Tropical Storm GONI Advisory Tue Aug 18

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 16W (GONI) WARNING NR 14//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 16W (GONI), LOCATED APPROXIMATELY 322 NM NORTHWEST
OF ANDERSEN AFB, HAS TRACKED WEST-NORTHWESTWARD AT 13 KNOTS OVER THE
PAST SIX HOURS. ANIMATED MSI DEPICTS A RAPIDLY CONSOLIDATED LLCC WITH
A 6 NM PINHOLE EYE. A 170641Z GPM IMAGE SHOWS A SMALL EYEWALL WITH A
SIGNIFICANT MOAT REGION AND TIGHTLY-CURVED SPIRAL BANDING WRAPPING
INTO THE CENTER. THERE IS VERY GOOD CONFIDENCE IN THE CURRENT POSITION
BASED ON THE SMALL EYE. TY GONI IS UNDERGOING RAPID INTENSIFICATION,
INCREASING NEARLY 60 KNOTS OVER THE PAST 24 HOURS WITH AN ASSESSED
CURRENT INTENSITY OF 115 KNOTS BASED ON DVORAK INTENSITY ESTIMATES
FROM ALL REPORTING AGENCIES. UPPER LEVEL ANALYSIS SHOWS VERY LOW (LESS
THAN 10 KNOTS) VWS AND VIGOROUS DUAL OUTFLOW CHANNELS. TY 16W
CONTINUES TO TRACK ALONG THE SOUTHERN PERIPHERY OF THE DEEP STR.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TY 16W WILL CONTINUE TO TRACK WEST-NORTHWESTWARD THROUGH TAU 72
UNDER THE STEERING INFLUENCE OF THE STR. DUE TO THE FAVORABLE
ENVIRONMENTAL CONDITIONS, INCLUDING LOW VWS, WARM SST AND EXCELLENT
OUTFLOW, TY 16W IS FORECAST TO CONTINUE TO INTENSIFY RAPIDLY THROUGH
TAU 24 WITH A PEAK OF 130 KNOTS. HOWEVER, DUE TO INCREASED VWS,
EXPECT A SLIGHT DIP IN INTENSITY AROUND TAU 48 DUE TO AN APPROACHING
TROUGH CAUSING SOME SUBSIDENCE OVER THE SYSTEM. BEYOND TAU 48, THE
SYSTEM WILL RE-INTENSIFY TO A SECOND PEAK OF 140 KNOTS DUE TO
IMPROVED POLEWARD OUTFLOW CAUSED BY THE PASSING OF THE SHORTWAVE
TROUGH.
   C. IN THE EXTENDED PERIOD, MODEL GUIDANCE WIDENS WITH REGARD TO
BOTH SPEED AND TIMING. THE STEERING ENVIRONMENT BECOMES MORE
COMPLICATED WITH THE PASSING MID-LATITUDE TROUGH AND A SMALL STR
ANCHORED OVER SHIKOKU AND A DEEP HIGH OVER EASTERN CHINA. THE SMALL
SIZE OF TY 16W WILL MAKE IT DIFFICULT TO FORCE POLEARD THOUGH ANY
(MARGINAL) BREAK IN THE RIDGE DUE TO THE PASSING ZONAL TROUGH. AS
SUCH, TY GONI IS EXPECTED TO SLOW ITS TRACK AND SLOWLY TURN POLEWARD
DUE TO THE WEAK STEERING ENVIRONMENT, TO INCLUDE SOME INFLUENCE OF
TY 17W TRACKING ALONG THE EASTERN PERIPHERY OF THE SHIKOKU STR,
REINFORCING THE RIDGES POSITION. INTENSITY IS EXPECTED TO DECREASE
DURING THE EXTENDED FORECAST DUE TO LAND INTERACTION. BECAUSE OF THE
COMPLEX STEERING ENVIRONMENT IN THE EXTENDED FORECAST, THERE IS HIGH
UNCERTAINTY IN THE JTWC FORECAST TRACK.//
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