377  
FXHW01 KWNH 291221  
PMDHI  
 
HAWAII EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
820 AM EDT SUN OCT 29 2017  
 
VALID 00Z MON OCT 30 2017 - 00Z MON NOV 06 2017  
 
AN AMPLIFIED, BLOCKY PATTERN IS EVIDENT IN THE UPCOMING DAYS  
ACROSS THE CENTRAL PACIFIC. INITIALLY, AN ELONGATED UPPER TROUGH  
WILL CONTINUE TO DRIFT AWAY FROM THE HAWAI`IAN ISLAND CHAIN WITH  
THE RESULTANT CLOSED LOW SPINNING WITHIN THE MID-LATITUDES JUST  
EAST OF 150W. LOOKING UPSTREAM, PRONOUNCED HEIGHT FALLS APPROACH  
FROM EAST OF THE INTERNATIONAL DATELINE WITH A CLOSED UPPER LOW  
DEVELOPING AROUND 30N/170W BY TUESDAY. A GRADUAL NORTHWARD SHIFT  
IS NOTED WHILE A BROAD UPPER HIGH STRENGTHENS OVER THE ISLANDS. BY  
LATE THURSDAY, A GENERAL CONSENSUS IS NOTED SUPPORTING A BROAD  
588-DM RIDGE SETTLING OVER THE REGION. THIS SHOULD CONTINUE TO BE  
THE CASE INTO NEXT WEEKEND AS THE FLOW ACROSS THE PACIFIC REMAINS  
VERY AMPLIFIED.  
 
AT THE SURFACE, A WEAK CONVERGENCE ZONE IS NOTED IN THE LOCAL WIND  
FIELDS WHICH WILL FOSTER THE DEVELOP OF SCATTERED SHOWER ACTIVITY.  
A GRADUAL SHIFT IN THE FLOW TAKES PLACE INTO EARLY NEXT WEEK AS A  
WARM ADVECTION REGIME ENSUES. BY MONDAY NIGHT INTO WEDNESDAY,  
SOUTH-SOUTHEASTERLY FLOW STRENGTHENS UP TO AROUND 15 KNOTS WHICH  
SPREADS HIGHER PRECIPITABLE WATER VALUES POLEWARD. THIS SHOULD  
EXPAND THE COVERAGE OF SHOWERS WITH FRONTAL ACTIVITY MOVING VERY  
CLOSE TO KAUAI BY THE WEDNESDAY/THURSDAY TIMEFRAME. THIS IS  
PARTICULARLY NOTED IN THE 06Z GFS AND 00Z CMC/UKMET SOLUTIONS.  
BEYOND THIS PERIOD, A STRONG SURFACE RIDGE SINKS DOWN FROM THE  
ALEUTIANS WITH A 1036-DM HIGH ANCHORING THE NORTHEASTERN PACIFIC  
BY FRIDAY EVENING INTO NEXT WEEKEND. THE RESULTANT SURFACE  
GRADIENTS LEADS TO A RETURN TO MODERATE TO OCCASIONALLY STRONGER  
TRADE WINDS OVER THE REGION. MODELS SHOW BROAD 20 TO 25 KNOT WINDS  
TO OVERSPREAD THE ISLANDS ALTHOUGH THIS APPEARS TO BE ACCOMPANIED  
BY A DECREASE IN TROPOSPHERIC MOISTURE. HOWEVER, WINDWARD SHOWERS  
WILL REMAIN LIKELY GIVEN THE RETURN TO A MORE CLIMATOLOGICAL TRADE  
WIND PATTERN.  
 
RUBIN-OSTER  
 

 
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab HPC Page Main Text Page