Freezing Rain Advisory 1, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
500 PM AKST WED FEB 8 2012

.ANALYSIS AND UPPER LEVELS...
VERY OUT OF THE ORDINARY SYNOPTIC PATTERN TODAY. ALMOST LOOKS LIKE A
SUMMERTIME PATTERN. A LARGE UPPER LOW SPINS SOUTH OF THE ALASKAN
PENINSULA IN THE NORTH PACIFIC. A SHARP SHORTWAVE TROUGH IS ROTATING
AROUND THE UPPER LOW INTO THE CENTRAL INTERIOR THIS AFTERNOON CUTTING
THROUGH THE UPPER RIDGE ALREADY IN PLACE. MOIST SOUTHEASTERLY FLOW
AND TROUGH EXTENDING FROM THE UPPER LOW IS KEEPING RAIN AND SNOW IN
THE FORECAST FOR THE GULF OF ALASKA AND COASTAL AREAS. FURTHER
WEST...AN UPPER LOW HOVERS JUST SOUTH OF THE KAMCHATKA PENINSULA AND
A FASTER WESTERLY FLOW KEEPS AN ACTIVE PATTERN IN STORE FOR THE
ALEUTIANS.

.MODEL DISCUSSION...
IN THE VERY NEAR TERM...IT APPEARS AS IF EMBEDDED SHORTWAVES IN THE
SOUTHEASTERN FLOW IN THE GULF OF ALASKA ARE NOT BEING RESOLVED WELL
AND ARE BEST DISTINGUISHED IN SATELLITE IMAGERY. GUIDANCE IS IN
PRETTY GOOD AGREEMENT WITH THE UPPER LEVEL SYNOPTIC PATTERN THROUGH
THE SHORT TERM. THE SURFACE PRESSURE PATTERN HAS SLIGHT DISCREPANCIES
FROM MODEL TO MODEL BUT THE GENERAL PATTERN IS AGREED UPON. THE MAIN
FEATURE TO LOOK AT IS A LOW PRESSURE SYSTEM MOVING INTO THE EASTERN
GULF OF ALASKA. IT WILL BE A DECAYING SYSTEM BUT EXACT PLACEMENT AND
RATE OF FILLING HAS YET TO BE AGREED UPON.

.SHORT TERM FORECAST...
SOUTHCENTRAL ALASKA...ONSHORE FLOW COMBINED WITH AN APPROACHING
TROUGH BRINGS CONTINUOUS RAIN TO MANY GULF LOCATIONS BUT WILL MIX
WITH SNOW AS TEMPERATURES COOL THIS EVENING. THE ANCHORAGE AREA WILL
STAY MOSTLY DRY DUE TO A DOWNSLOPING SOUTHEASTERLY FLOW AT ALL
LEVELS. THE NEXT SYSTEM TO AFFECT THE AREA WILL MOVE INTO THE EASTERN
GULF BY FRIDAY EVENING AND BRING ANOTHER ROUND OF RAIN AND SNOW TO
MAINLY EASTERN PRINCE WILLIAM SOUND.

SOUTHWEST ALASKA...A SOUTHEASTERLY WIND OF THE ALASKA RANGE BRINGS
MODERATED TEMPERATURES EASTERN PORTIONS OF THE AKPEN TODAY. THE DRY
AIR ASSOCIATED WITH THE WINDS WILL KEEP MOST OF THE PRECIPITATION
FROM REACHING THE GROUND BUT A STRAY SHOWER CAN'T BE RULED OUT. AS
SOME UPPER LEVEL FORCING WORKS NORTHWARD ON THURSDAY THE CHANCE FOR
SNOW WILL INCREASE FOR MOST OF THE AKPEN AND BRISTOL BAY ZONES
SPREADING NORTHWARD INTO THE KUSKOKWIM DELTA BY LATE TOMORROW.

BERING SEA AND ALEUTIANS...LOW PRESSURE JUST SOUTH OF THE AKPEN WILL
CONTINUE THE THREAT FOR PRECIPITATION FOR THE CENTRAL ALEUTIANS
EASTWARD. MAINLY SNOW FOR THE CENTRAL CHAIN WITH RAIN FOR THE EASTERN
CHAIN AND THE AKPEN. THE SYSTEM WILL DRIFT NORTHWARD TOMORROW KEEPING
THE THREAT FOR RAIN AND SNOW SHOWERS. FOR THE WESTERN CHAIN...A FRONT
ASSOCIATED WITH A KAMCHATKA LOW WILL BRING BLIZZARD CONDITIONS THIS
EVENING BEFORE WINDING DOWN TONIGHT. SHOWERS WILL STAY IN THE
FORECAST TOMORROW AS THE LOW DRIFTS OVERHEAD.

.LONG TERM FORECAST...
EXTENDED PERIOD WILL FEATURE A LARGE UPPER LOW OVER THE BERING SEA
WITH FASTER WESTERLIES TO THE SOUTH. THE SETUP WILL FAVOR AMPLIFYING
NORTHERN PACIFIC SYSTEMS THAT TRACK UP THE AKPEN OR INTO THE
GULF...KEEPING THE SEASONABLE MILD WEATHER AROUND THE SOUTH CENTRAL
FOR A LITTLE WHILE LONGER.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WARNING 191
MARINE...STORM 130 150
         GALE 120 125 132 140 141 155 160 176 185
FIRE WEATHER...NONE

MTL FEB 12