555  
FXHW01 KWNH 021218  
PMDHI  
 
HAWAII EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
717 AM EST FRI MAR 02 2018  
 
VALID 00Z SAT MAR 03 2018 - 00Z SAT MAR 10 2018  
 
FROM NOW INTO THE WEEKEND EXPECT A CONTINUATION OF MOIST  
SOUTHEASTERLY LOW LEVEL FLOW BETWEEN HIGH PRESSURE TO THE  
NORTHEAST OF THE STATE AND LOW PRESSURE/INVERTED TROUGH TO THE  
WEST. THIS FLOW ALONG WITH ONE OR MORE IMPULSES ALOFT AROUND THE  
SOUTHEAST PERIPHERY OF AN UPPER TROUGH/LOW TO THE WEST MAY ENHANCE  
WINDWARD-FOCUSED SHOWER ACTIVITY AT TIMES.  
 
GUIDANCE CONTINUES TO ADVERTISE A PATTERN CHANGE AS AN UPPER  
TROUGH/LOW DESCENDS OVER THE EASTERN PACIFIC EARLY NEXT WEEK WITH  
CYCLONIC FLOW AROUND THIS FEATURE PUSHING DRIER AIR INTO THE  
REGION. HOWEVER DURING TUESDAY-FRIDAY MODELS AND ENSEMBLES  
DIVERGE SOMEWHAT REGARDING THE AMPLITUDE/DEPTH OF ENERGY THAT  
ELONGATES SOUTHWESTWARD TOWARD/OVER THE ISLANDS. OVER THE PAST  
COUPLE DAYS THE OPERATIONAL GFS RUNS HAVE BEEN ON THE DEEPER AND  
MORE AMPLIFIED SIDE OF THE SPREAD AMONG MODELS/MEANS, BUT LATEST  
00Z/06Z RUNS ARE STILL WITHIN THE FULL ENSEMBLE SPREAD. THIS  
EVOLUTION ALOFT KEEPS LOWER PRESSURES JUST EAST/NORTHEAST OF THE  
STATE LATE IN THE WEEK. EVEN THOUGH THE 00Z ECMWF HOLDS THE CORE  
OF ENERGY ALOFT A LITTLE FARTHER NORTH, IT ACTUALLY HAS SOMEWHAT  
DEEPER LOW PRESSURE TO THE NORTHEAST OF THE STATE LATE THURSDAY  
ONWARD ALBEIT TRACKING FARTHER TO THE NORTHEAST. ON THE OTHER  
HAND THE 00Z CMC/CMC MEAN BECOME MUCH FLATTER WITH THE UPPER  
TROUGH THAN OTHER GUIDANCE. THROUGH 00Z THURSDAY THE 00Z UKMET  
LEANS TOWARD THE IDEA OF SOMEWHAT STRONGER UPPER TROUGH ELONGATION  
THAN THE MEANS, SO WOULD RECOMMEND THE 00Z ECMWF OR ONLY A SLIGHT  
COMPROMISE WITH THE MEANS AS THE BEST SINGLE FORECAST AT THIS  
TIME. FLOW AROUND CENTRAL PACIFIC SURFACE HIGH PRESSURE WILL  
PROMOTE NORTHEASTERLY LOW LEVEL WINDS NEXT WEEK, WITH PERIODS OF  
MOSTLY LIGHT TO MODERATE RAINFALL GIVEN BELOW NORMAL PRECIPITABLE  
WATER VALUES.  
 
RAUSCH  
 

 
 
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