Small Craft Advisory 918, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
428 AM ADT THU NOV 1 2007

.ANALYSIS AND UPPER LEVELS...
A STRONG AREA OF LOW PRESSURE NEAR KODIAK THIS MORNING IS BY FAR THE
MOST DOMINANT FEATURE. A WARM FRONT IS MOVING OUT AHEAD OF THE LOW
AND AFFECTING THE NORTH GULF COAST AND PRINCE WILLIAM SOUND WITH
RAIN AND WINDS EARLY THIS MORNING. A COLD FRONT EXTENDS WELL SOUTH
FROM THE LOW CENTER INTO THE MIDLATITUDES. A WELL DEFINED DRY SLOT
IS PRESENT BETWEEN THE COLD AND WARM FRONTS...THOUGH THE DRY SLOT
WILL PROGRESS MORE EAST THAN NORTH AND BRING LITTLE REPRIEVE TO THE
PRECIP FOR OUR AREA. OUTSIDE OF CHANNELED TERRAIN...THE STRONGEST
WINDS WITH THE LOW ARE ON THE IMMEDIATE BACKSIDE OF THE LOW...WHERE
WINDS UP TO 50 KNOTS OR SO ARE PRESENT. CYCLONIC FLOW AROUND THE LOW
IS PRESENT OUT TO THE WEST CENTRAL BERING SEA. RAIN AND SNOW IS
PRESENT WEST OF THE LOW AS WELL...OVER THE SOUTHWEST MAINLAND...WITH
SNOW AND RAIN SHOWERS PRESENT FURTHER WEST IN THE BERING/ALEUTIANS
UNDER COLD NORTHWEST FLOW.

THE LOW WILL MOVE INTO THE KENAI PENINSULA THIS EVENING AND THEN TO
ANCHORAGE...WEAKENING. A RIDGE OF HIGH PRESSURE WILL BUILD INTO THE
WESTERN ALEUTIANS/BERING TODAY.

.MODEL DISCUSSION...
MODELS ARE OVERALL IN GOOD AGREEMENT THROUGH THE SHORT TERM...THOUGH
THERE ARE SOME SLIGHT BUT IMPORTANT DIFFERENCES IN THE TRACK OF THE
LOW FROM KODIAK UP INTO SOUTHCENTRAL THROUGH THIS EVENING. FIRST
OFF...EARLY THIS MORNING...MSAS ANALYSIS AND GFS MODEL OBVIOUSLY
HAVE THE LOW CENTER WAY TOO FAR NORTH. NAM/WRF AND ECMWF ARE DOING A
BETTER JOB. WHETHER THE LOW CONTINUES ON THIS MORE
SOUTHERLY/EASTERLY TRACK IS ANOTHER STORY. WE SHOULD HAVE A MUCH
BETTER IDEA OF WHERE EXACTLY THE LOW WILL TRACK BY MIDDAY. ONE OF
THE RAMIFICATIONS THIS WILL HAVE IS FOR ANCHORAGE REGARDING HOW
QUICKLY THE COLD AIR CAN MOVE IN TONIGHT AND HOW MUCH SNOW (IF ANY)
FALLS. THE FURTHER SOUTH/EAST TRACK WOULD BE BETTER FOR ANCHORAGE TO
SEE SNOW.

.SHORT TERM FORECAST...
SOUTHCENTRAL FORECAST...
LOW PRESSURE TO CONTINUE NORTHEAST FROM KODIAK ISLAND INTO THE KENAI
PENINSULA LATE TODAY. RAIN WILL BE NEARLY CONTINUOUS FOR COASTAL
SOUTHCENTRAL THROUGH TONIGHT. THE USUAL DOWNSLOPE AREAS FROM KENAI
NORTH TO THE EASTERN SUSITNA VALLEY WILL REMAIN DRY UNTIL TONIGHT
WHEN THE COLD ADVECTION AND UP-INLET FLOW KICKS IN ON THE BACKSIDE
OF THE LOW. SNOW FORECAST FOR THE SOUTHCENTRAL WILL BE CHALLENGING.
THERE IS SOME MORE COLD AIR TO WORK WITH FOR THIS SYSTEM COMPARED TO
THE LAST SYSTEM. HOWEVER...THE TRACK OF THE LOW IS STILL NOT
CERTAIN. A DOWNSIDE IS THAT THERE IS NOT REALLY A STRONG SHORTWAVE
IN SOUTHWEST FLOW BEHIND THE LOW...SO THE SHOT OF SNOW FOR THE COOK
INLET REGION WILL BE RATHER BRIEF FROM LATE TONIGHT INTO FRIDAY
MORNING. PRECIPITATION WILL TAPER OFF DURING THE DAY FRIDAY. A
REMNANT LOW PERSISTS IN THE FAR NORTHERN GULF/PRINCE WILLIAM SOUND
INTO SATURDAY MORNING...HELPING TO KEEP LIGHT PRECIP GOING FROM
EASTERN PRINCE WILLIAM SOUND TO CORDOVA. IN GENERAL...A QUIET SPELL
OF WEATHER IS IN STORE FOR SOUTHCENTRAL FROM FRIDAY AFTERNOON INTO
SATURDAY.

SOUTHWEST MAINLAND FORECAST...
MAIN FORECAST CHALLENGE FOR THE SOUTHWEST MAINLAND COMES TODAY IN
FORECASTING SNOW OR RAIN CHANGING TO SNOW ON THE WEST SIDE OF THE
LOW FROM KING SALMON NORTH TO MCGRATH. AT THIS POINT IT LOOKS LIKE A
FEW INCHES OF SNOW ARE POSSIBLE TODAY INTO TONIGHT...BUT NOTHING
MAJOR. COLDER AIR WORKS INTO THE SOUTHWEST MAINLAND TONIGHT WITH
COLD HIGH PRESSURE PRESENT FRIDAY AND EARLY SATURDAY. A FRONT
APPROACHES THE SOUTHWEST COAST ON SATURDAY...MAKING LANDFALL
SATURDAY EVENING. THIS WILL BRING IN A WARMER AIRMASS AND RAIN AND
SNOW.

BERING SEA/ALEUTIAN FORECAST...
SNOW/RAIN SHOWER ACTIVITY AND GUSTY NORTHWEST WINDS WILL GRADUALLY
SHUT OFF FROM WEST TO EAST AS A RIDGE OF HIGH PRESSURE PROGRESSES
EAST. THE RIDGE WILL BE OVER THE WESTERN BERING/ALEUTIANS TODAY AND
MOVE EAST TO THE EASTERN BERING/ALEUTIANS FRIDAY. THE BREAK IN THE
WEATHER WILL NOT LAST...AS A STRONG FRONT WITH STORM FORCE WINDS
FOLLOWS THE RIDGE. THE FRONT WILL ENTER THE WESTERN BERING/ALEUTIANS
EARLY FRIDAY...THEN MOVE EAST TO THE EASTERN BERING/AKPEN ON
SATURDAY. PRECIPITATION WILL BE ENTIRELY RAIN WITH THIS FRONT...WITH
RAIN AND SNOW SHOWER ACTIVITY BEHIND THE FRONT.

.LONG TERM FORECAST...
NOT MUCH CONFIDENCE IN ANYTHING FROM SUNDAY ONWARD...AS MODELS HAVE
NOT BEEN CONSISTENT AT ALL. IT DOES APPEAR THAT THE BERING WILL BE
UNDER AN UNSETTLED WEATHER PATTERN WITH NUMEROUS LOW
PRESSURES...THOUGH WHERE EXACTLY THEY POSITION THEMSELVES IS UP IN
THE AIR. OVERALL...THE WHOLE FORECAST AREA WILL BE UNDER A WARM
WEATHER PATTERN.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...STORM WARNING ZONES 150 175 176 351 352 411.
         GALE WARNING ZONES 120 125 129 130 132 136 138 155 160 172
         180 412 413 414.
FIRE WEATHER...NONE.

FOISY NOV 07