264  
FXHW01 KWNH 011217  
PMDHI  
 
HAWAII EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
716 AM EST THU MAR 01 2018  
 
VALID 00Z FRI MAR 02 2018 - 00Z FRI MAR 09 2018  
 
WHILE THERE ARE SOME DETAIL DIFFERENCES AT THE SURFACE AND ALOFT,  
CURRENT MODELS AND ENSEMBLES AGREE IN PRINCIPLE ON A NOTICEABLE  
RETROGRESSION OF THE LARGE SCALE PATTERN ALOFT. THIS ADJUSTMENT  
OF THE MEAN PATTERN WILL ULTIMATELY LEAD TO A DRIER TREND FOR THE  
STATE NEXT WEEK.  
 
FROM NOW INTO THE WEEKEND EXPECT AREAS OF RAINFALL WITH VARYING  
INTENSITY. MULTIPLE INGREDIENTS WILL PLAY A ROLE IN THIS  
ACTIVITY. THESE INCLUDE RELATIVELY HIGH PRECIPITABLE WATER VALUES  
(MAXIMUM JUST TO THE SOUTH/WEST OF THE ISLANDS), SHORTWAVES  
EMBEDDED WITHIN FLOW AHEAD OF AN UPPER TROUGH/EMBEDDED LOW TO THE  
WEST OF THE STATE, AND MOIST LOW LEVEL EAST-SOUTHEASTERLY FLOW.  
BY THE START OF NEXT WEEK AN AMPLIFYING PACIFIC UPPER TROUGH ON  
EITHER SIDE OF 140W LONGITUDE--WITH SOME ELONGATION SOUTHWEST  
TOWARD/OVER HAWAI'I--WILL REPLACE A WEST COAST CONUS TROUGH, WHILE  
THE UPSTREAM MEAN RIDGE LIKEWISE SETS UP FARTHER WESTWARD. THIS  
PATTERN CHANGE WILL BRING MUCH DRIER FLOW ALOFT WITH PWATS  
TRENDING TO BELOW NORMAL VALUES. MEANWHILE SURFACE HIGH PRESSURE  
BECOMING ORIENTED NORTH-SOUTH ALONG 160-170W LONGITUDE WILL  
ENCOURAGE BRISK LOW LEVEL FLOW FROM THE EAST-NORTHEAST. EXPECT  
SOME LINGERING WINDWARD PRECIPITATION NEXT WEEK BUT WITH  
RELATIVELY LIGHT AMOUNTS GIVEN THE LOWER MOISTURE LEVELS. TOWARD  
THE END OF THE PERIOD NEXT THURSDAY THE 06Z GFS REPRESENTS ONE  
NOTABLE GUIDANCE DIFFERENCE WITHIN THE UPPER TROUGH, BRINGING AN  
UPPER LOW CENTER FARTHER SOUTHWEST THAN OTHER SOLUTIONS WITH SOME  
EFFECT ON THE SURFACE PATTERN OVER/EAST OF THE REGION. THUS AT  
THIS TIME WOULD RECOMMEND AN AVERAGE OF OTHER GUIDANCE.  
 
RAUSCH  
 

 
 
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