THE
ALASKA PENINSULA AND SOUTHWEST COAST BY 00Z THURSDAY. POSSIBLE
HAZARDS POSSIBLY ASSOCIATED WITH THIS LOW WILL BE GALE TO STORM
FORCE WINDS DEVELOPING WEDNESDAY NIGHT OVER ST LAWRENCE AND BERING
STRAIT AND A MESSY WINTRY MIX OF SNOW/FREEZING RAIN/RAIN OVER THE
SOUTHWEST...WHERE WARM AIR ADVECTION ALOFT AHEAD OF THE FRONT WILL
CREATE SOME ISSUES WITH PRECIPITATION TYPE STARTING AFTER 00Z
THURSDAY FOR ST LAWRENCE ISLAND AND THE YUKON DELTA.

MORNING AND EARLY IMAGES FROM THE SPORT MICROPHYSICS RGB
PRODUCT...SHOWS A BLANKET OF STRATUS OVER THE WESTERN TWO-THIRDS
OF ALASKA THAT IS GRADUALLY INCREASING IN AREAL EXTENT OVER
EASTERN ALASKA THIS AFTERNOON. THE PRESENCE OF STRATUS WILL
GREATLY IMPACT OVERNIGHT TEMPERATURES...KEEPING TEMPERATURES
WARMER THAN OTHERWISE WOULD BE WITHOUT STRATUS AND COLDER H850
TEMPERATURES.

IN REGARDS TO PRECIPITATION...AS THE AFOREMENTIONED UPPER LEVEL
TROUGH SHIFTS EAST OVER NORTHERN ALASKA...PERIODS OF SNOW DEVELOP
OVER THE CENTRAL/EASTERN INTERIOR AND EASTERN ARCTIC COAST TUESDAY
MORNING AND THEN GRADUALLY SHIFT EAST THROUGH THURSDAY. SNOW
ACCUMULATIONS WILL RANGE FROM A DUSTING UP TO 2 INCHES...WITH
POSSIBLE IMPACTS TO THE PUBLIC BEING HAZARDOUS ROAD CONDITIONS
ALONG THE HIGHWAYS.

COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
HEAVY FREEZING SPRAY WARNING FOR PKZ210.

&&

$$

LTH DEC 14





000
FXAK69 PAFG 221147
AFDAFG

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
247 AM AKST MON DEC 22 2014

.DISCUSSION...

QUIET WEATHER PATTERN IS EXPECTED TO CONTINUE OVER NORTHERN
ALASKA THROUGH FRI. SOMEWHAT COLDER TEMPERATURES CAN BE
EXPECTED OVER THE ARCTIC COAST AND MOST OF THE INTERIOR FOR
MOST OF THIS WEEK...WITH A WARMING TREND BEGINNING OVER THE
WEEKEND

UPPER AIR...
CURRENT GFS/NAM OPERATIONAL RUNS ARE SIMILAR THROUGH WED
NIGHT. A COLD UPPER LEVEL TROUGH EXTENDS FROM A WEAK LOW NEAR THE
NEW SIBERIAN ISLANDS SOUTHEASTWARD ALONG THE NORTHERN SIBERIA
COAST TO THE BERING STRAIT AND NORTON SOUND. THIS TROUGH AND ITS
COLDER AIR MASS WILL MOVE SLOWLY EASTWARD ACROSS THE NORTHERN TWO
THIRDS OF NORTHERN ALASKA THROUGH WED NIGHT. THE ECMWF RUN DIFFERS
FROM THE NAM/GFS...DEPICTING A SMOOTHER AND LOWER AMPLITUDE LONG
WAVE TROUGH WITH THE COLDEST AIR REMAINING NORTH OF THE ARCTIC
COAST. A WEAK SHORT WAVE MOVING OUT OF THE LONG WAVE PATTERN IS
CARRIED EASTWARD ACROSS NORTHERN ALASKA FROM THE BROOKS NORTHWARD
WITH TIMING SIMILAR TO THE MOVEMENT OF THE MAIN TROUGH ON THE
GFS/NAM RUNS. THE OPERATIONAL GFS SOLUTION IS WELL SUPPORTED BY
ITS ENSEMBLE MEAN. WE PREFER THE NAM/GFS CONSENSUS ON THE
HANDLING OF THIS UPPER TROUGH.

AFTER THE UPPER TROUGH EXITS TO THE NORTHEAST...A WEAK UPPER FLOW
PATTERN WILL BE MAINTAINED OVER NORTHERN ALASKA THROUGH FRI. THIS
WILL BE FOLLOWED BY THE DEVELOPMENT OF A HIGH AMPLITUDE UPPER
RIDGE WHICH WILL PUSH NORTHWARD INTO EASTERN ALASKA OVER THE
WEEKEND. THERE ARE MINOR DIFFERENCES BETWEEN THE GFS/ECMWF
OPERATIONAL RUNS BUT GOOD AGREEMENT BETWEEN THE GEFS/NAEFS AND
ECMWF ENSEMBLE MEANS. STRONG SOUTHERLY FLOW ON THE BACK SIDE OF
THE RIDGE WILL BRING WARMER TEMPERATURES TO NORTHERN
ALASKA...ESPECIALLY SOUTH OF THE BROOKS RANGE WHERE THE ENSEMBLE
MEANS ARE INDICATING 850 MB TEMPERATURES AS WARM AS -4C. BEHIND
THE RIDGE...AN UPPER LOW WILL INTO THE SOUTHERN BERING SEA.
POSITIONS FROM OF THE OPERATIONAL RUNS DIFFER...SO PREFER THE
ENSEMBLE MEANS WHICH HAVE A MEAN CENTER NEAR 55N/175-180W SAT
AFTERNOON.

SURFACE...
WINDS OVER THE NORTHWEST CAPES AND THE BERING STRAIT HAVE
DIMINISHED SINCE YESTERDAY WITH THE PRESSURE GRADIENT LOOSENING
NOTICEABLY SINCE FRI EVENING. EXTENSIVE STRATUS COVERS THE
NORTHERN BERING SEA...MUCH OF THE WEST COAST AND WESTERN/CENTRAL
INTERIOR AND ARCTIC COAST. THERE ARE AREAS OF STRATUS OVER PARTS
OF THE EASTERN AND NORTHEAST INTERIOR. WHILE A COLDER AIRMASS IS
EXPECTED OVER THE NORTHERN TWO THIRDS OF NORTHERN ALASKA FOR THE
NEXT FEW DAYS...SURFACE TEMPERATURES WILL BE CLOUD COVER
DEPENDENT...WITH MITIGATION OF THE AIR MASS RADIATIVE TEMPERATURES
IN AREAS OF STRATUS. A GENERALLY LIGHT WIND FLOW PATTERN WILL
CONTINUE OVER THE MAINLAND THROUGH WED.

SCATTERED SNOW SHOWERS TODAY OVER THE WEST COAST FROM THE
NORTHERN SEWARD PENINSULA NORTHWARD...NORTHWESTERN INTERIOR...AND
WESTERN PARTS OF THE ARCTIC SLOPE/BROOKS RANGE. SCATTERED SNOW
SHOWERS WILL SPREAD EASTWARD ACROSS THE REMAINDER OF NORTHERN
ALASKA THROUGH TUE AS THE UPPER LEVEL TROUGH MOVES EAST.

NOTICEABLY WARMER TEMPERATURES ARE EXPECTED OVER MOST OF NORTHERN
ALASKA BY SUN AS THE STRONG UPPER RIDGE BUILDS IN. CHINOOK WINDS
WILL LIKELY DEVELOP IN ALASKA RANGE PASSES SAT. EASTERLY GALES
ARE EXPECTED TO DEVELOP OVER THE NORTHERN BERING SEA INCLUDING ST
LAWRENCE ISLAND SAT AFTERNOON OR EVENING AS A MODERATELY STRONG
STORM MOVES NORTHWARD INTO THE BERING SEA. BY SAT EVENING...GEFS
ENSEMBLE MEAN PLACING A MEAN 962 MB CENTER ABOUT 150 MILES
SOUTHWEST OF ST MATTHEW ISLAND. CONSENSUS OF THE CURRENT GFS/ECMWF
OPERATIONAL RUNS PUTS THE LOW CENTER ABOUT 50-100 MILES EAST OF
THIS POSITION SAT EVENING. PRECIPITATION ASSOCIATED WITH THIS
SYSTEM EXPECTED TO SPREAD NORTHWARD TO THE SOUTHWEST INTERIOR AND
SOUTHERN WEST COAST SAT AFTERNOON. TEMPERATURES COULD BE WARM
ENOUGH FOR MIXED PRECIPITATION IN AREAS OF THE WEST COAST SOUTH OF
NORTON SOUND AS INDICATED BY GFS MODEL SOUNDINGS.


COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...

HEAVY FREEZING SPRAY WARNING...PKZ210.


$$

RF DEC 14





000
FXAK69 PAFG 221147
AFDAFG

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
247 AM AKST MON DEC 22 2014

.DISCUSSION...

QUIET WEATHER PATTERN IS EXPECTED TO CONTINUE OVER NORTHERN
ALASKA THROUGH FRI. SOMEWHAT COLDER TEMPERATURES CAN BE
EXPECTED OVER THE ARCTIC COAST AND MOST OF THE INTERIOR FOR
MOST OF THIS WEEK...WITH A WARMING TREND BEGINNING OVER THE
WEEKEND

UPPER AIR...
CURRENT GFS/NAM OPERATIONAL RUNS ARE SIMILAR THROUGH WED
NIGHT. A COLD UPPER LEVEL TROUGH EXTENDS FROM A WEAK LOW NEAR THE
NEW SIBERIAN ISLANDS SOUTHEASTWARD ALONG THE NORTHERN SIBERIA
COAST TO THE BERING STRAIT AND NORTON SOUND. THIS TROUGH AND ITS
COLDER AIR MASS WILL MOVE SLOWLY EASTWARD ACROSS THE NORTHERN TWO
THIRDS OF NORTHERN ALASKA THROUGH WED NIGHT. THE ECMWF RUN DIFFERS
FROM THE NAM/GFS...DEPICTING A SMOOTHER AND LOWER AMPLITUDE LONG
WAVE TROUGH WITH THE COLDEST AIR REMAINING NORTH OF THE ARCTIC
COAST. A WEAK SHORT WAVE MOVING OUT OF THE LONG WAVE PATTERN IS
CARRIED EASTWARD ACROSS NORTHERN ALASKA FROM THE BROOKS NORTHWARD
WITH TIMING SIMILAR TO THE MOVEMENT OF THE MAIN TROUGH ON THE
GFS/NAM RUNS. THE OPERATIONAL GFS SOLUTION IS WELL SUPPORTED BY
ITS ENSEMBLE MEAN. WE PREFER THE NAM/GFS CONSENSUS ON THE
HANDLING OF THIS UPPER TROUGH.

AFTER THE UPPER TROUGH EXITS TO THE NORTHEAST...A WEAK UPPER FLOW
PATTERN WILL BE MAINTAINED OVER NORTHERN ALASKA THROUGH FRI. THIS
WILL BE FOLLOWED BY THE DEVELOPMENT OF A HIGH AMPLITUDE UPPER
RIDGE WHICH WILL PUSH NORTHWARD INTO EASTERN ALASKA OVER THE
WEEKEND. THERE ARE MINOR DIFFERENCES BETWEEN THE GFS/ECMWF
OPERATIONAL RUNS BUT GOOD AGREEMENT BETWEEN THE GEFS/NAEFS AND
ECMWF ENSEMBLE MEANS. STRONG SOUTHERLY FLOW ON THE BACK SIDE OF
THE RIDGE WILL BRING WARMER TEMPERATURES TO NORTHERN
ALASKA...ESPECIALLY SOUTH OF THE BROOKS RANGE WHERE THE ENSEMBLE
MEANS ARE INDICATING 850 MB TEMPERATURES AS WARM AS -4C. BEHIND
THE RIDGE...AN UPPER LOW WILL INTO THE SOUTHERN BERING SEA.
POSITIONS FROM OF THE OPERATIONAL RUNS DIFFER...SO PREFER THE
ENSEMBLE MEANS WHICH HAVE A MEAN CENTER NEAR 55N/175-180W SAT
AFTERNOON.

SURFACE...
WINDS OVER THE NORTHWEST CAPES AND THE BERING STRAIT HAVE
DIMINISHED SINCE YESTERDAY WITH THE PRESSURE GRADIENT LOOSENING
NOTICEABLY SINCE FRI EVENING. EXTENSIVE STRATUS COVERS THE
NORTHERN BERING SEA...MUCH OF THE WEST COAST AND WESTERN/CENTRAL
INTERIOR AND ARCTIC COAST. THERE ARE AREAS OF STRATUS OVER PARTS
OF THE EASTERN AND NORTHEAST INTERIOR. WHILE A COLDER AIRMASS IS
EXPECTED OVER THE NORTHERN TWO THIRDS OF NORTHERN ALASKA FOR THE
NEXT FEW DAYS...SURFACE TEMPERATURES WILL BE CLOUD COVER
DEPENDENT...WITH MITIGATION OF THE AIR MASS RADIATIVE TEMPERATURES
IN AREAS OF STRATUS. A GENERALLY LIGHT WIND FLOW PATTERN WILL
CONTINUE OVER THE MAINLAND THROUGH WED.

SCATTERED SNOW SHOWERS TODAY OVER THE WEST COAST FROM THE
NORTHERN SEWARD PENINSULA NORTHWARD...NORTHWESTERN INTERIOR...AND
WESTERN PARTS OF THE ARCTIC SLOPE/BROOKS RANGE. SCATTERED SNOW
SHOWERS WILL SPREAD EASTWARD ACROSS THE REMAINDER OF NORTHERN
ALASKA THROUGH TUE AS THE UPPER LEVEL TROUGH MOVES EAST.

NOTICEABLY WARMER TEMPERATURES ARE EXPECTED OVER MOST OF NORTHERN
ALASKA BY SUN AS THE STRONG UPPER RIDGE BUILDS IN. CHINOOK WINDS
WILL LIKELY DEVELOP IN ALASKA RANGE PASSES SAT. EASTERLY GALES
ARE EXPECTED TO DEVELOP OVER THE NORTHERN BERING SEA INCLUDING ST
LAWRENCE ISLAND SAT AFTERNOON OR EVENING AS A MODERATELY STRONG
STORM MOVES NORTHWARD INTO THE BERING SEA. BY SAT EVENING...GEFS
ENSEMBLE MEAN PLACING A MEAN 962 MB CENTER ABOUT 150 MILES
SOUTHWEST OF ST MATTHEW ISLAND. CONSENSUS OF THE CURRENT GFS/ECMWF
OPERATIONAL RUNS PUTS THE LOW CENTER ABOUT 50-100 MILES EAST OF
THIS POSITION SAT EVENING. PRECIPITATION ASSOCIATED WITH THIS
SYSTEM EXPECTED TO SPREAD NORTHWARD TO THE SOUTHWEST INTERIOR AND
SOUTHERN WEST COAST SAT AFTERNOON. TEMPERATURES COULD BE WARM
ENOUGH FOR MIXED PRECIPITATION IN AREAS OF THE WEST COAST SOUTH OF
NORTON SOUND AS INDICATED BY GFS MODEL SOUNDINGS.


COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...

HEAVY FREEZING SPRAY WARNING...PKZ210.


$$

RF DEC 14




000
FXAK69 PAFG 212211
AFDAFG

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
111 PM AKST SUN DEC 21 2014

.DISCUSSION...

21/12Z DETERMINISTIC MODEL SUITE IS GENERALLY IN GOOD AGREEMENT
THROUGH 12Z TUESDAY WITH THE OVERALL SYNOPTIC PATTERN.
THEREAFTER...MODEL DIFFERENCES BETWEEN THE GFS AND ECWMF BECOME
APPARENT...WITH THE GFS PAINTING A MORE AMPLIFIED RIDGE ALOFT OVER
MAINLAND ALASKA AND SIGNIFICANT DIFFERENCES WITH THE SURFACE LOW
OVER THE BERING LATE THIS WEEK. USED A BLEND OF THE PREVIOUS
FORECAST AND MODEL BLEND THROUGH 00Z THURSDAY.

MAIN CONCERNS INCLUDE WINDS ALONG THE WEST COAST AND ST LAWRENCE
ISLAND AND FOG/LOW STRATUS DECK OVER THE ARCTIC COAST.
OTHERWISE...FAIRLY QUIET WEATHER PATTERN FOR MOST OF NORTHERN
ALASKA.

1929Z NPP/MODIS MICROPHYSICS RGB SATELLITE IMAGE SHOWS A BAND OF
STRATUS/FOG OVER THE ARCTIC COAST. THINKING THAT LOW STRATUS AND
AREAS OF FOG WILL PERSIST OVER THE NEXT FEW DAYS AS WINDS WILL BE LIGHT.

.ALOFT...

BROAD UPPER LEVEL TROUGH EXTENDS FROM CHUKOTSK PENINSULA SOUTHEAST
OVER THE WESTERN TWO-THIRDS OF AK WITH A RIDGE OVER THE EASTERN
THIRD OF AK AND WESTERN CANADA. THIS TROUGH IS EXPECTED TO WEAKEN
AND LIFTS NORTH THIS EVENING AS A 500 MB VORTEX MAX/TROUGH SWINGS
EAST FROM THE CHUKOTSK PENINSULA. ALL OPERATIONAL MODELS HAVE THIS
TROUGH DEEPENING AS IT PROGRESSES EAST OVER NORTHERN ALASKA.

COINCIDENT WITH THIS TROUGH...WEAK COLD AIR ADVECTION WILL ENSUE
OVER NORTHERN ALASKA. ORIGINATING OVER NORTHERN SIBERIA WITH
CHILLY H850 TEMPERATURES OF -30C...THIS AIRMASS WILL MODIFY AS IT
SPREADS SOUTHEAST AND OVER NORTHERN ALASKA. BY TUESDAY/WEDNESDAY H850
TEMPERATURES OF -15C TO -20C WILL RESIDE OVER THE BROOKS RANGE
NORTH AND -10C TO -15C NORTH OF THE ALASKA RANGE. THESE FORECAST
H850 TEMPERATURES ARE STILL SLIGHTLY ABOVE NORMAL FOR THIS TIME
OF YEAR. THERE ARE SLIGHT DIFFERENCES BETWEEN THE MODELS...ONLY 3C
TO 5C WARMER PER THE ECWMF. AT THE SURFACE...MAY SEE AROUND 10
DEGREES OF COOLING NORTH OF THE BROOKS RANGE BY MIDWEEK...BRINGING
TEMPERATURES BACK TO NEAR NORMAL.

A PROGRESSIVE AND HIGHLY AMPLIFIED RIDGE IS EXPECTED TO BEGIN
BUILDING OVER THE WESTERN BERING SEA MONDAY NIGHT...BY EARLY
WEDNESDAY AFTERNOON...THE RIDGE AXIS WILL EXTEND FROM THE CHUKOTSK
PENINSULA SOUTHEAST OVER SEWARD PENINSULA AND OVER KODIAK ISLAND.
THIS RIDGE WILL GRADUALLY SHIFT NORTHEAST THROUGH THE REMAINDER OF
THE WEEK.

WEAK SHORTWAVES WILL MOVE OVER THE NORTH SLOPE...WEST COAST...AND
WESTERN INTERIOR...BRINGING INCREASED CHANCES FOR SNOW SHOWERS
MONDAY. CHANCES FOR SNOW SHOWERS FOR THE REST OF THE INTERIOR WILL
INCREASE AS THE AFOREMENTIONED H500 TROUGH SWINGS EAST TUESDAY AND
WEDNESDAY.

.SURFACE...

A BROAD LOW PRESSURE/TROUGH EXISTS OVER THE NORTHERN GULF OF
ALASKA AND MAINLAND AK...WITH MULTIPLE LOW CENTERS BEING ANALYZED.
SURFACE HIGH PRESSURE RESIDES OVER SIBERIA AND ARCTIC OCEAN. THE
BROAD LOW PRESSURE/TROUGH WILL EXPAND NORTHWARD OVER THE BEAUFORT
SEA TONIGHT AND MONDAY...ALLOWING THE GRADIENT OVER THE WEST COAST TO
POINT HOPE AND ALONG THE ARCTIC COAST TO RELAX. THIS WILL ALLOW
WINDS TO GRADUALLY DIMINISH OVERNIGHT FOR THE EASTERN BEAUFORT
SEA...POINT HOPE AND THE YUKON DELTA COAST.

CURRENT GFS/NAM/ECWMF ARE DEVELOPING A STRONG LOW NEAR SHEMYA BY
12Z TUESDAY. AFTER 12Z TUESDAY...MODEL SOLUTIONS SIGNIFICANTLY
DIVERGE WITH THE DEVELOPMENT AND PROGRESSION OF THIS LOW AS IT
DEEPENS AND ROTATES AROUND OVER THE BERING SEA. WILL EVALUATE
FUTURE RUNS OF THE GFS/NAM/ECWMF AS DETAILS BECOME CLEARER TO SEE
IF THERE WILL BE IMPACTS FOR THE WEST COAST ASSOCIATED WITH THIS
LOW.


COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
HEAVY FREEZING SPRAY WARNING FOR PKZ210.

SMALL CRAFT ADVISORY FOR PKZ210.

GALE WARNING FOR PKZ220.

BRISK WIND ADVISORY FOR PKZ220-PKZ240-PKZ245.
&&

$$

LTH DEC 14





000
FXAK69 PAFG 211528 AAA
AFDAFG

NORTHERN ALASKA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE FAIRBANKS AK
628 AM AKST SUN DEC 21 2014

UPDATE ADDS PARAGRAPH TO SURFACE SECTION

.DISCUSSION...
CURRENT RUNS OF THE GFS/NAM/ECMWF/CANADA NH MODELS ARE IN
GENERALLY GOOD AGREEMENT OUT THROUGH 12Z WED.

UPPER AIR...
ALL OF THE OPERATIONAL MODELS ARE GRADUALLY DEEPENING AN UPPER
TROUGH SOUTHEASTWARD OUT OF SIBERIA AND THE WESTERN ARCTIC OCEAN
THROUGH MON NIGHT...BRINGING A COLDER AIR MASS TO NORTHWEST ALASKA
AND THE NORTHERN PARTS OF THE WEST COAST. THIS MORNING...THE NAM
AND ECMWF ARE FOLLOWING THE LEAD OF THE GFS IN MOVING THE TROUGH
EASTWARD ACROSS THE NORTHERN HALF OF NORTHERN ALASKA THROUGH WED
EVENING...PULLING THE COLDER AIR MASS EASTWARD ACROSS THE
NORTHERN PARTS OF NORTHERN ALASKA.

A PROGRESSIVE UPPER LEVEL RIDGE IS EXPECTED TO BEGIN BUILDING
OVER THE SOUTHERN BERING SEA AND WESTERN ALEUTIANS MON. BY
TUE AFTERNOON THE RIDGE WILL INCREASE CONSIDERABLY IN AMPLITUDE...
EXTENDING FROM EASTERN INTERIOR SIBERIA TO NUNIVAK ISLAND
AND THE ALASKA PENINSULA. BY WED AFTERNOON...THE RIDGE AXIS
WILL EXTENDING FROM THE NORTH COAST OF EASTERN SIBERIA TO
THE BERING STRAIT AND KODIAK ISLAND. A WEAK SHORT WAVE TROUGH
WILL MOVE THROUGH THE SOUTHERN PART OF THE RIDGE TUE NIGHT AND
WED AND LIKELY DAMPEN OUT ON WED. THIS FEATURE IS EXPECTED TO
HAVE LITTLE IF ANY IMPACT IN OUR FORECAST AREA. THE RIDGE
IS EXPECTED TO CONTINUE TO MOVE ACROSS NORTHERN ALASKA WED
AND THU AS A BROAD TROUGH SWINGS NORTHWARD ACROSS THE SOUTHERN
BERING SEA AND THE WEST COAST.

LATE THIS WEEK AND INTO THE WEEKEND...GEFS/NAEFS AND ECMWF
ENSEMBLE MEANS BUILDING A RIDGE OVER THE GULF OF ALASKA AND THE
ALASKA MAINLAND...BY SAT NIGHT THE MEAN RIDGE AXIS EXTENDS FROM
THE WESTERN ARCTIC OCEAN TO THE CENTRAL ARCTIC COAST THEN
SOUTHEASTWARD INTO THE NORTHERN PANHANDLE. SOUTH TO SOUTHWEST
ALOFT FLOW OVER THE NORTHERN ALASKA MAINLAND ON THE BACK SIDE OF
THE RIDGE WILL BRING IN WARMER AIR ALOFT AND AT THE SURFACE. THIS
TREND IS INDICATED IN GFS EXTENDED MOS TEMPERATURES AT MOST
FORECAST SITES TOWARDS THE END OF THE WEEK.

SURFACE...
THE BIGGEST SHORT TERM ISSUE IS WINDS OVER THE CENTRAL AND EASTERN
ARCTIC COAST AND INTERIOR ARCTIC SLOPE. THE 06Z MANUAL SURFACE
ANALYSIS INDICATED A NARROW TROUGH ALONG THE CENTRAL ARCTIC COAST
THEN TO SOUTH OF BARTER ISLAND...WITH A WEAK RIDGE OVER THE
INLAND ARCTIC COAST. THIS PATTERN IS RESULTING IN EASTERLY GALE
FORCE WINDS AT BARTER ISLAND AND MUCH LIGHTER WINDS FARTHER TO THE
WEST. THESE SURFACE FEATURES ARE GENERALLY NOT WELL HANDLED BY THE
MODELS...AND TEND TO BE MORE PERSISTENT THAN MODEL FORECASTS. AT
THIS TIME...LOOKING FOR THIS PATTERN TO HOLD TOGETHER TODAY THEN
BECOMING GRADUALLY SMOOTHED OUT WHICH SHOULD RESULT IN DECREASING
WINDS ALONG THE EASTERN ARCTIC COAST AND IN MARINE ZONE PKZ245.
WINDS ARE EXPECTED TO SHIFT TO LIGHT WESTERLY IN THIS AREA BY MON
WITH A WEAK SURFACE TROUGH PROGGED TO MOVE EASTWARD. IN ANY
EVENT...CONFIDENCE IN THE WIND FORECASTS IN THIS AREA IS BELOW
AVERAGE.

A TIGHT PINCH IN THE ISOBAR FIELD FROM THE NORTHWEST ALASKA CAPES
TO THE BERING STRAIT AND ST LAWRENCE ISLAND IS PRODUCING BRISK
NORTH TO NORTHEAST WINDS IN THESE AREAS...WITH GALE FORCE WINDS AT
TIN CITY AND GALE GUSTS AT POINT HOPE AND WALES. THIS TIGHT
GRADIENT IS EXPECTED TO GRADUALLY RELAX DURING THE NEXT 24
HOURS...RESULTING IN DECREASING WINDS.

LATE EVENING NASA/SPORT NIGHT MICROPHYSICS RGB IMAGE SHOWS
EXTENSIVE LOW STRATUS OVER THE ARCTIC COAST AND MUCH OF THE INLAND
ARCTIC COAST...WITH ONLY A FEW PATCHES ELSEWHERE IN THE INTERIOR.
PRESENCE OF THE STRATUS IN THESE AREAS IS WELL SUPPORTED BY
AVAILABLE SURFACE OBSERVATIONS.

SCATTERED SNOW SHOWERS OVER THE CENTRAL AND WESTERN ARCTIC
COAST AND OVER THE CHUKCHI AND NORTHERN BERING SEAS ARE
EXPECT TO SPREAD SLOWLY EASTWARD ACROSS THE NORTHERN PARTS
OF NORTHERN ALASKA THROUGH TUE AS THE COLD UPPER TROUGH
MARCHES SLOWLY EASTWARD. SCATTERED SNOW SHOWERS ARE EXPECTED
TO BREAK OUT OVER THE SOUTHERN AND EASTERN INTERIOR MON
NIGHT AND TUE.

BRISK EAST WINDS DEVELOPING OVER ST LAWRENCE ISLAND LATE TUE
AFTERNOON OR TUE EVENING...INCREASING TO GALE LATER TUE NIGHT AS A
WEATHER FRONT APPROACHES FROM THE SOUTH. EASTERLY GALES DEVELOPING
TUE IN THE EXTREME WESTERN PARTS OF MARINE ZONE PKZ210.

CURRENT GFS/ECMWF AND ENSEMBLE MEANS INDICATE THE POSSIBILITY
OF A MODERATELY STRONG LOW MOVING INTO THE SOUTHERN BERING SEA
FRIDAY AFTERNOON OR FRIDAY NIGHT...WITH POTENTIAL FOR GALES OVER
THE NORTHERN BERING SEA.


COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
HEAVY FREEZING SPRAY WARNING FOR PKZ210.

SMALL CRAFT ADVISORY FOR PKZ210.

GALE WARNING FOR PKZ220.

BRISK WIND ADVISORY FOR PKZ220-PKZ225-PKZ240-PKZ245.
&&

$$

DEC 14





000
FXAK69 PAFG 211528 AAA
AFDAFG

NORTHERN ALASKA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE FAIRBANKS AK
628 AM AKST SUN DEC 21 2014

UPDATE ADDS PARAGRAPH TO SURFACE SECTION

.DISCUSSION...
CURRENT RUNS OF THE GFS/NAM/ECMWF/CANADA NH MODELS ARE IN
GENERALLY GOOD AGREEMENT OUT THROUGH 12Z WED.

UPPER AIR...
ALL OF THE OPERATIONAL MODELS ARE GRADUALLY DEEPENING AN UPPER
TROUGH SOUTHEASTWARD OUT OF SIBERIA AND THE WESTERN ARCTIC OCEAN
THROUGH MON NIGHT...BRINGING A COLDER AIR MASS TO NORTHWEST ALASKA
AND THE NORTHERN PARTS OF THE WEST COAST. THIS MORNING...THE NAM
AND ECMWF ARE FOLLOWING THE LEAD OF THE GFS IN MOVING THE TROUGH
EASTWARD ACROSS THE NORTHERN HALF OF NORTHERN ALASKA THROUGH WED
EVENING...PULLING THE COLDER AIR MASS EASTWARD ACROSS THE
NORTHERN PARTS OF NORTHERN ALASKA.

A PROGRESSIVE UPPER LEVEL RIDGE IS EXPECTED TO BEGIN BUILDING
OVER THE SOUTHERN BERING SEA AND WESTERN ALEUTIANS MON. BY
TUE AFTERNOON THE RIDGE WILL INCREASE CONSIDERABLY IN AMPLITUDE...
EXTENDING FROM EASTERN INTERIOR SIBERIA TO NUNIVAK ISLAND
AND THE ALASKA PENINSULA. BY WED AFTERNOON...THE RIDGE AXIS
WILL EXTENDING FROM THE NORTH COAST OF EASTERN SIBERIA TO
THE BERING STRAIT AND KODIAK ISLAND. A WEAK SHORT WAVE TROUGH
WILL MOVE THROUGH THE SOUTHERN PART OF THE RIDGE TUE NIGHT AND
WED AND LIKELY DAMPEN OUT ON WED. THIS FEATURE IS EXPECTED TO
HAVE LITTLE IF ANY IMPACT IN OUR FORECAST AREA. THE RIDGE
IS EXPECTED TO CONTINUE TO MOVE ACROSS NORTHERN ALASKA WED
AND THU AS A BROAD TROUGH SWINGS NORTHWARD ACROSS THE SOUTHERN
BERING SEA AND THE WEST COAST.

LATE THIS WEEK AND INTO THE WEEKEND...GEFS/NAEFS AND ECMWF
ENSEMBLE MEANS BUILDING A RIDGE OVER THE GULF OF ALASKA AND THE
ALASKA MAINLAND...BY SAT NIGHT THE MEAN RIDGE AXIS EXTENDS FROM
THE WESTERN ARCTIC OCEAN TO THE CENTRAL ARCTIC COAST THEN
SOUTHEASTWARD INTO THE NORTHERN PANHANDLE. SOUTH TO SOUTHWEST
ALOFT FLOW OVER THE NORTHERN ALASKA MAINLAND ON THE BACK SIDE OF
THE RIDGE WILL BRING IN WARMER AIR ALOFT AND AT THE SURFACE. THIS
TREND IS INDICATED IN GFS EXTENDED MOS TEMPERATURES AT MOST
FORECAST SITES TOWARDS THE END OF THE WEEK.

SURFACE...
THE BIGGEST SHORT TERM ISSUE IS WINDS OVER THE CENTRAL AND EASTERN
ARCTIC COAST AND INTERIOR ARCTIC SLOPE. THE 06Z MANUAL SURFACE
ANALYSIS INDICATED A NARROW TROUGH ALONG THE CENTRAL ARCTIC COAST
THEN TO SOUTH OF BARTER ISLAND...WITH A WEAK RIDGE OVER THE
INLAND ARCTIC COAST. THIS PATTERN IS RESULTING IN EASTERLY GALE
FORCE WINDS AT BARTER ISLAND AND MUCH LIGHTER WINDS FARTHER TO THE
WEST. THESE SURFACE FEATURES ARE GENERALLY NOT WELL HANDLED BY THE
MODELS...AND TEND TO BE MORE PERSISTENT THAN MODEL FORECASTS. AT
THIS TIME...LOOKING FOR THIS PATTERN TO HOLD TOGETHER TODAY THEN
BECOMING GRADUALLY SMOOTHED OUT WHICH SHOULD RESULT IN DECREASING
WINDS ALONG THE EASTERN ARCTIC COAST AND IN MARINE ZONE PKZ245.
WINDS ARE EXPECTED TO SHIFT TO LIGHT WESTERLY IN THIS AREA BY MON
WITH A WEAK SURFACE TROUGH PROGGED TO MOVE EASTWARD. IN ANY
EVENT...CONFIDENCE IN THE WIND FORECASTS IN THIS AREA IS BELOW
AVERAGE.

A TIGHT PINCH IN THE ISOBAR FIELD FROM THE NORTHWEST ALASKA CAPES
TO THE BERING STRAIT AND ST LAWRENCE ISLAND IS PRODUCING BRISK
NORTH TO NORTHEAST WINDS IN THESE AREAS...WITH GALE FORCE WINDS AT
TIN CITY AND GALE GUSTS AT POINT HOPE AND WALES. THIS TIGHT
GRADIENT IS EXPECTED TO GRADUALLY RELAX DURING THE NEXT 24
HOURS...RESULTING IN DECREASING WINDS.

LATE EVENING NASA/SPORT NIGHT MICROPHYSICS RGB IMAGE SHOWS
EXTENSIVE LOW STRATUS OVER THE ARCTIC COAST AND MUCH OF THE INLAND
ARCTIC COAST...WITH ONLY A FEW PATCHES ELSEWHERE IN THE INTERIOR.
PRESENCE OF THE STRATUS IN THESE AREAS IS WELL SUPPORTED BY
AVAILABLE SURFACE OBSERVATIONS.

SCATTERED SNOW SHOWERS OVER THE CENTRAL AND WESTERN ARCTIC
COAST AND OVER THE CHUKCHI AND NORTHERN BERING SEAS ARE
EXPECT TO SPREAD SLOWLY EASTWARD ACROSS THE NORTHERN PARTS
OF NORTHERN ALASKA THROUGH TUE AS THE COLD UPPER TROUGH
MARCHES SLOWLY EASTWARD. SCATTERED SNOW SHOWERS ARE EXPECTED
TO BREAK OUT OVER THE SOUTHERN AND EASTERN INTERIOR MON
NIGHT AND TUE.

BRISK EAST WINDS DEVELOPING OVER ST LAWRENCE ISLAND LATE TUE
AFTERNOON OR TUE EVENING...INCREASING TO GALE LATER TUE NIGHT AS A
WEATHER FRONT APPROACHES FROM THE SOUTH. EASTERLY GALES DEVELOPING
TUE IN THE EXTREME WESTERN PARTS OF MARINE ZONE PKZ210.

CURRENT GFS/ECMWF AND ENSEMBLE MEANS INDICATE THE POSSIBILITY
OF A MODERATELY STRONG LOW MOVING INTO THE SOUTHERN BERING SEA
FRIDAY AFTERNOON OR FRIDAY NIGHT...WITH POTENTIAL FOR GALES OVER
THE NORTHERN BERING SEA.


COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
HEAVY FREEZING SPRAY WARNING FOR PKZ210.

SMALL CRAFT ADVISORY FOR PKZ210.

GALE WARNING FOR PKZ220.

BRISK WIND ADVISORY FOR PKZ220-PKZ225-PKZ240-PKZ245.
&&

$$

DEC 14




000
FXAK69 PAFG 211227
AFDAFG

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
327 AM AKST SUN DEC 21 2014

.DISCUSSION...
CURRENT RUNS OF THE GFS/NAM/ECMWF/CANADA NH MODELS ARE IN
GENERALLY GOOD AGREEMENT OUT THROUGH 12Z WED.

UPPER AIR...
ALL OF THE OPERATIONAL MODELS ARE GRADUALLY DEEPENING AN UPPER
TROUGH SOUTHEASTWARD OUT OF SIBERIA AND THE WESTERN ARCTIC OCEAN
THROUGH MON NIGHT...BRINGING A COLDER AIR MASS TO NORTHWEST ALASKA
AND THE NORTHERN PARTS OF THE WEST COAST. THIS MORNING...THE NAM
AND ECMWF ARE FOLLOWING THE LEAD OF THE GFS IN MOVING THE TROUGH
EASTWARD ACROSS THE NORTHERN HALF OF NORTHERN ALASKA THROUGH WED
EVENING...PULLING THE COLDER AIR MASS EASTWARD ACROSS THE
NORTHERN PARTS OF NORTHERN ALASKA.

A PROGRESSIVE UPPER LEVEL RIDGE IS EXPECTED TO BEGIN BUILDING
OVER THE SOUTHERN BERING SEA AND WESTERN ALEUTIANS MON. BY
TUE AFTERNOON THE RIDGE WILL INCREASE CONSIDERABLY IN AMPLITUDE...
EXTENDING FROM EASTERN INTERIOR SIBERIA TO NUNIVAK ISLAND
AND THE ALASKA PENINSULA. BY WED AFTERNOON...THE RIDGE AXIS
WILL EXTENDING FROM THE NORTH COAST OF EASTERN SIBERIA TO
THE BERING STRAIT AND KODIAK ISLAND. A WEAK SHORT WAVE TROUGH
WILL MOVE THROUGH THE SOUTHERN PART OF THE RIDGE TUE NIGHT AND
WED AND LIKELY DAMPEN OUT ON WED. THIS FEATURE IS EXPECTED TO
HAVE LITTLE IF ANY IMPACT IN OUR FORECAST AREA. THE RIDGE
IS EXPECTED TO CONTINUE TO MOVE ACROSS NORTHERN ALASKA WED
AND THU AS A BROAD TROUGH SWINGS NORTHWARD ACROSS THE SOUTHERN
BERING SEA AND THE WEST COAST.

LATE THIS WEEK AND INTO THE WEEKEND...GEFS/NAEFS AND ECMWF
ENSEMBLE MEANS BUILDING A RIDGE OVER THE GULF OF ALASKA AND THE
ALASKA MAINLAND...BY SAT NIGHT THE MEAN RIDGE AXIS EXTENDS FROM
THE WESTERN ARCTIC OCEAN TO THE CENTRAL ARCTIC COAST THEN
SOUTHEASTWARD INTO THE NORTHERN PANHANDLE. SOUTH TO SOUTHWEST
ALOFT FLOW OVER THE NORTHERN ALASKA MAINLAND ON THE BACK SIDE OF
THE RIDGE WILL BRING IN WARMER AIR ALOFT AND AT THE SURFACE. THIS
TREND IS INDICATED IN GFS EXTENDED MOS TEMPERATURES AT MOST
FORECAST SITES TOWARDS THE END OF THE WEEK.

SURFACE...
THE BIGGEST SHORT TERM ISSUE IS WINDS OVER THE CENTRAL AND EASTERN
ARCTIC COAST AND INTERIOR ARCTIC SLOPE. THE 06Z MANUAL SURFACE
ANALYSIS INDICATED A NARROW TROUGH ALONG THE CENTRAL ARCTIC COAST
THEN TO SOUTH OF BARTER ISLAND...WITH A WEAK RIDGE OVER THE
INLAND ARCTIC COAST. THIS PATTERN IS RESULTING IN EASTERLY GALE
FORCE WINDS AT BARTER ISLAND AND MUCH LIGHTER WINDS FARTHER TO THE
WEST. THESE SURFACE FEATURES ARE GENERALLY NOT WELL HANDLED BY THE
MODELS...AND TEND TO BE MORE PERSISTENT THAN MODEL FORECASTS. AT
THIS TIME...LOOKING FOR THIS PATTERN TO HOLD TOGETHER TODAY THEN
BECOMING GRADUALLY SMOOTHED OUT WHICH SHOULD RESULT IN DECREASING
WINDS ALONG THE EASTERN ARCTIC COAST AND IN MARINE ZONE PKZ245.
WINDS ARE EXPECTED TO SHIFT TO LIGHT WESTERLY IN THIS AREA BY MON
WITH A WEAK SURFACE TROUGH PROGGED TO MOVE EASTWARD. IN ANY
EVENT...CONFIDENCE IN THE WIND FORECASTS IN THIS AREA IS BELOW
AVERAGE.

A TIGHT PINCH IN THE ISOBAR FIELD FROM THE NORTHWEST ALASKA CAPES
TO THE BERING STRAIT AND ST LAWRENCE ISLAND IS PRODUCING BRISK
NORTH TO NORTHEAST WINDS IN THESE AREAS...WITH GALE FORCE WINDS AT
TIN CITY AND GALE GUSTS AT POINT HOPE AND WALES. THIS TIGHT
GRADIENT IS EXPECTED TO GRADUALLY RELAX DURING THE NEXT 24
HOURS...RESULTING IN DECREASING WINDS.

LATE EVENING NASA/SPORT NIGHT MICROPHYSICS RGB IMAGE SHOWS
EXTENSIVE LOW STRATUS OVER THE ARCTIC COAST AND MUCH OF THE INLAND
ARCTIC COAST...WITH ONLY A FEW PATCHES ELSEWHERE IN THE INTERIOR.
PRESENCE OF THE STRATUS IN THESE AREAS IS WELL SUPPORTED BY
AVAILABLE SURFACE OBSERVATIONS.

SCATTERED SNOW SHOWERS OVER THE CENTRAL AND WESTERN ARCTIC
COAST AND OVER THE CHUKCHI AND NORTHERN BERING SEAS ARE
EXPECT TO SPREAD SLOWLY EASTWARD ACROSS THE NORTHERN PARTS
OF NORTHERN ALASKA THROUGH TUE AS THE COLD UPPER TROUGH
MARCHES SLOWLY EASTWARD. SCATTERED SNOW SHOWERS ARE EXPECTED
TO BREAK OUT OVER THE SOUTHERN AND EASTERN INTERIOR MON
NIGHT AND TUE.

BRISK EAST WINDS DEVELOPING OVER ST LAWRENCE ISLAND LATE TUE
AFTERNOON OR TUE EVENING...INCREASING TO GALE LATER TUE NIGHT AS A
WEATHER FRONT APPROACHES FROM THE SOUTH. EASTERLY GALES DEVELOPING
TUE IN THE EXTREME WESTERN PARTS OF MARINE ZONE PKZ210.


COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
HEAVY FREEZING SPRAY WARNING FOR PKZ210.

GALE WARNING FOR PKZ245.

SMALL CRAFT ADVISORY FOR PKZ210.

BRISK WIND ADVISORY FOR PKZ220-PKZ225-PKZ240.
&&

$$

RF DEC 14




000
FXAK69 PAFG 211227
AFDAFG

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
327 AM AKST SUN DEC 21 2014

.DISCUSSION...
CURRENT RUNS OF THE GFS/NAM/ECMWF/CANADA NH MODELS ARE IN
GENERALLY GOOD AGREEMENT OUT THROUGH 12Z WED.

UPPER AIR...
ALL OF THE OPERATIONAL MODELS ARE GRADUALLY DEEPENING AN UPPER
TROUGH SOUTHEASTWARD OUT OF SIBERIA AND THE WESTERN ARCTIC OCEAN
THROUGH MON NIGHT...BRINGING A COLDER AIR MASS TO NORTHWEST ALASKA
AND THE NORTHERN PARTS OF THE WEST COAST. THIS MORNING...THE NAM
AND ECMWF ARE FOLLOWING THE LEAD OF THE GFS IN MOVING THE TROUGH
EASTWARD ACROSS THE NORTHERN HALF OF NORTHERN ALASKA THROUGH WED
EVENING...PULLING THE COLDER AIR MASS EASTWARD ACROSS THE
NORTHERN PARTS OF NORTHERN ALASKA.

A PROGRESSIVE UPPER LEVEL RIDGE IS EXPECTED TO BEGIN BUILDING
OVER THE SOUTHERN BERING SEA AND WESTERN ALEUTIANS MON. BY
TUE AFTERNOON THE RIDGE WILL INCREASE CONSIDERABLY IN AMPLITUDE...
EXTENDING FROM EASTERN INTERIOR SIBERIA TO NUNIVAK ISLAND
AND THE ALASKA PENINSULA. BY WED AFTERNOON...THE RIDGE AXIS
WILL EXTENDING FROM THE NORTH COAST OF EASTERN SIBERIA TO
THE BERING STRAIT AND KODIAK ISLAND. A WEAK SHORT WAVE TROUGH
WILL MOVE THROUGH THE SOUTHERN PART OF THE RIDGE TUE NIGHT AND
WED AND LIKELY DAMPEN OUT ON WED. THIS FEATURE IS EXPECTED TO
HAVE LITTLE IF ANY IMPACT IN OUR FORECAST AREA. THE RIDGE
IS EXPECTED TO CONTINUE TO MOVE ACROSS NORTHERN ALASKA WED
AND THU AS A BROAD TROUGH SWINGS NORTHWARD ACROSS THE SOUTHERN
BERING SEA AND THE WEST COAST.

LATE THIS WEEK AND INTO THE WEEKEND...GEFS/NAEFS AND ECMWF
ENSEMBLE MEANS BUILDING A RIDGE OVER THE GULF OF ALASKA AND THE
ALASKA MAINLAND...BY SAT NIGHT THE MEAN RIDGE AXIS EXTENDS FROM
THE WESTERN ARCTIC OCEAN TO THE CENTRAL ARCTIC COAST THEN
SOUTHEASTWARD INTO THE NORTHERN PANHANDLE. SOUTH TO SOUTHWEST
ALOFT FLOW OVER THE NORTHERN ALASKA MAINLAND ON THE BACK SIDE OF
THE RIDGE WILL BRING IN WARMER AIR ALOFT AND AT THE SURFACE. THIS
TREND IS INDICATED IN GFS EXTENDED MOS TEMPERATURES AT MOST
FORECAST SITES TOWARDS THE END OF THE WEEK.

SURFACE...
THE BIGGEST SHORT TERM ISSUE IS WINDS OVER THE CENTRAL AND EASTERN
ARCTIC COAST AND INTERIOR ARCTIC SLOPE. THE 06Z MANUAL SURFACE
ANALYSIS INDICATED A NARROW TROUGH ALONG THE CENTRAL ARCTIC COAST
THEN TO SOUTH OF BARTER ISLAND...WITH A WEAK RIDGE OVER THE
INLAND ARCTIC COAST. THIS PATTERN IS RESULTING IN EASTERLY GALE
FORCE WINDS AT BARTER ISLAND AND MUCH LIGHTER WINDS FARTHER TO THE
WEST. THESE SURFACE FEATURES ARE GENERALLY NOT WELL HANDLED BY THE
MODELS...AND TEND TO BE MORE PERSISTENT THAN MODEL FORECASTS. AT
THIS TIME...LOOKING FOR THIS PATTERN TO HOLD TOGETHER TODAY THEN
BECOMING GRADUALLY SMOOTHED OUT WHICH SHOULD RESULT IN DECREASING
WINDS ALONG THE EASTERN ARCTIC COAST AND IN MARINE ZONE PKZ245.
WINDS ARE EXPECTED TO SHIFT TO LIGHT WESTERLY IN THIS AREA BY MON
WITH A WEAK SURFACE TROUGH PROGGED TO MOVE EASTWARD. IN ANY
EVENT...CONFIDENCE IN THE WIND FORECASTS IN THIS AREA IS BELOW
AVERAGE.

A TIGHT PINCH IN THE ISOBAR FIELD FROM THE NORTHWEST ALASKA CAPES
TO THE BERING STRAIT AND ST LAWRENCE ISLAND IS PRODUCING BRISK
NORTH TO NORTHEAST WINDS IN THESE AREAS...WITH GALE FORCE WINDS AT
TIN CITY AND GALE GUSTS AT POINT HOPE AND WALES. THIS TIGHT
GRADIENT IS EXPECTED TO GRADUALLY RELAX DURING THE NEXT 24
HOURS...RESULTING IN DECREASING WINDS.

LATE EVENING NASA/SPORT NIGHT MICROPHYSICS RGB IMAGE SHOWS
EXTENSIVE LOW STRATUS OVER THE ARCTIC COAST AND MUCH OF THE INLAND
ARCTIC COAST...WITH ONLY A FEW PATCHES ELSEWHERE IN THE INTERIOR.
PRESENCE OF THE STRATUS IN THESE AREAS IS WELL SUPPORTED BY
AVAILABLE SURFACE OBSERVATIONS.

SCATTERED SNOW SHOWERS OVER THE CENTRAL AND WESTERN ARCTIC
COAST AND OVER THE CHUKCHI AND NORTHERN BERING SEAS ARE
EXPECT TO SPREAD SLOWLY EASTWARD ACROSS THE NORTHERN PARTS
OF NORTHERN ALASKA THROUGH TUE AS THE COLD UPPER TROUGH
MARCHES SLOWLY EASTWARD. SCATTERED SNOW SHOWERS ARE EXPECTED
TO BREAK OUT OVER THE SOUTHERN AND EASTERN INTERIOR MON
NIGHT AND TUE.

BRISK EAST WINDS DEVELOPING OVER ST LAWRENCE ISLAND LATE TUE
AFTERNOON OR TUE EVENING...INCREASING TO GALE LATER TUE NIGHT AS A
WEATHER FRONT APPROACHES FROM THE SOUTH. EASTERLY GALES DEVELOPING
TUE IN THE EXTREME WESTERN PARTS OF MARINE ZONE PKZ210.


COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
HEAVY FREEZING SPRAY WARNING FOR PKZ210.

GALE WARNING FOR PKZ245.

SMALL CRAFT ADVISORY FOR PKZ210.

BRISK WIND ADVISORY FOR PKZ220-PKZ225-PKZ240.
&&

$$

RF DEC 14





000
FXAK69 PAFG 211227
AFDAFG

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
327 AM AKST SUN DEC 21 2014

.DISCUSSION...
CURRENT RUNS OF THE GFS/NAM/ECMWF/CANADA NH MODELS ARE IN
GENERALLY GOOD AGREEMENT OUT THROUGH 12Z WED.

UPPER AIR...
ALL OF THE OPERATIONAL MODELS ARE GRADUALLY DEEPENING AN UPPER
TROUGH SOUTHEASTWARD OUT OF SIBERIA AND THE WESTERN ARCTIC OCEAN
THROUGH MON NIGHT...BRINGING A COLDER AIR MASS TO NORTHWEST ALASKA
AND THE NORTHERN PARTS OF THE WEST COAST. THIS MORNING...THE NAM
AND ECMWF ARE FOLLOWING THE LEAD OF THE GFS IN MOVING THE TROUGH
EASTWARD ACROSS THE NORTHERN HALF OF NORTHERN ALASKA THROUGH WED
EVENING...PULLING THE COLDER AIR MASS EASTWARD ACROSS THE
NORTHERN PARTS OF NORTHERN ALASKA.

A PROGRESSIVE UPPER LEVEL RIDGE IS EXPECTED TO BEGIN BUILDING
OVER THE SOUTHERN BERING SEA AND WESTERN ALEUTIANS MON. BY
TUE AFTERNOON THE RIDGE WILL INCREASE CONSIDERABLY IN AMPLITUDE...
EXTENDING FROM EASTERN INTERIOR SIBERIA TO NUNIVAK ISLAND
AND THE ALASKA PENINSULA. BY WED AFTERNOON...THE RIDGE AXIS
WILL EXTENDING FROM THE NORTH COAST OF EASTERN SIBERIA TO
THE BERING STRAIT AND KODIAK ISLAND. A WEAK SHORT WAVE TROUGH
WILL MOVE THROUGH THE SOUTHERN PART OF THE RIDGE TUE NIGHT AND
WED AND LIKELY DAMPEN OUT ON WED. THIS FEATURE IS EXPECTED TO
HAVE LITTLE IF ANY IMPACT IN OUR FORECAST AREA. THE RIDGE
IS EXPECTED TO CONTINUE TO MOVE ACROSS NORTHERN ALASKA WED
AND THU AS A BROAD TROUGH SWINGS NORTHWARD ACROSS THE SOUTHERN
BERING SEA AND THE WEST COAST.

LATE THIS WEEK AND INTO THE WEEKEND...GEFS/NAEFS AND ECMWF
ENSEMBLE MEANS BUILDING A RIDGE OVER THE GULF OF ALASKA AND THE
ALASKA MAINLAND...BY SAT NIGHT THE MEAN RIDGE AXIS EXTENDS FROM
THE WESTERN ARCTIC OCEAN TO THE CENTRAL ARCTIC COAST THEN
SOUTHEASTWARD INTO THE NORTHERN PANHANDLE. SOUTH TO SOUTHWEST
ALOFT FLOW OVER THE NORTHERN ALASKA MAINLAND ON THE BACK SIDE OF
THE RIDGE WILL BRING IN WARMER AIR ALOFT AND AT THE SURFACE. THIS
TREND IS INDICATED IN GFS EXTENDED MOS TEMPERATURES AT MOST
FORECAST SITES TOWARDS THE END OF THE WEEK.

SURFACE...
THE BIGGEST SHORT TERM ISSUE IS WINDS OVER THE CENTRAL AND EASTERN
ARCTIC COAST AND INTERIOR ARCTIC SLOPE. THE 06Z MANUAL SURFACE
ANALYSIS INDICATED A NARROW TROUGH ALONG THE CENTRAL ARCTIC COAST
THEN TO SOUTH OF BARTER ISLAND...WITH A WEAK RIDGE OVER THE
INLAND ARCTIC COAST. THIS PATTERN IS RESULTING IN EASTERLY GALE
FORCE WINDS AT BARTER ISLAND AND MUCH LIGHTER WINDS FARTHER TO THE
WEST. THESE SURFACE FEATURES ARE GENERALLY NOT WELL HANDLED BY THE
MODELS...AND TEND TO BE MORE PERSISTENT THAN MODEL FORECASTS. AT
THIS TIME...LOOKING FOR THIS PATTERN TO HOLD TOGETHER TODAY THEN
BECOMING GRADUALLY SMOOTHED OUT WHICH SHOULD RESULT IN DECREASING
WINDS ALONG THE EASTERN ARCTIC COAST AND IN MARINE ZONE PKZ245.
WINDS ARE EXPECTED TO SHIFT TO LIGHT WESTERLY IN THIS AREA BY MON
WITH A WEAK SURFACE TROUGH PROGGED TO MOVE EASTWARD. IN ANY
EVENT...CONFIDENCE IN THE WIND FORECASTS IN THIS AREA IS BELOW
AVERAGE.

A TIGHT PINCH IN THE ISOBAR FIELD FROM THE NORTHWEST ALASKA CAPES
TO THE BERING STRAIT AND ST LAWRENCE ISLAND IS PRODUCING BRISK
NORTH TO NORTHEAST WINDS IN THESE AREAS...WITH GALE FORCE WINDS AT
TIN CITY AND GALE GUSTS AT POINT HOPE AND WALES. THIS TIGHT
GRADIENT IS EXPECTED TO GRADUALLY RELAX DURING THE NEXT 24
HOURS...RESULTING IN DECREASING WINDS.

LATE EVENING NASA/SPORT NIGHT MICROPHYSICS RGB IMAGE SHOWS
EXTENSIVE LOW STRATUS OVER THE ARCTIC COAST AND MUCH OF THE INLAND
ARCTIC COAST...WITH ONLY A FEW PATCHES ELSEWHERE IN THE INTERIOR.
PRESENCE OF THE STRATUS IN THESE AREAS IS WELL SUPPORTED BY
AVAILABLE SURFACE OBSERVATIONS.

SCATTERED SNOW SHOWERS OVER THE CENTRAL AND WESTERN ARCTIC
COAST AND OVER THE CHUKCHI AND NORTHERN BERING SEAS ARE
EXPECT TO SPREAD SLOWLY EASTWARD ACROSS THE NORTHERN PARTS
OF NORTHERN ALASKA THROUGH TUE AS THE COLD UPPER TROUGH
MARCHES SLOWLY EASTWARD. SCATTERED SNOW SHOWERS ARE EXPECTED
TO BREAK OUT OVER THE SOUTHERN AND EASTERN INTERIOR MON
NIGHT AND TUE.

BRISK EAST WINDS DEVELOPING OVER ST LAWRENCE ISLAND LATE TUE
AFTERNOON OR TUE EVENING...INCREASING TO GALE LATER TUE NIGHT AS A
WEATHER FRONT APPROACHES FROM THE SOUTH. EASTERLY GALES DEVELOPING
TUE IN THE EXTREME WESTERN PARTS OF MARINE ZONE PKZ210.


COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
HEAVY FREEZING SPRAY WARNING FOR PKZ210.

GALE WARNING FOR PKZ245.

SMALL CRAFT ADVISORY FOR PKZ210.

BRISK WIND ADVISORY FOR PKZ220-PKZ225-PKZ240.
&&

$$

RF DEC 14




000
FXAK69 PAFG 211227
AFDAFG

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
327 AM AKST SUN DEC 21 2014

.DISCUSSION...
CURRENT RUNS OF THE GFS/NAM/ECMWF/CANADA NH MODELS ARE IN
GENERALLY GOOD AGREEMENT OUT THROUGH 12Z WED.

UPPER AIR...
ALL OF THE OPERATIONAL MODELS ARE GRADUALLY DEEPENING AN UPPER
TROUGH SOUTHEASTWARD OUT OF SIBERIA AND THE WESTERN ARCTIC OCEAN
THROUGH MON NIGHT...BRINGING A COLDER AIR MASS TO NORTHWEST ALASKA
AND THE NORTHERN PARTS OF THE WEST COAST. THIS MORNING...THE NAM
AND ECMWF ARE FOLLOWING THE LEAD OF THE GFS IN MOVING THE TROUGH
EASTWARD ACROSS THE NORTHERN HALF OF NORTHERN ALASKA THROUGH WED
EVENING...PULLING THE COLDER AIR MASS EASTWARD ACROSS THE
NORTHERN PARTS OF NORTHERN ALASKA.

A PROGRESSIVE UPPER LEVEL RIDGE IS EXPECTED TO BEGIN BUILDING
OVER THE SOUTHERN BERING SEA AND WESTERN ALEUTIANS MON. BY
TUE AFTERNOON THE RIDGE WILL INCREASE CONSIDERABLY IN AMPLITUDE...
EXTENDING FROM EASTERN INTERIOR SIBERIA TO NUNIVAK ISLAND
AND THE ALASKA PENINSULA. BY WED AFTERNOON...THE RIDGE AXIS
WILL EXTENDING FROM THE NORTH COAST OF EASTERN SIBERIA TO
THE BERING STRAIT AND KODIAK ISLAND. A WEAK SHORT WAVE TROUGH
WILL MOVE THROUGH THE SOUTHERN PART OF THE RIDGE TUE NIGHT AND
WED AND LIKELY DAMPEN OUT ON WED. THIS FEATURE IS EXPECTED TO
HAVE LITTLE IF ANY IMPACT IN OUR FORECAST AREA. THE RIDGE
IS EXPECTED TO CONTINUE TO MOVE ACROSS NORTHERN ALASKA WED
AND THU AS A BROAD TROUGH SWINGS NORTHWARD ACROSS THE SOUTHERN
BERING SEA AND THE WEST COAST.

LATE THIS WEEK AND INTO THE WEEKEND...GEFS/NAEFS AND ECMWF
ENSEMBLE MEANS BUILDING A RIDGE OVER THE GULF OF ALASKA AND THE
ALASKA MAINLAND...BY SAT NIGHT THE MEAN RIDGE AXIS EXTENDS FROM
THE WESTERN ARCTIC OCEAN TO THE CENTRAL ARCTIC COAST THEN
SOUTHEASTWARD INTO THE NORTHERN PANHANDLE. SOUTH TO SOUTHWEST
ALOFT FLOW OVER THE NORTHERN ALASKA MAINLAND ON THE BACK SIDE OF
THE RIDGE WILL BRING IN WARMER AIR ALOFT AND AT THE SURFACE. THIS
TREND IS INDICATED IN GFS EXTENDED MOS TEMPERATURES AT MOST
FORECAST SITES TOWARDS THE END OF THE WEEK.

SURFACE...
THE BIGGEST SHORT TERM ISSUE IS WINDS OVER THE CENTRAL AND EASTERN
ARCTIC COAST AND INTERIOR ARCTIC SLOPE. THE 06Z MANUAL SURFACE
ANALYSIS INDICATED A NARROW TROUGH ALONG THE CENTRAL ARCTIC COAST
THEN TO SOUTH OF BARTER ISLAND...WITH A WEAK RIDGE OVER THE
INLAND ARCTIC COAST. THIS PATTERN IS RESULTING IN EASTERLY GALE
FORCE WINDS AT BARTER ISLAND AND MUCH LIGHTER WINDS FARTHER TO THE
WEST. THESE SURFACE FEATURES ARE GENERALLY NOT WELL HANDLED BY THE
MODELS...AND TEND TO BE MORE PERSISTENT THAN MODEL FORECASTS. AT
THIS TIME...LOOKING FOR THIS PATTERN TO HOLD TOGETHER TODAY THEN
BECOMING GRADUALLY SMOOTHED OUT WHICH SHOULD RESULT IN DECREASING
WINDS ALONG THE EASTERN ARCTIC COAST AND IN MARINE ZONE PKZ245.
WINDS ARE EXPECTED TO SHIFT TO LIGHT WESTERLY IN THIS AREA BY MON
WITH A WEAK SURFACE TROUGH PROGGED TO MOVE EASTWARD. IN ANY
EVENT...CONFIDENCE IN THE WIND FORECASTS IN THIS AREA IS BELOW
AVERAGE.

A TIGHT PINCH IN THE ISOBAR FIELD FROM THE NORTHWEST ALASKA CAPES
TO THE BERING STRAIT AND ST LAWRENCE ISLAND IS PRODUCING BRISK
NORTH TO NORTHEAST WINDS IN THESE AREAS...WITH GALE FORCE WINDS AT
TIN CITY AND GALE GUSTS AT POINT HOPE AND WALES. THIS TIGHT
GRADIENT IS EXPECTED TO GRADUALLY RELAX DURING THE NEXT 24
HOURS...RESULTING IN DECREASING WINDS.

LATE EVENING NASA/SPORT NIGHT MICROPHYSICS RGB IMAGE SHOWS
EXTENSIVE LOW STRATUS OVER THE ARCTIC COAST AND MUCH OF THE INLAND
ARCTIC COAST...WITH ONLY A FEW PATCHES ELSEWHERE IN THE INTERIOR.
PRESENCE OF THE STRATUS IN THESE AREAS IS WELL SUPPORTED BY
AVAILABLE SURFACE OBSERVATIONS.

SCATTERED SNOW SHOWERS OVER THE CENTRAL AND WESTERN ARCTIC
COAST AND OVER THE CHUKCHI AND NORTHERN BERING SEAS ARE
EXPECT TO SPREAD SLOWLY EASTWARD ACROSS THE NORTHERN PARTS
OF NORTHERN ALASKA THROUGH TUE AS THE COLD UPPER TROUGH
MARCHES SLOWLY EASTWARD. SCATTERED SNOW SHOWERS ARE EXPECTED
TO BREAK OUT OVER THE SOUTHERN AND EASTERN INTERIOR MON
NIGHT AND TUE.

BRISK EAST WINDS DEVELOPING OVER ST LAWRENCE ISLAND LATE TUE
AFTERNOON OR TUE EVENING...INCREASING TO GALE LATER TUE NIGHT AS A
WEATHER FRONT APPROACHES FROM THE SOUTH. EASTERLY GALES DEVELOPING
TUE IN THE EXTREME WESTERN PARTS OF MARINE ZONE PKZ210.


COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
HEAVY FREEZING SPRAY WARNING FOR PKZ210.

GALE WARNING FOR PKZ245.

SMALL CRAFT ADVISORY FOR PKZ210.

BRISK WIND ADVISORY FOR PKZ220-PKZ225-PKZ240.
&&

$$

RF DEC 14





000
FXAK69 PAFG 202059
AFDAFG

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
1159 AM AKST SAT DEC 20 2014

.DISCUSSION...
DETERMINISTIC GUIDANCE ARE GENERALLY IN GOOD AGREEMENT WITH THE
LARGE SCALE PATTERN OUT TO 60-72 HRS. CONCERNS TODAY INCLUDE
MODERATE WINDS ACROSS THE BERING SEA/BERING STRAIT AND
COASTS...WITH GUSTS UP TO 40 MPH BEING OBSERVED AT TIMES AT POINT
HOPE...GAMBELL...AND CAPE ROMANZOFF. THE STRONGEST OF WHICH IS
BEING RECORED NEAR POINT HOPE.

ALSO FOG/STRATUS IS OBSERVED OVER THE NORTH SLOPE AND PORTIONS OF
THE INTERIOR AND WEST COAST THIS MORNING. FOG/STRATUS IS DEPICTED
FAIRLY WELL BY THE NASA SPORT NIGHTTIME MICROPHYSICS IMAGERY THIS
MORNING. IMAGERY SHOWS FOG/STRATUS CONFINED GENERALLY TO THE NORTH
SLOPE...NORTHERN HALF OF THE WEST COAST ZONES...AND OVER SMALL
SECTIONS OF THE AK INTERIOR. OBS INDICATE MAINLY STRATUS IN THE
INTERIOR...WITH FOG MORE PREVALENT OVER THE NORTH SLOPE.

.ALOFT...

BROAD 500 HPA LONGWAVE TROUGH IS POSITIONED OVER THE WESTERN TWO-
THIRDS OF AK WITH A RIDGE OVER NORTHERN AK. RIDGE IS POSITIONED
ACROSS THE NORTHWEST TERRITORIES AND YUKON. TROUGH WILL STAY
RELATIVE STATIONARY IN LOCATION WHILE WEAKENING THE NEXT 48 HRS AS
THE PATTERN ALOFT BECOMES MORE PROGRESSIVE. A RIDGE CURRENTLY JUST
SOUTH OF KAMCHATKA PENINSULA WILL BUILD AND MOVE EAST TOWARD THE
MIDDLE OF THE ALEUTIAN ISLANDS BY EARLY MON. RIDGE THEN MOVES EAST
INTO THE EASTERN ALEUTIAN ISLANDS BY EARLY TUE...THIS IS WHERE
DIFFERENCES START TO BECOME MORE APPARENT IN THE LARGE SCALE
PATTERN.

GFS BECOMES MORE BULLISH WITH THE 500 HPA TROUGH WHILE IT LIFTS
THE TROUGH NORTH ABOUT 60 HRS OUT LATE MON/EARLY TUE.
WHEREIN...THE TROUGH BASE BECOMES TILTED MORE NEGATIVE AT THIS
POINT AS WELL. 500 HPA HEIGHT FALLS OF AROUND 15-25 DAM ARE SEEN
IN THE GFS AND NAM COMPARED TO LESSER HEIGHT FALLS IN THE ECMWF.
THIS TRANSLATES TO A MORE COMPACT SFC LOW ON THE NAM AND GFS LATE
MON...COMPARED TO THE ECMWF...THAT WILL BE MOVING NORTHEAST INTO
SE AK EARLY TUE. GUIDANCE ARE SIMILAR IN MOVING THE TROUGH EAST
ACROSS MUCH OF NORTHERN AK BY THU...WITH THE GFS KEEPING THE
TROUGH STRONGER IN AMPLITUDE AND FARTHER SOUTH COMPARED TO THE
ECMWF.

MEANWHILE...COLDER AIR WILL BEGIN TO PENETRATE THE WEST COAST MON
AS THE TROUGH BEGINS TO LIFT NORTH. GFS IS A BIT COLDER AND MORE
BULLISH WITH HOW FAR THE COLD AIR PENETRATES INTO NORTHERN AK
HOWEVER...DIFFERENCES BETWEEN THE ECMWF ARE NOT THAT
GREAT...GENERALLY 3 TO 5 C.

.SURFACE...

A BROAD SFC LOW EXISTS SOUTH OF MAINLAND ALASKA AND THE ALEUTIAN
ISLANDS WITH MULTIPLE CENTERS ANALYZED...THE STRONGEST ABOUT 927
MB. THIS AREA OF LOW PRESSURE WILL WEAKEN AND BECOME MORE COMPACT
THE NEXT 48 HRS OVER THE GULF OF ALASKA. A NEW SFC LOW DEVELOPS IN
THE NORTHERN PACIFIC AS THE MID-LEVEL TROUGH ALOFT LIFTS NORTH AND
BECOMES MORE NEGATIVELY TILTED AT ITS BASE...BEGINNING ABOUT 54
HRS OUT. AS THE SFC LOW MOVES NORTHEAST INTO SE ALASKA TUE...LOW
PRESSURE WILL BEGIN BUILDING INTO THE INTERIOR.

HIGH PRESSURE CURRENTLY ACROSS THE ARCTIC OCEAN WILL MOVE INTO
THE CANADIAN ARCHIPELAGO BY MON. MEANWHILE...HIGH PRESSURE ACROSS
EASTERN SIBERIA WILL SPREAD INTO BERING AND CHUKCHI SEA AS WELL.

GUIDANCE ARE IN FAIR AGREEMENT WITH LOW PRESSURE DEVELOPING IN
THE WESTERN BERING SEA LATE MON/EARLY TUE. OUTSIDE OF A TROUGH OF
LOW PRESSURE EXTENDING FROM THE SFC LOW MOVING NORTH INTO NORTHERN
ALASKA...ITS CENTER IS NOT EXPECTED TO MOVE EAST MUCH BY WED.

WINDS ARE EXPECTED TO STAY ELEVATED OVER THE BERING SEA-BERING
STRAIT-EXTREME SOUTHERN END OF CHUKCHI SEA THE NEXT 36 HOURS AS
THE GRADIENT STAYS STRONG THERE. LOCAL WINDS...TANANA VALLEY
JET AND WINDS OVER THE NE YUKON FLATS...SHOULD BEGIN TO RELAX THE
NEXT 24 HRS AS LOW PRESSURE IN THE GULF OF ALASKA WEAKENS.

IN REGARD TO PRECIPITATION...DRY CONDITIONS EXPECT OVER THE NEXT
24 HRS OVER INTERIOR AK...WITH FLURRIES OR SNOW SHOWERS EXPECT
OVER THE NORTH SLOPE AND THE WEST COAST. A FEW SHORT-WAVE TROUGHS
WITH MODERATE VORT MAXES WILL TRAVERSE THE NORTH SLOPE...WEST
COAST...AND WESTERN INTERIOR MON AND PROVIDE INCREASE CHANCES FOR
SNOW. INCREASE CHANCES FOR SNOW ARE EXPECTED ON TUE OVER THE REST
OF THE INTERIOR AS THE AFOREMENTIONED 500 HPA TROUGH ALOFT BEGINS
TO LIFT AND MOVE EAST ACROSS NORTHERN AK.

COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
HEAVY FREEZING SPRAY WARNING FOR PKZ210.

SMALL CRAFT ADVISORY FOR PKZ210.

BRISK WIND ADVISORY FOR PKZ220-PKZ225-PKZ240-PKZ245.
&&

$$

ET DEC 14




000
FXAK69 PAFG 202059
AFDAFG

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
1159 AM AKST SAT DEC 20 2014

.DISCUSSION...
DETERMINISTIC GUIDANCE ARE GENERALLY IN GOOD AGREEMENT WITH THE
LARGE SCALE PATTERN OUT TO 60-72 HRS. CONCERNS TODAY INCLUDE
MODERATE WINDS ACROSS THE BERING SEA/BERING STRAIT AND
COASTS...WITH GUSTS UP TO 40 MPH BEING OBSERVED AT TIMES AT POINT
HOPE...GAMBELL...AND CAPE ROMANZOFF. THE STRONGEST OF WHICH IS
BEING RECORED NEAR POINT HOPE.

ALSO FOG/STRATUS IS OBSERVED OVER THE NORTH SLOPE AND PORTIONS OF
THE INTERIOR AND WEST COAST THIS MORNING. FOG/STRATUS IS DEPICTED
FAIRLY WELL BY THE NASA SPORT NIGHTTIME MICROPHYSICS IMAGERY THIS
MORNING. IMAGERY SHOWS FOG/STRATUS CONFINED GENERALLY TO THE NORTH
SLOPE...NORTHERN HALF OF THE WEST COAST ZONES...AND OVER SMALL
SECTIONS OF THE AK INTERIOR. OBS INDICATE MAINLY STRATUS IN THE
INTERIOR...WITH FOG MORE PREVALENT OVER THE NORTH SLOPE.

.ALOFT...

BROAD 500 HPA LONGWAVE TROUGH IS POSITIONED OVER THE WESTERN TWO-
THIRDS OF AK WITH A RIDGE OVER NORTHERN AK. RIDGE IS POSITIONED
ACROSS THE NORTHWEST TERRITORIES AND YUKON. TROUGH WILL STAY
RELATIVE STATIONARY IN LOCATION WHILE WEAKENING THE NEXT 48 HRS AS
THE PATTERN ALOFT BECOMES MORE PROGRESSIVE. A RIDGE CURRENTLY JUST
SOUTH OF KAMCHATKA PENINSULA WILL BUILD AND MOVE EAST TOWARD THE
MIDDLE OF THE ALEUTIAN ISLANDS BY EARLY MON. RIDGE THEN MOVES EAST
INTO THE EASTERN ALEUTIAN ISLANDS BY EARLY TUE...THIS IS WHERE
DIFFERENCES START TO BECOME MORE APPARENT IN THE LARGE SCALE
PATTERN.

GFS BECOMES MORE BULLISH WITH THE 500 HPA TROUGH WHILE IT LIFTS
THE TROUGH NORTH ABOUT 60 HRS OUT LATE MON/EARLY TUE.
WHEREIN...THE TROUGH BASE BECOMES TILTED MORE NEGATIVE AT THIS
POINT AS WELL. 500 HPA HEIGHT FALLS OF AROUND 15-25 DAM ARE SEEN
IN THE GFS AND NAM COMPARED TO LESSER HEIGHT FALLS IN THE ECMWF.
THIS TRANSLATES TO A MORE COMPACT SFC LOW ON THE NAM AND GFS LATE
MON...COMPARED TO THE ECMWF...THAT WILL BE MOVING NORTHEAST INTO
SE AK EARLY TUE. GUIDANCE ARE SIMILAR IN MOVING THE TROUGH EAST
ACROSS MUCH OF NORTHERN AK BY THU...WITH THE GFS KEEPING THE
TROUGH STRONGER IN AMPLITUDE AND FARTHER SOUTH COMPARED TO THE
ECMWF.

MEANWHILE...COLDER AIR WILL BEGIN TO PENETRATE THE WEST COAST MON
AS THE TROUGH BEGINS TO LIFT NORTH. GFS IS A BIT COLDER AND MORE
BULLISH WITH HOW FAR THE COLD AIR PENETRATES INTO NORTHERN AK
HOWEVER...DIFFERENCES BETWEEN THE ECMWF ARE NOT THAT
GREAT...GENERALLY 3 TO 5 C.

.SURFACE...

A BROAD SFC LOW EXISTS SOUTH OF MAINLAND ALASKA AND THE ALEUTIAN
ISLANDS WITH MULTIPLE CENTERS ANALYZED...THE STRONGEST ABOUT 927
MB. THIS AREA OF LOW PRESSURE WILL WEAKEN AND BECOME MORE COMPACT
THE NEXT 48 HRS OVER THE GULF OF ALASKA. A NEW SFC LOW DEVELOPS IN
THE NORTHERN PACIFIC AS THE MID-LEVEL TROUGH ALOFT LIFTS NORTH AND
BECOMES MORE NEGATIVELY TILTED AT ITS BASE...BEGINNING ABOUT 54
HRS OUT. AS THE SFC LOW MOVES NORTHEAST INTO SE ALASKA TUE...LOW
PRESSURE WILL BEGIN BUILDING INTO THE INTERIOR.

HIGH PRESSURE CURRENTLY ACROSS THE ARCTIC OCEAN WILL MOVE INTO
THE CANADIAN ARCHIPELAGO BY MON. MEANWHILE...HIGH PRESSURE ACROSS
EASTERN SIBERIA WILL SPREAD INTO BERING AND CHUKCHI SEA AS WELL.

GUIDANCE ARE IN FAIR AGREEMENT WITH LOW PRESSURE DEVELOPING IN
THE WESTERN BERING SEA LATE MON/EARLY TUE. OUTSIDE OF A TROUGH OF
LOW PRESSURE EXTENDING FROM THE SFC LOW MOVING NORTH INTO NORTHERN
ALASKA...ITS CENTER IS NOT EXPECTED TO MOVE EAST MUCH BY WED.

WINDS ARE EXPECTED TO STAY ELEVATED OVER THE BERING SEA-BERING
STRAIT-EXTREME SOUTHERN END OF CHUKCHI SEA THE NEXT 36 HOURS AS
THE GRADIENT STAYS STRONG THERE. LOCAL WINDS...TANANA VALLEY
JET AND WINDS OVER THE NE YUKON FLATS...SHOULD BEGIN TO RELAX THE
NEXT 24 HRS AS LOW PRESSURE IN THE GULF OF ALASKA WEAKENS.

IN REGARD TO PRECIPITATION...DRY CONDITIONS EXPECT OVER THE NEXT
24 HRS OVER INTERIOR AK...WITH FLURRIES OR SNOW SHOWERS EXPECT
OVER THE NORTH SLOPE AND THE WEST COAST. A FEW SHORT-WAVE TROUGHS
WITH MODERATE VORT MAXES WILL TRAVERSE THE NORTH SLOPE...WEST
COAST...AND WESTERN INTERIOR MON AND PROVIDE INCREASE CHANCES FOR
SNOW. INCREASE CHANCES FOR SNOW ARE EXPECTED ON TUE OVER THE REST
OF THE INTERIOR AS THE AFOREMENTIONED 500 HPA TROUGH ALOFT BEGINS
TO LIFT AND MOVE EAST ACROSS NORTHERN AK.

COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
HEAVY FREEZING SPRAY WARNING FOR PKZ210.

SMALL CRAFT ADVISORY FOR PKZ210.

BRISK WIND ADVISORY FOR PKZ220-PKZ225-PKZ240-PKZ245.
&&

$$

ET DEC 14





000
FXAK69 PAFG 201543 AAA
AFDAFG

NORTHERN ALASKA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE FAIRBANKS AK
643 AM AKST SAT DEC 20 2014

.DISCUSSION...
CURRENT OPERATIONAL MODELS AND ENSEMBLE MEANS INDICATE A
CONTINUATION OF A BENIGN WEATHER PATTERN OVER THE NORTHERN
ALASKA MAINLAND FOR THE UPCOMING WEEK.

UPPER AIR...
A WEAK UPPER LEVEL RIDGE EXTENDING EAST-WEST ACROSS THE NORTHERN
ALASKA INTERIOR WILL GRADUALLY BECOME REORIENTED NORTH-SOUTH ALONG
OR NEAR THE ALCAN BORDER BY SUN AFTERNOON. A WEAK LOW PRESSURE
TROUGH OVER CENTRAL SIBERIA WILL MOVE EASTWARD TO NORTHWEST ALASKA
AND THE WEST COAST BY TUE...BRINGING A COLDER AIR MASS ALOFT TO
THESE AREAS. CURRENT MODELS APPEAR TO BE IN GOOD AGREEMENT ON THE
HANDLING OF THIS FEATURE OUT THROUGH TUE. BEYOND TUE...THE GFS
CONTINUES TO BE MORE BULLISH THAN THE ECMWF MOVING THE TROUGH
EASTWARD ACROSS THE NORTHERN MAINLAND...DRAGGING THE COLDER AIR
WITH IT. THIS SOLUTION APPEARS TO BE AN OUTLIER...OPERATIONAL
ECMWF AND THE GFS/ECMWF/NAEFS ENSEMBLE MEANS INDICATING A WEAK
SOUTHWEST FLOW PATTERN PREDOMINATING...WITH WARMER TEMPERATURE
ALOFT.

IN DAYS 7-10..OPERATIONAL GFS/ECMWF BUILDING A STRONG UPPER
HIGH BUT DIFFER ON PLACEMENT...GFS BUILDS THE RIDGE AXIS OVER NW
CANADA WITH SOUTHERLY FLOW ACROSS MAINLAND ALASKA...ECMWF
BUILDS THE HIGH OVER SOUTHCENTRAL ALASKA...WESTERN INTERIOR
AND NORTHWEST ALASKA WITH THE EXTREME ASTERN INTERIOR ON
THE COLDER NORTHERLY FLOW SIDE OF THE RIDGE. BOTH MODELS
INDICATE HEIGHTS APPROACHING 654 DECAMETERS IN THE CORE
OF THE HIGH CENTER.

SURFACE...
A HIGH PRESSURE RIDGE EXTENDING EAST-WEST ACROSS THE ARCTIC OCEAN
WILL RECEDE NORTHEASTWARD INTO THE CANADIAN ARCHIPELAGO BY MON
NIGHT. A BROAD BUT RATHER WEAK LOW PRESSURE TROUGH WILL EXPAND
NORTHWARD ACROSS THE NORTHERN ALASKA MAINLAND AND INTO
THE WESTERN BEAUFORT SEA BY MON MORNING. THESE TWO FACTORS WILL
COMBINE TO RESULT IN GRADUALLY DECREASING WINDS OVER THE ARCTIC
COAST...CHUKCHI SEA AND BERING SEA. WINDS OVER THE FORECAST AREA
ARE EXPECTED TO BE GENERALLY LIGHT BY TUE MORNING.

CURRENT GFS AND ECMWF AGREE IN THE DEVELOPMENT OF A MODERATELY
STRONG LOW TO BE NEAR OR NORTHWEST OF SHEMYA BY 12Z TUE. FOR TUE
AND BEYOND...OPERATIONAL GFS/ECMWF RUNS DIVERGE OVER THE BERING
SEA. GFS/ECMWF MEANS SHOW A MEAN LOW CENTER OVER THE FAR WESTERN
BERING WITH A TROUGH EXTENDING EASTWARD TO BRISTOL BAY BY THU.
THERE IS A POSSIBILITY OF MINIMUM BRISK WINDS OVER ST LAWRENCE
ISLAND AND MARINE ZONE PKZ210 TUE INTO THU...BUT THE PROBABILITY
OF GALE FORCE WINDS APPEARS TO BE LOW.

NEAR THE END OF NEXT WEEK...GFS/ECMWF DIFFER ON THE DETAILS
BUT ALLUDE TO A MORE ACTIVE WEATHER PATTERN OVER THE
BERING SEA WITH GALE FORCE WINDS POSSIBLE.

IN THE SHORT TERM...AREAS OF STRATUS LIKELY PERSISTING OVER
THE EASTERN AND NORTHEASTERN INTERIOR...AND THE CENTRAL AND
EASTERN ARCTIC SLOPE. GOES IR AND NIGHTTIME RGB MICROPHYSICS FROM
POLAR SATELLITES SHOWING WIDESPREAD STRATUS OVER ZONE
224...PATCHES OF STRATUS ELSEWHERE OVER THE EASTERN AND NORTHEAST
INTERIOR...WIDESPREAD STRATUS OVER THE CENTRAL/EASTERN ARCTIC
COAST.




COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
HEAVY FREEZING SPRAY WARNING FOR PKZ210.

SMALL CRAFT ADVISORY FOR PKZ210.

BRISK WIND ADVISORY FOR PKZ220.
&&

$$

DEC 14





000
FXAK69 PAFG 201543 AAA
AFDAFG

NORTHERN ALASKA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE FAIRBANKS AK
643 AM AKST SAT DEC 20 2014

.DISCUSSION...
CURRENT OPERATIONAL MODELS AND ENSEMBLE MEANS INDICATE A
CONTINUATION OF A BENIGN WEATHER PATTERN OVER THE NORTHERN
ALASKA MAINLAND FOR THE UPCOMING WEEK.

UPPER AIR...
A WEAK UPPER LEVEL RIDGE EXTENDING EAST-WEST ACROSS THE NORTHERN
ALASKA INTERIOR WILL GRADUALLY BECOME REORIENTED NORTH-SOUTH ALONG
OR NEAR THE ALCAN BORDER BY SUN AFTERNOON. A WEAK LOW PRESSURE
TROUGH OVER CENTRAL SIBERIA WILL MOVE EASTWARD TO NORTHWEST ALASKA
AND THE WEST COAST BY TUE...BRINGING A COLDER AIR MASS ALOFT TO
THESE AREAS. CURRENT MODELS APPEAR TO BE IN GOOD AGREEMENT ON THE
HANDLING OF THIS FEATURE OUT THROUGH TUE. BEYOND TUE...THE GFS
CONTINUES TO BE MORE BULLISH THAN THE ECMWF MOVING THE TROUGH
EASTWARD ACROSS THE NORTHERN MAINLAND...DRAGGING THE COLDER AIR
WITH IT. THIS SOLUTION APPEARS TO BE AN OUTLIER...OPERATIONAL
ECMWF AND THE GFS/ECMWF/NAEFS ENSEMBLE MEANS INDICATING A WEAK
SOUTHWEST FLOW PATTERN PREDOMINATING...WITH WARMER TEMPERATURE
ALOFT.

IN DAYS 7-10..OPERATIONAL GFS/ECMWF BUILDING A STRONG UPPER
HIGH BUT DIFFER ON PLACEMENT...GFS BUILDS THE RIDGE AXIS OVER NW
CANADA WITH SOUTHERLY FLOW ACROSS MAINLAND ALASKA...ECMWF
BUILDS THE HIGH OVER SOUTHCENTRAL ALASKA...WESTERN INTERIOR
AND NORTHWEST ALASKA WITH THE EXTREME ASTERN INTERIOR ON
THE COLDER NORTHERLY FLOW SIDE OF THE RIDGE. BOTH MODELS
INDICATE HEIGHTS APPROACHING 654 DECAMETERS IN THE CORE
OF THE HIGH CENTER.

SURFACE...
A HIGH PRESSURE RIDGE EXTENDING EAST-WEST ACROSS THE ARCTIC OCEAN
WILL RECEDE NORTHEASTWARD INTO THE CANADIAN ARCHIPELAGO BY MON
NIGHT. A BROAD BUT RATHER WEAK LOW PRESSURE TROUGH WILL EXPAND
NORTHWARD ACROSS THE NORTHERN ALASKA MAINLAND AND INTO
THE WESTERN BEAUFORT SEA BY MON MORNING. THESE TWO FACTORS WILL
COMBINE TO RESULT IN GRADUALLY DECREASING WINDS OVER THE ARCTIC
COAST...CHUKCHI SEA AND BERING SEA. WINDS OVER THE FORECAST AREA
ARE EXPECTED TO BE GENERALLY LIGHT BY TUE MORNING.

CURRENT GFS AND ECMWF AGREE IN THE DEVELOPMENT OF A MODERATELY
STRONG LOW TO BE NEAR OR NORTHWEST OF SHEMYA BY 12Z TUE. FOR TUE
AND BEYOND...OPERATIONAL GFS/ECMWF RUNS DIVERGE OVER THE BERING
SEA. GFS/ECMWF MEANS SHOW A MEAN LOW CENTER OVER THE FAR WESTERN
BERING WITH A TROUGH EXTENDING EASTWARD TO BRISTOL BAY BY THU.
THERE IS A POSSIBILITY OF MINIMUM BRISK WINDS OVER ST LAWRENCE
ISLAND AND MARINE ZONE PKZ210 TUE INTO THU...BUT THE PROBABILITY
OF GALE FORCE WINDS APPEARS TO BE LOW.

NEAR THE END OF NEXT WEEK...GFS/ECMWF DIFFER ON THE DETAILS
BUT ALLUDE TO A MORE ACTIVE WEATHER PATTERN OVER THE
BERING SEA WITH GALE FORCE WINDS POSSIBLE.

IN THE SHORT TERM...AREAS OF STRATUS LIKELY PERSISTING OVER
THE EASTERN AND NORTHEASTERN INTERIOR...AND THE CENTRAL AND
EASTERN ARCTIC SLOPE. GOES IR AND NIGHTTIME RGB MICROPHYSICS FROM
POLAR SATELLITES SHOWING WIDESPREAD STRATUS OVER ZONE
224...PATCHES OF STRATUS ELSEWHERE OVER THE EASTERN AND NORTHEAST
INTERIOR...WIDESPREAD STRATUS OVER THE CENTRAL/EASTERN ARCTIC
COAST.




COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
HEAVY FREEZING SPRAY WARNING FOR PKZ210.

SMALL CRAFT ADVISORY FOR PKZ210.

BRISK WIND ADVISORY FOR PKZ220.
&&

$$

DEC 14




000
FXAK69 PAFG 201147
AFDAFG

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
247 AM AKST SAT DEC 20 2014

.DISCUSSION...
CURRENT OPERATIONAL MODELS AND ENSEMBLE MEANS INDICATE A
CONTINUATION OF A BENIGN WEATHER PATTERN OVER THE NORTHERN
ALASKA MAINLAND FOR THE UPCOMING WEEK.

UPPER AIR...
A WEAK UPPER LEVEL RIDGE EXTENDING EAST-WEST ACROSS THE NORTHERN
ALASKA INTERIOR WILL GRADUALLY BECOME REORIENTED NORTH-SOUTH ALONG
OR NEAR THE ALCAN BORDER BY SUN AFTERNOON. A WEAK LOW PRESSURE
TROUGH OVER CENTRAL SIBERIA WILL MOVE EASTWARD TO NORTHWEST ALASKA
AND THE WEST COAST BY TUE...BRINGING A COLDER AIR MASS ALOFT TO
THESE AREAS. CURRENT MODELS APPEAR TO BE IN GOOD AGREEMENT ON THE
HANDLING OF THIS FEATURE OUT THROUGH TUE. BEYOND TUE...THE GFS
CONTINUES TO BE MORE BULLISH THAN THE ECMWF MOVING THE TROUGH
EASTWARD ACROSS THE NORTHERN MAINLAND...DRAGGING THE COLDER AIR
WITH IT. THIS SOLUTION APPEARS TO BE AN OUTLIER...OPERATIONAL
ECMWF AND THE GFS/ECMWF/NAEFS ENSEMBLE MEANS INDICATING A WEAK
SOUTHWEST FLOW PATTERN PREDOMINATING...WITH WARMER TEMPERATURE
ALOFT.

SURFACE...
A HIGH PRESSURE RIDGE EXTENDING EAST-WEST ACROSS THE ARCTIC OCEAN
WILL RECEDE NORTHEASTWARD INTO THE CANADIAN ARCHIPELAGO BY MON
NIGHT. A BROAD BUT RATHER WEAK LOW PRESSURE TROUGH WILL EXPAND
NORTHWARD ACROSS THE NORTHERN ALASKA MAINLAND AND INTO
THE WESTERN BEAUFORT SEA BY MON MORNING. THESE TWO FACTORS WILL
COMBINE TO RESULT IN GRADUALLY DECREASING WINDS OVER THE ARCTIC
COAST...CHUKCHI SEA AND BERING SEA. WINDS OVER THE FORECAST AREA
ARE EXPECTED TO BE GENERALLY LIGHT BY TUE MORNING.

CURRENT GFS AND ECMWF AGREE IN THE DEVELOPMENT OF A MODERATELY
STRONG LOW TO BE NEAR OR NORTHWEST OF SHEMYA BY 12Z TUE. FOR TUE
AND BEYOND...OPERATIONAL GFS/ECMWF RUNS DIVERGE OVER THE BERING
SEA. GFS/ECMWF MEANS SHOW A MEAN LOW CENTER OVER THE FAR WESTERN
BERING WITH A TROUGH EXTENDING EASTWARD TO BRISTOL BAY BY THU.
THERE IS A POSSIBILITY OF MINIMUM BRISK WINDS OVER ST LAWRENCE
ISLAND AND MARINE ZONE PKZ210 TUE INTO THU...BUT THE PROBABILITY
OF GALE FORCE WINDS APPEARS TO BE LOW.

NEAR THE END OF NEXT WEEK...GFS/ECMWF DIFFER ON THE DETAILS
BUT ALLUDE TO A MORE ACTIVE WEATHER PATTERN OVER THE
BERING SEA WITH GALE FORCE WINDS POSSIBLE.

IN THE SHORT TERM...AREAS OF STRATUS LIKELY PERSISTING OVER
THE EASTERN AND NORTHEASTERN INTERIOR...AND THE CENTRAL AND
EASTERN ARCTIC SLOPE. GOES IR AND NIGHTTIME RGB MICROPHYSICS FROM
POLAR SATELLITES SHOWING WIDESPREAD STRATUS OVER ZONE
224...PATCHES OF STRATUS ELSEWHERE IN PARTS OF THE EASTERN AND
NORTHEAST INTERIOR...WIDESPREAD STRATUS OVER THE CENTRAL/EASTERN
ARCTIC COAST. SCATTERED FLURRIES AND/OR SNOW SHOWERS OVER THE
CENTRAL/WESTERN ARCTIC COAST TODAY AND TONIGHT...AND OVER THE
WESTERN ARCTIC COAST SUN. SCATTERED FLURRIES IN ZONES 224/EASTERN
ZONES 226 TODAY AND TONIGHT...AND IN ZONES 219-222-PARTS OF
ZONES 216-220-221 SUN.


COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
HEAVY FREEZING SPRAY WARNING FOR PKZ210.

SMALL CRAFT ADVISORY FOR PKZ210.

BRISK WIND ADVISORY FOR PKZ220.
&&

$$

RF DEC 14





000
FXAK69 PAFG 201147
AFDAFG

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
247 AM AKST SAT DEC 20 2014

.DISCUSSION...
CURRENT OPERATIONAL MODELS AND ENSEMBLE MEANS INDICATE A
CONTINUATION OF A BENIGN WEATHER PATTERN OVER THE NORTHERN
ALASKA MAINLAND FOR THE UPCOMING WEEK.

UPPER AIR...
A WEAK UPPER LEVEL RIDGE EXTENDING EAST-WEST ACROSS THE NORTHERN
ALASKA INTERIOR WILL GRADUALLY BECOME REORIENTED NORTH-SOUTH ALONG
OR NEAR THE ALCAN BORDER BY SUN AFTERNOON. A WEAK LOW PRESSURE
TROUGH OVER CENTRAL SIBERIA WILL MOVE EASTWARD TO NORTHWEST ALASKA
AND THE WEST COAST BY TUE...BRINGING A COLDER AIR MASS ALOFT TO
THESE AREAS. CURRENT MODELS APPEAR TO BE IN GOOD AGREEMENT ON THE
HANDLING OF THIS FEATURE OUT THROUGH TUE. BEYOND TUE...THE GFS
CONTINUES TO BE MORE BULLISH THAN THE ECMWF MOVING THE TROUGH
EASTWARD ACROSS THE NORTHERN MAINLAND...DRAGGING THE COLDER AIR
WITH IT. THIS SOLUTION APPEARS TO BE AN OUTLIER...OPERATIONAL
ECMWF AND THE GFS/ECMWF/NAEFS ENSEMBLE MEANS INDICATING A WEAK
SOUTHWEST FLOW PATTERN PREDOMINATING...WITH WARMER TEMPERATURE
ALOFT.

SURFACE...
A HIGH PRESSURE RIDGE EXTENDING EAST-WEST ACROSS THE ARCTIC OCEAN
WILL RECEDE NORTHEASTWARD INTO THE CANADIAN ARCHIPELAGO BY MON
NIGHT. A BROAD BUT RATHER WEAK LOW PRESSURE TROUGH WILL EXPAND
NORTHWARD ACROSS THE NORTHERN ALASKA MAINLAND AND INTO
THE WESTERN BEAUFORT SEA BY MON MORNING. THESE TWO FACTORS WILL
COMBINE TO RESULT IN GRADUALLY DECREASING WINDS OVER THE ARCTIC
COAST...CHUKCHI SEA AND BERING SEA. WINDS OVER THE FORECAST AREA
ARE EXPECTED TO BE GENERALLY LIGHT BY TUE MORNING.

CURRENT GFS AND ECMWF AGREE IN THE DEVELOPMENT OF A MODERATELY
STRONG LOW TO BE NEAR OR NORTHWEST OF SHEMYA BY 12Z TUE. FOR TUE
AND BEYOND...OPERATIONAL GFS/ECMWF RUNS DIVERGE OVER THE BERING
SEA. GFS/ECMWF MEANS SHOW A MEAN LOW CENTER OVER THE FAR WESTERN
BERING WITH A TROUGH EXTENDING EASTWARD TO BRISTOL BAY BY THU.
THERE IS A POSSIBILITY OF MINIMUM BRISK WINDS OVER ST LAWRENCE
ISLAND AND MARINE ZONE PKZ210 TUE INTO THU...BUT THE PROBABILITY
OF GALE FORCE WINDS APPEARS TO BE LOW.

NEAR THE END OF NEXT WEEK...GFS/ECMWF DIFFER ON THE DETAILS
BUT ALLUDE TO A MORE ACTIVE WEATHER PATTERN OVER THE
BERING SEA WITH GALE FORCE WINDS POSSIBLE.

IN THE SHORT TERM...AREAS OF STRATUS LIKELY PERSISTING OVER
THE EASTERN AND NORTHEASTERN INTERIOR...AND THE CENTRAL AND
EASTERN ARCTIC SLOPE. GOES IR AND NIGHTTIME RGB MICROPHYSICS FROM
POLAR SATELLITES SHOWING WIDESPREAD STRATUS OVER ZONE
224...PATCHES OF STRATUS ELSEWHERE IN PARTS OF THE EASTERN AND
NORTHEAST INTERIOR...WIDESPREAD STRATUS OVER THE CENTRAL/EASTERN
ARCTIC COAST. SCATTERED FLURRIES AND/OR SNOW SHOWERS OVER THE
CENTRAL/WESTERN ARCTIC COAST TODAY AND TONIGHT...AND OVER THE
WESTERN ARCTIC COAST SUN. SCATTERED FLURRIES IN ZONES 224/EASTERN
ZONES 226 TODAY AND TONIGHT...AND IN ZONES 219-222-PARTS OF
ZONES 216-220-221 SUN.


COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
HEAVY FREEZING SPRAY WARNING FOR PKZ210.

SMALL CRAFT ADVISORY FOR PKZ210.

BRISK WIND ADVISORY FOR PKZ220.
&&

$$

RF DEC 14




    US Dept of Commerce
    National Oceanic and Atmospheric Administration
    National Weather Service
    1325 East West Highway
    Silver Spring, MD 20910
    Page Author: NWS Internet Services Team
Disclaimer
Information Quality
Credits
Glossary
Privacy Policy
Freedom of Information Act (FOIA)
About Us
Career Opportunities