493  
FXHW01 KWNH 161231  
PMDHI  
 
HAWAII EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
730 AM EST THU NOV 16 2017  
 
VALID 00Z FRI NOV 17 2017 - 00Z FRI NOV 24 2017  
 
THE MAIN SYNOPTIC-SCALE SYSTEM IMPACTING THE WEATHER ACROSS HAWAII  
DURING THE FORECAST PERIOD WILL BE AN UPPER-LEVEL CUT-OFF/CLOSED  
LOW FORECAST TO DROP SOUTHWARD FROM THE HIGHER LATITUDES TOWARD  
HAWAII DURING THE WEEKEND. MODEL GUIDANCE DURING THE PAST 24  
HOURS HAS TRACKED THE UPPER VORTEX FARTHER TO THE SOUTH AND MORE  
DETACHED FROM THE MAIN FLOW TO THE NORTHEAST (PARTICULARLY THE  
ECMWF). IT APPEARS THAT A SECONDARY COLD FRONT ASSOCIATED WITH  
THE VORTEX COULD PUSH THROUGH THE ISLAND CHAIN ON SATURDAY WITH A  
BRIEF PERIOD OF ENHANCED SHOWER ACTIVITIES. THE VORTEX SHOULD  
THEN BEGIN TO PULL OUT ON SUNDAY, AND SHOULD OPEN UP AS A  
POSITIVELY TILTED TROUGH FURTHER TO THE NORTHEAST BY EARLY NEXT  
WEEK. IT APPEARS THAT HAWAII WILL BE SITUATED BETWEEN THE MARINE  
STRATUS LAYER ON THE BACK SIDE OF THIS SYSTEM AND THE PLUME OF  
TROPICAL MOISTURE WELL TO THE SOUTH AND EAST THROUGH THE FORECAST  
PERIOD. EXPECT THE TRADE WINDS TO SWITCH TO MORE WEST TO  
NORTHWEST DIRECTIONS AS THE SYSTEM APPROACHES DURING THE WEEKEND,  
FOLLOWED BY GRADUAL RESUMPTION OF THE TRADES TOWARD THE MIDDLE OF  
NEXT WEEK. BY NEXT WEDNESDAY, THE TROPICAL MOISTURE COULD BEGIN  
TO APPROACH HAWAII FROM THE SOUTH.  
 
KONG  
 

 
 
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