High Wind in Alaska, February 19, 2008

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
1240 PM AST TUE FEB 19 2008

.ANALYSIS AND UPPER LEVELS...ACTIVE STORM TRACK CONTINUES THIS
MORNING ACROSS MAINLAND ALASKA UNDER AN AMPLIFIED LONG-WAVE PATTERN
PATTERN OF TROUGH OVER THE BERING AND RIDGE OVER WESTERN U.S./CANADA.

SATELLITE IMAGE SHOWS TWO DEEP LOWS FOLLOWING THE UPPER FLOW FROM
THE NORTHEAST PACIFIC NORTHWARD TO THE SOUTHERN MAINLAND. A 960 MB
LOW IS JUST EAST OF KODIAK ISLAND TRACKING TO THE WEST-NORTHWEST.
STORM FORCE WINDS ARE BEING OBSERVED AHEAD OF THE LOW FROM SHELIKOF
STRAIT TO THE BARREN ISLANDS TO THE NORTHERN GULF. STRONG GAP WINDS
HAVE ALSO DEVELOPED OVER SOUTHCENTRAL ALASKA AND DOWNSLOPE SIGNATURE
(WARM CLOUD TOPS) ALONG THE WESTERN KENAI MOUNTAINS IS APPARENT IN
LATEST SATELLITE IMAGERY. RADAR IMAGERY SHOWS PRECIPITATION HAS
OVERSPREAD MUCH OF COASTAL SOUTHCENTRAL AND IS OVERSPREADING
SOUTHWEST ALASKA. PRECIPITATION TYPE IS MAINLY RAIN OVER SOUTHCENTRAL
AND SNOW AS YOU HEAD FARTHER WEST OVER SOUTHWEST ALASKA. THE NEXT
LOW IS NOT FAR BEHIND...AT 45N 157W (20Z) WITH A CENTRAL PRESSURE
APPROACHING 960 MB AND TRACKING NORTHEASTWARD. A DECAYING LOW IS
SPINNING EAST OF ADAK WITH A SLOW SOUTHWARD MOVEMENT PRODUCING A
FEW SNOW SHOWERS IN ITS VICINITY. COLD ADVECTION SHOWERS ARE EVIDENT
BEHIND THE LOW ACROSS THE CENTRAL TO WESTERN BERING.

.MODEL DISCUSSION...SATELLITE IMAGERY AND A 15Z QUIKSCAT WIND
IMAGE SHOWS NAM IS TOO FAR NORTH WITH THE LOW CENTER WHILE THE
GFS/UKMET/ECMWF ARE ALL VERY CLOSE. NAM IS ALSO ABOUT 8 MB TOO
WEAK WHILE THE OTHER MODELS ARE JUST A FEW MILLIBARS TOO WEAK.
THEREFORE...PREFER THE GLOBAL MODELS OVER THE NAM. NAM ALSO APPEARS
TO BE THE ODD MAN OUT IN TRACK OF NEXT LOW...ALTHOUGH IT IS STILL
IN THE VICINITY OF THE OTHER MODELS. THERE IS FAIR RUN-TO-RUN
CONSISTENCY WITH THIS TRACK SO NO MAJOR CHANGES WILL BE MADE TO
EXISTING FORECAST.

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...GREATEST IMPACT OF THE CURRENT STORM SYSTEM
MOVING THROUGH THE REGION WILL BE WIND. AS THE REMNANTS OF THE
OCCLUDED FRONT REACH THE NORTH GULF COAST THIS AFTERNOON EXPECT
STRONGEST WINDS THROUGH CHANNELED AREAS ALONG THE COAST WITH WARNING
LEVEL WINDS THROUGH PORTAGE VALLEY AND TURNAGAIN ARMS. WHILE THE
LOW TRACK IS REMAINS OVER OR EAST OF KODIAK ISLAND EXPECT STRONGEST
WINDS THROUGH PORTAGE VALLEY AND EAST TURNAGAIN ARM. THEN AS THE LOW
MOVES WEST OF KODIAK ISLAND THIS EVENING STRONGEST WINDS WILL SHIFT
TO WEST TURNAGAIN ARM AS A TIGHT EAST-WEST PRESSURE GRADIENT SETS UP.

THE FRONT WILL COMPLETELY FALL APART AT THE SURFACE...BUT MOVE INLAND
ALOFT TONIGHT. THERE WILL ALSO BE SHARP PRESSURE RISES THROUGH THE
NIGHT AS THE LOW DEPARTS AND HIGH PRESSURE BUILDS ALONG THE COAST
AHEAD OF THE NEXT LOW MOVING TOWARD THE GULF. THIS WILL RESULT IN
WIDESPREAD GUSTY SOUTHWEST WINDS ACROSS SOUTHCENTRAL BEGINNING THIS
EVENING AND CONTINUING THROUGH EARLY WEDNESDAY MORNING. WILL EXTEND
HIGH WIND WARNING FOR WESTERN TURNAGAIN ARM AND THE ANCHORAGE
HILLSIDE TO RUN THROUGH THE NIGHT. THESE WINDS ALONG WITH WARM
ADVECTION ASSOCIATED WITH THE SYSTEM WILL RESULT IN A DAY SIMILAR
TO SUNDAY...WITH TEMPERATURES RISING INTO THE UPPER 30S TO MID 40S
ACROSS MUCH OF THE REGION TONIGHT. THE NEXT STORM WILL NOT ALLOW FOR
MUCH OF A BREAK IN THE WEATHER WITH PRECIPITATION AND WINDS
ASSOCIATED WITH NEW LOW MOVING INTO COASTAL REGIONS BY LATE
WEDNESDAY. THIS NEXT LOW WILL INITIALLY TAKE A SIMILAR TRACK TO THE
CURRENT SYSTEM...BUT WILL STALL OUT IN THE BARREN ISLANDS REGION
LATE THURSDAY AS THE TROUGH REFORMS FARTHER EAST AND A RIDGE BEGINS
TO BUILD OUT WEST. THEREFORE...DO NOT LOOK FOR A REPEAT OF WIDESPREAD
WINDS AND WARMTH.

SOUTHWEST ALASKA...SNOW WILL CONTINUE TO SPREAD WESTWARD ACROSS
SOUTHWEST ALASKA THIS AFTERNOON AND EVENING. GUSTY NORTHERLY WINDS
AHEAD OF THE LOW WILL RESULT IN AREAS OF BLOWING SNOW...MAINLY
ALONG THE KUSKOKWIM DELTA COAST WHERE TEMPERATURES ARE COLDEST.
MEANWHILE...NEAR THE ALEUTIAN AND ALASKA RANGES TEMPERATURES WILL
BE WARM ENOUGH FOR RAIN. PRECIPITATION WILL LIKELY MIX WITH OR
CHANGE TO SNOW OVERNIGHT AS SOMEWHAT COLDER AIR ALOFT MOVES BACK IN.
HOWEVER...PRESSURE RISES BEHIND THE LOW WILL RESULT IN GUSTY
SOUTHEASTERLIES LATE TONIGHT THROUGH WEDNESDAY MORNING WHICH WILL
PROVIDE LOTS OF MIXING AND KEEP SURFACE TEMPERATURES FAIRLY WARM.
DRYING WILL OCCUR BY WEDNESDAY AFTERNOON AS THE LOW PULLS AWAY.
THE NEXT LOW WILL SPREAD MOISTURE INTO BRISTOL BAY BY WEDNESDAY
EVENING...BUT AS THE LOW STALLS IN THE BARREN ISLAND REGION THURSDAY
WILL NOT SEE AS MUCH PRECIPITATION AS WITH THE CURRENT SYSTEM AND
THE CHARACTER OF THE PRECIPITATION WILL BE MORE SHOWERY. COLD
ADVECTION WILL MOVE IN AT WEEKS END AS RIDGE BUILDS OVER THE BERING.
COMBINATION OF THE COLD ADVECTION WITH WEAK UPPER DISTURBANCES WILL
SET UP A SHOWERY REGIME.

BERING SEA/ALEUTIANS...DECAYING LOW NEAR ATKA WILL FINALLY SINK
SOUTH AND DISSIPATE THIS EVENING. A WEAK UPPER SHORT-WAVE OVER THE
WESTERN BERING WILL CROSS THE BERING TONIGHT AND WEDNESDAY WHILE A
RIDGE BEGINS TO BUILD BEHIND IT. COLD ADVECTION WILL INCREASE BEHIND
THIS SHORT-WAVE RESULTING IN SNOW SHOWERS AND GUSTY WINDS ACROSS THE
CENTRAL BERING THROUGH THURSDAY AND EASTERN BERING THROUGH FRIDAY.
CALM WEATHER WILL SET UP UNDER THE BUILDING RIDGE ACROSS THE CENTRAL
BERING THURSDAY AND FRIDAY.

.LONG TERM FORECAST...PATTERN CHANGE LOOKS TO BE ON TRACK FOR LATE
THIS WEEK AS THE TROUGH SWINGS EASTWARD TO THE GULF AND A RIDGE
BUILDS OVER THE BERING SEA. THIS WILL RESULT IN COOLER AND DRIER
WEATHER ACROSS MAINLAND ALASKA BEGINNING THIS WEEKEND. ITS TOO
EARLY TO TELL WHETHER THIS NEW PATTERN WILL HANG AROUND FOR A
WHILE OR CONTINUE TO PROGRESS AND EVOLVE.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...HIGH WIND WARNING...101 AND 125.
MARINE...GALE WARNING...120 125 129 130 132 139 140 141.
         HEAVY FREEZING SPRAY... 179 185.
FIRE WEATHER...NONE.

SEB FEB 08