Area Forecast Discussion
Issued by NWS Anchorage, AK

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FXAK68 PAFC 201313
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
413 AM AKST THU NOV 20 2014

FOR NOVEMBER 20TH MORNING AFD PACKAGE:

.ANALYSIS AND UPPER LEVELS...
AN UPPER LEVEL VERTICALLY STACKED CLOSED LOW IS LOCATED SOUTH OF
THE EASTERN ALEUTIANS NEAR 52N 157W. THIS IS REFLECTED AT THE
SURFACE WITH AN OCCLUDED STORM FORCE LOW WITH A BUOY REPORTING
THE LOW AT 951 MB THIS MORNING. THE SATELLITE IMAGERY IS SHOWING A
LARGE COMMA CLOUD OVER THE EASTERN ALEUTIANS STREAMING OVER INTO
THE EASTERN BERING SEA. THE ASCAT SCATTEROMETER WINDS WERE SHOWING
A SWATH OF GALE FORCE WINDS HEADING INTO THE EASTERN
ALEUTIANS...WHILE STORM FORCE WINDS WERE SOUTH OF THE OCCLUDED
LOW. THE SOUTHWEST ALASKA REGION HAS AN UPPER LEVEL WEAK INVERTED
TROUGH THROUGH THE AREA. THE RADAR IS SHOWING SCATTERED RAIN
SHOWERS WITH THE SURFACE TEMPERATURES IN THE UPPER 30S EXCEPT
UPPER 20S THROUGH THE KUSKOKWIM VALLEY. THE NORTHERN GULF HAS AN
UPPER LEVEL WEAK SHORTWAVE TRACKING THROUGH WITH THE RADAR
SHOWING SHOWERS THROUGH THE NORTHERN GULF COASTLINE EXTENDING INTO
PRINCE WILLIAM SOUND REGION. THE ANCHORAGE BOWL AND THE EASTERN
KENAI IS DOWNSLOPE DRYING WITH ANY PRECIPITATION DIMINISHING OVER
THE CHUGACH AND KENAI MOUNTAINS.

&&

.MODEL DISCUSSION...
MODELS ARE IN GOOD AGREEMENT WITH THE STORM FORCE LOW TRACKING
JUST SOUTH OF SAND POINT THIS MORNING. THIS LOW WILL CROSS THE
EASTERN ALEUTIANS NEAR SAND POINT BY FRIDAY MORNING BEFORE
DRIFTING BACK TO PACIFIC SIDE...THEN BECOME NEARLY STATIONARY IN
THE NEXT FEW DAYS. THE ASSOCIATED FRONT WITH THIS STORM FORCE LOW
WILL MOVE INTO THE SOUTHWEST GULF THIS MORNING BEFORE TRACKING TO
THE NORTHERN GULF BY FRIDAY AFTERNOON. THIS WILL BRING SOUTHEAST
TO EAST STORM FORCE WINDS THROUGH THE BARREN ISLANDS EXTENDING
TOWARD KAMISHAK BAY. THERE WILL BE GALE FORCE WINDS ALONG THE
EASTERN KENAI PENINSULA...EAST SIDE OF KODIAK ISLAND...SHELIKOF
STRAIT AND LOWER COOK INLET BEFORE DIMINISHING BY EARLY FRIDAY
MORNING. THE GEM-REG/ECMWF WERE THE PREFERRED MODELS OF CHOICE
THROUGH THE SHORT TERM FORECAST. THE FORECAST CONFIDENCE REMAINS
HIGH GOING INTO THE WEEKEND.


&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
THE MAIN WEATHER STORY IS THE STRONG LOW IN THE SOUTHWEST GULF AND
ITS ASSOCIATED FRONT. THE SURFACE LOW...AT ABOUT 953 MB THIS
MORNING...WILL MOVE NORTH TODAY AND REACH THE ALASKA PENINSULA
AROUND MIDNIGHT TONIGHT. THE LOW WILL THEN CROSS INTO THE BERING
SEA FRIDAY MORNING AND SLOWLY DRIFT TO THE WEST THROUGH FRIDAY
NIGHT...SLOWLY WEAKENING TO ABOUT 968 MB BY LATE FRIDAY NIGHT. THE
ASSOCIATED SURFACE FRONT CURRENTLY STRETCHES SOUTHEAST FROM
KODIAK ISLAND ACROSS THE SOUTHERN GULF. THIS FRONT WILL SLOWLY
MOVE NORTH WITH ITS ASSOCIATED WINDS AND PRECIPITATION. WINDS WILL
REACH STORM FORCE TODAY THROUGH THE BARREN ISLANDS...WITH GALES
OVER THE REST OF GULF AS WELL AS SHELIKOF STRAIT AND SOUTHERN COOK
INLET. THE FRONT WILL WEAKEN AND MOVE NORTH TONIGHT...ELONGATING
AND EVENTUALLY ORIENTED EAST/WEST BY FRIDAY MIDDAY. THE FRONT WILL
BASICALLY FALL APART AS IT MOVES INTO THE GULF COAST. VERY LITTLE
TO NO PRECIPITATION WILL REACH THE INLAND VALLEYS DUE TO THE
ORIENTATION OF THE FRONT AND MID/UPPER LEVEL WINDS.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 THROUGH 3)...

A STRONG LOW PRESSURE SYSTEM FROM THE NORTH PACIFIC CONTINUES TO
PUSH NORTH TOWARD THE ALASKA PENINSULA THIS MORNING. THIS HAS LEAD
TO A SWATH OF GALE FORCE WINDS EXTENDING FROM THE SHUMAGIN ISLANDS
EASTWARD TOWARD THE GULF OF ALASKA. RAIN CHANCES WILL BE ON THE
RISE ACROSS THE ALASKA PENINSULA AND ALONG THE ALEUTIAN RANGE THIS
MORNING AS THIS LOW PRESSURE SYSTEM CONTINUES TO MOVES NORTH.
GUSTY WINDS UP TO 45 MPH WILL BE SEEN ACROSS CHANNELED TERRAIN IN
THE ALASKA PENINSULA...WHILE GUSTS BETWEEN 50 TO 60 MPH WILL BE
SEEN THROUGH THE GAPS OF THE ALEUTIAN RANGE AND ALONG THE WESTERN
CAPES OF THE BRISTOL BAY AREA. RAIN (HEAVY AT TIMES) WILL CONTINUE
ACROSS THE ALASKA PENINSULA THROUGH THE END OF THE WEEK AS THE
AREA OF LOW PRESSURE REMAINS NEARLY STATIONARY OVER THE ALASKA
PENINSULA. FURTHER NORTH INTO THE KUSKOKWIM DELTA AND LOWER
KUSKOKWIM VALLEY...A CHANCE FOR SOME SCATTERED RAIN AND SNOW
SHOWERS WILL BE POSSIBLE THROUGH THE END OF THE WEEK WITH THE
MAJORITY OF THE MOISTURE AND DYNAMIC LIFT REMAINING FURTHER SOUTH.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 THROUGH 3)...

A WEAKENING AREA OF LOW PRESSURE JUST TO THE NORTH OF ATKA WILL
DISSIPATE THIS AFTERNOON AS A BULK OF THE ENERGY PHASES WITH THE
NORTH PACIFIC LOW MOVING TOWARD THE ALASKA PENINSULA. LARGE SCALE
CYCLONIC FLOW WILL PERSIST ACROSS THE BERING SEA LEADING TO
SCATTERED RAIN SHOWERS CONTINUING ACROSS THE BERING SEA. RAIN WILL
BE MORE LIKELY ACROSS THE EASTERN ALEUTIANS AS MOISTURE ASSOCIATED
WITH THE LOW OVER THE BERING SEA UPSLOPES ALONG THE MOUNTAINS. BY
THE END OF THE WEEK...SOME SNOW SHOWERS MAY MIX WITH RAIN SHOWERS
OVER THE WESTERN HALF OF THE BERING SEA AS COLDER AIR FROM SIBERIA
BEGINS TO BE ADVECTED SOUTHWARD.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...
BEYOND THE WEEKEND INTO NEXT WEEK THE FORECAST WILL CENTER AROUND
THE REMNANTS OF THE CURRENT DEEP LOW PRESSURE SOUTH OF THE ALASKA
PENINSULA. BY THIS POINT THE SYSTEM WILL BE WEAKENING AND THE
FRONT ASSOCIATED WITH IT WILL BE HANGING AND STALLED AROUND THE
NORTH GULF COAST. RAIN SHOWERS ASSOCIATED WITH THE SYSTEM WILL BE
MAINLY CONFINED TO THE NORTH GULF COAST AND KODIAK ISLAND. THERE
IS STILL SOME CHANCE FOR PRECIPITATION INLAND OVER THE COOK INLET
REGION BUT THIS WILL BE DEPENDENT ON INDIVIDUAL SHORTWAVES AND
STRENGTH OF DEEP LAYER SOUTHEASTERLY WIND OVER THE KENAI/CHUGACH
MOUNTAINS. AS THIS SYSTEM WEAKENS AND SLIDES EASTWARD INTO THE
GULF THROUGH MID-WEEK SHOWER COVERAGE WILL DIMINISH. NORTHERLY
DOWN-INLET FLOW WILL DIMINISH THROUGH THE FORECAST PERIOD WITH
GENERALLY LIGHT WINDS PREVAILING INTO NEXT WEEK. GUIDANCE IS
SIGNALLING A PATTERN CHANGE AS THIS SYSTEM DISSIPATES AND A
KAMCHATKA LOW SENDS A FRONTAL BOUNDARY ACROSS THE BERING SEA.
MODELS ARE IN GENERAL AGREEMENT WITH THE PATTERN BUT EXACT LOW
POSITION AND FRONTAL PROGRESSION ARE STILL UNCLEAR. EXPECT AN
INCREASE IN CLOUDINESS AND CHANCES FOR PRECIPITATION OVER THE
SOUTHCENTRAL AS THE FRONTAL BOUNDARY PUSHES OVER THE MAINLAND BY
MID-WEEK. THERE IS MUCH HIGHER CONFIDENCE IN THIS FRONT AS IT
PUSHES ACROSS THE BERING SEA.

&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...STORM 130 131.
         GALE 119 120 132 136 137 138 139 150 155 160 165 180.
FIRE WEATHER...NONE.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...PD
SOUTHCENTRAL ALASKA...LUDWIG
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...CLAY
LONG TERM...MTL


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