High Wind in Alaska, November 29 to 30, 2007

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
538 AM AST THU NOV 29 2007

.DISCUSSION...NARROW 500MB RIDGE BUILDING FROM GULF OF ALASKA UP
THROUGH BEAUFORT SEA. ON THE WESTERN EDGE OF THIS RIDGE A HIGH
SPEED SOUTHERLY FLOW IS ZIPPING UP ALASKAS WEST COAST. BASIC
PATTERN WONT CHANGE MUCH UNTIL SUNDAY WHEN A SHORT WAVE TROUGH
RIDING DOWN ON THE EAST SIDE OF THE RIDGE UNDERCUTS THE RIDGE DOWN
IN THE GULF OF ALASKA...THE RESULT IS DEVELOPMENT OF A CLOSED HIGH
ALOFT CENTERED OVER THE BEAUFORT SEA. NUMERICAL MODELS HAVE BEEN
PRETTY CONSISTENT AND ACCURATE THIS WEEK CONCERNING THIS PATTERN.

WEST COAST...BUSY COUPLE OF DAYS COMING UP. SUBSTANTIAL WARM
ADVECTION WITH THE SOUTHERLY FLOW HAS BROUGHT SURFACE
TEMPERATURES FROM BERING STRAIT SOUTH UP TO FREEZING OR A LITTLE
HIGHER WITH PRECIPITATION MIXING WITH RAIN...SO AS PLANNED THE
CONCERN IS FOR HIGH WIND AND NOT BLIZZARDS. WILL UPGRADE HIGH WIND
WATCHES FOR ZONES 211>214 TO HIGH WIND WARNINGS. THIS WILL BE A
LONG EVENT...AND MAY NOT END UNTIL LATE FRIDAY BECAUSE A COUPLE OF
SHORT WAVE FEATURES NEED TO RIPPLE THROUGH BEFORE ITS ALL OVER.
WINDS WILL NOT DROP TO COMPARATIVELY QUIET LEVELS UNTIL SAT NIGHT OR
SUNDAY WHEN THE RIDGE ALOFT CUTS OFF AND PIVOTS SLIGHTLY TO THE
WEST AND NUDGES THE STEERING FLOW OUT INTO THE CENTRAL BERING SEA.
DESPITE STRONG WINDS ALONG THE WEST COAST...THE OFFSHORE
DIRECTION IS NOT OPTIMAL FOR PRODUCING COASTAL FLOODING AT THE
MOST VULNERABLE COMMUNITIES. REGARDING PRECIP...NOME RADAR HAS
NICELY SHOWN FIRST SHOT MOVING THROUGH WITH A DRY PERIOD NOW IN
PLACE. NEXT BOUT OF PRECIP WILL ARRIVE LATER TODAY. THERE IS ALSO
A CHANCE FOR LEGITIMATE FREEZING RAIN IN WESTERN ZONE 216 FRIDAY
AND FRIDAY NIGHT. THE MECHANISM WILL BE FOR COLD AIR TO BE DAMMED
UP AND TRAPPED ALONG THE NULATO HILLS...AND THEN WARMER AIR WILL
MOVE IN ABOVE THIS AND PRODUCE SOME RAIN. IF THIS ACTUALLY COMES
TO PASS...THE AFFECTED AREA COULD GET A COUPLE TENTHS OF AN INCH
OF FREEZING RAIN. SUCH EVENTS ARE RARE IN NORTHERN ALASKA...BUT
THIS SCENARIO IS ONE WAY TO ACHIEVE THEM. CONFIDENCE IS NOT REAL
HIGH...BUT IS WORTH A WATCH AT THIS TIME.

INTERIOR...DRY WEATHER FOR THE REST OF THE WEEK. WINDS WILL PICK
UP AGAIN IN THE PASSES OF THE CENTRAL AND WESTERN ALASKA RANGE.
UPPER LEVEL SUPPORT AT 700MB WILL NOT BE PARTICULARLY STRONG FOR
THIS...BUT THERE SHOULD BE AMPLE SEA LEVEL PRESSURE GRADIENT OUT
OF A MESO-HIGH CENTERED IN THE COPPER RIVER BASIN. HI-RES NAM/WRF
MODEL DOES A GOOD JOB IDENTIFYING THE MESO-HIGH. THE TANANA VALLEY
JET SHOULD ALSO ACTIVATE FOR ZONE 223 OVER THE NEXT 24 HOURS DUE
TO PRESSURE GRADIENT EFFECTS. THESE WINDS LOOK AT MOST TO BE OF
ADVISORY CRITERIA...HIGH WIND WARNINGS WONT BE IN THE CARDS
WITHOUT MORE UPPER LEVEL SUPPORT.

NORTH SLOPE...EARLY MORNING POES IR IMAGERY SHOWS RESILIENT STRATUS
HOLDING ALONG THE IMMEDIATE COAST...WITH CLEARER AND COLDER
WEATHER NOT FAR INLAND. WILL NOT TRY TO FORECAST ANY BREAK-UP OF
THIS FOG AND STRATUS TODAY...BUT WITH TIME PERHAPS THERE WILL BE
SOME DECREASE OVERNIGHT. WIND SPEEDS WILL INCREASE SOMEWHAT OVER
NEXT 24 HOURS...BUT WONT BE UP TO ADVISORY CRITERIA.

COASTAL HAZARD POTENTIAL DAYS 3 AND 4...WINDS WILL BE MUCH QUIETER
BY SUNDAY...THEN INCREASING OUT OF THE NORTH FOR MONDAY. DOES NOT
LOOK VERY THREATENING FOR SHISHMAREF OR KIVALINA AT THIS TIME.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FOR AKZ216.

HIGH WIND WARNING FOR AKZ211-AKZ212-AKZ213-AKZ214.

HEAVY FREEZING SPRAY WARNING FOR PKZ225.

GALE WARNING FOR PKZ200-PKZ210-PKZ215-PKZ220-PKZ225.

SMALL CRAFT ADVISORY FOR PKZ225.

BRISK WIND ADVISORY FOR PKZ215-PKZ230-PKZ235-PKZ240-PKZ245.
&&

ES NOV 07