High Wind in Alaska, January 11, 2005

SOUTHEAST ALASKA FORECAST DISCUSSION
1100 AM AST TUE JAN 11 2005

.SYNOPSIS...
.SHORT RANGE...THE VERY COLD ARCTIC AIR IS DEFINITELY ON ITS WAY
INTO THE PANHANDLE. IN THE JUNEAU AREA TEMPERATURES HAVE BEEN
FALLING AT THE RATE OF A DEGREE AND A HALF AN HOUR SINCE
YESTERDAY AFTERNOON. WITH THE LOW WINTER SUN ANGLE TODAYS
SUNSHINE WILL ONLY MODERATE THIS TREND SLIGHTLY. COLD AIR WILL
CONTINUE TO MOVE SOUTH THROUGH THE PANHANDLE THROUGH THE DAY...SO
EXPECT TO SEE SOUTHERN PANHANDLE TEMPERATURES ALSO PLUMMET AS THE
ARCTIC FRONT MOVES THROUGH. SNOW IS STILL LINGERING IN A FEW
LOCATIONS IN THE SOUTHERN PANHANDLE BUT SHOULD END WITHIN THE
NEXT HOUR OR TWO. HYDER WILL LIKELY BE THE LAST PLACE FOR THE
SNOW TO END WITH ANOTHER INCH OR SO OF ACCUMULATION TO TOP OFF
THE 13 INCHES THEY HAVE RECEIVED SO FAR IN LAST 24 HOURS. BY
AFTERNOON SKIES SHOULD BE CLEAR ACROSS THE PANHANDLE.

SUSTAINED WINDS HAVE BEEN OUT OF THE NORTH BETWEEN 35 AND 40 KT
ALL NIGHT AT BOTH ELDRED ROCK AND FIVE FINGER LIGHTHOUSE.
ALTHOUGH THERE ARE NO OBSERVATIONS IN CHATHAM STRAIT I WOULD
EXPECT THAT CONDITIONS WERE SIMILAR IN THAT LOCATION AS WELL.
NORTHERLY GALES WILL CONTINUE THROUGH THE DAY AND THEN DIMINISH
TO 25 TO 30 KT THROUGH WED MORNING AS THE PRESSURE GRADIENT
SHIFTS TO THE EAST. EASTERLY WINDS WILL INCREASE WED AFTERNOON
THROUGH WED NIGHT AS THE OFFSHORE PRESSURE TIGHTENS WITH THE
APPROACH OF SURFACE LOW INTO TO THE EASTERN GULF.

AS THE PRESSURE GRADIENT SHIFTS TO THE NORTHEAST TONIGHT THE
CRITICAL LEVEL WILL INCREASE TO BETWEEN 600 AND 700 MB MAKING
CONDITIONS IN THE JUNEAU AREA MORE FAVORABLE FOR THE FORMATION OF
MOUNTAIN WAVES AND A TAKU WIND EVENT. THIS EVENT LOOKS TO HAVE
THE POTENTIAL FOR WIND GUSTS UP TO 55 MPH IN DOWNTOWN JUNEAU AND
DOUGLAS WITH THE STRONGEST GUSTS IN THE LATE EVENING. WITH THE
TIGHTENING EASTERLY GRADIENT FROM THE APPROACH OF THE SURFACE LOW
WED NIGHT BEARS WATCHING FOR A SIGNIFICANTLY STRONGER TAKU EVENT.

.LONG RANGE...AN UPPER LEVEL LOW OVER NORTH CENTRAL CANADA WILL
BE SLOW TO MOVE EAST THU THROUGH SAT WHICH SLOWS DOWN THE PATTERN
CHANGE AND KEEPS A BUILDING UPPER LEVEL RIDGE OVER THE GULF OF
ALASKA AND INTO NORTHERN ALASKA THROUGH SAT. THE ARCTIC SURFACE
HIGH OVER NORTHWEST CANADA WILL THEN REBUILD OVER THE YUKON TO
AROUND 1050 MB INTO THU AS ANOTHER REINFORCING SHOT OF ARCTIC AIR
MOVES IN. THIS HIGH WILL SLOWLY WEAKEN AS IT MOVES SOUTH THROUGH
BRITISH COLUMBIA FRI AND SAT. THE LOW LEVEL FLOW WILL THEN REMAIN
NORTHEAST TO EAST THROUGH SAT KEEPING COLD TEMPERATURES OVER THE
PANHANDLE THU AND FRI THEN TEMPERATURES WILL BEGIN MODIFYING ON
SAT AND SAT NIGHT AS THE FLOW WEAKENS.

THE BIGGEST FORECAST PROBLEM THU THROUGH SAT WILL BE A WEAK LOW
THAT THAT FORMS IN THE FRONTAL ZONE OVER THE NORTHERN GULF AND
MOVES SOUTHEAST ALONG THE COAST. MODELS CONTINUE TO BE IN
DISAGREEMENT AND INCONSISTENT WITH THIS FEATURE. CURRENT ETA AND
MESOETA SOLUTIONS BUILD A MUCH STRONGER HIGH OVER NORTHWEST
CANADA AND A SHARP 850 MB RIDGE OFFSHORE WHICH KEEPS MOST OF THE
OVERRUNNING SNOW PRODUCED BY THIS LOW OFFSHORE. THE GFS SOLUTION
HAS A WEAKER HIGH AND 850 MB RIDGE WHICH BRINGS ONSHORE FLOW AT
850 MB AND BRINGS A PERIOD OF OVERRUNNING SNOW TO THE NORTHERN
AND CENTRAL PANHANDLE WED NIGHT INTO EARLY THU THEN OVER THE
SOUTHERN THIRD THU INTO THU EVENING.

WILL CONTINUE THE CURRENT FORECAST TREND AND FAVOR THE GFS AT
THIS TIME. SINCE TEMPERATURES WILL BE IN THE SINGLE DIGITS TO
TEENS SNOW RATIOS WOULD RUN HIGH WITH THIS EVENT SO WILL CONTINUE
THE WINTER STORM WATCH FOR THE SOUTHERN HALF INTO THU. OFFSHORE
FLOW IN THE LOW LEVELS AND NORTHWEST FLOW ALOFT WILL BRING
CLEARING SKIES FOR FRI AND SAT WITH UPPER LEVEL CLOUDS SPILLING
OVER THE RIDGE KEEPING SKIES PARTLY CLOUDY OVER THE NORTHERN
HALF. WINDS WILL ALSO INCREASE OVER THE NORTHERN PANHANDLE ON THU
THEN OVER THE REMAINDER INTO THU NIGHT. EXPECT MAINLY SMALL CRAFT
TO GALES WITH HIGHER GUSTS OUT OF INTERIOR PASSES. ADVISORY GUSTS
OUT OF PASSES WILL BE POSSIBLE OVER ZONES 25 26 28 AND 29 THROUGH
FRI NIGHT THEN DIMINISH ON SAT.

CONFIDENCE IS NOT HIGH ON HOW QUICKLY THE PATTERN WILL CHANGE
LATE WEEKEND INTO EARLY NEXT WEEK. THE GFS AND CURRENT FORECAST
ARE STILL FAVORING A WARMER PATTERN SETTING UP WITH THE UPPER
LEVEL RIDGE MOVING INTO WESTERN CANADA AND A FEW MILD SYSTEMS
MOVING NORTH INTO THE GULF AND PANHANDLE SUN THROUGH TUE. THE
LATEST ECMWF AND DGEX ARE BEGINNING TO RUN MUCH SLOWER WITH THIS
CHANGE. DUE TO THESE LATEST DIFFERENCES WILL NOT MAKE ANY MAJOR
CHANGES TO THE EXTENDED FORECAST PERIOD AT THIS TIME.

.AJK...WATCHES/WARNINGS/ADVISORIES
PUBLIC...WIND ADVISORY ZONES 18 19 23 24 25 26 28 29
         WIND CHILL ADVISORY ZONES 18 19 20
         HEAVY SNOW WATCH 23 24 26 27 28

MARINE...GALES AREAS 12 13 21 22 31 32 33 34 AND INTERIOR PASSES
         SCA OUTSIDE WATERS AND AREAS 11 35 36
         HEAVY FREEZING SPRAY WARNING AREAS 11 12 13

JER/TAR