WTPA32 PHFO 212045
TCPCP2

BULLETIN
TROPICAL STORM LOKE ADVISORY NUMBER 4
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI CP042015
1100 AM HST FRI AUG 21 2015

…FOUR-C UPGRADED TO TROPICAL STORM LOKE…

SUMMARY OF 1100 AM HST…2100 UTC…INFORMATION
———————————————–
LOCATION…16.4N 177.2W
ABOUT 510 MI…820 KM W OF JOHNSTON ISLAND
ABOUT 815 MI…1310 KM S OF MIDWAY ISLAND
MAXIMUM SUSTAINED WINDS…45 MPH…75 KM/H
PRESENT MOVEMENT…N OR 355 DEGREES AT 6 MPH…9 KM/H
MINIMUM CENTRAL PRESSURE…1001 MB…29.56 INCHES

WATCHES AND WARNINGS
——————–
THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.

DISCUSSION AND 48-HOUR OUTLOOK
——————————
AT 1100 AM HST…2100 UTC…THE CENTER OF TROPICAL STORM LOKE WAS
LOCATED NEAR LATITUDE 16.4 NORTH…LONGITUDE 177.2 WEST. LOKE IS
MOVING TOWARD THE NORTH NEAR 6 MPH…9 KM/H…AND THIS MOTION IS
EXPECTED TO SWING SLIGHTLY TO THE NORTH NORTHWEST AND NORTHWEST
THROUGH SUNDAY.

MAXIMUM SUSTAINED WINDS ARE NEAR 45 MPH…75 KM/H…WITH HIGHER
GUSTS. LOKE WILL SLOWLY INTENSITY THROUGH SUNDAY.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 25 MILES…35 KM
FROM THE CENTER.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1001 MB…29.56 INCHES.

HAZARDS AFFECTING LAND
———————-
NONE.

NEXT ADVISORY
————-
NEXT COMPLETE ADVISORY…500 PM HST.

$$
FORECASTER POWELL



WTPA42 PHFO 212102
TCDCP2

TROPICAL STORM LOKE DISCUSSION NUMBER 4
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI CP042015
1100 AM HST FRI AUG 21 2015

FOUR-C ORGANIZATION HAS IMPROVED RAPIDLY THIS MORNING…MOST
NOTICEABLY SINCE THE 1800Z SATELLITE ANALYSIS CYCLE. AS A
RESULT…FOUR-C IS UPGRADED TO TROPICAL STORM LOKE. OBJECTIVE DVORAK
SATELLITE ANALYSIS INTENSITY ESTIMATES RANGED FROM 2.0…30
KT…FROM PHFO AND JTWC…TO 2.5…35 KT…FROM SAB.
HOWEVER…SATELLITE DEVELOPMENTS SINCE THESE VALUES WERE DERIVED
SHOW THEY ARE LIKELY UNREPRESENTATIVE NOW…WITH DEEP CONVECTION
WRAPPING AROUND ALL BUT THE SOUTH QUADRANT AND A WELL DEFINED LLCC
LIKELY LOCATED AT THE NORTHERN TIP OF THE CONVECTION-FREE SLOT AS
OF 2000Z. INITIAL INTENSITY IS SET AT 40 KT…HIGHER THAN 1800Z
DVORAK BUT POSSIBLY STILL UNDERESTIMATING SYSTEM STRENGTH BASED ON
PRESENTATION ALONE. LOKE INTENSITY MAY HAVE TO BE BUMPED UP
NOTICEABLY FOR THE NEXT FORECAST CYCLE.

INITIAL MOTION IS ALMOST DUE NORTH…OR 355/05 KT. THE LLCC WHICH
HAS BECOME APPARENT OVER THE PAST FEW HOURS HAS INCREASED CONFIDENCE
IN THIS MOTION. TIMELY MICROWAVE IMAGERY EARLIER THIS MORNING
FURTHER INCREASED POSITION CONFIDENCE. LOKE IS MOVING SLOWLY ALONG
THE WESTERN FLANK OF A MID LEVEL RIDGE WHICH EXTENDS WESTWARD FROM
THE HAWAIIAN ISLANDS. TRACK GUIDANCE REMAINS TIGHTLY CLUSTERED
THROUGH 48 HOURS…INDICATING A RATHER SLOW MOTION GRADUALLY BENDING
TO THE NORTHWEST…AS THE TROPICAL CYCLONE MOVES ALONG THE WESTERN
PERIPHERY OF THE RIDGE. MOST OF THE GUIDANCE THEN TURNS THE TROPICAL
CYCLONE TO THE NORTH AND EVENTUALLY NORTH-NORTHEAST BEYOND 72
HOURS…WITH AN INCREASE IN FORWARD SPEED…AS THE CYCLONE INTERACTS
WITH A DEEPENING MID LATITUDE TROUGH ALONG THE INTERNATIONAL DATE
LINE. THE NEW FORECAST TRACK IS VERY SIMILAR TO THE PREVIOUS TRACK
THROUGH 48 HOURS…THEN IS ALTERED A BIT TO THE RIGHT AT TAU 72…96
AND 120 TO MORE CLOSELY FOLLOW TRACK CONSENSUS. THE FORECAST TRACK
KEEPS LOKE WITHIN THE CENTRAL NORTH PACIFIC…BARELY.

LOKE IS MOVING OVER VERY WARM WATERS…IN EXCESS OF 28C… AND IS
WITHIN A LOW SHEAR ENVIRONMENT. HOWEVER…INTENSITY GUIDANCE HAS NOT
CHANGED MUCH SINCE THE LAST CYCLE…WITH GFS STILL WANTING TO
DISSIPATE THIS SYSTEM BY 96 HOURS. FOLLOWING THE TREND FROM THE LAST
FORECAST CYCLE…WE WILL BRING LOKE TO PEAK STRENGTH OF 55 KT IN 48
HOURS…WITH SLOW WEAKENING DEPICTED AFTERWARDS.
FORECAST POSITIONS AND MAX WINDS

INIT 21/2100Z 16.4N 177.2W 40 KT 45 MPH
12H 22/0600Z 17.1N 177.6W 45 KT 50 MPH
24H 22/1800Z 17.9N 178.2W 50 KT 60 MPH
36H 23/0600Z 18.8N 179.1W 50 KT 60 MPH
48H 23/1800Z 19.9N 179.7W 55 KT 65 MPH
72H 24/1800Z 23.3N 179.2W 50 KT 60 MPH
96H 25/1800Z 26.4N 177.6W 50 KT 60 MPH
120H 26/1800Z 29.6N 175.8W 40 KT 45 MPH

$$
FORECASTER POWELL