Small Craft Advisory 14, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 PM AST WED JAN 3 2007

.DISCUSSION...

...SUMMARY...
TWO MAIN CONCERNS FOR THIS FORECAST PACKAGE INCLUDE SNOW OVER
SOUTHCENTRAL...AND A STRONG LOW PRESSURE OVER THE CENTRAL AND
WESTERN ALEUTIANS. THE SNOW OVER SOUTHCENTRAL IS FROM A LOW PRESSURE
WHICH MOVED THROUGH PRINCE WILLIAM SOUND AND IS PRESENTLY MOVING
INLAND AND DISSIPATING.  SNOW WILL GRADUALLY TAPER OFF TONIGHT OVER
MOST AREAS...WITH SNOW MOSTLY ENDING FOR THE DAY THURSDAY.  THE
STRONG LOW PRESSURE OVER THE CENTRAL AND WESTERN ALEUTIANS IS
BRINGING STORM FORCE WINDS WITH RAIN MIXED WITH SNOW ALONG AND AHEAD
OF THE LOW...AND SNOW AND BLIZZARD CONDITIONS ON THE BACK SIDE OF
THE LOW. THIS STORM WILL BE A CONCERN AS IT MOVES FROM WEST TO EAST
ALONG THE ALEUTIANS THROUGH THURSDAY NIGHT. A TRIPLE POINT LOW IS
EXPECTED TO FORM TONIGHT OFF THE EAST WEST ORIENTED FRONT EXTENDING
EAST FROM THE ABOVE MENTIONED LOW. THIS LOW WILL TRACK INTO THE
CENTRAL GULF OF ALASKA THURSDAY AND THURSDAY NIGHT...TAKING A TRACK
SLIGHTLY FURTHER SOUTH THAN PREVIOUS LOW PRESSURES...MEANING
PRECIPITATION IS NOT EXPECTED TO MAKE IT TOO FAR INLAND WITH THIS
SYSTEM. VERY COLD TEMPERATURES AND GENERALLY DRY CONDITIONS TO
DOMINATE THE INTERIOR THROUGH THE WEEKEND.

...MODELS...
IN THE EAST...MODELS ARE IN DECENT AGREEMENT...BUT HAVE A SLIGHT
PREFERANCE OF GFS OVER NAM/WRF. IN THE WEST...MODELS START OUT QUITE
DIFFERENT BUT THEN CONVERGE REGARDING THE EVOLUTION OF LOWS IN THE
CENTRAL AND WESTERN ALEUTIANS. FAVORING THE GFS OVER THE NAM/WRF
SINCE NAM/WRF APPEARS TO BE THE OUTLIER WHEN TAKING UKMET AND ECMWF
INTO ACCOUNT...THOUGH NONE OF THE MODELS ARE DOING THAT WONDERFULLY.

...FORECAST EAST AND SOUTH OF THE ALASKA RANGE...
SNOW HAS REALLY PILED UP LATE LAST NIGHT INTO TODAY OVER
SOUTHCENTRAL ALASKA. SEE PNSAFC FOR MORE DETAILED SNOW TOTALS...BUT
BASICALLY MANY AREAS FROM THE KENAI UP TO THE ANCHORAGE BOWL HAVE
TOTALS AROUND A FOOT AS OF THIS WRITING. LOCALIZED WINDS HAVE LED TO
BLOWING SNOW AND BLIZZARD CONDITIONS OVER SOME AREAS. SNOW IS ALSO
PILING UP FROM VALDEZ TO CORDOVA. THE LOW RESPONSIBLE FOR ALL THE
SNOW HAS MOVED INLAND ALREADY AND IS DISSIPATING. HOWEVER...THE 700
MB TROUGH HAS YET TO PASS...AND UNTIL THIS DOES...EXPECT SOME SNOW
TO KEEP GOING THROUGH MUCH OF THE NIGHT ALONG AND NORTH OF A LINE
FROM KENAI TO CORDOVA. FOR ANCHORAGE...STRONG COLD ADVECTION AND
FLOW UP COOK INLET WILL ALLOW SNOW TO CONTINUE TONIGHT BEFORE THE
AIR DRIES OUT FOR THURSDAY. SUBSEQUENT AREAS OF LOW PRESSURE
EXPECTED TO TRACK A BIT FURTHER SOUTH...MEANING A DRIER AND COLDER
WEATHER PATTERN SETTING UP FOR INLAND AREAS. SOME OF THE UPCOMING
LOW PRESSURES COULD BRUSH AREAS AS FAR NORTH AS PALMER AND
ANCHORAGE...BUT GENERALLY SPEAKING...A BREAK FROM THE MAJOR
SNOWSTORMS IS IN STORE ALLOWING TIME TO DIG OUT FROM THE LATEST
STORM. COASTAL AREAS OF SOUTHCENTRAL WILL STILL GET BRUSHED BY THE
LOWS OVER THE GULF OF ALASKA THROUGH THE WEEKEND...THOUGH NOTHING
MAJOR IS EXPECTED. GUSTY OFFSHORE WINDS THROUGH GAPS IN THE TERRAIN
CAN BE EXPECTED IN THIS PATTERN.

...FORECAST FOR THE SOUTHWEST MAINLAND...
GENERALLY VERY QUIET AND VERY COLD WEATHER TO PERSIST FOR THE
SOUTHWEST MAINLAND THROUGH THE WEEKEND WITH ARCTIC HIGH PRESSURE
OVER THE AREA. SOME SNOW FALLING AROUND MCGRATH TODAY ON THE FAR
WEST SIDE OF THE PLUME OF MOISTURE FROM THE DISSIPATING LOW OVER
SOUTHCENTRAL...BUT THIS SNOW SHOULD DISSIPATE BY THURSDAY. SOME
AREAS WILL SEE TEMPERATURES AROUND 45 BELOW OVER THE NEXT FEW DAYS.

...FORECAST FOR THE BERING/ALEUTIANS...
A STRONG LOW IS BRINGING STORM FORCE WINDS AND BLOWING SNOW WITH
LOCALIZED BLIZZARD CONDITIONS MAINLY ON ITS BACK SIDE. SIGNIFICANT
SNOW OR SNOW CHANGING TO RAIN IS PRESENT ALONG A FRONT EXTENDING TO
THE EAST OF THE LOW ALONG THE CHAIN. THE LOW AND ASSOCIATED FRONT
WILL MOVE EAST THROUGH THE ALEUTIANS...EXITING THE AREA ON FRIDAY.
ONLY WEAK SYSTEMS WILL BE PRESENT OVER THE REGION FOR THE WEEKEND.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WARNING 191.
         BLIZZARD WATCH 187.
MARINE...STORM WARNINGS 130 172.
         GALE WARNINGS 120 132 138 140 141 155 170 171 175 176.
         HEAVY FREEZING SPRAY WARNINGS 120 121 130 132 138 140 141
         150 160 165 185 179.

FOISY JAN 07