137  
FXHW01 KWNH 111219  
PMDHI  
 
HAWAII EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
818 AM EDT WED OCT 11 2017  
 
VALID 00Z THU OCT 12 2017 - 00Z THU OCT 19 2017  
 
THE WEATHER PATTERN ACROSS THE HAWAII DOMAIN DURING THE SHORT  
RANGE PERIOD THROUGH FRIDAY WILL CONSIST OF A GRADUALLY WEAKENING  
INVERTED SURFACE TROUGH SLOWING TRACKING WESTWARD, WITH A LESSER  
MAGNITUDE OF THE TRADES COMPARED TO NORMAL. THIS IS FORECAST TO  
TRANSITION TO A MORE ZONAL FLOW PATTERN BY THE WEEKEND AND INTO  
EARLY NEXT WEEK AS A LARGE SURFACE HIGH SETTLES SOUTHWARD FROM  
JUST SOUTH OF THE ALEUTIANS TO 35 DEGREES NORTH BY MONDAY,  
BECOMING ESTABLISHED NORTH OF THE ISLANDS AND STRENGTHENING THE  
EASTERLY TRADE WINDS OWING TO THE TIGHTER PRESSURE GRADIENT TO THE  
NORTH. SIMILAR TO WHAT WAS DEPICTED YESTERDAY, BOTH THE GEFS AND  
EC MEAN CONTINUE TO INDICATE THE POTENTIAL FOR A WEAK POSITIVELY  
TILTED 500MB TROUGH EARLY NEXT WEEK, WITH A STRONG UPPER LEVEL  
RIDGE BUILDING IN NORTHWEST OF THE STATE. WHILE GREATER  
DIFFERENCES EXIST IN THE MORE PROGRESSIVE FLOW PATTERN ACROSS THE  
NORTHERN PACIFIC, THE MODELS ARE IN DECENT AGREEMENT AT THE LOWER  
LATITUDES ON THE SYNOPTIC SCALE.  
 
IN TERMS OF EXPECTED SENSIBLE WEATHER, SHOWER ACTIVITY IS EXPECTED  
FOR THE FAVORED WINDWARD TERRAIN ALONG WITH GUSTY EASTERLY WINDS  
BEYOND THURSDAY. A PLUME OF ENHANCED MOISTURE, WITH PWS  
APPROACHING 2 INCHES AS DEPICTED BY THE GFS, SHOULD BE NEAR THE  
EASTERN ISLANDS BY FRIDAY AFTERNOON AND INTO EARLY SATURDAY ALONG  
WITH A GREATER COVERAGE OF SHOWERS AND ISOLATED THUNDERSTORMS.  
THE DEEPER MOISTURE SHOULD BE SUPPRESSED TO THE SOUTH BY TUESDAY  
AS THE RIDGE ADVECTS DRIER AIR INTO THE REGION.  
 
D. HAMRICK  
 

 
 
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