874  
FXHW01 KWNH 261210  
PMDHI  
 
HAWAII EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
710 AM EST TUE DEC 26 2017  
 
VALID 00Z WED DEC 27 2017 - 00Z WED JAN 03 2018  
 
SHORTWAVE EXPECTED TO CROSS HAWAI'I TODAY THROUGH EARLY WED, WITH  
AN ADDITIONAL SHORTWAVE AMPLIFYING JUST NORTH OF THE ISLANDS EARLY  
THU. IN GENERAL, MODELS AND ENSEMBLE SHOW GOOD AGREEMENT WITH  
RESPECT TO BOTH OF THESE FEATURES. THE PRIMARY EXCEPTION WAS THE  
00Z UKMET, WHICH APPEARED TO BE OVERLY AMPLIFIED WITH BOTH WAVES.  
AT THE SURFACE, EXPECT A COLD FRONT TO PASS THROUGH THE STATE  
WED/WED NIGHT, WITH LOW-LEVEL FLOW VEERING FROM SOUTHERLY TODAY  
AND TONIGHT TO NORTHERLY OR NORTHEASTERLY IN THE WAKE OF THE COLD  
FRONT. EXPECT CONVECTION TO ACCOMPANY THE FRONT ACROSS HAWAI'I.  
SATELLITE LOOP EARLY THIS MORNING SHOWS AN ACTIVE AREA OF  
CONVECTION IN ASSOCIATION WITH THE FRONTAL SYSTEM. THIS SHOULD  
CONTINUE AS THE FRONT CROSSES THE ISLANDS, WITH THE GFS AND ECMWF  
IN GENERAL AGREEMENT ON THIS SCENARIO, INDICATING THE POTENTIAL  
FOR 1-2 INCHES OF RAINFALL, AND LOCALIZED HIGHER AMOUNTS.  
 
FROM FRI NIGHT ONWARD THROUGH THE MIDDLE OF NEXT WEEK,  
MODELS/ENSEMBLES ARE IN GOOD AGREEMENT ON BUILDING UPPER RIDGING  
FROM WEST OF HAWAI'I EASTWARD ACROSS THE STATE. LOW-LEVEL  
EASTERLIES SHOULD RESUME AS THE SURFACE HIGH INITIALLY NORTH OF  
HAWAI'I MOVES EASTWARD. THIS FEATURE SHOULD KEEP A SOURCE OF  
LOW-LEVEL DRY AIR IN PLACE INTO NEXT WEEK, WITH SHOWER ACTIVITY  
RATHER SPARSE, AND LIMITED TO THE TYPICAL FAVORED EAST-FACING  
TERRAIN.  
 
RYAN  
 

 
 
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