Heavy Freezing Spray Warning 101, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
500 PM AKST TUE MAR 6 2012

.ANALYSIS AND UPPER LEVELS...
AMPLIFIED PATTERN CONTINUES TODAY WITH TROUGHING FROM THE ARCTIC DOWN
THROUGH THE BERING SEA. A RIDGE LIES IN THE EASTERN PACIFIC AND
PUSHES UP INTO THE GULF OF ALASKA. BETWEEN THESE TWO FEATURES A
CUTOFF UPPER LOW IS MEANDERING NORTHWARD...ABOUT TO BE PICKED UP BY
THE TROUGH TRANSLATING EASTWARD OVER THE NORTHERN PACIFIC. THE UPPER
TROUGH OF THE PAST DAY AND JET STREAM ARE BOTH PUSHING EASTWARD
LEAVING RELATIVELY QUIET WEATHER OVER MOST OF MAINLAND ALASKA. A
SURFACE LOW IS MOVING EAST...JUST NORTH OF SAINT PAUL ISLAND A
TIGHTLY WOUND SYSTEM IS MOVING ALONG THE ICE EDGE. IN THE WESTERLY
FLOW FROM THE CENTRAL BERING THROUGH THE NORTHERN PACIFIC A SHOWERY
REGIME EXISTS IN THE RELATIVELY COLD AIR.

.MODEL DISCUSSION...
IN THE SHORT TERM MODEL GUIDANCE ISN'T HANDLING THE EXACT POSITION OF
THE LOW IN THE BERING SEA. MOST ARE SLIGHTLY TOO FAR NORTHEAST WITH
THE LOW CENTER. THIS LOW WILL CONTINUE TO MOVE EASTWARD TOWARD THE
WEST COAST WHILE FILLING. THE NEXT PLAYERS IN ALASKAN WEATHER ARE TWO
LOW PRESSURE SYSTEMS OF COMPLETELY DIFFERENT ORIGINS. THE FIRST IS
PART OF AN UPPER LEVEL DISTURBANCE OFF THE KAMCHATKA PENINSULA. IT
WILL BRING ANOTHER SERIES OF FRONT ACROSS THE ALEUTIANS. THE SECOND
IS AN UPPER LEVEL LOW IN THE CENTRAL PACIFIC...THIS LOW WILL PHASE
WITH THE TROUGH CURRENTLY MOVING EASTWARD IN THE BERING SEA AND
DEVELOP A SURFACE LOW THAT MOVES UP INTO EASTERN PRINCE WILLIAM
SOUND. GUIDANCE IS SLOWLY COMING TOGETHER FOR THIS EVENT BUT THE
EXACT POSITION OF THE LOW HAS YET TO BE DETERMINED. ANY FURTHER
WESTWARD MOVEMENT OF THE LOW WILL BRING MORE PRECIPITATION FOR THE
ANCHORAGE AREA.

.SHORT TERM FORECAST...
SOUTHCENTRAL ALASKA...CURRENTLY INBETWEEN SYSTEMS MANY AREAS HAVE
CLEARED AND ARE BEGINNING TO SEE BLUE SKIES. CLOUDS ARE HANGING ON IN
THE SUSITNA VALLEY AND COULD PRODUCE A LITTLE BIT OF SNOW FOR MAINLY
AREAS NORTH OF TALKEETNA. CLOUDS WILL STAY IN THE MAT-SU THROUGH
WEDNESDAY WITH CLOUDS MAINLY AROUND THE MOUNTAINS IN THE ANCHORAGE
AREA. THE NEXT CHANCE FOR SNOW WILL COME WITH THE DEVELOPING LOW
PRESSURE SET TO MOVE INTO THE EASTERN GULF. THE UPPER TROUGH
ASSOCIATED WITH THE LOW IS SET ROTATE OVER THE KENAI PENINSULA AND
HAS POTENTIAL TO BRING SNOW TO ANCHORAGE AND THE MAT-SU.

SOUTHWEST ALASKA...SOUTHWESTERLY FLOW AHEAD OF THE INCOMING BERING
SEA LOW PRESSURE KEEPS CLOUDS IN MOST LOCATION. AS THE UNSTABLE AIR
CONTINUES TO PUSH EAST NUMEROUS SNOW SHOWERS WILL AFFECT MOST AREAS
THROUGH TOMORROW MORNING. THE LOW WILL PUSH ONTO THE MAINLAND
WEDNESDAY KEEPING SNOW IN THE FORECAST BUT DIMINISHING IN COVERAGE AS
THE LOW DISSIPATES.

BERING SEA AND ALEUTIANS...THE UNSTABLE AIRMASS CHARACTERIZED BY
WIDESPREAD SNOW SHOWERS WILL STICK AROUND THROUGH WEDNESDAY FOR MOST
LOCATIONS. IN THE WESTERN ALEUTIANS THE NEXT LOW PRESSURE WILL SWING
A WARM FRONT NORTH BRINGING WIDESPREAD RAIN AND SNOW. ON THURSDAY THE
FRONT WILL PROGRESS EASTWARD ON THURSDAY FOR THE REST OF THE CHAIN.

.LONG TERM FORECAST...
THE EXTENDED PATTERN WILL FEATURE A TROUGH OVER MUCH OF MAINLAND
ALASKA THAT EXTENDS INTO THE GULF. A SERIES OF LOWS FROM THE WEST
LOOK TO REINFORCE THE UPPER LOW OVER THE GULF. THE PATTERN WILL
FEATURE DISTURBANCES THAT COME FROM EAST ASIA/NORTHWEST PACIFIC AND
TRACK FROM THE WESTERN CHAIN INTO THE GULF OF ALASKA.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...HEAVY FREEZING SPRAY 138 165 179
         GALE 172 175 176 179 185
FIRE WEATHER...NONE

MTL MAR 12