Small Craft Advisory 848, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
413 PM AKDT MON OCT 28 2013

.ANALYSIS AND UPPER LEVELS...
THE NEGATIVELY TILTED LONG-WAVE TROUGH WHICH EXTENDS FROM THE EASTERN
BERING TO APPROXIMATELY 45N WILL CONTINUE TO TRACK NORTHEAST. AS THIS
TROUGH CONTINUES ITS NORTHEASTWARD PROGRESSION...THE ASSOCIATED FRONT
AHEAD OF THE TROUGH WILL TRACK EASTWARD AND BRING AN END TO THE
HEAVIER PRECIPITATION AND GUSTY WINDS IN SOUTHCENTRAL ALASKA BY LATE
TONIGHT. A SECOND UPPER LEVEL TROUGH...STRETCHING FROM THE WESTERN
BERING DOWN TO 45N...AND ITS ASSOCIATED SURFACE LOW SOUTH OF SHEMYA
BEGIN TO DE-AMPLIFY THIS EVENING AS ENERGY BEGINS TO TRANSFER TO THE
NORTH PACIFIC LOW SOUTH OF DUTCH HARBOR.

A SLIGHT BREAK FOR THE KENAI PENINSULA AND WESTERN PARTS OF
SOUTHCENTRAL CAN BE EXPECTED TUESDAY MORNING...HOWEVER WITH THE
STRENGTHENING NORTH PACIFIC LOW APPROACHING FROM THE
SOUTHWEST...WETTER AND GUSTY CONDITIONS CAN BE EXPECTED TO PICK UP
AGAIN AS EARLY AS TUESDAY EVENING. GUIDANCE IS CONTINUING TO SHOW
GOOD SUPPORT FOR THIS SYSTEM TO RAMP UP SOUTHWEST OF KODIAK ISLAND
TUESDAY MORNING AS IT RIDES THE LEFT EXIT REGION OF AN UPPER LEVEL
JET WITH A 145 KT CORE.

.MODEL DISCUSSION...
THE NEXT BIG THING FOR SOUTHCENTRAL IS A LOW THAT IS CURRENTLY IN THE
NORTH PACIFIC NEAR 45N 165W. THIS DEVELOPING LOW IS SITUATED AT THE
JET EXIT REGION ALONG WITH A SHORT WAVE TROUGH AND IMPROVING
BAROCLINICITY AT THE SURFACE. THE LOW TO RIDE THE WAVE OF THE JET
EXIT REGION AND SHORT WAVE TO SOUTH OF KODIAK TOMORROW. ALL THE
MODELS HAVE A SIMILAR SOLUTION FOR THIS LOW. HOWEVER...THE INTENSITY
AND TRACK OF THE LOW IS STILL UP FOR DEBATE. THE NAM HAS BEEN A BIT
OF AN OUTLIER WITH THE INTENSITY OF THE LOW BUT HAS COME AROUND A BIT
WITH THE 18Z RUN. THE DIFFERENCE IN THE MODELS IS DUE TO THE PHASING
OF ALL ASPECTS OF THE LOW MENTIONED ABOVE. ONE HAS THE SHORT WAVE
MOVING AHEAD OF THE LOW TOO FAST WHILE OTHERS HAVE THE JET SHOOTING
OFF FARTHER TO THE EAST. RIGHT NOW...THE MOST LIKELY SCENARIO IS FOR
THE LOW TO DEEPEN NEAR 970 MB SOUTH OF KODIAK TOMORROW NIGHT AND RUN
UP TO THE NORTHERN GULF WEDNESDAY. AGAIN...THE POSITION IS SUSPECT
ONCE IT HITS THE NORTHERN GULF AREA. ALL MODELS PUSH THE JET ENERGY
INTO CANADA...LEAVING A FILLING LOW IN THE NORTHERN GULF THROUGH
FRIDAY. IF HISTORY IS A GUIDE...THE LOW WILL LIKELY PARK SOUTH OF THE
SOUND AND REMAIN AS A WEAK LOW WITH SHOWERS RINGING THE GULF.

OUT WEST...MODELS ARE IN GENERAL AGREEMENT THAT THE SURFACE LOW IN
THE YK DELTA TO LIFT NORTH TONIGHT WITH THE REMNANT LOWS IN THE
NORTHERN BERING WEAKENING AND ROTATING SOUTH TO THE PRIBILOFS. THE
AREA OF LOW PRESSURE TO REMAIN IN THE CENTRAL AND EASTERN BERING
THROUGH THE WEEK AS COLD AIR AND MULTIPLE DISTURBANCES ROTATE THROUGH
THE BERING IN THE LONG WAVE TROUGH.

THE SLOW PATTERN TO BREAK DOWN THROUGH THE WEEK TO A MORE PROGRESSIVE
FLOW. HOWEVER...A STRONG UPPER LOW WILL MOVE INTO THE BERING BY THE
END OF THE WEEK.

.SHORT TERM FORECAST...
SOUTHCENTRAL...THE FRONT THAT IS PASSING THROUGH SOUTHCENTRAL TODAY
CONTINUES TO BRING STRONG WINDS AND RAIN TO MUCH OF THE AREA. THE
UPPER TROUGH TO PASS THROUGH THE AREA TONIGHT ENDING PRECIP FROM THE
SOUTHWEST. WINDS WILL DIMINISH AS WELL THROUGH THE NIGHT. SOME COOLER
TEMPS TO FILTER INTO THE AREA BEHIND THE LOW TONIGHT AND TOMORROW.
MAY SEE SOME FOG TONIGHT OR EARLY TOMORROW MORNING. THE LOW
DEVELOPING IN THE NORTH PACIFIC TO MOVE CLOSER TO KODIAK AREA
TOMORROW AFTERNOON. WINDS WILL PICK UP FROM THE SOUTHEAST AND PRECIP
TO BEGIN ON KODIAK ISLAND BY THE EVENING. IN THE MEANTIME...SOUTH
CENTRAL WILL BE RELATIVELY DRY OUTSIDE OF COASTAL SHOWERS IN THE
NORTHERN GULF. THE LOW WILL CONTINUE TO WORK TO THE NORTHERN GULF
COAST BY WEDNESDAY MORNING. GALE FORCE WINDS WILL ACCOMPANY THE NEAR
970 MB LOW FROM THE NORTHERN COAST THROUGH SHELIKOF STRAIT. GIVEN THE
FLOW OF THE PATTERN AT THIS TIME...MOST PRECIP WILL REMAIN ALONG THE
COAST. THE LOW WILL FILL WEDNESDAY THROUGH THURSDAY ALONG THE
NORTHERN COAST WITH SHOWERS AND WINDS SLOWLY DIMINISHING IN THIS
PERIOD.

SOUTHWEST...THE LOW IN THE YK DELTA TO LIFT NORTH TONIGHT. ENOUGH
COLD AIR HAS FILTERED IN BEHIND THIS LOW THAT RAIN AND SNOW IS BEING
EXPERIENCED IN SOUTHWEST ALASKA. RAIN AND SNOW TO END TONIGHT AS THE
LOW LIFTS NORTH. HOWEVER...MVFR AND IFR CONDITIONS TO PERSIST ALONG
THE COAST WITH POSSIBLE FOG DEVELOPMENT. WINDS ARE NOT ALL THAT
STRONG BUT WILL PICK UP ON TUESDAY AND WEDNESDAY ALONG THE ALEUTIAN
CHAIN WITH THE LOW IN THE WESTERN GULF. THIS IS WHERE THE PRECIP WILL
BE AS WELL DURING THE PROGRESSION OF THE LOW IN THE GULF. THE COLD
AIR TO CONTINUE TO FILTER INTO THE AREA THROUGH THURSDAY WITH SNOW
SHOWERS.

BERING SEA AND ALEUTIANS...A WEAK LOW IN THE CENTRAL BERING TO
PERSIST THROUGH WEDNESDAY WITH GOOD NORTHWEST FLOW COLD AIR
ADVECTION. WITH COLD AIR IN PLACE OVER THE BERING EXPECT INSTABILITY
SHOWERS TO REMAIN OVER THE AREA THROUGH MUCH OF THE WEEK. NO DISCRETE
SURFACE LOW PRESSURE SYSTEMS PAST MID WEEK BUT INSTABILITY SHOWERS TO
REMAIN.  MEANWHILE...THE EASTERN ALEUTIANS WILL INCREASE IN WINDS AND
PRECIP AS THE LOW IN THE WESTERN GULF TUESDAY AFTERNOON AND NIGHT.
SOME GUSTS THROUGH THE AKPEN AND EASTERN ALEUTIANS WILL BE THE MAIN
IMPACT WITH NORTHWEST GUSTS THROUGH GAPS IN THE TERRAIN.

.LONG TERM FORECAST...
THE LOW IN THE GULF TO WEAKEN THROUGH THE DAY FRIDAY. A STRENGTHENING
LOW SOUTH OF THE WESTERN ALEUTIANS WILL TRACK OVER THE WESTERN AND
CENTRAL ALEUTIANS THURSDAY NIGHT INTO FRIDAY AND MAKE ITS WAY INTO
THE CENTRAL BERING BY FRIDAY NIGHT. CURRENTLY MODEL GUIDANCE IS
HINTING AT GOOD UPPER LEVEL JET AND BAROCLINIC SUPPORT FOR
CYCLOGENESIS...AS WELL AS DECENT SUPPORT FOR AMPLIFICATION. WITH ALL
OF THE ABOVE VARIABLES ALIGNING AT THE SAME TIME...ALONG WITH THE
SUBTROPICAL MOISTURE BEING PROPAGATED NORTHWARD WITH THIS
SYSTEM...THE ALEUTIAN CHAIN AS WELL AS SOUTHWEST AND SOUTHCENTRAL
ALASKA COULD SEE ANOTHER ROUND OF WARMER THAN NORMAL TEMPERATURES AND
WET/WINDY CONDITIONS.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...FLOOD WATCH 131 135
MARINE...GALE 119 120 128 130 131 132 136 137 138 139 150
FIRE WEATHER...NONE

JN OCT 13