841  
FXHW01 KWNH 181230  
PMDHI  
 
HAWAII EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
730 AM EST MON DEC 18 2017  
 
VALID 00Z TUE DEC 19 2017 - 00Z TUE DEC 26 2017  
   
..HEAVY RAIN THREAT NEXT WEEK
 
 
AN UPPER LOW THAT HAS BEEN RETROGRADING NORTH OF HAWAII FOR THE  
PAST FEW DAYS IS FORECAST TO WEAKEN WHILE GRADUALLY LIFTING  
NORTHEASTWARD AWAY FROM THE ISLANDS. AN UPPER-LEVEL TROUGH FROM  
THE HIGHER LATITUDES WILL QUICKLY APPROACH THE ISLANDS FROM THE  
NORTHWEST, AND WILL HELP DEVELOP A COLD FRONT A HEAD OF THE  
TROUGH. MODELS INDICATE A DECENT AMOUNT OF MOISTURE AHEAD OF THE  
FRONT, WHICH SHOULD MOVE FROM WEST TO EAST ACROSS THE ISLANDS FROM  
WEDNESDAY INTO THURSDAY. THE GFS SHOWS A FASTER EASTWARD MOTION  
OF THE MOISTURE COMPARED WITH THE ECMWF. A COMPROMISE BETWEEN THE  
TWO SHOULD YIELD A GOOD STARTING POINT FOR THE TIMING OF THE  
PRECIPITATION. DRY AIR WITH THEN FILTER INTO THE ISLANDS BEHIND  
THE FRONT THROUGH THE WEEKEND INTO MONDAY OF NEXT WEEK UNDER BRISK  
NORTHWEST THEN NORTHERLY WINDS. MODELS INDICATE THE POTENTIAL OF  
A TROPICAL CYCLONES PASSING A FEW HUNDRED MILES EAST OF THE  
ISLANDS LATE THIS WEEK FOLLOWING THE PASSAGE OF THE COLD FRONT.  
 
KONG  
 

 
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab HPC Page Main Text Page