WNP: 06W(CHAMPI) is forecast to intensify rather rapidly next 36hours to Typhoon intensity, 24/03utc update

WARN13 ISSUED AT 24/03UTC.FORECAST DISCUSSION: TROPICAL STORM 06W (CHAMPI) WILL CONTINUE TRACKING NORTHWARD DURING THE NEXT 48 HOURS AS IT ROUNDS THE PERIPHERY OF THE SUBTROPICAL RIDGE TO THE EAST. AT THIS POINT, THE CYCLONE WILL TURN SLIGHTLY NORTHEASTWARD AS IT NEARS THE BAIU FRONTAL BOUNDARY SOUTHEAST OF JAPAN. THE JTWC INTENSITY FORECAST CALLS FOR STEADY INTENSIFICATION TO A PEAK OF 70 KNOTS/ US CATEGORY 1 AROUND 36H AS LOW TO MODERATE SHEAR PERSISTS, WHICH SHOULD ALLOW AN INNER CONVECTIVE CORE TO ORGANIZE. PERIODIC INGESTION OF DRY AIR AND LIMITED OUTFLOW IS LIKELY TO LIMIT INTENSIFICATION TO SOME EXTENT. AFTER 48H, THE CYCLONE WILL PASS INTO COOLER WATERS OF 18-20C, AND INTERACTION WITH THE BAIU FRONTAL BOUNDARY WILL INCREASE VERTICAL SHEAR. THESE FACTORS WILL LEAD TO WEAKENING TO 45 KNOTS BY THE TIME OF EXTRATROPICAL TRANSITION AROUND 96H.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS AN EXPOSED, TIGHTLY WRAPPED LOW LEVEL CIRCULATION (LLC) WITH SHALLOW BANDING AND DEEP CONVECTION STARTING TO FLARE OVER THE CENTER. A 232304Z 89GHZ MHS MICROWAVE IMAGE SHOWS FRAGMENTED BANDING WRAPPING INTO A DEFINED LLC. A 231933Z 91GHZ SSMIS IMAGE DEPICTS A MICROWAVE EYE FEATURE WITH TIGHTLY CURVED BANDING, HOWEVER, THIS FEATURE WAS SHORT-LIVED AND DEGRADED SIGNIFICANTLY SINCE THAT TIME. THE HIGH CONFIDENCE IN THE INITIAL POSITION IS BASED ON THE WELL DEFINED NATURE OF THE CENTER IN VISIBLE IMAGERY. THERE IS SOME UNCERTAINTY IN THE INITIAL INTENSITY DUE THE RAPIDLY EVOLVING CONVECTIVE STRUCTURE OVER THE PAST SIX HOURS. THE INITIAL INTENSITY IS BASED ON THE PGTW AND RJTD DVORAK CURRENT INTENSITY ESTIMATES AND A 232311Z PARTIAL ASCAT-A IMAGE SHOWING 35-40 KT WINDS OVER EASTERN SEMICIRCLE. OVERALL THE ENVIRONMENT IS FAVORABLE, HOWEVER, POLEWARD OUTFLOW IS WEAK AND THERE IS DRY OVER THE WESTERN SEMICIRCLE.

MODEL DISCUSSION: THE JTWC FORECAST IS IN LINE WITH THE MULTI-MODEL CONSENSUS AND IS CONSISTENT WITH THE PREVIOUS FORECAST TRACK. CONFIDENCE IN THE FORECAST TRACK IS MEDIUM DUE TO MODEL SPREADING IN THE EXTENDED FORECAST WITH A CROSS TRACK SPREAD OF 370 KM AT 72H AND 620 KM AT 96H. THERE IS UNCERTAINTY IN THE INTENSITY FORECAST WITH SOME POTENTIAL FOR A HIGHER PEAK INTENSITY AS INDICATED BY THE HWRF GUIDANCE SHOWING A PEAK NEAR 85 KNOTS.

23/18UTC. HWRF INTENSITY GUIDANCE: 96KNOTS AT +54H.

23/18UTC. AVN INTENSITY GUIDANCE: 82KNOTS AT +60H.

24/00UTC.24H SHEAR TENDENCY.UW-CIMSS Experimental Vertical Shear and TC Intensity Trend Estimates: CIMSS Vertical Shear Magnitude : 7.3 m/s (14.3 kts)Direction : 20.4deg Outlook for TC Intensification Based on Current Env. Shear Values and MPI Differential: FAVOURABLE OVER 24H.

THE JTWC IS ISSUING 6HOURLY WARNINGS AND 3HOURLY SATELLITE BULLETINS ON 06W.

24/00UTC.

24/00UTC.