Hurricane Force Wind Warning 1, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
300 PM AKST TUE JAN 20 2015

.SHORT TERM...ATMOSPHERIC RIVER IS MOVING NNE INTO THE AREA LATE
THIS AFTERNOON. THIS WILL REMAIN MAINLY E OF 140W THRU WED. LOW
PRESSURE OVER THE N-CENTRAL GULF WILL WEAKEN THRU TONIGHT...WHILE
ANOTHER LOW MOVES NNE THRU THE ERN GULF WED. FRONTAL SYSTEM OVER
THE FAR ERN GULF WILL GENERALLY STAY THERE THRU WED MORNING...THEN
PUSH ONSHORE SE AK WED AFTERNOON. USED BLEND OF THE 12Z NAM AND
ECMWF AS THEY HAD THE BEST HANDLE ON THE MAIN FEATURES.

MAIN FORECAST CONCERNS WILL BE PRECIP AMOUNTS...WINDS...POTENTIAL
FOR LAND/MUDSLIDES/SMALL STREAM FLOODING...AND TEMPS. RIGHT
NOW...GIVEN A STRONG AND DEEP LAYER SSW FLOW AND ANOMALOUSLY HIGH
PRECIPITABLE WATER VALUES BEING ADVECTED IN (0.8-1.1 INCHES) WITH
THE ATMOSPHERIC RIVER...AM EXPECTING WIDESPREAD HEAVY PRECIP FOR
THE MAIN PART OF THE PANHANDLE THRU WED. RAINFALL AMOUNTS OF 3+
INCHES ARE LIKELY IN MOST OF THOSE AREAS THRU WED AFTERNOON. STILL
SOME SNOW FALLING AT HIGHER ELEVATIONS...AND EVEN REACHING SEA
LEVEL NEAR PAGY ATTM DUE TO SNOWMELT COOLING EFFECT. AS WARMER AIR
MOVES IN THRU TONIGHT...EXPECT ANY SNOW IN THE LOWER ELEVATIONS
(BELOW 1500 FT) TO BECOME RAIN BY EARLY EVENING. KEPT THE WINTER
WX ADVY FOR THE HAINES ZONE NEAR THE BORDER THRU 6 PM THIS
EVENING...AND WINTER STORM WARNING FOR WHITE PASS THRU 5 AM WED.
THINK THE PASS WILL SEE AROUND ANOTHER FOOT OF SNOW BEFORE IT
WARMS ENOUGH FOR RAIN TO MIX IN WED MORNING. THE PAYA AREA WILL
MISS A LOT OF THE PRECIP WITH THIS SYSTEM UNTIL WED
AFTERNOON...WHEN LOW MOVING IN SHOULD PULL A BAND OF PRECIP BACK
TO THE W TO THAT AREA. DID KEEP LOW POPS GOING THERE THRU WED
MORNING AS THERE COULD BE A FEW SPRINKLES OR LIGHT RAIN SHOWERS
DURING THAT TIME.

WINDS WILL REMAIN FAIRLY STRONG ESPECIALLY OVER THE SE HALF OF THE
AREA. EXPECT GALES TO CONTINUE OVER MOST OF THAT AREA INTO WED
AFTERNOON. THERE WILL BE SMALL INCREASES THEN DECREASES DURING
THIS TIME DUE TO PASSING SHORTWAVES ALOFT...BUT IN GENERAL GALES
SHOULD BE THE RULE. GOING WITH STRONG WIND HEADLINES FOR ZONES
26...27...AND 28 FOR TONIGHT AND WED...WITH ZONE 23 JOINING IN FOR
WED.

THE COMBINATION OF THE HEAVY RAIN AND STRONG WINDS MAY CAUSE LAND
AND MUDSLIDES ESPECIALLY ON SLOPES FACING FROM SELY TO SWLY. THE
HIGH RAINFALL AMOUNTS EXPECTED MAY CAUSE SOME URBAN AND SMALL
STREAM FLOODING ISSUES OVER MUCH OF THE AREA...BUT NOT EXPECTING
ANY LARGE RIVER FLOODING AS WATER LEVELS IN THOSE BASINS ARE ON
THE LOW SIDE. GOING TO ISSUE AN URBAN AND SMALL STREAM FLOOD ADVY
FOR MOST PARTS OF THE MAIN PANHANDLE AREA.

TEMPS WILL BE FAIRLY STEADY OR RISE A BIT DURING THE NIGHT
TONIGHT. TEMPS ON WED WILL ONLY RISE A COUPLE MORE DEGREES IN MOST
PLACES FROM WHERE THEY ARE EARLY WED MORNING.

.LONG TERM...MODELS REMAIN IN GENERAL AGREEMENT THROUGH FRIDAY
FOR CONTINUED WET WEATHER WITH ABOVE NORMAL TEMPERATURES ACROSS
SOUTHEAST ALASKA. USED A BLEND OF THE ECMWF AND NAM FOR THEIR GOOD
CONSENSUS THROUGH FRIDAY. PRECIPITATION WILL BE ALL RAIN OVER THE
PANHANDLE...EXCEPT THE FAR NORTHERN HIGHWAYS WHERE SNOW WILL
CONTINUE NEAR WHITE PASS AND MIXED PRECIPITATION NEAR THE BORDER
OF HAINES HIGHWAY. OCCASIONAL HEAVY RAINFALL IS EXPECTED WITH A
SERIES OF WAVES MOVING ACROSS THE AREA. EACH WAVE PASSING OVER THE
PANHANDLE WILL LIKELY TO ACCOMPANY GUSTY WINDS TO MAINTAIN
POTENTIAL HIGH RISK OF MUDSLIDES. USED THE SREF GUIDANCE FOR POPS
AND QPF FIELDS AND TONED DOWN RAINFALL RATE A BIT.

EXPECT MORE WAVES MOVING INTO SOUTHEAST ALASKA THROUGH THE MID
WEEK NEXT WEEK...BUT MODEL DIFFERENCES BECOME LARGER AND USED THE
LATEST WPC ENSEMBLE SOLUTIONS FROM SATURDAY ONWARD. ONE NOTICEABLE
CHANGE OVER THE UPPER LEVEL PATTERN WITH THE LATEST MODEL
CONSENSUS HINTS AN UPPER LOW OVER THE ALASKA INTERIOR
STRENGTHENING AND MOVING INTO THE NORTHERN GULF SUNDAY NIGHT INTO
EARLY NEXT WEEK FOR A COLDER AIR ADVANCING TO THE NORTHERN
PANHANDLE...GIVING A CHANCE FOR SEASONAL JANUARY TEMPERATURES.
HOWEVER...NEXT STORM FROM THE SOUTH WILL LIKELY TO PUSH THE COLD
AIR BACK TO THE NORTHWEST AND THE PANHANDLE WILL RETURN TO ABOVE
NORMAL TEMPERATURES BY THE MID WEEK.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND THROUGH WEDNESDAY AFTERNOON FOR AKZ026.
         STRONG WIND THROUGH WEDNESDAY AFTERNOON FOR AKZ027-028.
         STRONG WIND FROM WEDNESDAY MORNING THROUGH WEDNESDAY AFTERNOON
     FOR AKZ023.
         WINTER WEATHER ADVISORY UNTIL 6 PM AKST THIS EVENING FOR AKZ019.
         WINTER STORM WARNING UNTIL 5 AM AKST WEDNESDAY FOR AKZ018.
MARINE...GALE WARNING FOR PKZ031-034>036-041-042.
         SMALL CRAFT ADVISORY FOR PKZ013-021-022-032-033-043-051>053.

&&

RWT/AHN

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