Small Craft Advisory 162, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
200 PM AKST TUE FEB 19 2013

.MODEL DISCUSSION...MODELS ARE IN FAIR AGREEMENT IN THE BROAD
SYNOPTIC FLOW. THE CHALLENGE IS IS THE EXACT LOW PLACEMENTS IN GULF
OF ALASKA AS THE UPPER LONGWAVE ELONGATES. FOR NOW A BLEND OF THE GFS
AND ECMWF APPEARS TO BE AN ADEQUATE REPRESENTATION. POSITIONING OF
CENTERS IN THE BERING SEA ARE IN GENERALLY GOOD AGREEMENT.

.ANALYSIS AND UPPER LEVELS...
A 970S MB LOW NEAR THE WESTERN AK PEN THIS AFTERNOON IS STACKED WITH
THE UPPER CENTER AND SHOULD WEAKEN AS IT MOVES INTO THE GULF ON WED.
ITS ASSOCIATED OCCLUDED FRONT EXTENDING WEST TO DUTCH HARBOR TO OVER
BRISTOL BAY/KODIAK ISLAND MOVES NORTH AND EAST THROUGH WED. STRONG
WINDS ON BACKSIDE OF THE CENTER ARE PRODUCING HURRICANE GUSTS NEAR
DUTCH HARBOR AND FALSE PASS THIS AFTERNOON. GUSTY WINDS AND MODERATE
TO HEAVY SNOW WAS ALSO OBSERVED IN BRISTOL BAY. LIGHT SNOW SHOWERS
WITH AN OLD FRONTAL BOUNDARY FRONT WAS EVIDENT ACROSS THE NORTH GULF
COAST.

A PROGRESSIVE LONG WAVE PATTERN WILL CONTINUE ACROSS THE NORTH
PACIFIC OVER THE NEXT COUPLE OF DAYS. A SERIES OF SHORT WAVES WILL
MOVE RAPIDLY EAST ACROSS THE NORTH PACIFIC SOUTH OF THE AK PEN
THROUGH THU. THE SURFACE LOWS ASSOCIATED WITH THESE WAVES WILL
GENERALLY STAY SOUTH OF THE MAINLAND. THE AGREEMENT IN THE LARGE
SCALE PATTERN BECOMES MORE PROBLEMATIC BEYOND THU AS MODELS DIVERGE
ON SOLUTIONS.

.SHORT TERM FORECAST...

.SOUTHCENTRAL ALASKA...
THE LOW SOUTH OF THE AK PEN MOVES INTO THE GULF WED. THE ASSOCIATED
OCCLUDED FRONT MOVES TO THE NORTH GULF WED AND THEN WEAKENS
OVERNIGHT. PRECIPITATION IN ADVANCE OF THE FRONT WILL BE
SNOW...BECOMING MIXED WITH THE BOUNDARY AND BEHIND. KODIAK SHOULD
SHIFT OVER TO A MIX THIS AFTERNOON AND EVENING. THE EASTERN KENAI
WILL ALSO LIKELY SEE SOME RAIN MIXED IN WITH SNOW TONIGHT. STRONG
WINDS IN ADVANCE OF THE FRONT WILL PRODUCE GALES ACROSS THE NORTH
GULF WITH EVEN SOME POTENTIAL FOR STORMS WEST OF THE BARREN ISLANDS
AND ALONG THE NORTH GULF COAST TONIGHT. WINDS SHOULD DIMINISH ACROSS
MUCH OF THE AREA ON WED. MODERATE SNOW AND BLOWING SNOW LIKELY OVER
THE EASTERN KENAI PENINSULA(EAST TURNAGAIN ARM AND PORTAGE VALLEY)
WITH APPROACH OF FRONTAL TROUGH. BLIZZARD CONDITIONS SHOULD DIMINISH
WED MORNING AS WINDS DIMINISH.

.SOUTHWEST...THE LOW NEAR THE WESTERN AK PEN MOVES RAPIDLY EAST
TONIGHT. BLIZZARD CONDITIONS OVER THE BRISTOL BAY ZONE WILL CONTINUE
THROUGH THIS EVENING...BUT SHOULD DIMINISH AFTER MIDNIGHT AS WINDS
DIMINISH. BLOWING SNOW MAY ALSO BE A CONCERN THIS EVENING OVER THE
DELTA AS SOME LIGHT SNOW SPREADS WEST. WINDS AND BLOWING SNOW WILL
MOVE RAPIDLY EAST ACROSS THE AK PEN TONIGHT AS THE LOW AND OCCLUDED
FRONT PUSH EAST. THIS WILL PRODUCE SOME TEMPORARY LOW VISIBILITIES
AND STRONG WINDS.

.BERING SEA AND ALEUTIANS...WINDS WILL DIMINISH THROUGH THIS EVENING
OVER THE EASTERN ALEUTIANS. THE CENTRAL AND WESTERN ALEUTIANS WILL
HAVE CONTINUED SOUTHERLY FLOW AND SHOWERS AS A SERIES OF WESTERN
BERING LOWS PASS THROUGH THE AREA OVER THE NEXT 24 HRS.

.LONG TERM FORECAST...
IT STILL APPEARS THAT THE WEATHER PATTERN LATE THIS WEEK WILL BECOME
LESS ACTIVE THAN THE CURRENT ONE. THIS WILL OCCUR AS A PACIFIC RIDGE
NOSES NORTHWARD...PREVENTING ANY DEEP OR FAST MOVING SYSTEMS INTO THE
AREA.  THIS SETUP LOOKS TO THEN BREAK DOWN EARLY NEXT WEEK AS THE
PACIFIC RIDGE MOVES OVER THE WESTERN COAST OF THE CONTINENTAL UNITED
STATES.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...WINTER STORM WARNING 161 AND BLIZZARD WARNING 125.
MARINE...STORM...150
         GALE...GALE 120 125 130 138 140 155.
         HEAVY FREEZING 160 165 411
FIRE WEATHER...NONE.

RMC FEB 13