476  
FXHW01 KWNH 191202  
PMDHI  
 
HAWAII EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
702 AM EST SUN NOV 19 2017  
 
VALID 00Z MON NOV 20 2017 - 00Z MON NOV 27 2017  
 
GUIDANCE IS AGREEABLE AND CONSISTENT IN DEPICTING A PERSISTENT  
MEAN TROUGH ALOFT ORIENTED NORTHEAST-SOUTHWEST OVER THE STATE.  
UNDER THE CYCLONIC FLOW PRECIPITABLE WATER VALUES ARE FORECAST TO  
BE BELOW NORMAL THROUGH THE PERIOD BUT WITH SOME DIFFERENCES,  
NAMELY THE ECMWF BEING SOMEWHAT DRIER THAN 00Z/06Z GFS RUNS. THE  
RELATIVELY LOW MOISTURE LEVELS SHOULD KEEP MOST SHOWER ACTIVITY  
(WINDWARD FOCUSED BUT OCCASIONALLY STRAYING TO LEEWARD LOCATIONS)  
FAIRLY LIGHT. HOWEVER THE UPPER TROUGHING WITH MULTIPLE EMBEDDED  
SHORTWAVE IMPULSES MAY HELP TO OPTIMIZE WHAT RAINFALL COULD OCCUR  
GIVEN AVAILABLE MOISTURE.  
 
DEEPEST UPPER TROUGHING/SURFACE LOW PRESSURE INITIALLY TO THE  
NORTHEAST OF THE STATE WILL LIFT AWAY DURING THE FIRST PART OF THE  
WEEK. AS THIS OCCURS AND CENTRAL PACIFIC HIGH PRESSURE BUILDS  
SOUTHEASTWARD, EXPECT NORTHWESTERLY/NORTHERLY LOW LEVEL WINDS TO  
BECOME MORE NORTHEASTERLY BY MIDWEEK AND THEN EVENTUALLY  
EAST-NORTHEASTERLY. THERE IS REASONABLE CONSENSUS THAT HIGH  
PRESSURE SHOULD REACH A POSITION NORTH OF THE ISLANDS BETWEEN  
30-40N LATITUDE BY NEXT SUNDAY. A FAIRLY TIGHT PRESSURE GRADIENT  
WILL PROMOTE BRISK/WINDY TRADES FROM LATE WEEK THROUGH THE WEEKEND.  
 
RAUSCH  
 

 
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab HPC Page Main Text Page