Blizzard and High Wind in Alaska, February 7 to 9, 2010

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
200 PM AKST SUN FEB 7 2010

.ANALYSIS AND UPPER LEVELS...
LONG WAVE PATTERN REMAINS AMPLIFIED AND ACTIVE. THE COLD CORE LOW
THAT WAS OVER THE KUSKOKWIM DELTA YESTERDAY IS DRIFTING NORTH TOWARD
NORTON BAY. AN UPPER LEVEL TROF EXTENDS SOUTH AND EAST FROM THIS
FEATURE WITH AXIS NEAR THE BARREN ISLANDS. TWO SHORTWAVES ARE
EMBEDDED WITHIN THE SOUTHERLY FLOW ALONG THE TROF AXIS...THE MORE
POTENT ONE IS MOVING RAPIDLY TOWARD YAKUTAT AND WILL HAVE LITTLE
IMPACT ON OUR FORECAST. THE SECOND WEAKER ONE HAS A SURFACE
REFLECTION NEAR THE SOUTHERN POINT OF THE KENAI PENINSULA.

FURTHER WEST...A RAPIDLY DEEPENING LOW IS EVIDENT ON SATELLITE
IMAGERY SOUTH OF THE CENTRAL ALEUTIANS. IT IS BEING FUELED BY A 200
KT JET FLOWING AROUND THE BASE OF THE TROF NEAR 35N. THIS FEATURE
WILL BE THE FOCUS OF OUR ATTENTION FOR THE NEXT SEVERAL DAYS.

.MODEL DISCUSSION...THE MODEL DISCUSSION IS A LITTLE MORE COMPLICATED
THAN THE PREVIOUS COUPLE OF DAYS BECAUSE THE DIFFERENCES ARE NOW IN
THE SHORT TERM AND HAVE LARGE IMPACTS ON WATCH/WARNING DECISIONS. THE
EASTERN HALF OF OUR DOMAIN IS IN RELATIVELY GOOD SHAPE WITH ALL MAJOR
FEATURES ACCOUNTED FOR AND CONSISTENT THROUGH THE SHORT TERM.

OUT WEST...MODELS ARE HAVING A VERY DIFFICULT TIME WITH THE COMPLEX
LOW AND STORM FORCE FRONT THAT IS DEVELOPING TODAY. THE NAM IS BY FAR
THE OUTLIER SO WAS DISCARDED FOR THIS PACKAGE. SYNOPTICALLY...THE GFS
AND ECMWF ARE IN MUCH BETTER AGREEMENT. THE DIFFERENCES SURROUND THE
LOCATION AND STRENGTH OF THE SHORT WAVES AND THEIR SURFACE
REFLECTIONS. A BLEND OF THESE TWO WERE USED AS NO PREFERENCE COULD BE
GIVEN TO EITHER. FORECAST CONFIDENCE IS ABOVE AVERAGE IN THE FIRST 48
HOURS...BUT DIMINISHES BEYOND THAT.

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...THE MAIN FEATURE IN THE EASTERN DOMAIN IS A
WEAK SURFACE LOW NEAR THE TIP OF THE KENAI PENINSULA. WIDESPREAD SNOW
SHOWERS CAN BE SEEN ON THE KENAI AND MIDDLETON RADARS...AND ARE
SPREADING NORTH TOWARD THE ANCHORAGE BOWL AND LOWER SUSITNA VALLEY.
AS EXPECTED...LIGHT SNOW SHOULD DEVELOP THIS EVENING AND CONTINUE
THROUGH THE EARLY MORNING HOURS. THE SHOWERS WILL LINGER LONGEST
ALONG THE MOUNTAINS WHERE SNOWFALL TOTALS MIGHT REACH 3 INCHES...BUT
OTHERWISE ARE EXPECTING ONLY AN INCH OR SO OVER MOST AREAS.

HIGH PRESSURE QUICKLY BUILDS BEHIND THE DEPARTING SHORTWAVE AND THEN
EYES TURN WEST WITH THE ADVANCING STORM FORCE FRONT MONDAY AFTERNOON.
SNOW WILL CHANGE OVER TO RAIN RELATIVELY QUICKLY ACROSS KODIAK ISLAND
MONDAY EVENING AS WELL AS THE NORTH GULF COAST. THE WESTERN KENAI UP
TO THE MATANUSKA VALLEY WILL REMAIN DOWNSLOPED FOR THIS EVENT...WITH
MAYBE ONLY A FEW FLURRIES FALLING DURING THE INITIAL OVERRUNNING
MOISTURE. THE UPSTREAM UPPER LEVEL RIDGE WILL EFFECTIVELY BLOCK THE
FRONT AND ASSOCIATED PRECIPITATION FROM ADVANCING TOO FAR INLAND. THE
UPPER LEVEL PATTERN REMAINS RELATIVELY UNCHANGED THROUGH MID WEEK
WITH THE TROF AXIS OVER THE CENTRAL ALEUTIANS AND HIGH PRESSURE ALONG
THE ALCAN BORDER...RESULTING IN SOUTHEASTERLY FLOW ACROSS
SOUTHCENTRAL ALASKA AND PRECIPITATION BEING CONFINED TO THE COAST.
TEMPERATURES WILL BE AT OR ABOVE AVERAGE THIS WEEK.

SOUTHWEST ALASKA...HIGH PRESSURE IS BUILDING IN THE WAKE OF THE
DEPARTING UPPER LEVEL LOW. THE PLEASANT WEATHER WILL NOT LAST LONG AS
THE FRONT APPROACHES THE ALASKA PENINSULA MONDAY EVENING...POSSIBLY
BRINGING BLIZZARD CONDITIONS TO THE KUSKOKWIM DELTA MONDAY NIGHT.
STRONG WINDS ARE LIKELY THROUGH THE ALASKA PENINSULA WITH GUSTS TO 65
MPH NOT OUT OF THE QUESTION THROUGH CHANNELED TERRAIN. DEPENDING ON
HOW FAST WARMER AIR MOVES INLAND...WILL ALSO HAVE TO CONSIDER
BLIZZARD CONDITIONS IN THE BRISTOL BAY ZONE...ESPECIALLY THE WESTERN
CAPES...AS WELL MONDAY EVENING THROUGH EARLY TUESDAY MORNING.

THE WEATHER WILL REMAIN ACTIVE IN THIS REGION WITH IMPULSES ROTATING
NORTHWARD ACROSS THE AKPEN THROUGH LATE IN THE WEEK...BRINGING
OCCASIONAL RAIN AND SNOW SHOWERS AS WELL AS GUSTY WINDS.

BERING SEA/ALEUTIANS...THE MUCH ADVERTISED FRONT IS DEVELOPING AND
APPROACHING THE CENTRAL ALEUTIANS THIS AFTERNOON. BLIZZARD WARNINGS
AND WATCHES ARE POSTED ALONG THE CHAIN AND THE PRIBILOFS FOR STRONG
WINDS AND HEAVY PRECIPITATION. SOME QUESTIONS STILL REMAIN AS TO HOW
FAST THE SNOW WILL CHANGE OVER TO RAIN. WE WILL WATCH CLOSELY WHAT
HAPPENS IN THE CENTRAL AND EASTERN ALEUTIANS AND USE THAT TO GAGE THE
POTENTIAL FOR BLIZZARD CONDITIONS OVER THE ALASKA PENINSULA.
CONFIDENCE IS MUCH HIGHER FOR THE PRIBILOFS AS THE ICE EDGE IS
BUTTING UP AGAINST THE ISLANDS...MAKING THEM ESSENTIALLY A
CONTINENTAL LOCATION. MODELS DISAGREE ON THE ONSET OF THE PRECIP BUT
ONCE IT BEGINS TO FALL...EXPECT BLIZZARD CONDITIONS FOR AN EXTENDED
TIME UNTIL THE FRONT MOVES THROUGH LATE MONDAY NIGHT.

ON THE BACKSIDE OF THE LOW...GUSTY WINDS AND WIDESPREAD SNOW SHOWERS
WILL PERSIST THROUGH LATE IN THE WEEK. THESE SHOWERS AND BLUSTERY
WINDS COULD REDUCE VISIBILITY TO ONE QUARTER MILE FOR SOME TIME. NOT
CONFIDENT ENOUGH TO ISSUE ANY 3RD OR 4TH PERIOD WATCHES BUT SOMETHING
ELSE WE WILL HAVE TO ACCOUNT FOR THIS WEEK.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WARNING 187
         BLIZZARD WATCH 185 195.
MARINE...STORM 130 132 138 140 150 155 160 165 170 171 175
         GALE WARNING...120 141 176 180 185
FIRE WEATHER...NONE.

AB FEB 10