WTPA33 PHFO 300840
TCPCP3

BULLETIN
HURRICANE IGNACIO ADVISORY NUMBER 22
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP122015
1100 PM HST SAT AUG 29 2015

…MAJOR HURRICANE IGNACIO CONTINUES MOVING STEADILY NORTHWEST…

SUMMARY OF 1100 PM HST…0900 UTC…INFORMATION
———————————————–
LOCATION…17.4N 147.9W
ABOUT 495 MI…800 KM ESE OF HILO HAWAII
ABOUT 705 MI…1135 KM ESE OF HONOLULU HAWAII
MAXIMUM SUSTAINED WINDS…145 MPH…230 KM/H
PRESENT MOVEMENT…NW OR 315 DEGREES AT 8 MPH…13 KM/H
MINIMUM CENTRAL PRESSURE…942 MB…27.82 INCHES

WATCHES AND WARNINGS
——————–
CHANGES WITH THIS ADVISORY…

NONE.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT…

A TROPICAL STORM WATCH IS IN EFFECT FOR…
* MAUI COUNTY…INCLUDING THE ISLANDS OF MAUI…MOLOKAI…LANAI AND
KAHOOLAWE.
* HAWAII COUNTY

A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE
POSSIBLE WITHIN THE WATCH AREA…GENERALLY WITHIN 48 HOURS OF THE
INITIAL ISSUANCE.

INTERESTS ELSEWHERE IN THE MAIN HAWAIIAN ISLANDS SHOULD CONTINUE TO
CLOSELY MONITOR THE PROGRESS OF IGNACIO.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA…PLEASE MONITOR
PRODUCTS ISSUED BY THE NATIONAL WEATHER SERVICE OFFICE IN
HONOLULU HAWAII.

DISCUSSION AND 48-HOUR OUTLOOK
——————————
AT 1100 PM HST…0900 UTC…THE CENTER OF HURRICANE IGNACIO WAS
LOCATED NEAR LATITUDE 17.4 NORTH…LONGITUDE 147.9 WEST. IGNACIO IS
MOVING TOWARD THE NORTHWEST NEAR 8 MPH…13 KM/H…AND THIS MOTION
IS EXPECTED TO CONTINUE FOR THE NEXT COUPLE OF DAYS. ON THE FORECAST
TRACK…THE CENTER OF IGNACIO IS EXPECTED TO PASS TO THE NORTHEAST
OF THE BIG ISLAND ON MONDAY.

MAXIMUM SUSTAINED WINDS ARE NEAR 145 MPH…230 KM/H…WITH HIGHER
GUSTS. IGNACIO IS A CATEGORY FOUR HURRICANE ON THE SAFFIR-SIMPSON
HURRICANE WIND SCALE. IGNACIO HAS LIKELY REACHED PEAK INTENSITY AND
WILL WEAKEN THROUGH MONDAY.

HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 30 MILES…45 KM…FROM
THE CENTER…AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 140
MILES…220 KM.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 942 MB…27.82 INCHES.

HAZARDS AFFECTING LAND
———————-
WIND…TROPICAL STORM CONDITIONS ARE POSSIBLE ON THE BIG ISLAND OF
HAWAII STARTING LATE SUNDAY NIGHT OR EARLY MONDAY…AND STARTING
MONDAY ON MAUI.

RAINFALL…STORM TOTAL RAINFALL AMOUNTS OF 2 TO 4 INCHES…WITH
ISOLATED MAXIMUM AMOUNTS NEAR 6 INCHES MAINLY IN AREAS OF HIGHER
TERRAIN…ARE POSSIBLE IN THE WATCH AREA.

SURF…LARGE SWELLS GENERATED BY IGNACIO WILL ARRIVE ALONG EAST
AND SOUTHEAST FACING SHORES OF THE MAIN HAWAIIAN ISLANDS OVER THE
NEXT SEVERAL DAYS. RESULTANT SURF WILL BE LARGE AND POTENTIALLY
LIFE-THREATENING…ESPECIALLY ON THE BIG ISLAND LATER THIS WEEKEND
AND EARLY NEXT WEEK.

NEXT ADVISORY
————-
NEXT INTERMEDIATE ADVISORY…200 AM HST.
NEXT COMPLETE ADVISORY…500 AM HST.

$$
FORECASTER POWELL



WTPA43 PHFO 300905
TCDCP3

HURRICANE IGNACIO DISCUSSION NUMBER 22
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP122015
1100 PM HST SAT AUG 29 2015

IGNACIO PRESENTS A WELL-DEFINED 20 NM WIDE EYE WITH A DEEP
CONVECTIVE CANOPY WHICH HAS BEEN STEADILY SHRINKING SINCE 0600 UTC.
ALL THREE SATELLITE CENTERS DERIVED SUBJECTIVE DVORAK SATELLITE
INTENSITY ESTIMATES OF 6.0…115 KT…AT 0600 UTC. UW-CIMSS ADT WAS
HIGHER AT 6.3 OR 122 KT. HOWEVER…WEATHER RECONNAISSANCE AIRCRAFT
SFMR FOUND 126 KT WITHIN THE NORTHEAST EYEWALL DURING THE SECOND OF
THREE…YES THREE…CENTER FLYTHROUGHS. SPLASH WIND CORRECTED
CENTRAL PRESSURE WAS FOUND TO BE 942 MB…LOWER THAN EXPECTED…ON
THE FIRST PASS BUT 945 MB ON THE THIRD PASS. BOTH PRESSURE ESTIMATES
WERE LOWER THAN IN THE PREVIOUS ADVISORY. IGNACIO LIKELY REACHED A
PEAK INTENSITY OF 125 KT AS THE AIRCRAFT WAS SAMPLING ITS
STRUCTURE…AND THIS WILL BE THE INITIAL INTENSITY FOR THIS
ADVISORY.

FORECAST PHILOSOPHY HAS CHANGED LITTLE SINCE THE LAST ADVISORY.
IGNACIO CONTINUES TO TRACK NORTHWEST…315 DEGREES AT 7 KT OVER THE
PAST 12 HOURS…THROUGH A WEAKNESS IN THE MID-LEVEL RIDGE EAST OF
HAWAII AND TOWARD A WEAK TROUGH LOCATED TO THE NORTH OF THE
NORTHWESTERN HAWAIIAN ISLANDS. THE ONLY CHALLENGE IS THAT…IN THE
SHORTER RANGE…THREE TO SIX HOURS…THERE ARE HINTS OF A MORE
NORTHERLY MOTION. LIKE THE LAST FEW RUNS…TRACK GUIDANCE THIS TIME
REMAINS TIGHTLY PACKED…TAKING THIS HURRICANE ALMOST IN A STRAIGHT
LINE NORTHWESTWARD THROUGH THE FIVE-DAY FORECAST PERIOD. HWRF AND
GFDL SHIFTED A BIT TO THE RIGHT…AS DID MOST CONSENSUS BLENDS.
HOWEVER…THE GFS SHIFTED SLIGHTLY LEFT. WE HAVE CONSISTENTLY KEPT
THE FORECAST TRACK ALONG THE LEFT EDGE OF THE GUIDANCE ENVELOPE AND
WE WILL DO SO THIS TIME AS WELL. THAT SAID…THE FORECAST TRACK WAS
SHIFTED SLIGHTLY TO THE RIGHT TO ACCOUNT FOR THE SHORT TERM MOTION
BEING A BIT MORE NORTHERLY THAN 12 HOUR MOTION. THIS CHANGE IS
ACTUALLY QUITE CONSERVATIVE…KEEPING THE TRACK LEFT OF CONSENSUS
AND CLOSELY ALIGNED WITH GFS. A 1 OR 2 KT DECREASE IN FORWARD MOTION
WAS ALSO INTRODUCED THROUGH 36 HOURS…NOT ENOUGH TO CHANGE THE
STATUS OF TROPICAL STORM WATCHES ACROSS THE HAWAIIAN ISLANDS.

SATELLITE LOOP SHOWS SHEAR IS BEGINNING TO TAKE ITS TOLL ON THIS
SYSTEM…IN SPITE OF THE INTENSITY MAX LIKELY REACHED A FEW HOURS
AGO. OUTFLOW APPEARS TO BE HINDERED TO THE NORTHWEST AND THE EROSION
ALONG THE WESTERN FLANK OF THE DEEP CONVECTIVE CANOPY SEEMS TO
CONFIRM THE PRESENCE OF INCREASING WESTERLY SHEAR. SHIPS INTENSITY
GUIDANCE DEPICTS STEADILY INCREASING SHEAR THROUGH 96 HOURS AND THE
FORECAST CALLS FOR IGNACIO TO FOLLOW A WEAKENING TREND SIMILAR TO
THAT OF THE LAST ADVISORY. WE KEEP THIS SYSTEM STRONGER THAN SHIPS
DEPICTS THROUGH DAY FIVE BUT WEAKER THAN DEPICTED IN DYNAMIC
MODELS.

IGNACIO WILL PASS CLOSE ENOUGH TO THE MAIN HAWAIIAN ISLANDS TO
JUSTIFY KEEPING A TROPICAL STORM WATCH IN EFFECT FOR THE BIG ISLAND
AND THE ISLANDS OF MAUI COUNTY.

FORECAST POSITIONS AND MAX WINDS

INIT 30/0900Z 17.4N 147.9W 125 KT 145 MPH
12H 30/1800Z 18.2N 148.9W 115 KT 135 MPH
24H 31/0600Z 19.2N 150.2W 110 KT 125 MPH
36H 31/1800Z 20.3N 151.6W 95 KT 110 MPH
48H 01/0600Z 21.3N 152.9W 80 KT 90 MPH
72H 02/0600Z 23.4N 155.8W 75 KT 85 MPH
96H 03/0600Z 25.6N 159.2W 65 KT 75 MPH
120H 04/0600Z 27.8N 162.3W 60 KT 70 MPH

$$
FORECASTER POWELL