883 
ATHW40 PHFO 150034
SIMHI 

HAWAIIAN ISLANDS SATELLITE INTERPRETATION MESSAGE
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI
0030 UTC SUN SEP 15 2013

BASED ON DATA THROUGH 0000 UTC SEPTEMBER 15 2013

THE MOST IMPRESSIVE FEATURE IN REGIONAL SATELLITE IMAGERY THIS 
AFTERNOON REMAINS A LINE OF STRONG THUNDERSTORMS JUST WEST OF MIDWAY 
ATOLL IN THE FAR NORTHWESTERN PORTION OF THE HAWAIIAN ISLAND CHAIN. 
ALTHOUGH THE LINE HAS NARROWED AND WEAKENED SOMEWHAT OVER THE PAST 6 
TO 8 HOURS...LIGHTNING DETECTION NETWORKS CONTINUE TO OBSERVE 
PROLIFIC LIGHTNING OCCURRING WITHIN THIS LINE. THE LEADING EDGE OF 
THE 250 TO 300 MILE WIDE BAND IS ABOUT 60 MILES WEST OF MIDWAY 
ATOLL...AND LIES ALONG A LINE THROUGH 32N 175W TO 30N 177W TO 27N 
180...WITH THE CLOUD BAND EXTENDING BOTH NORTHEAST AND SOUTHWEST 
FROM THIS LINE. THE BAND IS ASSOCIATED WITH AN AREA OF DEVELOPING 
LOW PRESSURE ABOUT 1700 MILES NORTHWEST OF KAUAI NEAR 33N 175E...AND
ITS FORWARD MOTION APPEARS TO HAVE SLOWED SINCE THIS MORNING...NOW 
MOVING EAST AT JUST OVER 10 MPH. 

MEANWHILE...CLOSER TO THE MAIN HAWAIIAN ISLANDS...THUNDERSTORMS 
CONTINUE TO DEVELOP WITHIN AN AREA OF INCREASED MOISTURE THAT 
RECENTLY MOVED WEST OF KAUAI...WITH THE CLUSTER OF THUNDERSTORMS 
ABOUT 75 TO 150 MILES SOUTH OF NIHOA...OR ABOUT 150 MILES SOUTHWEST 
OF NIIHAU...MOVING STEADILY TOWARD THE WEST AT 10 TO 15 MPH. THICK 
MID AND HIGH LEVEL CLOUDS STREAMING NORTHWARD FROM THE TOPS OF 40 
THOUSAND FOOT TALL THUNDERSTORMS ARE MAKING FOR OVERCAST CONDITIONS 
OVER NIHOA...WITH INCREASING CLOUDS AND SHOWERS ENCROACHING UPON 
NECKER ISLAND FROM THE EAST. 

OVER THE MAIN HAWAIIAN ISLANDS...CLOUD COVER OVER LAND HAS INCREASED 
MARKEDLY SINCE THIS MORNING...AND DECREASED SOMEWHAT OVER ADJACENT 
WINDWARD WATERS...AS IS EXPECTED GIVEN TYPICAL DIURNAL TRENDS. THIN 
HIGH CLOUDS ARE SEEN STREAMING NORTHEASTWARD OVER ALL ISLANDS ON 
VISIBLE IMAGERY...BUT LOW CLOUD FEATURES ARE EASILY SEEN. ON 
KAUAI...SCATTERED TO LOCALLY BROKEN LOW CLOUDS ARE SEEN OVER THE 
INTERIOR OF THE ISLAND...WITH LOW CLOUDS IN GREATEST CONCENTRATION 
OVER THE SOUTHWESTERN COASTAL AREAS. BROKEN TO OVERCAST LOW CLOUDS 
LINE THE RIDGES OF BOTH THE KOOLAU AND WAIANAE RANGES ON 
OAHU...LEAVING THE CENTRAL PLATEAU UNDER MOSTLY SUNNY SKIES...WITH 
PARTLY CLOUDY SKIES ALONG EASTERN...WESTERN AND NORTHWESTERN 
SHORES. FEW TO SCATTERED LOW CLOUDS PREVAIL OVER THE WATERS AROUND 
KAUAI AND OAHU. BROKEN TO OVERCAST LOW CLOUDS LINE THE LOWER SLOPES 
OF HALEAKALA ON MAUI...WITH SOME LOW CLOUDS SPREADING OVER THE 
SUMMIT AREAS AS WELL. ELSEWHERE IN MAUI COUNTY...BROKEN LOW CLOUDS 
ARE OVER NORTHEASTERN AND SOUTHWESTERN MOLOKAI...MUCH OF LANAI...AND
THE LOWER SLOPES...BOTH WINDWARD AND LEEWARD...OF THE WEST MAUI 
MOUNTAINS. MOST OF THE LOWER SLOPES ON THE BIG ISLAND ARE COVERED IN 
BROKEN TO OVERCAST LOW CLOUDS...WITH THESE CLOUDS SPREADING 
SOUTHWARD OVER THE KAU AND KONA COASTS. WINDWARD BIG ISLAND BEACHES 
ARE UNDER MOSTLY SUNNY SKIES...ASIDE FROM THIN HIGH CLOUDS. 

A LOW-LEVEL TROUGH AXIS IS SEEN ABOUT 100 MILES EAST OF MAUI...200 
MILES EAST OF OAHU AND 300 MILES EAST OF KAUAI...MOVING TOWARD THE 
WEST-NORTHWEST AT 10 TO 15 MPH. SHOWERY LOW CLOUDS ASSOCIATED WITH 
THIS FEATURE HAVE DIMINISHED IN COVERAGE SINCE THIS MORNING...BUT 
CLOUD TOPS ASSOCIATED WITH THIS FEATURE CONTINUE TO REACH HEIGHTS 
BETWEEN 15 AND 20 THOUSAND FEET.  
 
WATER VAPOR IMAGERY SHOWS A COMPLEX LOW ALOFT CENTERED ABOUT 650 
MILES NORTHWEST OF KAUAI...WITH A VIGOROUS SHORTWAVE TROUGH ROTATING 
THROUGH THE BASE OF THE TROUGH NEAR 17N 175W. THE LOW IS NEARLY 
STATIONARY...AND IS PRODUCING LITTLE IN THE WAY OF DEEP 
CONVECTION...ASIDE FROM THE AFOREMENTIONED AREA OF THUNDERSTORMS 
SOUTHWEST OF KAUAI...AND A CLUSTER OF THUNDERSTORMS NEAR 19N 173W.  

$$

BIRCHARD