ZCZC MIATCDEP3 ALL TTAA00 KNHC DDHHMM Tropical Storm Rachel Discussion Number 55 NWS National Hurricane Center Miami FL EP182026 200 PM PDT Sat Oct 10 2026 Rachel continues to trend toward transitioning to a post-tropical storm. Convection remains shallow and has become further sheared well northeast of the center due to strong southwesterly shear. A 1731 UTC ASCAT-B scatterometer pass showed an asymmetric system with peak winds of 48 kt located just west of the center. Based on this data, the initial intensity was raised to 55 kt. The initial motion is estimated to be north-northeast, or 025/26 kt. A turn toward the north with an increase in forward speed is anticipated, as noted in the previous advisory. This change in the steering flow is due to the storm's interaction with a mid-level cut-off low located to its northwest. The updated NHC track forecast was nudged eastward initially, but otherwise closely mirrors the previous track and aligns with the latest HCCA aid. Rachel has undergone slight intensification since the previous advisory, likely due to its interaction with an upper-level trough. The storm is forecast to degrade further given its hostile environment, specifically because of strong southwesterly shear. Rachel is anticipated to move inland just after 12 h and become post-tropical by 24 h. The new intensity forecast is largely unchanged. Key Messages: 1. Rachel is expected to make landfall along the coast of northern Baja California at tropical storm strength tonight. Tropical storm conditions are expected in portions of Baja California and northern Baja California Sur, Mexico, where Tropical Storm Warnings are in effect. Tropical storm conditions are also possible in extreme Southern California, eastern Baja California, and portions of northwestern Mexico where Tropical Storm Watches are in effect. 2. Damaging wind gusts associated with Rachel and its remnants are expected to spread over portions of northwestern Mexico and interior portions of the Southwest United States, especially in areas of higher terrain, tonight and Sunday. 3. Rachel and its moisture will continue to spread over portions of the Southwest United States and northern Baja California peninsula. This will lead to increasing coverage of rainfall and for the potential for significant flash and urban flooding this weekend. 4. Waves generated by Rachel, combined with an incoming long-period southerly swell, will produce life-threatening surf and rip current conditions along the coasts of Southern California and northern Baja California. Major coastal flooding has already been occurring in some areas, with observed water levels running as much as 1.5 feet above predictions. Coastal flooding and erosion are expected to worsen tonight into Sunday morning as the highest waves associated with Rachel coincide with high tides and already elevated water levels. Hazardous coastal conditions are expected to continue into early next week. Please consult products from your local weather office. FORECAST POSITIONS AND MAX WINDS INIT 10/2100Z 27.0N 118.3W 55 KT 65 MPH 12H 11/0600Z 30.4N 116.3W 50 KT 60 MPH 24H 11/1800Z 36.3N 114.1W 40 KT 45 MPH...POST-TROPICAL 36H 12/0600Z...DISSIPATED $$ Forecaster Pierce/Cangialosi NNNN

ZCZC MIATCDEP5 ALL TTAA00 KNHC DDHHMM Hurricane Simon Discussion Number 14 NWS National Hurricane Center Miami FL EP202026 300 PM CST Sat Oct 10 2026 Air Force Reserve Hurricane Hunters have been investigating Simon this afternoon, finding that the hurricane is indeed a Category 4 storm. The minimum pressure is estimated to be down to 932 mb, and the peak 700 mb flight level winds were 134 kt in the eastern quadrant of the hurricane. While a standard 0.9 reduction would typically support a 10 meter sustained wind of 120-125 kt, the entire wind field of Simon was not fully sampled. In addition, there was an earlier partial Synthetic Aperture Radar (SAR) RCM-1 pass which had a peak wind of 138 kt. Satellite intensity estimates, which have been lagging behind the estimated intensity of Simon, have also risen somewhat today. Taking all these data points together, the initial intensity is held at 130 kt this advisory. The aircraft also reported concentric eyewalls, with the inner eyewall 12 n mi and outer wall at 36 n mi. Some concentric bands were also picked up by a recent AMSR-3 microwave pass. After slowing down to a crawl earlier, aircraft fixes indicate that Simon starting to move due north again, with an estimated motion at 360/4 kt. As previously discussed, the hurricane is being primarily steered by a weak mid-level ridge to the east, providing deep-layer southerly flow. A subtle narrow mid-level ridge to the northwest is also imparting a slight amount of northerly flow. Once again, the track guidance this afternoon has made a slower adjustment. In addition, there is a bit of an eastward shift in the guidance envelope. One notable change from this morning, now all the hurricane-regional model runs (HWRF, HMON, HAFS-A, HAFS-B) all show Simon making landfall in Jalisco in 24-36 h. In addition, both the Google DeepMind ensemble mean (GDMI) and its upgraded Weather Next model (WN3I) also nudged their tracks eastward. Thus, the NHC track forecast has shifted a bit to the east, but still lies on the eastern end of the guidance. Part of the reason for favoring the eastern edge of the guidance is that there is a pretty well-known bias that tropical cyclones in this area tend to track east of the forecast track due to interaction with the high topography of coastal Mexico. As mentioned this morning, the future intensity forecast of Simon is heavily influenced by Simon's ultimate track. Because large-scale environmental conditions remain favorable, Simon's short-term intensity forecast will likely be controlled by inner-core fluctuations, like eyewall replacement cycles. This is pertinent given the concentric eyewalls noted by the aircraft mission. However, as Simon nears the Mexican coast, the high topography will interact with the hurricane's outer circulation, and spot soundings in the HAFS-A/B runs show evidence of downslope subsidence occurring as Simon nears landfall. This effect will both cause the hurricane's wind field to shrink in size, and will likely result in weakening even before the hurricane makes landfall in Mexico. Weakening is expected to begin between 12-24 h, with more substantial weakening occurring when Simon moves fully onshore. Once again, this intensity forecast is quite uncertain. If Simon remains offshore, like the ECMWF and a decent chunk of GDM ensemble members show, it may remain much stronger than the latest NHC intensity forecast. The latest forecast is a bit lower than the prior one, with a bit more confidence that Simon will move inland, though the latest forecast still shows Simon dissipating over Mexico after 60 h. Key Messages: 1. Catastrophic wind and life-threatening storm surge impacts are likely along a portion of the west-central coast of Mexico, and a Hurricane Warning is in effect from Punta San Telmo to El Roblito. Preparations to protect life and property should be completed this afternoon. 2. Heavy rainfall asso…

WDPN33 PGTW 102100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 27W (KOGUMA) WARNING NR 024// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 22.9N 149.6E INITIAL INTENSITY: 120 KTS GEOGRAPHIC REFERENCE: 510 NM NORTH-NORTHEAST OF SAIPAN MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 10 KTS SIGNIFICANT WAVE HEIGHT: 46 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TYPHOON (TY) 27W (KOGUMA) AS A VIGOROUS, COMPACT, AND SYMMETRICAL SYSTEM WITH AN EYE MEASURING APPROXIMATELY 20 NM IN DIAMETER. THE 101844Z SUITE OF GMI IMAGES REVEALS THE STORM IS GEARING UP FOR A SECOND EYEWALL REPLACEMENT CYCLE (ERC), WITH A PARTIAL OUTER EYEWALL BEGINNING TO FORM ABOUT 40 NM FROM THE CENTER. ENVIRONMENTAL ANALYSIS REVEALS A HIGHLY FAVORABLE ENVIRONMENT, CHARACTERIZED BY LOW (0-5 KTS) VERTICAL WIND SHEAR (VWS), WARM (27-28 C) SEA SURFACE TEMPERATURES (SST), GOOD (50-75 KJ PER CM SQUARED) OCEAN HEAT CONTENT (OHC), AND STRONG RADIAL OUTFLOW. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE WELL-DEFINED EYE IN ANIMATED EIR. THE INITIAL INTENSITY OF 120 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE GOOD AGREEMENT OF THE AGENCY DVORAK FIXES AND THE CIMSS AUTOMATED INTENSITY ESTIMATES LISTED BELOW. INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: THE SOUTHWESTERN PERIPHERY OF THE SUBTROPICAL RIDGE (STR) CENTERED TO THE NORTHEAST AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T6.0 - 115 KTS RJTD: T6.0 - 115 KTS RCTP: T5.5 - 102 KTS CIMSS SATCON: 121 KTS AT 101830Z CIMSS ADT: 109 KTS AT 101800Z CIMSS AIDT: 115 KTS AT 101800Z CIMSS D-MINT: 117 KTS AT 101840Z CIMSS D-PRINT: 117 KTS AT 101800Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE VWS: 0-5 KTS SST: 27-28 CELSIUS OUTFLOW: STRONG RADIAL ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: LOW 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TY 27W IS FORECAST TO TRACK NORTH-NORTHWESTWARD FOR THE NEXT 12 HOURS WHILE IT REMAINS ON THE SOUTHWESTERN PERIPHERY OF THE STEERING RIDGE. FOLLOWING TAU 12, 27W WILL CURVE NORTHWARD AS IT BEGINS TO ROUND THE STR. KOGUMA IS EXPECTED TO ROUND THE RIDGE AXIS AROUND TAU 24 AND RECURVE TO THE NORTHEAST. 27W WILL MAINTAIN A NORTHEASTWARD TRACK FROM TAU 36 THROUGH THE END OF THE FORECAST. REGARDING INTENSITY, 27W IS ASSESSED TO BE AT ITS PEAK INTENSITY, AND IS EXPECTED TO GRADUALLY WEAKEN FOR THE NEXT 36 HOURS AS THE ENVIRONMENT SLOWLY BECOMES LESS FAVORABLE. BY TAU 36, VWS IS EXPECTED TO INCREASE TO 15-20 KTS WHICH WILL INDUCE MID-LEVEL DRY AIR ENTRAINMENT. ADDITIONALLY, OHC IS EXPECTED TO DROP TO 0 KJ PER CM SQUARED AS KOGUMA CROSSES THE 26C ISOTHERM AROUND TAU 36. HOWEVER, THE RATE OF WEAKENING FOR THE NEXT 36 HOURS MAY BE INCREASED IF 27W ATTEMPTS A SECOND ERC AND FAILS TO COMPLETE THE CYCLE. FOLLOWING TAU 36, 27W IS EXPECTED TO RAPIDLY WEAKEN THROUGH TAU 72 AS THE ENVIRONMENT TURNS HOSTILE. KOGUMA IS FORECAST TO ENCOUNTER 40-50 KTS OF VWS, SIGNIFICANT DRY AIR ENTRAINMENT, COLD (LESS THAN 24C) SSTS, AND SUPPRESSED OUTFLOW CAUSED BY INCREASING PROXIMITY TO THE UPPER-LEVEL WESTERLIES. 27W IS EXPECTED TO SKIRT THE EQUATORWARD FRINGES OF THE WESTERLIES BETWEEN TAU 72-96, BEFORE FINALLY BECOMING EMBEDDED IN THE FLOW BY TAU 120. AS A RESULT, KOGUMA IS FORECAST TO BEGIN EXTRATROPICAL TRANSITION BY TAU 96 AND COMPLETE TRANSITION BY TAU 120. MODEL DISCUSSION: DETERMINISTIC MODEL TRACK GUIDANCE IS IN STRONG AGREEMENT THROUGH THE DURATION OF THE FORECAST PERIOD, THOUGH NAVGEM, GALWEM, AND GSM ARE NOTABLE OUTLIERS. DISCOUNTING THOSE MODELS, THE JTWC TRACK FORECAST IS PLACED WITH OVERAL…