Flood in Alaska, December 14, 2013

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
608 AM AKST SAT DEC 14 2013

.SHORT TERM...ONE SYSTEM PUSHING INTO NORTHWEST CANADA, THE NEXT
SYSTEM, BOTH A FROZEN PRECIPITATION EXTENDER FOR THE HAINES
HIGHWAY AND WHITE PASS AND A WIND MAKER, POSSIBLY STARTING
EARLIER THAN FORECAST...PANHANDLE WIDE.

 FIRST EXTENDED THE WINTER STORM WARNING FOR WHITE PASS AND THE
HAINES HIGHWAY THROUGH 4 PM THIS AFTERNOON. GIVEN RECENT WARMING
AT MOORE CREEK OB, THE WEATHER AT WHITE PASS...MAY IMPROVE A
LITTLE QUICKER THAN ANTICIPATED AN HOUR AGO. GIVEN WARMING
TEMPERATURES, THINK BLOWING SNOW WILL NOT BE AS MUCH OF AN ISSUE,
BUT THE POTENTIAL FOR HEAVY SNOW...AN ADDITIONAL 5 TO 7 INCHES
STILL EXIST AT THE VERY TOP. CONFIDENCE GREATER IN EXTENDING THE
WARNING FOR THE HAINES HIGHWAY, PARTICULARLY THE BORDER. MOS
GUIDANCE KEEPING THESE COOL FOR HAINES, AND NAM MOS IN PARTICULAR
KEEPING WINDS NORTHWEST. NOW, AS HAINES ITSELF HAS CAUGHT THE
SOUTHERLY SURGE FROM LYNN CANAL, ITS TEMPERATURE HAS SKYROCKETED
AS IT TYPICALLY DOES, WELL ABOVE FREEZING. IN ADDITION, THE WARM
AIR ADVECTION IS TURNING THE SNOW TO RAIN AT SOME OF THE
MIDLEVELS, AND THUS THINK THERE WILL BE LIKELIHOOD OF FREEZING
RAIN COMBINED WITH THE SNOW ALONG THE HAINES HIGHWAY, LESS
CONCERN FOR THE KLONDIKE HIGHWAY. FOR MUCH OF THE MORNING,
FREEZING RAIN WAS REPORTED AT THE HAINES AIRPORT WITH
TEMPERATURES IN THE LOWER TO MIDDLE 20S. SNOWFALL AMOUNTS MAY NOT
BE AS GREAT AS THE 5 TO 7 INCHES ADDITIONAL CALLED FOR, BUT FEEL
IT IS JUSTIFIED WITH THE FREEZING RAIN ACCUMULATION...AROUND
0.25 INCHES POSSIBLE.

 THE NEXT ISSUE OF FOCUS IS THE WIND. WHILE BOUNDARY LAYER WINDS
SUGGESTING STORM FORCE IN PARTS OF THE OUTSIDE WATERS, AND AT
SOME POINTS, I DID GO WITH 50 KT...BUT WENT WITH MAJORITY OF THE
AREA AND KEPT THE MAX GALES FOR THIS AFTERNOON FOR THE OUTSIDE
WATERS BEGINNING WITH 41 THIS AFTERNOON AND SPREADING NORTHWARD
EARLY THIS EVENING. WENT WITH STRONG WINDS FOR ZONE 27 AND
28 TODAY AS WELL AS 23 STARTING LATER THIS MORNING AS THE FRONT
APPROACHES SHORE. IN ADDITION, JUNEAU GRADIENT WILL REACH STRONG
WIND THIS AFTERNOON AND WILL REMAIN STRONG TONIGHT, BUT GIVEN
CURRENT OBS...WINDS MAY BE AT THIS POINT EARLIER. IT SHOULD BE
NOTED THAT POST-FRONTAL PASSAGE THIS EVENING, WINDS WILL QUICKLY
BURST TO SOUTHWEST FOR THIS EVENING, SO AUKE BAY MARINERS BE
FOREWARNED. AIRPORT WILL LIKELY GO SOUTHWEST AS WELL, OR AT LEAST
THE FISH CREEK OUTFLOW MAY PRESENT AN ISSUE FOR AVIATION.
DOWNTOWN SHOULD REMAIN SOUTHEAST. WENT WITH SOUTH WORDING FOR
JUNEAU TONIGHT TO COVER BOTH SOUTHEAST AND SOUTHWEST. A PLETHORA
OF GALES ACROSS THE NORTH-SOUTH CHANNELS EXTENDING FROM THE SOUTH
TO THE NORTH LATE THIS AFTERNOON INTO THIS EVENING. IN ADDITION,
WATCH THE WESTERLIES BLOW THROUGH CROSS SOUND TO 40 KT...THIS MAY
BE UNDERFORECAST DUE TO THE COLD AIR ADVECTION BEGINNING THIS
EVENING POST-FRONTAL.

 A HIGH WIND WATCH WAS ISSUED FOR SKAGWAY FOR TONIGHT FOR WINDS
OF 60 MPH OR GREATER POSSIBLE. GRADIENTS ARE SUPER STRONG, AND IT
ALMOST SEEMS THAT GRADIENTS WEAKEN TO SUCH A DEGREE THIS
AFTERNOON, SUCH THAT AS THE LOW MOVES ASHORE. THIS EVENING, THE
MOMENTUM LIKE A SLING WILL RELEASE THE WINDS UP THE CANAL. NO
CHANGES TO THE STORM FORCE, BUT IN TAIYA INLET THE SET-UP IS VERY
FAVORABLE FOR THE GUSTS. GFS MOS CALLING FOR 51 MPH SUSTAINED
AROUND 9 PM. NAM IS MUCH MORE TEMPERED, BUT IT SHOULD BE NOTED
THAT THE MODELS ARE NOT PRODUCING THE WINDS AND GRADIENTS WE ARE
EXPERIENCING NOW. WINDS AND GRADIENTS SEEM TO BE UNDERFORECAST AT
THIS POINT, SO FELT COMPELLED TO ISSUE THE WATCH WHILE WILL
EITHER BE UPGRADED TO A HIGH WIND WARNING THIS AFTERNOON OR CALL
ATTENTION TO STRONG WINDS IN A HEADLINE IF WIND GUSTS WILL NOT
REACH 60 MPH.

 MOST OTHER ELEMENTS UNCHANGED FROM LAST PACKAGE. STILL EXPECT
SNOW LEVELS TO FALL TO THE SURFACE FROM THE CENTRAL PANHANDLE
NORTHWARD LATE TONIGHT WITH SOME ACCUMULATION SNOW SHOWERS UP TO
3 INCHES IN SPOTS.

 MODELS OF CHOICE WERE ECMWF AND NAM. CONFIDENCE IN FORECAST
SHAKY TODAY FOR WINTER STORM AT WHITE PASS...BETTER FOR HAINES
BORDER...BETTER FOR STRONG AND HIGH WINDS TONIGHT...LESS SO WITH
WINDS THIS MORNING.

.LONG TERM...UPPER TROF OVER THE GULF WILL SHIFT SLOWLY EWD AND
BE E OF THE AREA BY MIDWEEK. UPPER RIDGE WILL GRADUALLY BUILD INTO
THE GULF FOR THE LATTER PART OF THE WEEK...BUT THE RIDGE TOP LOOKS
LIKE IT WILL BE FAIRLY FLAT. THE RIDGE SHOULD GRADUALLY PUSH
ONSHORE BY NEXT WEEKEND. ENDED UP USING A 00Z GFS/NAM BLEND FOR
PRESSURES THRU MON AFTERNOON...THEN WENT WITH LATEST HPC FOR MON
NIGHT ONWARD.

 FOR SUN-MON...AIRMASS OVER THE AREA WILL SLOWLY COOL DURING THIS
PERIOD. ONSHORE FLOW WILL PERSIST AND THIS WILL KEEP THE SHOWERS
COMING. THEY WILL GENERALLY BE TRANSITIONING FROM RAIN SHOWERS TO
SNOW SHOWERS FROM NW TO SE DURING THIS TIME...EXCEPT THE FAR SERN
AREA WILL LIKELY ONLY GET TO MIXED PRECIP. HEAVIEST PRECIP SHOULD
BE ALONG SW FACING TERRAIN DURING THIS PERIOD.

 FOR MON NIGHT AND TUE...FORECAST GETS A BIT TRICKIER ESPECIALLY
OVER THE S. MODELS ARE SHOWING A SHORTWAVE TROF AND SFC LOW
RIDING NE TOWARD THE FAR SERN AREA IN GENERAL...BUT DIFFER ON
TRACK AND TIMING ENOUGH TO MAKE PRECIP POTENTIAL AND TYPE
FORECAST DIFFICULT. HAVE HEDGED ON THIS BY GOING WITH LIKELY POPS
OVER THE SRN AREA FOR MON NIGHT INTO TUE MORNING AT LEAST. OVER
THE N...THE SNOW SHOWERS SHOULD GRADUALLY DIMINISH AND ARCTIC AIR
SHOULD BEGIN TO DROP SWD INTO THE AREA AS A SFC HIGH BUILDS OVER
THE YUKON.

 FOR TUE NIGHT AND WED...COLDER AIR SHOULD CONTINUE TO WORK ITS
WAY SWD...WITH LEADING EDGE OF IT GETTING TO THE FAR S BY WED.
THIS PERIOD LOOKS DRY AS WELL AS UPPER TROF WILL BE INLAND AND
LOW LEVEL FLOW WILL BE N-NE. THERE ARE MODEL DIFFERENCES ON HOW
MUCH COLD AIR GETS IN...WITH THE GFS GENERALLY COLDER THAN THE
ECMWF. GEM IS IN BETWEEN. DID LOWER TEMPS SOME FOR MOST PLACES AS
EVEN THE WARMEST ECMWF MOS WAS 5-10 DEGREES LOWER THAN WHAT WAS
IN THERE BEFORE.

 FOR LATE WEEK...LOOKING LIKE A SNOW RIDGE SETUP WILL BE
DEVELOPING  WITH FLAT TOPPED UPPER RIDGE AND ARCTIC AIRMASS IN
PLACE. ITS WAY TOO EARLY TO TELL HOW MUCH SNOW WOULD FALL...OR
WHEN ANY PRECIP TYPE TRANSITION TO RAIN WOULD OCCUR...BUT IT
SHOULD GRADUALLY WARM UP DURING THIS PERIOD. DID DIFFER FROM HPC
POPS SOME AS THERE IS BROAD MODEL AGREEMENT ON AN OVERRUNNING
EVENT OCCURRING...SO BROUGHT LIKELY POPS FURTHER N FOR THU-THU
NIGHT.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND UNTIL 6 PM AKST THIS EVENING FOR AKZ027-028.
         STRONG WIND FROM 3 PM AKST THIS AFTERNOON THROUGH LATE TONIGHT
     FOR AKZ025.
         STRONG WIND FROM 6 PM AKST THIS EVENING THROUGH THIS EVENING FOR
     AKZ022.
         STRONG WIND FROM NOON AKST TODAY THROUGH THIS EVENING FOR AKZ023.
         STRONG WIND THIS EVENING FOR AKZ020.
         STRONG WIND FROM 6 PM AKST THIS EVENING THROUGH LATE TONIGHT FOR
     AKZ019.
         WINTER STORM WARNING UNTIL 4 PM AKST THIS AFTERNOON FOR AKZ018-
     019.
         HIGH WIND WATCH FROM 6 PM AKST THIS EVENING THROUGH LATE TONIGHT
     FOR AKZ018.
MARINE...STORM WARNING FOR PKZ012-013.
         GALE WARNING FOR PKZ021-022-031>033-036-041>043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ011-034-035-053.

&&

JWA/RWT

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE JUNEAU AK
804 AM AKST SAT DEC 14 2013

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

0700 AM     HEAVY SNOW       20 WNW HAINES           59.35N 135.96W
12/14/2013  M18.0 INCH                          AK   COUNTY OFFICIAL

            REPORTED BY AK DOT

0700 AM     HEAVY SNOW       38 WNW HAINES           59.45N 136.44W
12/14/2013  M9.0 INCH                           AK   OTHER FEDERAL

            REPORT BY HAINES CUSTOMS

&&

RCL