Small Craft Advisory 51, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
600 AM AKST THU JAN 16 2014

.ANALYSIS AND UPPER LEVELS...
THE UPPER LEVEL TROUGH THAT HAS BEEN THE DOMINANT SYSTEM OVER THE
BERING AND NORTHERN PACIFIC QUICKLY IS SPINNING UP A LOW CENTER 900
MILES SOUTH OF THE ALASKA PENINSULA. THE TROUGH AXIS IS BECOMING
NEGATIVELY TILTED AS AN AMPLIFIED RIDGE HOLDS OVER THE NORTHEAST
PACIFIC. BETWEEN THE TWO SYSTEMS ABUNDANT MOISTURE HAS SURGED OVER
SOUTHERN ALASKA IN DEEP SOUTHERLY FLOW. ACROSS THE BERING THERE ARE
TWO LOW CENTERS...ONE IS NEAR SAINT MATHEW ISLAND AND THE OTHER IS
OVER THE CENTRAL ALEUTIANS. AT THE SURFACE...A WARM FRONT EXTENDS
FROM THE BRISTOL BAY INTO THE NORTHERN GULF COAST. GUSTY WINDS ALONG
THE FRONT ARE STRONGEST NORTH OF A LOW CENTER THAT IS TIGHTENING THE
PRESSURE GRADIENT IN THE NORTHERN GULF. PRECIPITATION CONTINUES TO
DEVELOP ALONG THE FRONT SPREADING INLAND AS THE WARM OVERRUNNING AIR
MASS SURGES NORTH. ACROSS MUCH OF BRISTOL BAY...PRECIPITATION HAS
CHANGED OVER TO MAINLY ALL RAIN DURING THE EARLY MORNING HOURS AS
TEMPERATURES WARMED INTO THE LOW AND MID 30S. A COLD AIR MASS ALONG
THE SOUTHWEST COAST FROM CAPE NEWENHAM NORTH AND THROUGH THE
BERING IS KEEPING PRECIPITATION IN THE FORM OF SNOW. GUSTY WINDS
AROUND THE MULTIPLE LOW PRESSURE CENTERS ARE CAUSING BLOWING SNOW
ACROSS THE SOUTHWEST COAST...CENTRAL BERING AND EASTERN ALEUTIANS.

.MODEL DISCUSSION...
MODELS ARE IN FAIR AGREEMENT THROUGH THE SHORT TERM WITH THE OVERALL
SYNOPTIC PATTERN. THE MAIN CHALLENGE IN THE FORECAST IS THE CLOSED
LOW IN THE NORTHERN PACIFIC. THIS SYSTEM WILL QUICKLY MOVE NORTH
ALONG A 120+ KT JET STREAM THAT ORIENTS SOUTH TO NORTH TONIGHT INTO
FRIDAY. WARM AIR AND SIGNIFICANT MOISTURE ADVECTION IS EXPECTED TO
SPREAD NORTH INTO THE GULF LATE TONIGHT AND INTO THE SOUTHERN
MAINLAND ON FRIDAY. THE UPPER LOW WILL MOVE A 950 MB SURFACE LOW TO
THE ALASKA PENINSUALA WITH THE CENTER NEAR SAND POINT BY FRIDAY
MORNING. THIS LOW STAYS ON A NORTHERLY TRACK THROUGH THE EASTERN
BERING IMPACTING THE SOUTHERN MAINLAND...ALEUTIAN CHAIN...AND BERING.
A COMBINATION OF THE GFS AND ECMWF WAS PRIMARILY USED TO UPDATE THE
FORECAST. THERE IS SOME UNCERTAINTY IN THE STRENGTH AND TIMING OF
THIS STORM SYSTEM AND THEREFORE SHOULD CONTINUE TO MONITOR FOR
UPDATES.

.SHORT TERM FORECAST...
SOUTHCENTRAL ALASKA...
RAIN WILL CONTINUE THROUGH LATE MORNING ALONG THE COASTAL LOCATIONS
WITH A CHANGEOVER TO SNOW AT LOCATIONS FURTHER INLAND. SNOW AMOUNTS
WILL BE HIGHEST ALONG UPSLOPE TERRAIN WITH SNOW AMOUNTS RANGING FROM
1 TO 5 INCHES. THE WINTER WEATHER ADVISORIES FOR THE ANCHORAGE
BOWL...MATANUSKA VALLEY AND SUSTINA VALLEY SHOULD EXPIRE ON TIME AS
SNOW WILL TAPER OFF WHEN THE LOW CENTER DIMINISHES INLAND THIS
AFTERNOON. GUSTY WINDS ALONG THE FRONT WILL ALSO DIMINISH AS THE
PRESSURE GRADIENT RELAXES LATER TODAY.

THE WINDS INCREASE AGAIN ACROSS THE SOUTHERN AND WESTERN GULF LATE
TONIGHT AS THE NEXT STORM SYSTEM PUSHES NORTH. STRONG WINDS DEVELOP
FIRST ACROSS THE WESTERN GULF INCLUDING KODIAK ISLAND. WINDS INCREASE

ACROSS THE SOUTHERN MAINLAND AND COASTAL LOCATIONS FRIDAY MORNING
WITH STRONG WINDS DEVELOPING ALONG MOUNTAIN PASSES AND CHANNELED
TERRAIN. A HIGH WIND WATCH WAS ISSUED THIS MORNING FOR TURNAGAIN ARM
AND HIGHER ELEVATIONS AND ALSO PORTAGE VALLEY. WIDESPREAD
PRECIPITATION WILL MAINLY BE ALL RAIN WITH THE HIGHEST AMOUNTS
EXPECTED ACROSS THE GULF AND JUST INLAND. PRECIPITATION WILL BE
MIXED WITH SNOW AT TIMES ACROSS THE COPPER RIVER AND SUSTINA VALLEY.

SOUTHWEST ALASKA...
RAIN WILL CONTINUE ACROSS THE ALASKA PENINSULA WITH A MIX OF RAIN AND
SNOW ACROSS THE SOUTHWEST MAINLAND. A FREEZING RAIN ADVISORY WAS
ISSUED THIS MORNING FOR THE LOWER KUSKOKWIM VALLEY AS THE WARM
PACIFIC AIRMASS SPREADS NORTH. SNOW WILL TAPER OFF ACROSS THE
KUSKOKWIM DELTA THIS AFTERNOON AS THE UPPER LOW PRESSURE PULLS WEST
ACROSS THE BERING. THE NEXT STORM SYSTEM LIFTS NORTH TOWARD THE
ALASKA PENINSULA LATE TODAY. STRONG WINDS DEVELOP ACROSS THE
PENINSULA OVER NIGHT ALONG WITH MODERATE TO HEAVY PRECIPITATION.
STORM CONDITIONS WILL MOVE NORTH OVERSPREADING THE EASTERN HALF OF
THE BERING AND SOUTHWEST FRIDAY AND SATURDAY. A WINTER STORM WATCH
HAS BEEN ISSUED FOR THE KUSKOKIM DELTA FOR TONIGHT FOR THE THREAT OF
SNOW...BLOWING SNOW...FREEZING RAIN...AND STRONG WINDS. CONDITIONS
WILL IMPROVE OVER THE WEEKEND.

ALEUTIANS/BERING SEA...
THE NORTH PACIFIC STORM WILL BRING STORM-FORCE WINDS THIS EVENING
TO EASTERN ALEUTIANS AND EASTERN AREAS OF THE BERING. SNOW AND
BLOWING SNOW WILL ACCOMPANY THIS SYSTEM SO A BLIZZARD WATCH HAS BEEN
ISSUED FOR THE PRIBILOF ISLANDS AND A BLIZZARD WARNING FOR THE
EASTERN ALEUTIANS. CONDITIONS WILL IMPROVE IN THE LATTER PART
OF THE WEEKEND.

.LONG TERM FORECAST...
WITH THE LONGWAVE PATTERN STAYING IN PLACE INTO THE MIDDLE OF THE
NEXT WEEK A SEASONABLY WARM AND VERY ACTIVE WEATHER PATTERN WILL
CONTINUE FOR THE SOUTHERN MAINLAND OF ALASKA. A COLD AND SHOWERY
AIRMASS STAYS IN PLACE OVER THE BERING. BETWEEN THE TWO AIR
MASSES...THE POTENTIAL FOR MORE SIGNIFICANT WINTER WEATHER WILL
INCREASE EARLY NEXT WEEK OVER SOUTHWEST ALASKA AND THE EASTERN BERING
WHERE THE TWO AIR MASSES WILL CLASH.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WARNING 185 195
         WINTER STORM WATCH 155
         HIGH WIND WATCH 101 111.
MARINE...GALES 120 125 130 131 132 136 137 138 139 155 160 165 170
171 173 174 176 179 180 181 185
         STORM WARNING 119 150 172
         HEAVY FREEZING SPRAY 179 180 185.
FIRE WEATHER...NONE.

KH JAN 16

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1051 AM AKST THU JAN 16 2014

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0900 AM     SNOW             8 S TALKEETNA           62.23N 150.07W
01/16/2014  M1.2 INCH                           AK   COCORAHS

0900 AM     SNOW             4 SE WILLOW             61.70N 149.99W
01/16/2014  M5.4 INCH                           AK   COCORAHS

0900 AM     SNOW             1 NNW PALMER            61.62N 149.13W
01/16/2014  M1.3 INCH                           AK   COCORAHS

0900 AM     SNOW             SW BIRCHWOOD            61.41N 149.49W
01/16/2014  M2.0 INCH                           AK   COCORAHS

0900 AM     SNOW             2 SE EAGLE RIVER        61.30N 149.52W
01/16/2014  M3.5 INCH                           AK   NWS EMPLOYEE

0900 AM     SNOW             1 ENE POTTER MARSH      61.06N 149.75W
01/16/2014  M1.8 INCH                           AK   COCORAHS

0900 AM     SNOW             6 SW ANCHORAGE          61.16N 149.98W
01/16/2014  M1.8 INCH                           AK   OFFICIAL NWS OBS

0900 AM     SNOW             4 SE WILLOW             61.70N 149.99W
01/16/2014  E6.0 INCH                           AK   PUBLIC

&&

DSTRICKL

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1130 AM AKST THU JAN 16 2014

AKZ125-131-135-171800-

...WARM AND VERY WET CONDITIONS ARE EXPECTED OVER THE EASTERN KENAI
PENINSULA AND NORTH GULF COAST FRIDAY...

A DEVELOPING STORM SYSTEM IS MOVING RAPIDLY NORTH TOWARD THE ALASKA
PENINSULA. ITS ASSOCIATED WEATHER FRONT APPROACHES THE NORTH GULF
COAST FRIDAY AND MOVES EAST OF THE AREA SATURDAY. MOIST SOUTHEASTERLY
FLOW AHEAD OF THE APPROACHING WEATHER FRONT WILL BRING MODERATE TO
HEAVY RAINFALL TO THE EASTERN KENAI PENINSULA AND THE NORTH GULF
COAST BEGINNING FRIDAY MORNING AND CONTINUING INTO THE EARLY MORNING
HOURS SATURDAY. RAINFALL AMOUNTS OF 3 TO 5 INCHES ARE EXPECTED DURING
THIS PERIOD...WITH POTENTIALLY HIGHER AMOUNTS ON EAST AND SOUTH
EXPOSURES. ADDITIONALLY WARMING TEMPERATURES WILL RAISE FREEZING
LEVELS AND INCREASE SNOW MELT RUNOFF.

WARM TEMPERATURES COMBINED WITH RAIN...SNOW MELT AND FROZEN GROUND
WILL CREATE SOGGY CONDITIONS...ESPECIALLY AT LOWER ELEVATIONS.  THIS
MAY CAUSE INCREASED FLOW IN LOCAL STREAMS...DRAINAGE BACKUPS AND
STANDING WATER IN LOW LYING AREAS.

FURTHER UPDATES WILL BE ISSUED AS CONDITIONS WARRANT.

RMC