Brisk Wind Advisory 35, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
345 PM AKDT THU MAR 19 2009

.MODEL DISCUSSION...

THE GFS IS THE PREFERRED MODEL THROUGH THE SHORT TERM.
LITTLE TO NO CHANGES WERE MADE TO THE EXISTING LONG RANGE
FORECAST.

.ANALYSIS AND UPPER LEVELS...

THE DOMINANT WEATHER FEATURES ON THE MAP ARE A PLETHORA OF
STACKED LOWS ROTATING AROUND EACH OTHER IN THE GULF OF
ALASKA...A NEARLY STACKED RIDGE EXTENDING FROM EASTERN
SIBERIA THROUGH MOST OF THE BERING SEA AND THE CENTRAL AND
EASTERN ALEUTIANS INTO THE NORTH PACIFIC...AND ANOTHER LARGE
UPPER LOW BEGINNING TO TRY TO UNDERCUT THE UPPER RIDGE TO ITS
NORTH AND EAST TO THE SOUTH OF THE WESTERN ALEUTIANS.  A
STRONG NORTHERLY JET EXTENDING FROM BRISTOL BAY ACROSS THE
AKPEN INTO THE FAR WESTERN GULF CONTINUES TO BRING STRONG
WINDS TO THE SURFACE...ESPECIALLY THROUGH CHANNELED TERRAIN.
SURFACE HIGH PRESSURE IS IN CONTROL OVER THE NORTHERN PART OF
THE STATE....WITH A TROUGH OF LOW PRESSURE EXTENDING BACK
ACROSS THE COOK INLET REGION INTO THE INTERIOR OF THE STATE
FROM THE LOW PRESSURE SYSTEMS IN THE GULF...WHICH HAS HAD
LITTLE SIGNIFICANT IMPACT ON THE WEATHER.

.SHORT TERM FORECAST...

THE RIDGING THAT EXTENDS ACROSS EASTERN SIBERIA THROUGH THE
BERING SEA INTO THE NORTH PACIFIC WILL BE FORCED TO SPLIT BY
THE UPPER LOW SOUTH OF THE WESTERN ALEUTIANS.  THIS RESULTS
IN THE QUICK MOVEMENT EASTWARD OF THE SOUTHERN PART OF THE
RIDGE AND THE NORTHERN PART OF THE RIDGE REBUILDING TO THE
NORTH OF AND BEHIND THE UPPER LOW.  AS THE RIDGE BUILDS OVER
EASTERN SIBERIA...COMPENSATING HEIGHT FALLS OVER INTERIOR
ALASKA COMBINED WITH THE ARRIVAL OF THE UPPER LOW FROM THE
WEST WILL RESULT IN A MERGER INTO ONE LARGE DEEP UPPER LOW
SOMEWHERE OVER FAR SOUTHWESTERN ALASKA...WHICH WILL RESULT IN
UNSETTLED WEATHER ACROSS NEARLY ALL OF THE AREA OF
RESPONSIBILITY BEGINNING LATE SUNDAY.

ALEUTIANS...A STRONG PRESSURE GRADIENT CREATED BY HIGH
PRESSURE TO THE NORTH AND THE LOW PRESSURE SYSTEM TO THE
SOUTH OF THE WESTERN ALEUTIANS WILL RESULT IN STRONG WINDS
OVER THE WESTERN AND CENTRAL ALEUTIANS COINCIDING WITH THE
ARRIVAL OF SIGNIFICANT PRECIPITATION.  THE RESULT IS LIKELY
TO BE SNOW AND BLOWING SNOW...HEAVY AT TIMES...WITH WINDS UP
TO 40 MPH AND GUSTS POTENTIALLY TO 50 MPH.  AS OF RIGHT
NOW...WITH MARGINAL TEMPERATURES AND LOW SNOW:LIQUID
RATIOS...EXPECT THAT VISIBILITIES WILL NOT BE REDUCED ENOUGH
TO RESULT IN BLIZZARD CONDITIONS...BUT CONDITIONS WILL LIKELY
NOT BE MUCH BETTER THAN THAT FROM EARLY FRIDAY THROUGH MOST
OF SATURDAY.  MORE TRANQUIL WEATHER WITH HIGH PRESSURE
BUILDING OVER THE AREA LATE SATURDAY THROUGH SUNDAY WILL
RESULT IN CALMER WINDS...THOUGH NORTHERLY WINDS WILL INCREASE
ACROSS THE CENTRAL AND EASTERN ALEUTIANS ON THE BACK SIDE OF
THE STRONG LOW PRESSURE SYSTEM DEVELOPING OVER SOUTHWEST
ALASKA SUNDAY.

WEST OF THE ALASKA RANGE...WINDS WILL SUBSIDE BELOW GALE
FORCE BEGINNING FRIDAY MORNING OVER THE AKPEN AS THE STRONG
JET MOVES SOUTH OF THE AREA.  THE SURFACE RIDGE AXIS WILL
MOVE OVERHEAD LATE FRIDAY INTO EARLY SATURDAY BEFORE THE
SYSTEM FROM THE WEST MOVES TOWARDS SOUTHWEST AK AND MERGES
WITH THE UPPER LOW DEVELOPING OVER THE INTERIOR.  THE RESULT
WILL BE A DEEPENING OF THE SURFACE LOW IN THE GULF AND AN
INCREASE IN NORTHERLY WINDS ON THE BACKSIDE OF THE
LOW...ESPECIALLY ACROSS THE AKPEN.  TEMPERATURES WILL THUS
CONTINUE TO BE COLD...WITH A REINFORCING SHOT FOR THE SECOND
HALF OF THE WEEKEND.

SOUTH AND EAST OF THE ALASKA RANGE...MOSTLY TRANQUIL YET
COOLER WEATHER WILL PERSIST THROUGH THE FIRST PART OF THE
WEEKEND AS LOW PRESSURE PERSISTS IN THE GULF.  THE MODELS
CONTINUE TO STRUGGLE WITH THE CURRENT CONGLOMERATION OF SMALL
LOWS ROTATING ABOUT EACH OTHER IN THE GULF...WITH THE CURRENT
PRIMARY LOW FORECASTED RIGHT NOW TO REMAIN NEARLY STATIONARY
BEFORE WEAKENING FRIDAY NIGHT.  A SECOND LOW WILL MOVE INTO
THE WESTERN GULF AND STRENGTHEN SUNDAY AS IT MOVES NORTH INTO
THE GULF...LIKELY RESULTING IN UNSETTLED WEATHER FOR MUCH OF
THE COASTAL REGIONS OF SOUTHCENTRAL ALASKA.

.LONG TERM FORECAST...

STILL LOTS OF QUESTIONS CONCERNING THE EVOLUTION OF THE RIDGE
ACROSS THE BERING SEA.  THE LATEST HPC GUIDANCE SHOWS THE
STRONG UPPER LOW PERSISTING ACROSS SOUTHWEST ALASKA OR THE
WESTERN GULF...WITH THE RIDGE REMAINING TO THE WEST BACK OVER
EASTERN SIBERIA AND PERHAPS BUILDING INTO NORTHWEST ALASKA BY
THE MIDDLE OF NEXT WEEK.  THIS WILL POSSIBLY MEAN A GRADUAL
DECLINE IN UNSETTLED WEATHER THROUGH THE FIRST PART OF THE
WEEK FOR SOUTHERN COASTAL REGIONS...AND UNSEASONABLY COLD
WEATHER FOR MUCH OF THE STATE THROUGH THE PERIOD.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE...130 150 155 172 175 176
         HVY FRZG SPRY...121 130 138 150 155 165 170 179
FIRE WEATHER...NONE.

CC MAR 09