400  
FXHW01 KWNH 091216  
PMDHI  
 
HAWAII EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
716 AM EST TUE JAN 09 2018  
 
VALID 00Z WED JAN 10 2018 - 00Z WED JAN 17 2018  
 
GUIDANCE CONTINUES TO BE FAIRLY AGREEABLE WITH AT LEAST THE LARGE  
SCALE ASPECTS OF THE FORECAST. A NARROW SHORTWAVE ALOFT SETTLING  
OVER THE ISLANDS AROUND WEDNESDAY-THURSDAY WILL BRING A WEAK FRONT  
WITH ACCOMPANYING LIGHT RAINFALL TOWARD KAUAI. THIS FRONT SHOULD  
STALL AND WEAKEN TO A TROUGH IN THE MID-LATE WEEK TIME FRAME.  
MEANWHILE THE SHORTWAVE WILL DRAW A SEPARATE WEAK UPPER FEATURE  
AND POCKET OF MOISTURE TOWARD THE BIG ISLAND, LEADING TO A BRIEF  
PERIOD OF POTENTIALLY ENHANCED RAINFALL OVER/NEAR THE BIG ISLAND  
PRIMARILY AROUND WEDNESDAY-THURSDAY. THE COMBINATION OF SHORTWAVE  
ENERGY WILL LIKELY DEPART TO THE EAST FRIDAY ONWARD. A MODEST DIP  
IN THE WESTERLIES WILL BRING ANOTHER FRONT CLOSE TO THE STATE  
DURING THE WEEKEND BUT UPPER RIDGING BUILDING IN FROM THE WEST  
SHOULD THEN HELP TO PUSH IT BACK TO THE NORTH/NORTHEAST. AROUND  
THE BEGINNING OF NEXT WEEK THERE IS SOME SPREAD WITH THE NORTHWARD  
EXTENT OF MOISTURE, WITH THE 06Z GFS FARTHEST NORTH WITH 1.5 INCH  
PW VALUES. THE 00Z GEFS MEAN KEEPS THE MOISTURE MUCH FARTHER  
SOUTH, FAVORING AT LEAST A COMPROMISE BETWEEN THE 00Z GFS AND  
ECMWF. OTHERWISE, INTO THE WEEKEND LINGERING SURFACE TROUGHING OR  
ONLY WEAK SURFACE RIDGING SHOULD KEEP WINDS FAIRLY LIGHT, LEADING  
TO MORE SEA/LAND BREEZE FOCUS FOR ANY SHOWERS. BY MONDAY-TUESDAY  
MOST MODELS/MEANS (MINUS THE 00Z CMC AGAIN) MAINTAIN THE IDEA THAT  
THE SURFACE RIDGE WILL BECOME ALIGNED NORTH OF THE STATE TO  
SUPPORT TRADE FLOW, ALBEIT IN THE LIGHTER HALF OF THE SPECTRUM,  
AND SOMEWHAT MORE WINDWARD FOCUS FOR SHOWERS.  
 
RAUSCH  
 

 
 
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