Freezing Rain Advisory 5, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
500 AM AKST THU NOV 8 2012

.MODEL DISCUSSION...
THE MODELS ARE DOING ALRIGHT FOR THE FIRST 48 HOURS BUT THEN START TO
DIVERGE. THEY ARE ALL BRINGING THE LOW IN THE EASTERN BERING ACROSS
THE ALASKA PENINSULA AND EVENTUALLY INTO THE GULF BUT TIMING AND
PLACEMENT VARIES BETWEEN THE MODELS. THE 00Z RUN OF THE NAM HAD THE
LOW MOVING INTO THE Y-K DELTA BUT THE 06Z RUN HAS IT FLOWING THE PATH
OF THE OTHER MODELS. THE GFS HAS BEEN THE MOST CONSISTENT FROM RUN TO
RUN AND WAS THE MODEL OF CHOICE.

.ANALYSIS AND UPPER LEVELS...
RIDGING RESIDES OVER THE CENTRAL PART OF THE STATE KEEPING THE
EASTERN SIDE VOID OF MOST PRECIP. ON THE WEST SIDE OF THE RIDGE A
FRONT IS MOVING THROUGH THE SOUTHWEST PART OF THE STATE FROM THE
SOUTHWEST. THIS FRONT IS BRINGING IN WARM MOIST AIR FROM THE NORTH
PACIFIC INTO THE REGION THAT IS OVERRUNNING THE COLD AIR THAT HAS
BEEN IN PLACE OVER THE SOUTHWEST. THE LOW ASSOCIATED WITH THIS FRONT
SITS TO THE SOUTH OF THE CENTRAL ALEUTIANS AND WHILE IT IS WEAKENING
ANOTHER LOW IS BEGINNING TO FORM ALONG THE BOUNDARY SOUTH OF THE
EASTERN ALEUTIANS.

.SHORT TERM FORECAST...
SOUTHCENTRAL...THE FRONT IS CURRENTLY MAKING ITS WAY THROUGH KODIAK
AND WILL MAKE IT TO THE KENAI PENINSULA BY THIS AFTERNOON AND TO THE
REMAINDER OF THE SOUTHCENTRAL OVERNIGHT. A SECOND FRONT WILL MOVE IN
OVER KODIAK BY FRIDAY MORNING AND INTO THE REST OF THE SOUTHCENTRAL
BY FRIDAY EVENING. AS THESE FRONTS PASS THROUGH THE DOMAIN THE PRECIP
WILL START OFF AS SNOW AND TRANSITION OVER TO RAIN DUE TO THE
ABUNDANCE OF WARM AIR BEING BROUGHT UP FROM THE SOUTH. AREAS FURTHER
NORTH WILL BE MORE LIKELY TO HAVE COLD AIR POOLING AT THE SURFACE
CAUSING THE WARMER AIR TO OVERRUN LEAVING THE POTENTIAL FOR FREEZING
RAIN FRIDAY NIGHT. AT THIS TIME CONFIDENCE IN FREEZING RAIN FOR THE
SOUTHCENTRAL IS LOW.

SOUTHWEST ALASKA...THE FIRST FRONT IS ALREADY MOVING THROUGH AREAS
NEAR THE COAST CAUSING OVERRUNNING WITH THE WARMER AIR BEING BROUGHT
IN BY THE FRONT. THIS IS CAUSING AREAS OF LIGHT FREEZING RAIN IN THE
AREA. AS THAT FRONT FALLS APART THE NEXT ONE WILL MOVE IN THIS
EVENING BRINGING FREEZING RAIN BACK TO AREAS THROUGHOUT SOUTHWEST
ALASKA. OVERNIGHT TONIGHT THE CONSTANT PUSH OF WARMER AIR FROM THE
SOUTHWEST WILL CAUSE AREAS ALONG THE COAST TO TRANSITION OVER TO RAIN
AND THIS WILL SLOWLY MAKE ITS WAY FURTHER INLAND.

BERING SEA AND ALEUTIAN ISLANDS...LOW PRESSURE THAT RESIDES SOUTH OF
THE ISLANDS IS BRINGING CONSISTENT WARM MOIST AIR OVER THE ISLANDS
AND INTO THE BERING. THIS IS KEEPING RAIN SHOWERS THROUGHOUT THE AREA
THAT WILL LAST INTO FRIDAY. BY FRIDAY AFTERNOON HIGH PRESSURE WILL
BUILD IN OVER THE WESTERN AND CENTRAL ALEUTIANS PUSHING THE RAIN OFF
TO THE EAST. FOLLOWING THIS HIGH PRESSURE ANOTHER LOW AND ASSOCIATED
FRONT WILL MOVE IN OVER THE WESTERN ALEUTIANS ON SATURDAY BRINGING
MORE PRECIP TO THE AREA.

.LONG TERM FORECAST...
THE ACTIVE PATTERN THAT HAS BEEN DOMINANT OVER THE REGION WILL LAST
THROUGH THE WEEKEND BUT THEN BECOME MORE AMPLIFIED AS HIGH PRESSURE
BUILDS IN OVER MAINLAND ALASKA EARLY NEXT WEEK. THE MODELS ARE ALSO
INDICATING A FAIRLY DEEP LOW MOVING INTO THE BERING THAT WILL BRING
MOIST SOUTHWEST FLOW TO THE STATE.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALE WARNING...127 120 130 150 155 160 165 180 170 179
         HEAVY FREEZING SPRAY...180
FIRE WEATHER...NONE

DWK NOV 12