Small Craft Advisory 25, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
415 AM AST SAT JAN 6 2007

.DISCUSSION...

..SUMMARY..
A VAST UPPER LEVEL CUTOFF LOW CIRCULATING OVER THE Y-K DELTA AND
STRETCHING FROM THE PRIBILOFS TO THE ALASKA RANGE IS SLOWLY BEGINNING
TO MOVE SOUTHEAST. UNDER AND BEHIND THIS LOW THERE IS SIGNIFICANT
COLD AIR THAT HAS DROPPED TEMPS IN THE KUSKOKWIM VALLEY NEAR -50 THIS
MORNING. LIGHT SNOW CONTINUES TO DEVELOP OVER COOK INLET AND MOVE
INTO THE WESTERN KENAI AND ANCHORAGE BOWL AS WELL AS THE SOUTHERN
SUSITNA VALLEY. THE RATIO WAS MEASURED AT 75 TO 1 SNOW TO LIQUID
EQUIVALENT AT THE WFO. THE CAA IS PROVIDING ADDED LIFT TO THE
SHORTWAVE THAT IS MOVING OVER THE NORTHERN INLET. WATER VAPOR IMAGERY
SHOWS MOISTURE MOVING INTO SOUTHCENTRAL FROM THE CUTOFF LOW. INLET
MOISTURE IS ENHANCING THIS. BY SUN EVENING THE UPPER LEVEL LOW SHOULD
BE NEAR PRINCE WILLIAM SOUND WITH A SFC LOW TO THE EAST AND WILL
LEAVE THE AREA ON MON.

..SOUTHCENTRAL..
LIGHT SNOW WILL CONTINUE ACROSS THE ANCHORAGE BOWL..WESTERN
KENAI..AND MAT-SU VALLEYS TODAY AND MOVE EAST THROUGH THE DAY
TOMORROW. VERY COLD TEMPS ARE EXPECTED ACROSS THE REGION THROUGH
TUESDAY. MORNING LOWS IN ANCHORAGE AND SURROUNDING AREAS MAY DROP
INTO THE NEGATIVE 30S WHILE THE COPPER RIVER VALLEY WILL FALL EVEN
LOWER.

..SOUTHWEST MAINLAND..
SNOW SHOWERS AND LOW CLOUDS WILL FILTER ACROSS THE AREA AS THE
CUT-OFF LOW MOVES SOUTHEAST. VERY COLD TEMPS WILL REMAIN AS A HIGH
BUILDS IN. A CHANGE IS IN STORE TUE NIGHT AND WED AS A FRONTAL SYSTEM
BEGINS TO PUSH THE RIDGE OUT AND BRING SOUTHERLY FLOW AND PRECIP.

..ALEUTIANS..
WEAK LOWS MOVING SOUTH OF THE CENTRAL ALEUTIANS AND EVENTUALLY TOWARD
THE AK PENN TODAY AND TOMORROW WILL BRING LOCALIZED GALE FORCE WINDS
AND SNOW. OTHERWISE THE NEXT BIG SYSTEM WILL MOVE INTO THE WESTERN
ALEUTIANS SUN NIGHT. MODELS ARE STILL A LITTLE UNCERTAIN ON THE EXACT
TIMING OF THE NEXT SYSTEM SO THAT COULD CHANGE 12 HRS EITHER WAY.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE 130 132 170 185
         HEAVY FREEZING SPRAY 120 121 125 129 130 132 138 141 150
                              165 179 185

RNW JAN 07