Small Craft Advisory 932, NWS Anchorage, AK

AREA FORECAST DISCUSSION...CORRECTED
SOUTHCENTRAL AND SOUTHWEST ALASKA
107 PM AKST SUN NOV 15 2009

CORRECTED TYPO

.ANALYSIS AND UPPER LEVELS...DEEP COLD TROUGH IS FIRMLY ENTRENCHED
OVER MAINLAND ALASKA AND THE GULF WITH A HIGH AMPLITUDE SHORT-WAVE
RIDGE OVER THE WESTERN BERING. THE HEMISPHERIC PATTERN IS PROGRESSING
EASTWARD VERY SLOWLY...MORE LIKE A DRIFT. SHORT-WAVES EMBEDDED IN
FLOW AROUND THE TROUGH...SOUTHWARD ACROSS THE BERING...EAST INTO
THE GULF...AND THEN NORTH INTO EASTERN SOUTHCENTRAL ALASKA...ARE
COMBINING WITH COLD ADVECTION TO PRODUCE WIDESPREAD SNOW SHOWERS
AND GUSTY WINDS ACROSS THE REGION.

.MODEL DISCUSSION...SHORT-TERM MODEL SOLUTIONS ARE ALL OVER THE
PLACE WITH POSITION OF SURFACE LOWS OVER THE GULF. HOWEVER...BOTTOM
LINE IS TIGHTENING PRESSURE GRADIENT AND ARCTIC AIR MOVING FROM
NORTH INTO GULF WILL PRODUCE STRONG AND GUSTY GAP WINDS.
THEREFORE...CHANGES WILL BE CONFINED PRIMARILY TO THESE LOCALIZED
WINDS AND SYNOPTIC FORECAST WILL BE LEFT AS IS. OUT WEST...MODELS
ARE INCONSISTENT IN POSITIONING OF FRONT AS IT STALLS OUT
TUESDAY...AND DISAGREE ON TRACK OF LOWS ALONG THIS FRONT. WILL
TREND FRONT FURTHER SOUTH AND WEST...IN LINE WITH MODEL TRENDS.
OTHERWISE...AS IN THE EAST WILL STICK PRIMARILY WITH EXISTING
SHORT-TERM FORECAST.

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...SOUTHERN END OF TROUGH WILL SWING EASTWARD
ACROSS THE GULF THROUGH TUESDAY...RESULTING IN COLD ADVECTION FROM
SOUTHWEST ALASKA ACROSS THE ALASKA PENINSULA AND INTO THE GULF.
MEANWHILE...SURFACE LOWS WILL TRACK NORTHWARD UP THE EAST SIDE OF
THE TROUGH INTO THE EAST TO CENTRAL GULF...HELPING TO TIGHTEN UP
THE SURFACE PRESSURE GRADIENT AND PRODUCE STRONG GAP WINDS ALONG
THE GULF COASTAL AREA. SO...WINDS HAVE BEEN INCREASED ACROSS THE
BOARD TO ACCOUNT FOR THIS. SNOW SHOWERS WILL CONTINUE IN THE SAME
GENERAL AREA THAT THEY ARE OCCURRING RIGHT NOW...ACROSS THE GULF
AND NORTHWARD TO EASTERN PRINCE WILLIAM SOUND AND THE COPPER RIVER
BASIN. THE REST OF SOUTHCENTRAL WILL REMAIN DRY AND COLD. THIS
PATTERN WILL HOLD THROUGH THE MIDDLE OF NEXT WEEK...AT WHICH TIME
IT LOOKS LIKE THE UPPER TROUGH WILL BEGIN TO PULL OUT TO THE EAST.

SOUTHWEST ALASKA...SOUTHWEST ALASKA WILL REMAIN IN THE BACK SIDE
OF THE UPPER TROUGH THROUGH THE MIDDLE ON NEXT WEEK...KEEPING THE
ARCTIC AIR FIRMLY IN PLACE OVER THE REGION. COLD ADVECTION SNOW
SHOWERS WILL BE CONFINED TO THE KUSKOKWIM DELTA COAST AND ALONG
THE ALASKA PENINSULA WHILE THE REST OF SOUTHWEST REMAINS COLD AND
DRY UNDER OFFSHORE FLOW.

BERING SEA/ALEUTIANS...SNOW SHOWERS AND WINDS WILL GRADUALLY
DIMINISH FROM WEST TO EAST ACROSS THE REGION TONIGHT THROUGH MONDAY
NIGHT AS THE TROUGH DIGS SOUTHEASTWARD INTO THE NORTH PACIFIC AND
GULF AND UPPER RIDGE MOVES IN FROM THE WEST. THE EASTWARD PROGRESSION

OF THE RIDGE WILL THEN ALLOW A FRONT EXTENDING FROM A LOW OVER THE
SEA OF OKHOTSK TO MOVE ACROSS THE BERING. THE UPPER JET WILL DRIVE
RIGHT THROUGH THE BASE OF THE RIDGE...HELPING TO ELONGATE AND STALL
THE FRONT FROM THE CENTRAL BERING TO EASTERN ALEUTIANS TUESDAY.
MODELS ALSO INDICATE A COUPLE LOWS FORMING ALONG THE FRONT...BUT
DISAGREE ON THE TRACK OF THESE. FORTUNATELY THE FAST FLOW WILL KEEP
ANY OF THESE FROM DEVELOPING INTO ANYTHING SIGNIFICANT. WARM AIR
WITH THE FRONT WILL CHANGE PRECIPITATION TO RAIN ALONG THE ALEUTIANS
WITH A MIX OF RAIN AND SNOW OVER THE BERING SEA.

.LONG TERM FORECAST...FAIRLY HIGH CONFIDENCE IN THE SYNOPTIC SCALE
PATTERN IN THE EXTENDED...WITH AN UPPER LOW CENTERED OVER THE
NORTHERN MAINLAND AND A MAJOR SURFACE LOW MOVING INTO THE BERING
SEA MID WEEK AND THEN TRACKING EASTWARD TOWARD THE GULF LATE NEXT
WEEK AND INTO THE WEEKEND. IT IS STILL TOO EARLY TO DETERMINE
THE EXACT STRENGTH OR TRACK OF THIS LOW...BUT STORM FORCE WINDS
ARE LIKELY AS IT MOVES INTO THE BERING...AND THERE IS A VERY GOOD
CHANCE SNOW WILL MOVE BACK INTO THE SOUTHERN MAINLAND BY WEEKS END.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WARNING 155.
MARINE...GALE WARNING...130 132 150 155 165 170 171 172 175 176 179.
         HEAVY FREEZING SPRAY WARNING...121 130 132 138 150 160 165
                                        179 180 185.
FIRE WEATHER...NONE.

SEB NOV 09