ZCZC MIATCDEP3 ALL TTAA00 KNHC DDHHMM Hurricane Rachel Discussion Number 25 NWS National Hurricane Center Miami FL EP182026 200 AM MST Sat Oct 03 2026 Rachel has become less organized during the past several hours. The associated convection is now occurring only over the southern semicircle, and the latest microwave imagery indicates that there is no longer any eyewall. Satellite intensity estimates are in the 70-90 kt range and are trending downward. Based on the trend, the initial intensity is lowered to 80 kt. The initial motion is 275/4 kt. A mid-level anticyclone over the western United States has a ridge extending southwest to the west of Rachel, and this anticyclone is expected to build westward during the next 72 h. This evolution should steer the cyclone slowly west-northwestward for the next day or two, followed by a more westward motion. By 96-120 h, a west-northwestward motion is likely to resume as Rachel approaches the western end of the ridge. The new forecast track is close to the previous forecast for 48-60 h, and then is nudged a little south based on a southward shift in the guidance envelope. Additional slow weakening is forecast during the next 24-36 h as Rachel continues to experience northeasterly shear and crosses the cold water wake of Hurricane Polo. After that, the sea surface temperatures increase slightly at a time where the hurricane is likely to entrain dry air. These competing factors are expected to result in little net change in strength between 36-72 h. After 72 h, Rachel should move over progressively colder water and continue to entrain dry air, which should cause a steady weakening. FORECAST POSITIONS AND MAX WINDS INIT 03/0900Z 19.4N 111.8W 80 KT 90 MPH 12H 03/1800Z 19.6N 112.4W 80 KT 90 MPH 24H 04/0600Z 19.9N 113.2W 75 KT 85 MPH 36H 04/1800Z 20.1N 114.1W 70 KT 80 MPH 48H 05/0600Z 20.2N 115.2W 70 KT 80 MPH 60H 05/1800Z 20.4N 116.7W 70 KT 80 MPH 72H 06/0600Z 20.6N 118.4W 70 KT 80 MPH 96H 07/0600Z 21.2N 121.7W 65 KT 75 MPH 120H 08/0600Z 22.2N 125.0W 55 KT 65 MPH $$ Forecaster Beven NNNN

WDPN32 PGTW 030900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 26W (CHOI-WAN) WARNING NR 014// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 19.4N 145.9E INITIAL INTENSITY: 80 KTS GEOGRAPHIC REFERENCE: 252 NM NORTH OF SAIPAN MOVEMENT PAST 6 HOURS: NORTH-NORTHEASTWARD AT 09 KTS SIGNIFICANT WAVE HEIGHT: 32 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TYPHOON 26W (CHOI-WAN) WITH A CLOUD-FILLED EYE AND A MORE DISORGANIZED CONVECTIVE STRUCTURE COMPARED TO 6 HOURS AGO. THE MSI ALSO SHOWS SOME DRY AIR BEING PULLED INTO THE CORE OF 26W ALONG THE WESTERN PERIPHERY, WHICH COULD BE THE CAUSE FOR THE HALTED DEVELOPMENT. A 030228Z AMSR3 37 GHZ MICROWAVE IMAGE REVEALED AN ELLIPTIC MICROWAVE EYE FEATURE WITH A SLIGHT WEAKNESS IN THE WESTERN SEMICIRCLE. THE 89 GHZ VERSION OF THE SAME PASS SHOWED THE STRONGEST CONVECTION CONFINED TO THE SOUTHEASTERN QUADRANT OF THE SYSTEM. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE ANIMATED MSI AND EXTRAPOLATION FROM THE AMSR3 MICROWAVE IMAGE SUITE. THE INITIAL INTENSITY OF 80 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON A COMBINATION OF THE AGENCY DVORAK FIXES OF T5.0 AND THE LOWER CIMSS INTENSITY ESTIMATES. INITIAL WIND RADII BASIS: PERSISTENCE FROM THE 022345Z METOP-B ASCAT PASS WITH MINOR ADJUSTMENTS BASED ON THE OBJECTIVE BEST TRACK CURRENT STEERING MECHANISM: THE WESTERN EXTENSION OF A SUBTROPICAL RIDGE (STR) POSITIONED TO THE NORTHEAST AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T5.0 - 90 KTS RJTD: T5.0 - 90 KTS RCTP: T5.0 - 90 KTS CIMSS SATCON: 77 KTS AT 030600Z CIMSS ADT: 59 KTS AT 030600Z CIMSS AIDT: 63 KTS AT 030600Z CIMSS D-PRINT: 76 KTS AT 030600Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 5-10 KTS SST: 29-30 CELSIUS OUTFLOW: STRONG POLEWARD AND EQUATORWARD OTHER FACTORS: SLIGHT DRY AIR ENTRAINMENT ALONG THE WESTERN PERIPHERY ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: MEDIUM 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: THE STEERING MECHANISM FOR 26W HAS SHIFTED FROM THE NEAR EQUATORIAL RIDGE TO THE SUBTROPICAL RIDGE TO THE NORTHEAST. THIS HAS CAUSED THE TRAJECTORY TO BECOME SLIGHTLY MORE NORTHWARD OVER PAST 6 HOURS. 26W IS FORECAST TO TURN FURTHER NORTHWARD AS IT TRACKS ALONG THE WESTERN PERIPHERY OF THE STR THROUGH TAU 72. AFTER TAU 72, THE SYSTEM WILL ACCELERATE NORTHEASTWARD AS IT ROUNDS THE RIDGE AXIS AND BEGINS TO INTERACT WITH THE STRONG UPPER-LEVEL FLOW. EXTRATROPICAL TRANSITION IS EXPECTED TO BE COMPLETE AROUND TAU 96, SOUTH OF THE KAMCHATKA PENINSULA, ONCE THE SYSTEM BECOMES EMBEDDED UNDERNEATH THE JET. IN TERMS OF INTENSITY, 26W IS FORECAST TO INTENSIFY OVER THE NEXT 24 HOURS TO A PEAK INTENSITY OF AROUND 105 KTS AS THE ENVIRONMENT REMAINS FAVORABLE WITH LOW SHEAR, VERY WARM SST, AND ROBUST OUTFLOW. THE PRIMARY LIMITING FACTOR WILL BE THE DRY AIR TO THE WEST. AROUND TAU 36, OCEAN HEAT CONTENT WILL START TO DROP AND EQUATORWARD OUTFLOW WILL BECOME RESTRICTED, CAUSING 26W TO WEAKEN THROUGH TAU 72. FOLLOWING TAU 72, THE SYSTEM WILL TAP INTO AN EXTREME POLEWARD OUTFLOW CHANNEL, SUPPORTED BY A VERY STRONG JET MAX TO THE NORTH. THIS WILL OFFSET THE COOL SST AND HIGH SOUTHWESTERLY VERTICAL WIND SHEAR, ALLOWING FOR 26W TO LIKELY MAINTAIN TYPHOON INTENSITY THROUGH THE INITIAL STAGES OF FRONTOGENESIS. MODEL DISCUSSION: MODEL TRACK GUIDANCE IS IN MODERATE AGREEMENT THROUGH TAU 72 WITH MOST OF THE UNCERTAINTY REVOLVING AROUND THE SPEED OF ADVANCE AROUND THE RIDGE. WHILE CROSS-TRACK SPREAD IS ONLY AROUND 100 NM AT TAU 72, ALONG-TRACK SPREAD IS ABOUT 250 NM. GFS AND NAVGEM ARE THE SLOWEST TRA…