Area Forecast Discussion - Southeastern


FXAK67 PAJK 172220
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
220 PM AKDT THU APR 17 2014
.SHORT TERM...EARLY AFTERNOON SATELLITE IMAGERY SHOWS A MATURE
YET COMPACT LOW PRESSURE SYSTEM JUST OFF THE COAST OF PRINCE OF
WALES ISLAND JUST SOUTH OF CAPE DECISION. THIS LOW WILL CONTINUE
TO PUSH NORTH AND HUG ALONG THE COAST, AND WEAKEN. BY FRIDAY,
THIS AREA OF LOW PRESSURE WILL BECOME AN OPEN TROUGH. A RIDGE OF
HIGH PRESSURE WILL BUILD ACROSS THE PANHANDLE FROM THE SOUTH ON
FRIDAY. 

 A RATHER MILD THURSDAY, AS HIGH TEMPERATURES IN THE AREA RISE TO
THE UPPER 40S TO THE LOW 50S. SOUTHERN AREAS ARE A BIT COOLER DUE
TO RAIN SHOWERS IN THE AREA. DRY CONDITIONS CONTINUE FOR THE
NORTHERN PANHANDLE , AS NORTHEASTERLY FLOW KEPT THE PRECIPITATION
FROM MOVING INTO THE AREA. 

 AS THE LOW TRACKS NORTH, IT TIGHTENS THE NORTHERLY PRESSURE
GRADIENT ACROSS NORTHERN PANHANDLE. NORTHERLY WIND OF 10 TO
15 MPH CAN BE FOUND IN SKAGWAY, HAINES, GUSTAVUS, AND LYNN CANAL
THIS AFTERNOON. THE WEATHER FRONT IS SITUATED ALONG CENTRAL
PANHANDLE, AND WILL CONTINUE TO PUSH NORTH THIS EVENING. ONCE THE
WEATHER FRONT PUSHES THROUGH, WINDS WILL BECOME SOUTHERLY. WITH A
RIDGE OF HIGH PRESSURE BUILDING IN BEHIND FROM THE SOUTH, THAT
WILL GENERATE A STRONG PUSH OF SOUTHERLY WIND ACROSS THE
PANHANDLE. DO EXPECT THE STRONGER SOUTHERLY WINDS TO IMPACT
SOUTHERN PANHANDLE THROUGH THIS EVENING. THE AREA OF STRONGER
SOUTH WINDS WILL MOVE NORTH THROUGH TONIGHT INTO FRIDAY. 

 FORECAST CONFIDENCE IS ABOVE AVERAGE. MOST NUMERICAL WEATHER
MODELS ARE SHOWING CONSENSUS ON THE WEAKENING LOW TONIGHT AND A
BUILDING RIDGE ON FRIDAY. UTILIZE A SUPERBLEND OF MODELS TO
UPDATE THE INHERITED FORECAST PACKAGE.  

&&
.LONG TERM...MODELS ARE IN GENERAL AGREEMENT THROUGH LATE SUNDAY
FOR A WEAK UPPER LEVEL AND SURFACE RIDGE BUILDING ACROSS THE
EASTERN GULF AND SOUTHEAST ALASKA FROM THE SOUTH. THE RIDGE WILL
MOVE NORTHEASTWARD AWAY FROM THE AREA AS A LOW MOVES INTO THE
SOUTHEASTERN GULF BY SATURDAY MORNING. THE LOW WILL CONTINUE TO
ROTATE OVER THE GULF THROUGH THE WEEKEND. REFRESHED THE INHERITED
FORECAST PACKAGE WITH THE ECMWF THROUGH SUNDAY EVENING FOR ITS GOOD
CONSISTENCY. FOR EARLY NEXT WEEK...THE UPPER LOW AND ASSOCIATED
SURFACE FEATURE ACROSS THE ALASKA GULF WILL BEGIN WEAKENING AND
DRIFTING SOUTHEASTWARD. THEN A RIDGE WILL REBUILD OVER THE GULF
THROUGH THE MID WEEK. MODEL DIVERGENCE BECOMES MORE SIGNIFICANT
BETWEEN THE ERODING RIDGE AND A DEVELOPING LOW OVER THE WESTERN
ALASKA PENINSULA. BLENDED NEXT WEEK FORECAST PACKAGE WITH THE WPC
SOLUTIONS OF THE OPERATIONAL ECMWF THROUGH WEDNESDAY AND MIXED
WITH A LITTLE ECMWF ENSEMBLE FOR THURSDAY. 

 AS THE RIDGE BUILDS FROM THE SOUTH...SOUTHERLY WINDS WILL
CONTINUE TO INCREASE FRIDAY NIGHT THEN BY EARLY SATURDAY
MORNING GALE FORCE WINDS WILL BEGIN AFFECTING THE SOUTHERN
OFFSHORE...OUTSIDE WATERS AND THE SOUTHERN INNER CHANNELS AS A LOW
MOVES INTO THE SOUTHERN GULF. STRONG WINDS HEADLINE MAY NEED FOR
PRINCE OF WALES ISLANDS. VERY ROUGH SEAS OF 20 TO 25 FEET ARE ALSO
EXPECTED OVER THE SOUTHERN OUTER WATERS. AS THE LOW CONTINUES
PROGRESSING...PRESSURE GRADIENT WILL SHIFT FOR A GRADUAL INCREASE
OF NORTHERLY WINDS ACROSS THE PANHANDLE LATE FRIDAY NIGHT INTO
SATURDAY...THEN CONTINUE THROUGH EARLY NEXT WEEK. FOR THE
REMAINING LONG TERM FORECAST PERIODS...EXPECT A BRIEF RIDGE BUILDS
ACROSS THE PANHANDLE ON MONDAY AHEAD OF THE NEXT DEVELOPING SYSTEM
ACROSS THE FAR WESTERN GULF. AS THE SYSTEM SLOWLY DRIFTS
EASTWARD...SEVERAL POORLY ORGANIZED WEAK LOWS WILL MOVE INTO THE
EASTERN GULF THROUGH THE WEEK. RELATIVELY HIGHER POPS WILL LIKELY
TO FOCUS OVER THE SOUTHERN PANHANDLE WEDNESDAY AND THURSDAY.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING FOR PKZ036. 
         SMALL CRAFT ADVISORY FOR PKZ012-013-031-041-042. 
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ043. 

&&

$$

RCL/AHN