754  
FXHW01 KWNH 061214  
PMDHI  
 
HAWAII EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
714 AM EST WED DEC 06 2017  
 
VALID 00Z THU DEC 07 2017 - 00Z THU DEC 14 2017  
 
GUIDANCE CONTINUES TO INDICATE THAT A SERIES OF FEATURES WITHIN A  
PERSISTENT EAST-CENTRAL PACIFIC TROUGH ALOFT WILL SUPPORT THE  
APPROACH AND IN MOST CASES PASSAGE OF MULTIPLE FRONTS DURING THE  
PERIOD. THERE IS REASONABLE AGREEMENT IN FORECAST DETAILS UNTIL  
SOME SPREAD ARISES BY NEXT TUESDAY-WEDNESDAY.  
 
HIGH PRESSURE TO THE WEST-NORTHWEST OF THE STATE WILL EXTEND A  
NARROW RIDGE OVER THE REGION OVER THE NEXT COUPLE DAYS, LEADING TO  
FAIRLY LIGHT WINDS. A FRONT WILL APPROACH FROM THE NORTH ON  
THURSDAY BUT MOST LIKELY STAY JUST NORTH OF THE NORTHERN ISLANDS.  
THE NEXT FRONT WILL HAVE STRONGER UPPER SUPPORT AND PROGRESS  
THROUGH THE STATE DURING THE WEEKEND. THESE FRONTS SHOULD BE  
ACCOMPANIED BY FAIRLY LIGHT RAINFALL EVEN WITH THE POSSIBILITY  
THAT SOME MOISTURE MAY LINGER NEAR THE BIG ISLAND INTO EARLY NEXT  
WEEK. THE LAST FRONT TO AFFECT THE STATE WILL COME THROUGH IN THE  
TUESDAY-WEDNESDAY TIME FRAME. PRIMARY MODEL DIFFERENCES INVOLVE  
THE 00Z/06Z GFS RUNS BECOMING MORE AMPLIFIED ON THE SOUTHEAST SIDE  
OF THE UPPER TROUGH, LEADING TO A FARTHER SOUTHEAST PROGRESSION OF  
THE FRONT. THE 00Z GEFS MEAN IS A LITTLE MORE AMPLIFIED WITH THE  
TROUGH THAN REMAINING GUIDANCE BUT OTHERWISE ALIGNS BETTER WITH  
THE 00Z ECMWF/CMC AND THEIR ENSEMBLE MEANS. EVEN WITHIN THE  
PREFERRED NON-GFS MAJORITY SCENARIO, THERE ARE SOME MOISTURE AND  
FRONTAL TIMING DIFFERENCES THAT WILL TAKE SOME TIME TO BE  
RESOLVED. STRONGER DYNAMICS THAN WITH PRECEDING FRONTS SEEM TO  
FAVOR A COMPROMISE FOR ACCOMPANYING RAINFALL, BETWEEN THE 00Z  
ECMWF AND WETTER GEFS/ECMWF MEANS AND 12Z/05 ECMWF.  
 
RAUSCH  
 

 
 
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