Area Forecast Discussion
Issued by NWS Anchorage, AK

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FXAK68 PAFC 211339
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
439 AM AKST FRI NOV 21 2014

FOR NOVEMBER 21TH MORNING AFD PACKAGE:

.ANALYSIS AND UPPER LEVELS...
AN OCCLUDED GALE FORCE LOW IS LOCATED JUST SOUTH OF CHIGNIK. AN
ASSOCIATED FRONTAL BOUNDARY IS LOCATED THROUGH THE BARREN ISLANDS
EXTENDING INTO THE NORTHERN GULF COAST. THE ASCAT SCATTEROMETER
WINDS ARE SHOWING GALE FORCE AND SMALL CRAFT ADVISORY WINDS
THROUGH THE AFOREMENTIONED REGION. THE UPPER LEVELS HAVE A CLOSED
VERTICALLY STACKED LOWS ALOFT OVER THE EASTERN ALEUTIANS. THE
SATELLITE IMAGERY SHOWS A LARGE SWATH OF MOISTURE THROUGHOUT
SOUTHCENTRAL ALASKA AND SPREADING INTO THE SOUTHWEST ALASKA
REGION. THE RADAR IS SHOWING RAIN ALONG THE NORTHERN GULF
COASTLINE SPREADING INLAND WITH SURFACE TEMPERATURES IN THE 40S.
THE ANCHORAGE BOWL CONTINUES TO HAVE DOWNSLOPE DRYING DUE TO THE
CROSS BARRIER FLOW WITH SOME SHOWERS ALONG THE CHUGACH MOUNTAINS
ON THE RADAR. WITH THE NEARLY STATIONARY UPPER LEVEL LOW OVER THE
EASTERN ALEUTAINS...THERE IS WEAK SHORTWAVES ROTATING AROUND THE
LOW WHICH IS PRODUCING SHOWERY PRECIPITATION THROUGH THE BRISTOL
BAY AREA AND ALONG THE KUSKOKWIM DELTA COASTLINE. THE SOUTHEAST
ALASKA AREA HAS AN NEGATIVE TILTED HIGH PRESSURE RIDGE EXTENDING
INTO THE BROOKS RANGE WITH THE SATELLITE IMAGERY SHOWING MOSTLY
CLEAR SKIES OVER THE YUKON TERRITORY EXTENDING INTO BARROW.


&&

.MODEL DISCUSSION...
MODELS ARE IN GOOD AGREEMENT WITH THE OCCLUDED LOW OVER THE
EASTERN ALEUTIANS AS IT CONTINUES TO BECOME NEARLY STATIONARY
HEADING INTO THE WEEKEND. THE MODELS OF CHOICE WERE THE NAM/GEM-
REG THROUGH THE SHORT TERM FORECAST PERIOD. THE FORECAST
CONFIDENCE REMAINS HIGH.


&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
A VERTICALLY STACKED LOW WILL REMAIN CENTERED OVER THE ALASKA
PENINSULA THROUGH SATURDAY NIGHT. THE FRONTAL SYSTEM OVER THE
NORTHERN GULF WILL WEAKEN AND MOVE SLOWLY NORTH TODAY...REACHING
THE GULF COAST THIS EVENING THEN DISSIPATING. FLOW ALOFT WILL
REMAIN CYCLONIC AND THIS WILL KEEP PLENTY OF SHOWERS OVER THE
GULF AND GULF COAST. LITTLE OR NO PRECIPITATION IS EXPECTED FOR
THE INLAND VALLEYS TODAY...BUT CHANCES WILL START TO INCREASE
TONIGHT THROUGH SATURDAY NIGHT AS THE CROSS-BARRIER FLOW WEAKENS
AFTER THE FRONT DISSIPATES AND A WEAK UPPER TROUGH MOVES IN. NOT A
HUGE AMOUNT OF MOISTURE LEFT BY THAT POINT...SO CHANCES ARE STILL
SMALL.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...

A STRONG AREA OF LOW PRESSURE CURRENTLY RESIDES ALONG THE ALASKA
PENINSULA JUST TO THE NORTH OF THE SHUMAGIN ISLANDS. THE LOW HAS
WEAKENED SLIGHTLY IN THE PAST 12 HOURS...WITH ONLY PATCHES OF GALE
FORCE WINDS REMAINING ALONG THE COAST OF THE ALASKA PENINSULA AND
ON THE SOUTH END OF THE LOW NEAR CHIRIKOF ISLAND. GUSTY WINDS TO
50 MPH HAVE BEEN OBSERVED ACROSS PORTIONS OF THE BRISTOL BAY
AREA...GENERALLY THROUGH THE GAPS AND PASSES OF THE ALASKA RANGE.
THESE WINDS WILL DIMINISH THIS MORNING AS THE PRESSURE GRADIENT
WEAKENS A BIT AND BECOMES LESS FAVORABLY ORIENTED TO FORCE WINDS
THROUGH THE AFOREMENTIONED GAPS. PRECIPITATION WILL CONTINUE OVER
THE ALASKA PENINSULA THROUGH THE WEEKEND AS THE AREA OF LOW
PRESSURE REMAINS NEARLY STATIONARY OVER THE ALASKA PENINSULA.
STRONG SOUTHEASTERLY WINDS AT MOUNTAIN TOP LEVEL WILL CREATE
DOWNSLOPING CONDITIONS FOR PARTS OF THE BRISTOL BAY AREA...WHILE
UPSLOPE REGIONS OF THE ALASKA RANGE AND THE AHKLUN MOUNTAINS WILL
PRODUCE ADDITIONAL RAIN SHOWER ACTIVITY. TEMPERATURES ACROSS THE
KUSKOKWIM DELTA AND LOWER KUSKOKWIM VALLEY WILL DROP CLOSER TO
NEAR NORMAL TEMPERATURES OVER THE WEEKEND BUT CONTINUE TO REMAIN
ABOVE NORMAL THROUGH THE PERIOD.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...

THE AREA OF LOW PRESSURE SITUATED OVER THE ALASKA PENINSULA WILL
MEANDER WESTWARD SLIGHTLY WHICH WILL LEAD TO A CONTINUATION OF
STRATIFORM RAINFALL ACROSS THE EASTERN ALEUTIANS. THIS RAIN IS
EXPECTED TO LINGER THROUGH THE WEEKEND...ALTHOUGH BECOMING MORE
SHOWERY IN NATURE BY SUNDAY. BROAD CYCLONIC FLOW WILL PERSIST
ACROSS THE REMAINDER OF THE BERING SEA...LEADING TO SCATTERED RAIN
SHOWERS PERSISTING ACROSS THE REGION. SNOW SHOWERS WILL BEGIN TO
MIX WITH THE RAIN SHOWERS OVER THE WESTERN HALF OF THE BERING SEA
BY THE END OF THE WEEKEND.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...
LATE THIS WEEKEND INTO EARLY NEXT WEEK A BIT OF A PATTERN CHANGE
IS IN STORE FOR THE ALEUTIANS AND THE SOUTHERN MAINLAND. THE
CURRENT OCCLUDED LOW OVER THE ALASKA PENINSULA WILL RETROGRADE
WESTWARD WHILE WEAKENING AS THE FRONT WILL FALL APART OVER THE
NORTHERN GULF. WAY TO THE WEST...A SHORTWAVE TROUGH FEEDING OFF
THE WARM KUROSHIO CURRENT WILL PHASE WITH ANOTHER WAVE COMING OFF
OF EAST ASIA. THE RESULT WILL BE A CLASSIC KAMCHATKA LOW WITH
FRONTAL BOUNDARY PROGRESSING FROM WEST TO EAST OVER THE ALEUTIANS.
THE FLOW ALOFT WILL BECOME MORE PROGRESSIVE AND THE REMNANTS OF
THE PREVIOUS SYSTEM WILL GET PUSHED INTO THE GULF WITH ONLY
SHOWERY ACTIVITY REMAINING. GUIDANCE STRUGGLES WITH THE PATTERN
INTO MID-WEEK NAMELY WITH INDIVIDUAL WAVES ROTATING AROUND THE
PARENT LONGWAVE AS WELL AS ANOTHER SYSTEM IN THE CENTRAL PACIFIC.
THE MAIN FACET TO TAKE AWAY IS THAT THE GLOBAL MODELS ARE
SIGNALLING A REX BLOCK SETTING UP IN OUR VICINITY WHICH WOULD KEEP
SENSIBLE WEATHER DRY AND TEMPERATURES AT OR SLIGHTLY ABOVE NORMAL.
EXPECT SHOWERY CONDITIONS IN THE GULF THROUGH EARLY NEXT WEEK WITH
DRIER CONDITIONS INLAND ALONG WITH NEAR NORMAL TEMPERATURES.

&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE 119 130 131 139 160 180.
FIRE WEATHER...NONE.

&&

$$

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


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