Small Craft Advisory 103, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
441 AM AKST MON FEB 2 2015

.ANALYSIS AND UPPER LEVELS...
EARLY MORNING SATELLITE IMAGERY INDICATES THAT THE BLOCKING
PATTERN THAT HAS DOMINATED THE WEATHER THROUGHOUT THE MAINLAND AND
BERING SEA IS BEGINNING TO BREAK DOWN...AT LEAST TEMPORARILY.
RIDGING CONTINUES FROM THE SOUTHERN BERING INTO THE SOUTHERN
MAINLAND CAUSING PATCHY FOG AND LOW CLOUDS TO CONTINUE OVERNIGHT
ALONG COOK INLET...ESPECIALLY IN THE ANCHORAGE BOWL WHERE THE FOG
MOMENTARILY BECAME DENSE AT TIMES. AN UPPER LEVEL SHORTWAVE CAN BE
SEEN ENTERING THE SOUTHWEST COAST...WITH SIGNIFICANT FOG AND
STRATUS DEVELOPING BEHIND IT FROM THE KUSKOKWIM DELTA COAST INTO
THE BERING. A NORTH PACIFIC LOW CONTINUES TO SPIN WELL SOUTH OF
THE EASTERN ALEUTIANS WITH ITS ASSOCIATED FRONT SLOWLY WEAKENING.

&&

.MODEL DISCUSSION...
AS IS USUALLY THE CASE DURING BLOCKING PATTERNS SUCH AS THIS THE
MODELS REMAIN IN VERY GOOD SYNOPTIC AGREEMENT THROUGH THE SHORT
TERM...BUT THERE HAVE RECENTLY BEEN SOME CRITICAL CHANGES SINCE
YESTERDAY. THE MODELS ARE NOW ALL IN GREAT AGREEMENT THAT THE
SHORTWAVE ENTERING THE MAINLAND WILL QUICKLY DIVE SOUTHWARD INTO
THE AKPEN BY LATE TONIGHT...RATHER THAN TRAVELING THROUGH
SOUTHCENTRAL LIKE PREVIOUS RUNS HAD INDICATED. THIS WILL BRING THE
FIRST ROUND OF COLD AIR MOSTLY TO THE WESTERN MAINLAND RATHER
THAN TO SOUTHCENTRAL TONIGHT...CAUSING OVERNIGHT LOWS TO BE
CHANGED WITH THE MORNING PACKAGE. THIS CHANGE WILL ALSO ALLOW WEAK
RIDGING TO REMAIN OVER SOUTHCENTRAL TONIGHT...CREATING THE
POSSIBILITY OF CONTINUED FOG AND STRATUS ALONG COOK INLET. AS FOR
THE NEXT UPPER LEVEL LOW TO ENTER NORTHWESTERN CANADA TUESDAY
EVENING...THE EASTWARD TREND OF THIS FEATURE CONTINUES AND THERE
IS NOW VERY GOOD CONFIDENCE THAT RIDGING WILL RETURN TO THE
MAINLAND FOR WEDNESDAY AND THURSDAY.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
HIGH PRESSURE OVER SOUTHERN ALASKA WILL SLOWLY DROP SOUTH INTO
THE GULF TODAY. A WEAK EASTWARD MOVING TROUGH OVER SOUTHWEST
ALASKA WILL STALL TODAY THEN DISSIPATE TONIGHT. A STRONGER RIDGE
OVER THE BERING SEA WILL THEN PUSH EASTWARD INTO SOUTHERN ALASKA
TUESDAY AND TUESDAY NIGHT. THE RESULT OF ALL OF THIS WILL BE
CONTINUED DRY CONDITIONS. THE SURFACE GRADIENT IS VERY WEAK BUT
WILL INCREASE AGAIN TUESDAY NIGHT AS THE NEXT RIDGE BUILDS IN.
PATCHY FOG IS ALSO POSSIBLE IN THE WEAK FLOW WITH A DECENT
INVERSION SET UP.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
A CONTINUATION FOR CLEAR AND COLD TODAY AND TOMORROW FOR THE LOWER
KUSKOKWIM VALLEY AND INTERIOR BRISTOL BAY. THE DELTA WILL SEE A
BIT OF A CHANGE AS A "COLD FRONT" BRINGS WARMER TEMPERATURES AND
CLOUD COVER. WINDS ON THE DELTA WILL SHIFT OUT OF THE NORTH
TONIGHT AND AGAIN DRY THINGS OUT RETURNING TO CLEAR AND COLDER
CONDITIONS. SOME INSIGNIFICANT LIGHT SNOW AND PATCHY FOG IS
POSSIBLE TODAY UNDER THE STRATUS DECK.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
HIGH PRESSURE SITS OVER THE BERING AT THE SURFACE BUT A STRONG
DISTURBANCE ALOFT WILL MOVE OFF THE MAINLAND THIS AFTERNOON AND
BRING SNOW SHOWERS TO THE EASTERN ALEUTIANS AND ALASKA PENINSULA
LATE TONIGHT. THESE WILL MOVE FROM EAST TO WEST THROUGH MID
WEEK...LEAVING A CHANCE FOR RAIN AND SNOW FROM A DECAYING FRONT
SOUTH OF THE CHAIN.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...
HIGH PRESSURE WILL SIT OVER THE NORTHERN BERING FOR THE LATTER
PART OF THE WEEK. THIS WILL RESULT IN CONTINUED DRY CONDITIONS FOR
THE SOUTHWEST AND SOUTHCENTRAL. ON FRIDAY AN UPPER LEVEL TROUGH
WILL PUSH DOWN FROM THE NORTH THAT WILL BRING COLDER TEMPERATURES
TO THE REGION.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...HEAVY FREEZING SPRAY...414.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...DEK
SOUTHCENTRAL ALASKA...BL
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...MTL
LONG TERM...DK