Ice Storm Warning 1, NWS Anchorage, AK

586 
WWAK41 PAFC 221332
WSWAER

URGENT - WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE ANCHORAGE AK
432 AM AKST SUN FEB 22 2015


AKZ141-221445-
/O.CAN.PAFC.IS.W.0001.000000T0000Z-150222T1500Z/
COPPER RIVER BASIN-
INCLUDING THE CITIES OF...GLENNALLEN...EUREKA...MCCARTHY...
PAXSON...SLANA
432 AM AKST SUN FEB 22 2015

...ICE STORM WARNING IS CANCELLED...

THE NATIONAL WEATHER SERVICE IN ANCHORAGE HAS CANCELLED THE ICE
STORM WARNING. 


$$

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
423 PM AKST SAT FEB 21 2015

.ANALYSIS AND UPPER LEVELS...
THE MAIN CYCLONIC CIRCULATION ALOFT HAS SHIFTED TO THE BERING SEA
IN RESPONSE TO THE STRONG SHORTWAVE AND FRONT. A DEEP MOIST
SOUTHERLY FLOW ALOFT STREAMS IN FROM THE MID LATITUDES AS THE HIGH
AMPLITUDE EASTERN PACIFIC RIDGE SITS IN PLACE. DESPITE STRONG
SOUTHEASTERLY WINDS IN TURNAGAIN ARM AND THE UPPER ELEVATIONS OF
THE CHUGACH...MODERATE RAIN IS FALLING TO THE SURFACE AS UPPER
LEVEL WINDS AND MOISTURE ARE MITIGATING ANY DOWNSLOPE DRYING FROM
CROSS-BARRIER FLOW. THE MAJORITY OF SURFACE TEMPERATURES IN THE
SOUTHCENTRAL ARE ABOVE FREEZING SO WIDESPREAD ICING IS NOT
EXPECTED...BUT ANY ICE OR SNOW COVERED ROADS WILL STILL REMAIN
SLICK. THE ONLY AREA WITH A FREEZING RAIN THREAT REMAINING IS THE
COPPER RIVER BASIN WHERE WARM AIR IS PUSHING OVERHEAD FROM THE
GULF WHILE COLD AIR REMAINS ENTRENCHED AT THE SURFACE.

&&

.MODEL DISCUSSION...
GUIDANCE CONTINUES TO BE IN GOOD AGREEMENT WITH THE SYNOPTIC
PATTERN THROUGH THE WEEKEND. THE BIGGEST FEATURE GUIDANCE
CONTINUES TO STRUGGLE WITH IS THE AMOUNT OF DOWNSLOPE DRYING OVER
THE CHUGACH. THE EAST AND WEST DOMAINS PREFERRED THE 21/12Z
NAM/GEM IN THE SHORT TERM.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
LOW PRESSURE OVER THE BERING WILL SEND MULTIPLE SHORTWAVES OVER
THE GULF OF ALASKA AND THE SOUTHERN MAINLAND THROUGH THE BEGINNING
OF THE WORK WEEK. RAIN WILL CONTINUE TO DEVELOP ACROSS THE GULF
AND SPREAD NORTH. THE MAIN PRECIPITATION CHALLENGES ARE ACROSS THE
COPPER RIVER VALLEY AND SUSITNA VALLEY WHERE POCKETS OF COLD AIR
AT THE SURFACE ARE CAUSING RAIN TO FREEZE AT THE SURFACE. THE
FREEZING RAIN ADVISORY HAS BEEN EXTENDED THROUGH 6 AM SUNDAY
MORNING FOR THE COPPER RIVER VALLEY FROM GLENNALLEN EAST.
CONDITIONS SHOULD IMPROVE AS PRECIPITATION TAPERS OFF ACROSS THE
SOUTHERN MAINLAND EARLY SUNDAY. RAIN WILL CONTINUE ACROSS THE GULF
THROUGH MONDAY AS A WEAK BOUNDARY REMAINS ALONG THE COAST.

THE NEXT CHALLENGE IN THE FORECAST WILL BE THE COLD FRONT THAT
PUSHES INTO THE WESTERN GULF SUNDAY NIGHT INTO MONDAY. THE UPPER
LOW IN THE BERING PUSHES A COLD FRONT FROM THE ALASKA PENINSULA
INTO THE WESTERN GULF BY EARLY MONDAY MORNING. THE FRONT SLOWLY
MOVES NORTHEAST ON MONDAY BRINGING A CHANCE FOR RAIN AND SNOW
ACROSS SOUTHCENTRAL.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
UNSEASONABLY WARM TEMPERATURES AND WET CONDITIONS SHOULD PERSIST
THROUGH THE WEEKEND OVER MUCH OF THE SOUTHWEST AREA...AS
SOUTHERLY FLOW ASSOCIATED WITH THE LOW OVER THE BERING CONTINUES
TO FEED IN WARM MOIST AIR FROM THE NORTH PACIFIC OVER THE AREA.
MOST LOCATIONS CONTINUE TO REPORT RAIN AS THE DOMINANT
PRECIPITATION TYPE...AND EVEN THE TYPICAL "COLD" SPOTS IN THE
KUSKOKWIM VALLEY AND ALONG THE NORTH COAST OF THE DELTA ARE ABOVE
FREEZING AT THE SURFACE. PRECIPITATION WILL BECOME MORE SHOWERY
OVERNIGHT TONIGHT AS THE WAVE PUSHES FURTHER NORTHWARD...HOWEVER
THE SHOWERS WILL BE SHORT-LIVED AS ANOTHER ROUND OF STEADY RAIN
MOVES IN SUNDAY MORNING WITH THE NEXT WAVE TRACKING IN FROM THE
NORTH PACIFIC. GUSTY WINDS OVER THE MAINLAND WILL CONTINUE TO
DIMINISH THROUGH THIS EVENING...AS THE GRADIENT OVER THE AREA
BEGINS TO SLACKEN. ONCE THE LOW OVER THE BERING TRACKS FURTHER
NORTHWEST AND THE UPPER LEVEL TROUGH OVER THE BERING MOVES IN
PLACE OVER THE SOUTHWEST MAINLAND MONDAY MORNING...SOME COLDER AIR
(BY NO MEANS ARCTIC) WILL BEGIN TO FILTER INTO THE SOUTHWEST COAST
AND COOL OFF PARTS OF THE SOUTHWEST MAINLAND.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
A LARGE LOW PRESSURE COMPLEX OVER THE EASTERN HALF OF THE BERING
CONTINUES TO PUMP DEEP WARM AIR INTO THE STATE. MEANWHILE...ON
THE BACKSIDE THIS SYSTEM...COLDER AIR BEGINS TO MIGRATE OFF THE
KAMCHATKA PENINSULA AND FILTER INTO MUCH OF THE BERING SEA
TONIGHT...WHICH WILL HELP TO CREATE A FAIRLY WIDE SWATH OF GUSTY
WINDS DOWN THROUGH THE CENTRAL ALEUTIANS. A ROBUST UPPER LEVEL LOW
OVER NORTHEASTERN RUSSIA WILL BEGIN TO TRACK SOUTHEAST OVERNIGHT
TONIGHT. A SERIES OF EMBEDDED WAVES WILL SWING OFF OF THIS
SYSTEM...DEVELOPING A SURFACE LOW OVER THE WESTERN BERING LATE
SUNDAY AND TRACKING TOWARD THE PRIBILOFS ON MONDAY. THIS LOW WILL
HELP KEEP THE PATTERN MORE PROGRESSIVE (WEST TO EAST FLOW) THAN
IT HAS BEEN THE PAST WEEK...AND WILL HELP PUSH SOME OF THAT
COLDER AIR TOWARD THE MAINLAND BY MONDAY. THIS SHOULD START TO
TURN SOME OF THE LINGERING SHOWERS FROM RAIN TO SNOW OVER THE
EASTERN ALEUTIANS. BUT LIMITED MOISTURE WILL MAKE FOR ALMOST NIL
ACCUMULATIONS.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...A COLD UPPER LEVEL
TROUGH WILL REACH THE WEST COAST OF ALASKA MONDAY. THE BULK OF
THE COLD AIR HOWEVER WILL BE HELD MAINLY TO THE NORTH AND WEST OF
THE FORECAST AREA BY A STRONG RIDGE ALOFT BUILDING FROM THE GULF
OF ALASKA INTO SOUTHWEST THEN SOUTH CENTRAL ALASKA MONDAY NIGHT
AND TUESDAY. IN ADDITION TO HOLDING THE COLD AIR AT BAY...THE
RIDGE WILL ALSO DRY CONDITIONS OUT AS THE TROUGHY WEST
SOUTHWESTERLY FLOW IS TEMPORARILY CUT OFF.

THE NEXT FRONTAL SYSTEM WILL APPROACH THE EASTERN ALEUTIANS AND
WESTERN ALASKA PENINSULA TUESDAY THEN LIFT NORTH AND EAST TO THE
FAR SOUTHWEST ALASKA MAINLAND ON WEDNESDAY BREAKING DOWN THE
RIDGE. THE LOW WILL WEAKEN TO A TROUGH AS IT CROSSES THE GULF
WEDNESDAY NIGHT AND THURSDAY BEFORE SWINGING CLEAR OF THE AREA
THURSDAY AFTERNOON OR EVENING. UPPER LEVEL RIDGING WILL RETURN
THURSDAY NIGHT AND FRIDAY THOUGH THERE IS A GOOD BIT OF MODEL
UNCERTAINTY ABOUT HOW LONG IT WILL LAST.

ANOTHER POTENTIAL CONCERN OUT IN THE MID TERM AND EXTENDED IS A
SERIES OF INCREASINGLY STRONG FRONTAL SYSTEMS SWEEPING THROUGH THE
WESTERN ALEUTIANS THROUGH THE WEEK. THE FIRST ARRIVES AROUND
TUESDAY... FOLLOWED BY THE NEXT SOMEWHAT STRONGER ONE THURSDAY AND
A THIRD MORE POWERFUL SYSTEM TOWARD THE WEEKEND.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALES 119 130 131
         HEAVY FREEZING SPRAY 185
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...ML
SOUTHCENTRAL ALASKA...KH
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...TP
LONG TERM...CC

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
501 PM AKST SAT FEB 21 2015

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

0445 PM     ICE STORM        30 S GLENNALLEN         61.65N 145.60W
02/21/2015                                      AK   PUBLIC

            SEMI-TRAILER SLID OFF NEAR THE EDGERTON CUT OFF. SLICK
            ROAD SURFACES ARE MAKING ROADS IMPASSABLE.

&&

KHOEPPNER