Blizzard in Alaska, March 8, 2012

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
500 PM AKST WED MAR 7 2012

.ANALYSIS AND UPPER LEVELS...
THE MAJOR PLAYERS IN ALASKAN WEATHER HAVEN'T CHANGED SINCE YESTERDAY.
AN UPPER LEVEL TROUGH STRETCHING FROM SOUTHWEST ALASKA DOWN INTO THE
CENTRAL PACIFIC HAS ENVELOPED A MEANDERING CUTOFF LOW AND IS
CURRENTLY DEVELOPING A SURFACE LOW MOVING NORTHWARD. THE INTERACTION
OF THIS SYSTEM WITH A FAST MOVING LOW IN THE WESTERN BERING SEA WILL
DETERMINE THE EXACT TRACK OF THE SYSTEM MOVING INTO THE EASTERN GULF.
A WEAKENING SURFACE LOW IS BRINGING SNOW SHOWERS TO PARTS OF THE
SOUTHWEST INTERIOR...MAINLY THE BRISTOL BAY ZONE. THE NORTHWEST FLOW
BEHIND THE LOW IS SUPPORTING SNOW SHOWERS OVER THE EASTERN ALEUTIANS
AND THE AKPEN. FURTHER WEST THE QUICK MOVING LOW PRESSURE IS
SPREADING RAIN AND SNOW OVER THE WESTERN ALEUTIANS AS A WARM FRONT
MOVES OVER THE AREA.

.MODEL DISCUSSION...
GUIDANCE IS COMING TOGETHER ON A SOLUTION FOR BOTH LOW PRESSURE
SYSTEMS THE WESTERN BERING SEA SYSTEM HAS BEEN TRENDING FASTER WITH
EACH CONSECUTIVE MODEL RUN AND CONSEQUENTLY KEEPING THE NORTHEASTERN
PACIFIC STORM FROM PROGRESSING ANY FURTHER WEST AS IT MATURES. SPREAD
AMONG INDIVIDUAL MODELS HAS DECREASED CONSIDERABLY SINCE YESTERDAY SO
FORECAST CONFIDENCE WITH THE TRACK OF EACH LOW IS INCREASED. THE
BERING LOW LOOKS TO CROSS THE EASTERN ALEUTIANS AND FOLLOW THE
CURRENT LONGWAVE PATTERN INTO THE GULF. AS THE NORTHEAST PACIFIC LOW
MOVES INTO THE GULF LATE THURSDAY INTO FRIDAY THE TWO SYSTEMS WILL
FIRST ROTATE AROUND EACH OTHER THEN CONSOLIDATE INTO ONE SURFACE
LOW...SETTING THE PATTERN FOR THE NEXT WEEK.

.SHORT TERM FORECAST...
SOUTHCENTRAL ALASKA...QUIET CONDITIONS EXPECTED FOR TONIGHT. THE BIG
QUESTION WILL BE HOW LONG THE STRATUS IN THE SUSITNA VALLEY HANGS
AROUND AND WILL IT BUILD BACK IN THIS EVENING. AREAS OF CLEARING IN
THE COPPER RIVER BASIN SHOULD CONTINUE TO SPREAD WESTWARD INTO THE
MAT VALLEY...BUT THE STRATUS IN THE SUSITNA VALLEY DOWN INTO COOK
INLET SHOULD BEGIN TO BUILD BACK TO THE EAST IN THE EVENING/OVERNIGHT
HOURS. THE NEXT STORM SYSTEM WILL BEGIN TO AFFECT THE EASTERN COPPER
RIVER BASIN THURSDAY MORNING AS IT PUSHES UP INTO THE EASTERN GULF OF
ALASKA. THE PRECIPITATION SHIELD WILL PROGRESS WESTWARD OVER THE
BASIN BUT DOES NOT LOOK TO GET INTO THE MAT-SU OR ANCHORAGE BOWL AT
THIS TIME.

SOUTHWEST ALASKA...WEAKENING LOW MOVING INTO THE MAINLAND CONTINUES
TO BRING SNOW SHOWERS TO THE BRISTOL BAY ZONE. THE NORTHWEST FLOW ON
THE BACKSIDE OF THE SYSTEM HAS BROUGHT CLEARING TO THE KUSKOKWIM
DELTA. CLEARING AND LIGHT WINDS SHOULD ALLOW FOR SOME LOW STRATUS AND
FOG TO BUILD IN THE THE DELTA. SNOW SHOWERS WILL CONTINUE FOR THE
NORTHWEST PORTION OF THE AKPEN AS THE NORTHWESTERLY FLOW SUPPORTS
SNOW SHOWERS.

BERING SEA AND ALEUTIANS...THE NEXT LOW PRESSURE SYSTEM TO AFFECT THE
CHAIN IS RAPIDLY MOVING EASTWARD THIS AFTERNOON. AS WARM AIR SURGES
NORTHWARD OVER THE CENTRAL ALEUTIANS A RAIN/SNOW MIX WILL BE
SUPPORTED. AS THE WARM FRONT MOVES TOWARD SAINT PAUL TOMORROW
BLIZZARD CONDITIONS WILL BE POSSIBLE. THE FRONT WILL KEEP PROGRESSING
EASTWARD ON THURSDAY BUT STALL AS THE WHOLE SYSTEM DIVES
SOUTHEASTWARD INTO THE LONGWAVE TROUGH CURRENTLY APPROACHING THE
GULF.

.LONG TERM FORECAST...
THE EXTENDED PATTERN WILL KEEP WEAK TROUGHING FROM SOUTH CENTRAL
ALASKA THROUGH THE GULF. THE PREDOMINANT STORM TRACK WILL BE FROM THE
NORTHWEST PACIFIC ACROSS THE ALEUTIANS THEN INTO THE GULF OF ALASKA.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WATCH 195
MARINE...HEAVY FREEZING SPRAY 121 129 130 138 165 179
         GALE 129 130 170 172 175 176 179
FIRE WEATHER...NONE

MTL MAR 12