High Wind in Alaska, January 17, 2016

SOUTHEAST ALASKA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE JUNEAU AK
547 AM AKST SUN JAN 17 2016

.SHORT TERM...SATELLITE IMAGERY SHOWS A LOW PRESSURE SYSTEM
CROSSING 50N/135W AS IT MOVES N-NNW. MODELS REMAIN IN GOOD
AGREEMENT WITH THIS LOW MOVING N TODAY...PASSING W OF DIXON
ENTRANCE WITH A MIN PRES OF 968 MB THIS AFTERNOON...THEN
CONTINUING NW ACROSS THE GULF AS IT FILLS TO AROUND 980 MB
OVERNIGHT. BUOY 46004 NEAR THE CENTER REPORTED EASTERLY GALES
WITH SEA LEVEL PRESSURE AT 968MB AT 12Z. FRONTAL BAND ASSOCIATED
WITH THIS LOW MOVING ACROSS HAIDA GWAII ATTM WITH GUSTS TO 50 KT
REPORTED AT CYZP AND 64 KT AT CAPE ST JAMES. THESE OBS SUPPORT THE
65-70KT LOW LEVEL JET AT 925MB DEPICTED IN HIGHER RES MODELS.
STRONG WINDS AND PRECIP WILL SPREAD N TODAY...WITH THE SOUTHERN
PANHANDLE RECEIVING THE GREATEST IMPACTS FROM THIS STORM AND A
HIGH WIND WARNING REMAINS IN EFFECT FOR AKZ027. WINDS...GUSTING TO
20-25KT ATTM OVER PRINCE OF WALES...WILL CONTINUE TO INCREASE
BEFORE PEAKING THIS AFTERNOON AND EVENING AS THE STORM PASSES TO
THE W. WEIGHED EXPANDING HIGH WIND WARNING INTO AKZ028...BUT WITH
THE LOW BEGINNING TO FILL AND MOVING W...THINKING IS MAJORITY OF
ZONE WILL EXPERIENCE GUSTS OF 40-50 MPH EXCEPT THE FAR SOUTHERN
TIP OF PRINCE OF WALES ISLAND...BUT DID NOT FEEL THAT REPRESENTED
THE MAJORITY OF AKZ028. REGARDLESS...A WINDY DAY IS IN STORE FOR
SE AK.

OVER MARINE AREAS...STORM FORCE WINDS WILL ACCOMPANY THIS SYSTEM
AND STORM WARNINGS WERE RAISED FOR PKZ041>043. ELSEWHERE... SMALL
CRAFT TO GALE FORCE WINDS WILL DEVELOP AS THE LOW PROGRESSES NNW
OVER THE ERN GULF SUN AFTERNOON/NIGHT. GIVEN THE STRONG OFFSHORE
COMPONENT IN LOW-LEVEL WINDS...WIND GUSTS TO 40-50 MPH ARE ALSO
EXPECTED FOR LOCATIONS SUCH AS PASI...PAJN AND PAGY. WINDS WILL
EASE AND PRECIP WILL DIMINISH OVERNIGHT INTO MON AS THE LOW FILLS
AND MOVES INTO THE WESTERN GULF.

INHERITED FORECAST WAS 5-10 MB TOO WEAK WITH THE LOW AS IT MOVED
ACROSS THE GULF...SO USED GFS22 TO UPDATE PRESSURE AND WIND FIELDS
FOR THIS AFTERNOON AND EVENING. BIGGEST CHANGES RESULTED IN STORM
WARNINGS FOR PKZ042-043.

.LONG TERM...AS THE WEAKENING LOW BIDS ADIEU INTO THE NORTHWEST
GULF, A NEW WAVE/LOW WILL FOLLOW CLOSELY BEHIND, THIS ONE
SUPPORTING 40 KT GALES ON MONDAY AS IT ENTERS THE SOUTHEAST GULF.
THERE IS STILL SOME UNCERTAINTY AS TO HOW LONG IT CAN SUSTAIN ITS
STRENGTH AS IT CHURNS NORTHWEST ACROSS THE GULF. THE 00Z GFS
ARRIVED AT A SOLUTION MUCH DEEPER THAN THE ECMWF, BUT THE 06Z GFS
HAS BACKED OFF FROM THIS STRENGTH QUITE A BIT. THEREFORE WE HAVE
WEAKENED WINDS BELOW GALE FORCE AS EARLY AS 12Z TUESDAY AND KEPT
IT BELOW THIS THRESHOLD THROUGH ITS FINAL PASSAGE TO THE WEST.
OVER THE PANHANDLE WE EXPECT BREEZY CONDITIONS TO PERSIST INTO
MONDAY NIGHT AS THE NEW WAVE/LOW PASSES OFFSHORE.

PRECIPITATION WILL LIFT NORTHWEST CLOSELY FOLLOWING THE LOW'S
PASSAGE. A PATH HIGHLIGHTED BY UPSLOPE ACROSS THE FAR NORTHERN
PANHANDLE MAY ENHANCE SNOWFALL CLOSE TO BORDERLINE ADVISORY
LEVELS LATE SUNDAY NIGHT INTO MONDAY MORNING...ESPECIALLY FOR THE
HAINES BORDER. AS THIS EVENT BEGINS TO REVEAL ITSELF WITHIN THE
TIME DOMAIN OF HIGHER RES MODELS, CONFIDENCE MAY RISE IN SNOWFALL,
BUT AS IT IS NOW, COARSER MODELS MAY BE OVERSPREADING THE
PRECIPITATION INTO THE CHILKAT VALLEY. MODELS ARE INDICATING MORE
OF A SOUTHERLY FLOW DURING THIS PERIOD WHICH MAY BE ON THE CUSP
BETWEEN RAIN SHADOWING AND EFFECTIVELY OVERCOMING THE BARRIER BY
BYPASSING IT.

MUCH OF SOUTHEAST ALASKA MAY EXPERIENCE A DRIER DAY WEDNESDAY/WEDNESDAY
NIGHT AHEAD OF ANOTHER DEEP SYSTEM WHICH MODELS ARE TRENDING
TOWARDS A WETTER LATTER HALF OF THE WEEK AS FLOW BEGINS TO TAKE ON
A MORE DIRECTLY ONSHORE TRAJECTORY. CHANCES OF SNOW CONTINUE TO
LOOK QUESTIONABLE OVER THE CENTRAL PANHANDLE DURING THE EXTENDED
FORECAST BUT MOS GUIDANCE CONTINUES TO INSIST ON LOWER
TEMPERATURES THAN WHAT WE HAVE IN THE FORECAST. THEREFORE,
CONFLICTING ADVICE PREVENTS US FROM COMPLETELY REMOVING IT...EVEN
AS TEMPERATURES REMAIN WITHIN THE 30 TO 38 DEGREE RANGE IN THE
REGION HOSTING THE RAIN/SNOW LINE.

WE USED GFS/ECMWF FOR THEIR ROBUST AGREEMENT WITH PASSING WAVES.
CONFIDENCE GENERALLY GOOD FOR THE MID-RANGE AND FALLS TOWARD THE
END OF THE WEEK.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...HIGH WIND WARNING FROM NOON TODAY TO 9 PM AKST THIS EVENING FOR
     AKZ027.
         STRONG WIND FROM 9 AM THIS MORNING TO NOON AKST TODAY FOR AKZ027.
         STRONG WIND FROM NOON AKST TODAY THROUGH THIS EVENING FOR AKZ018-
     025-028.
         STRONG WIND FROM 3 PM AKST THIS AFTERNOON THROUGH THIS EVENING
     FOR AKZ023.
MARINE...STORM WARNING FOR PKZ041>043.
         GALE WARNING FOR PKZ012-022-033>036-051>053.
         SMALL CRAFT ADVISORY FOR PKZ011-013-021-031-032.

&&

BC/JWA

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