Heavy Freezing Spray Warning 52, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
500 AM AKST MON JAN 23 2012

.MODEL DISCUSSION...
MODELS GENERALLY IN GOOD AGREEMENT FOR THE SHORT TERM. SOME
DISCREPANCIES IN HOW THEY HANDLE INDIVIDUAL IMPULSES IN THE GULF
LOW...BUT THIS IS TO BE EXPECTED WITH SUCH SMALL SCALE FEATURES.
FORECASTS INCORPORATE A BLEND OF MODELS WITH THE INHERITED
FORECASTS.

FOR THE EXTENDED PERIOD THE GFS AND ECMWF ARE IN FAIRLY GOOD
AGREEMENT IN THE LARGE SCALE PATTERN. THERE ARE NATURALLY SOME
DIFFERENCES IN THE TIMING/STRENGTH OF SYNOPTIC SYSTEMS. MOSTLY
USED A BLEND OF MODELS WITH HPC GUIDANCE FOR THIS PORTION OF THE
FORECAST.

.ANALYSIS AND UPPER LEVELS...
THERE IS A LARGE CLOSED UPPER LOW CENTERED JUST SOUTHWEST OF KODIAK
ISLAND THIS MORNING. ALL OF SOUTHERN ALASKA IS INVOLVED IN THE
CYCLONIC FLOW WITH THIS SYSTEM...AS WELL AS THE EASTERN BERING SEA.
AN UPPER LEVEL RIDGE IS SITUATED OVER THE EXTREME WESTERN BERING
SEA. STRONG AND DEEP NORTHERLY FLOW IS SITUATED BETWEEN THESE TWO
FEATURES.

.SHORT TERM FORECAST...
THE UPPER LOW WILL SLOWLY WORK ITS WAY EAST OVER THE NEXT COUPLE OF
DAYS...THEN RETREAT NORTH INTO SOUTH CENTRAL ALASKA ON WEDNESDAY.

SOUTH CENTRAL ALASKA WILL GENERALLY BE UNDER CYCLONIC FLOW THROUGH
WEDNESDAY. WITH SOMEWHAT LIMITED MOISTURE...PRECIPITATION WILL
MOSTLY BE CONFINED TO COASTAL AREAS.

FOR SOUTHWEST ALASKA AND THE BERING SEA THE DEEP NORTHERLY FLOW WILL
WEAKEN AND SPREAD WESTWARD AS THE WESTERN BERING RIDGE MOVES
NORTHWEST INTO SIBERIA. VERY COLD TEMPERATURES WILL CONTINUE TO PUSH
INTO THE AREA. SHOWERS ARE EXPECTED TO CONTINUE OVER THE ALEUTIANS.

.LONG TERM FORECAST...
THE UPPER LOW WILL BEGIN THE EXTENDED PERIOD OVER CENTRAL ALASKA
AND THEN SLOWLY RETROGRADE LATER IN THE WEEK INTO THE EASTERN BERING
SEA.

SOUTH CENTRAL ALASKA...
TEMPERATURES WILL REMAIN BELOW NORMAL THROUGH THE EXTENDED. THERE
WILL BE PERIODIC CHANCES OF SNOW AS THE MODELS ARE HINTING AT FLOW
BECOMING MORE SOUTHWESTERLY ALOFT.

SOUTHWEST ALASKA AND THE BERING SEA...
TEMPERATURES WILL BE WELL BELOW NORMAL. SNOW SHOWERS ARE EXPECTED
OVER MUCH OF THE BERING SEA...ALEUTIANS...AND ALASKA PENINSULA IN
CONTINUED NORTHERLY FLOW. SOME SNOW IS POSSIBLE FRIDAY INTO SATURDAY
FOR SOUTHWEST ALASKA AS SOUTHWESTERLY FLOW ALOFT MAKES A BRIEF
APPEARANCE.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WARNING 155 181.
         HIGH WIND WARNING 185.
MARINE...GALE WARNING 150 155 160 165 170 171 172 179 180 185.
         HEAVY FREEZING SPRAY 121 126 127 128 129 130 138 140 141
                       150 155 165 170 171 172 179 185.
FIRE WEATHER...NONE.

LUDWIG JAN 12