High Wind in Alaska, March 24 to 25, 2014

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
545 AM AKDT MON MAR 24 2014

.SHORT TERM...STRONG OUTFLOW REMAINS THE MAIN PLAYER IN THE
SHORT RANGE FORECAST TODAY WITH WINDS FORECAST TO BE STRONGER
THEN THEY WERE YESTERDAY. THE MAIN REASON FOR THIS IS A
COMBINATION OF THE INTERACTION OF THE LOW AND FRONT ACROSS THE
SOUTHERN GULF WITH THE YUKON HIGH, AND THE UPPER LEVEL TROUGH
THAT IS SLOWLY DROPPING SOUTH ACROSS THE AREA. LOCAL PRESSURE
GRADIENTS HAVE BEEN INCREASING OVERNIGHT AND THE JUNEAU TO
SKAGWAY GRADIENT IS ALREADY UP TO 6.1 MB AS OF 5 AM. THIS
GRADIENT IS NOT EXPECTED TO CHANGE MUCH TODAY. IF ANYTHING IT
WILL INCREASE THROUGH THE DAY AND REMAIN MOSTLY STEADY TONIGHT.
OUTFLOW WINDS HAVE INCREASED AS A RESULT. CROSS SOUND HAS ALREADY
REACHED GALE FORCE THIS MORNING WITH GUSTS TO 50 KT, ELDRED ROCK
HAS 30 KT WINDS WITH GUSTS TO 40 KT, AND POINT BISHOP HAS SEEN
GUSTS TO 40 KT THIS MORNING AS WELL. THESE WINDS ARE EXPECTED TO
CONTINUE WITH GALE WARNINGS UP FOR MOST OF THE NORTHERN INNER
CHANNELS THROUGH TONIGHT AND STRONG WIND HEADLINES FOR SKAGWAY
AND HAINES NEAR LYNN CANAL.

 IN ADDITION, A RATHER IMPRESSIVE TAKU WIND EVENT IS BEGINNING TO
TAKE SHAPE FOR DOWNTOWN JUNEAU AND DOUGLAS FOR LATER TODAY INTO
TONIGHT. THE SET UP FOR THIS IS ALMOST NEAR PERFECT WITH A LOW
OVER THE NE PACIFIC AND A HIGH OVER THE YUKON FUNNELING NORTHEAST
WINDS OVER THE RIDGES. CROSS BARRIER FLOW IS CURRENTLY AT ABOUT
40 KT AS SEEN AT SHEEP MOUNTAIN. THAT IS EXPECTED TO INCREASE TO
55 KT OR MORE BY THIS EVENING. ADDING TO THESE INGREDIENTS IS THE
UPPER LEVEL TROUGH THAT IS PROVIDING WESTERLY WINDS ALOFT FORMING
A CRITICAL LEVEL OF LOW WINDS AROUND 600 MB RIGHT NOW, BUT WILL
BE RISING TO AROUND 500 MB BY THIS EVENING WHICH IS EVEN BETTER
FOR HIGH WIND GUSTS. LAST BUT NOT LEAST IS AN INVERSION ABOVE
RIDGE TOP WHICH AIRLINE MDCRS SOUNDINGS FROM LAST EVENING SHOW AT
AROUND 750 MB. SO FAR THIS HAS RESULTED IN GUSTS AS HIGH AS
52 MPH AT SOUTH DOUGLAS THIS MORNING. EXPECTED WIND GUSTS WILL BE
IN THE 40 TO 50 MPH RANGE THROUGH THE DAY EVEN AS CROSS BARRIER
FLOW INCREASES BECAUSE THE INVERSION WILL BE DESTROYED BY SOLAR
HEATING TODAY. THE INVERSION WILL REFORM THIS EVENING ALLOWING
THE GUSTS TO RESUME AT A HIGHER LEVEL DUE TO THE HIGHER CROSS
BARRIER FLOW. THE HIGH WIND WARNING FOR DOWNTOWN JUNEAU AND
DOUGLAS REMAINS IN EFFECT FROM THIS AFTERNOON THROUGH TUES
AFTERNOON FOR GUSTS OF 70 TO 80 MPH. HIGHEST GUSTS ARE EXPECTED
EARLY TUES MORNING AS THE INVERSION REACHES ITS PEAK STRENGTH.

 THE OTHER FEATURES TO WORRY ABOUT IS THE WEAKENING FRONT THAT IS
TRYING TO COME UP FROM THE SOUTH. SO FAR THE OUTFLOW ACROSS THE
PANHANDLE HAS SUPPRESSED IT TO THE POINT THAT NO PRECIP HAS BEEN
OBSERVED SO FAR IN THE PANHANDLE. AT THIS POINT IT APPEARS THAT
CLOUD COVER WILL BE THE MOST SIGNIFICANT EFFECT FROM IT BUT I
STILL HAVE LIKELY TO CAT POP OVER THE SOUTHERN PANHANDLE AS THERE
STILL IS A GOOD CHANCE OF AT LEAST A SHORT PERIOD OF LIGHT RAIN
IN THE FAR SOUTH TODAY AND TONIGHT PROVIDED IT CAN GET THROUGH
THE DRY AIR MASS AT THE SURFACE. OTHERWISE THE PERSISTENT OUTFLOW
AND THE UPPER LEVEL TROUGH DROPPING SOUTH WILL KEEP THIS FEATURE
AS MAINLY A SOUTHERN PANHANDLE EVENT BUT HIGH LEVEL CLOUDS WILL
STILL STREAM OVER THE REST OF THE PANHANDLE THROUGH TONIGHT.

 SHORT RANGE MODELS WERE IN GOOD AGREEMENT THIS MORNING. ONCE
AGAIN IT APPEARS THAT THE ECMWF WAS THE BEST AT DEPICTING THE
PRESSURE GRADIENT ALONG THE PANHANDLE WITH THE OTHERS BEING TOO
AGGRESSIVE. HOWEVER THE NAM STILL HAD THE BEST HANDLE ON CURRENT
OUTFLOW WINDS PATTERNS ACROSS THE AREA. IN LIGHT OF THIS MAINLY
PREFERRED NAM FOR WINDS WITH A COMBO OF NAM AND EC FOR MOST OTHER
FIELDS THROUGH TONIGHT.

 &&

 .LONG TERM...LONG RANGE WEATHER PATTERN SHOWING LITTLE CHANGE
WITH BLOCKING FEATURES REMAINING IN PLACE THROUGH THE WEEK AND
INTO THE WEEKEND. HIGH PRESSURE OVER NORTHWESTERN CANADA WILL
STAY IN PLACE BUT WEAKEN THROUGH THE WEEK. LOW PRESSURE CURRENTLY
MOVING INTO THE SE GULF WILL EXIT TO THE SOUTHEAST AS A SECOND
LOW MOVING ACROSS THE NORTH PACIFIC MOVES OFF THE COAST OF HAIDA
GWAII BY THU. NORTHERN PORTIONS OF THE PANHANDLE WILL REMAIN DRY
WITH MOSTLY CLEAR SKIES AND LARGE DIURNAL TEMPERATURE RANGE.
SOUTHERN PANHANDLE WILL BE MOSTLY CLOUDY WITH CHANCE PRECIP FROM
LOW PRESSURE SYSTEMS IN THE SOUTHERN AK GULF. THERE ARE
INDICATIONS THAT THE REX BLOCK OVER AK INTERIOR AND N PACIFIC
WILL BREAK DOWN TOWARDS NEXT WEEK BUT STILL SOME UNCERTAINTY WITH
THIS.

 THE TIGHT PRESSURE GRADIENT OVER THE PANHANDLE BETWEEN THE
CANADIAN HIGH AND SE GULF LOW PRODUCING THE STRONG OUTFLOW WINDS
WILL DIMINISH AS THE LOW TRACKS TO THE SE AND THE CANADIAN HIGH
WEAKENS. GRADIENT WILL PICK UP AS THE NEXT LOW MOVES IN ON THU
BUT THE GRADIENT WILL BE NO WHERE NEAR AS STRONG AS THE CURRENT
SYSTEM. GUST WINDS WILL SUBSIDE THROUGH THE DAY ON TUE BUT WILL
STILL EXPECT SOME HIGHER GUSTS CONTINUING INTO TUE EVENING. FOR
THE TAKU WINDS IN DOWNTOWN JUNEAU AS THE CROSS BARRIER FLOW
SUBSIDES SO WILL THE HIGH GUSTS.

 ECMWF CONTINUES TO INITIALIZE WELL AND HAS BEEN CONSISTENT
THROUGH MID WEEK. MODEL SPREAD AND RUN TO RUN VARIATIONS DEVELOP
BY THE END OF THE WEEK. USED A BLEND OF ECMWF WITH SOME NAM FOR
OUTFLOW WIND DETAILS TO DAY 4 THEN TRANSITIONED TO WPC. INHERITED
GRIDS WERE STILL IN LINE WITH NEW MODELS SO ANY CHANGES WERE
MINOR. HIGH CONFIDENCE IN GENERAL SYNOPTIC PATTERN THROUGH THE
WEEK BUT THE OUTFLOW WINDS WILL CAUSE UNCERTAINTY WITH LOCAL
EFFECTS.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...HIGH WIND WARNING FROM 4 PM THIS AFTERNOON TO 4 PM AKDT TUESDAY
     FOR AKZ025.
         STRONG WIND THROUGH LATE TUESDAY NIGHT FOR AKZ018-019.
MARINE...GALE WARNING FOR PKZ012-013-022-031-035-041>043-051.
         SMALL CRAFT ADVISORY FOR PKZ011-021-032>034-036-052-053.

&&

EAL/PRB