Area Forecast Discussion
Issued by NWS Anchorage, AK

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124
FXAK68 PAFC 221330 AAA
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
530 AM AKDT FRI MAY 22 2015

...RECORD OR NEAR-RECORD HIGH TEMPERATURES TODAY ACROSS THE
COPPER RIVER BASIN AND MAT-SU VALLEY...

.ANALYSIS AND UPPER LEVELS...
THE STRONG UPPER LEVEL RIDGE REMAINS POSITIONED OVER THE GULF
STRETCHING NORTHWARD INTO THE YUKON TERRITORY AND EXTENDS THROUGH
THE COPPER RIVER BASIN WESTWARD INTO THE KUSKOKWIM DELTA BEFORE
ENDING UP IN THE EASTERN SIBERIAN REGION. THIS IS KEEPING A
PORTION OF THE SOUTHCENTRAL ALASKA REGION UNDER SUNNY AND DRIER
CONDITIONS AS WE HEAD INTO THE WEEKEND. THE SATELLITE IMAGERY IS
SHOW LOW STRATUS CLOUDS UNDER THE HIGH PRESSURE RIDGE OVER THE
GULF. WHILE...THE WEAK SURFACE LOW REMAINS SOUTH OF THE EASTERN
ALEUTIANS. THIS SYNOPTIC FEATURE COMBINED WITH BEING ON THE
BACKSIDE OF THE HIGH PRESSURE RIDGE OVER THE GULF IS RESULTING IN
MOISTURE FROM THE LOW BEING PUSHED UP INTO THE SOUTHWESTERN
GULF...AND SPILLING ACROSS THE ALASKA PENINSULA AND THE BRISTOL
BAY INTERIOR. THE STRONG 160 KNOT ZONAL JET STREAK REMAINS
POSITIONED EAST OF JAPAN EXTENDING SOUTH OF THE WESTERN ALEUTIANS
AND THE LEFT EXIT REGION OF THE JET STREAK ENTERING INTO THE ADAK
REGION THIS MORNING. THIS JET STREAK IS STEERING THE STORM FORCE
LOW AT THE SURFACE THAT IS JUST SKIRTING THE EDGE OF THE WESTERN
BERING SEA LOCATED NEAR 57N 173E THIS MORNING. THIS IS PRODUCING
GUSTY SOUTHERLY WINDS FROM KISKA EASTWARD TO ATKA ACCOMPANIED BY
A LARGE SWATH OF MOISTURE SPREADING FROM THE NORTH PACIFIC INTO
THE CENTRAL TO WESTERN BERING SEA THIS MORNING. THIS IS BEING
VERIFIED WITH THE ASCAT SCATTEROMETER WIND IMAGERY SHOWING GALE
FORCE SOUTHERLY WINDS FOR THE CENTRAL ALEUTIANS AND SPREADING OVER
INTO THE CENTRAL BERING SEA.

&&

.MODEL DISCUSSION...
THE MODELS ARE IN BETTER AGREEMENT WITH THE REMNANTS OF THE TYPHOON
DOLPHIN AS IT TRACKS INTO THE WESTERN BERING SEA THIS MORNING
BEFORE IT BECOMES SOMEWHAT STATIONARY THROUGH THIS WEEKEND. THE
SOUTHCENTRAL AND THE GULF REGION WILL CONTINUE TO BE UNDER THE
INFLUENCE OF THE HIGH PRESSURE RIDGE FOR SEVERAL MORE DAYS. THE
NAM/GFS WERE THE PREFERRED MODELS OF CHOICE AS WERE HEADING INTO
THE WEEKEND. THE MODELS THEN HAVE SOME UNCERTAINTY ON THE BERING
SIDE BY SUNDAY WITH A SECONDARY LOW DROPPING DOWN FROM THE
KAMCHATKA PENINSULA. THESE TWO LOW PRESSURES SYSTEMS WILL THEN
MERGE TOGETHER AND THE MODELS ARE STRUGGLING WITH THIS PHASING IN
THE EARLY PART OF NEXT WEEK. THE FORECAST CONFIDENCE REMAINS ABOVE
AVERAGE BEFORE WEAKENING BY NEXT WEEK.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
THE OVERALL PATTERN REMAINS UNCHANGED. THAT MEANS ANOTHER SUNNY
AND WARM DAY IS ON TRACK FOR MUCH OF THE SOUTHERN MAINLAND. HIGH
CLOUDINESS WILL CONTINUE TO BE A FACTOR MAINLY FROM THE ANCHORAGE
AREA SOUTHWARD AND WESTWARD. HOWEVER...EVEN DESPITE SOME HIGH
CLOUDS...A SURGING THERMAL TROUGH TODAY WILL ALLOW TEMPERATURES TO
AGAIN SOAR WELL INTO THE 60S AND 70S...POSSIBLY BREAKING HIGH
TEMPERATURE RECORDS ACROSS THE MAT-SU VALLEY. THE COPPER BASIN WILL
BE EVEN WARMER WITH TEMPERATURES POSSIBLY BREAKING THE 80 DEGREE
MARK...WHICH WOULD ALSO BE IN RECORD TERRITORY. OVERALL...TODAY WILL
AGAIN BE ONE OF THE WARMEST OF THE SEASON SO FAR. KODIAK ISLAND
REMAINS ON THE WEST OR "WET" SIDE OF THE LONGWAVE RIDGE THAT IS
GENERATING SUCH NICE WEATHER OVER SOUTHCENTRAL. THIS MEANS CLOUDS
AND PERIODS OF RAIN WILL CONTINUE FOR THE FORESEEABLE FUTURE.

BEGINNING SATURDAY...THE RIDGE STARTS TO MOVE EASTWARD...AND WILL
ALLOW CLOUDS AND RAIN TO EXPAND UP COOK INLET AND INTO PRINCE
WILLIAM SOUND. MOST OF THIS PRECIP WILL BE DRIVEN BY A SHORTWAVE
TROUGH MOVING UP COOK INLET. WITH MINIMAL CROSS-BARRIER FLOW AT
MOUNTAINTOP...EVEN ANCHORAGE SHOULD SEE SOME LIGHT RAINFALL BY
SATURDAY EVENING.

.FIRE WEATHER...
EXTREMELY DRY CONDITIONS WILL AGAIN DEVELOP ACROSS THE COPPER
RIVER BASIN TODAY. SOME SOUTHERLY WINDS ARE ALSO EXPECTED TO
DEVELOP ALONG THE COPPER RIVER THIS AFTERNOON BUT SHOULD STAY
UNDER 15 MPH OR SO. SATURDAY WILL BE A DIFFERENT STORY AS MORE
ACTIVE WEATHER IN THE GULF STARTS TO PUSH INTO THE COASTAL
MOUNTAINS. WHILE RELATIVE HUMIDITY VALUES WILL BE A LITTLE HIGHER
ON SATURDAY AFTERNOON/EVENING COMPARED TO FRIDAY...STRONG
SOUTHERLY WINDS ARE EXPECTED TO DEVELOP DURING THE AFTERNOON. A
RED FLAG WARNING REMAINS IN EFFECT THROUGH LATE SATURDAY EVENING.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
WHILE THE TAP OF DEEP SUBTROPICAL MOISTURE HAS BEEN BROKEN...THE
MAINLAND IS STILL UNDER THE INFLUENCE OF SOUTHERLY FLOW ALOFT
WHICH WILL BRING SEVERAL DISTURBANCES OVERHEAD THE NEXT COUPLE
DAYS. EXCEPT AREAS OF LIGHT RAIN BEGINNING THIS MORNING...MAINLY
FOR THE WOOD RIVER MOUNTAINS AND KUSKOKWIM DELTA COAST. OVERNIGHT
TONIGHT AN UPPER LEVEL LOW PRESSURE IN THE NORTH PACIFIC WILL
PHASE INTO THE APPROACHING EXTRATROPICAL REMNANTS AND SPREAD MORE
AREAS OF RAIN ACROSS THE MAINLAND...HOWEVER INCREASING DEEP LAYER
SOUTHEASTERLY FLOW WILL KEEP THE USUAL SUSPECTS (LEES OF THE
ALEUTIAN RANGE AND KILBUCKS) ON THE DRIER SIDE. THE REMNANTS OF
THE OLD TROPICAL SYSTEM WILL CONTINUE TO IMPINGE ON THE MAINLAND
ON LATE SATURDAY KEEPING THE ACTIVE PATTERN GOING.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
THE OCCLUDED FRONT ASSOCIATED WITH THE EXTRATROPICAL REMNANTS OF
TYPHOON DOLPHIN WILL CONTINUE TO MOVE EASTWARD ACROSS THE BERING
TODAY ALBEIT SLOWLY AND NEARLY STALLING BY EVENING. A DIFFERENT
DISTURBANCE COMING THROUGH THE LONGWAVE WILL PICK UP THE FRONT AND
CONTINUE EASTWARD THROUGH THE WEEKEND AS IT WEAKENS. EXPECT AREAS
OF DENSE FOG IN THE NORTHEAST BERING SEA AHEAD OF THE APPROACHING
FRONT.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...
THE TENACIOUS RIDGE OVER MUCH OF MAINLAND AK WILL CONTINUE
MIGRATING SOUTHEAST OVER THE WEEKEND. THIS WILL ALLOW MOIST
ONSHORE FLOW TO BRING RAIN TO THE NORTH GULF COAST THROUGH
MON...WITH SOME SHOWER ACTIVITY CROSSING THE COASTAL MOUNTAINS
INTO SOUTHCENTRAL. BY MIDWEEK HIGH PRESSURE REBUILDS AND ENDS MOST
PRECIPITATION FOR SOUTH CENTRAL...ALTHOUGH RAIN ALONG THE WESTERN
FLANK OF THE HIGH WILL AFFECT KODIAK ISLAND.

A BROAD AREA OF LOW PRESSURE WILL REMAIN OVER THE WESTERN BERING
AND ALEUTIANS FOR SEVERAL DAYS...WITH DECAYING FRONTS REACHING SW
AK. THIS WILL KEEP RAIN AND SHOWERS OVER THE REGION THROUGH NEXT
WEEK.

&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING...155 170 172 173 174 175 176 177 178 180
                        185.
FIRE WEATHER...RED FLAG WARNING...141.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...PLD
SOUTHCENTRAL ALASKA...AD/RF
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...MTL
LONG TERM...DS



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