18W(NORU): Rapid Intensification(RI) expected next 36h//TS 19W(KULAP)//Invest 97W//TS 09L(IAN): RI likely after 24h,26/06utc

JTWC IS ISSUING 6HOURLY WARNINGS AND 3HOURLY SATELLITE BULLETINS ON 18W(NORU) AND 19W(KULAP).

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: TY 18W HAS WEAKENED SLIGHTLY, HOWEVER, THE SYSTEM IS WELL-ORGANIZED WITH IMPROVING POLEWARD OUTFLOW. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS THE BULK OF THE SPIRAL BANDING OVER THE SOUTHERN SEMICIRCLE WITH FLARING DEEP CONVECTION OVER THE CENTER, HOWEVER, FRAGMENTED BANDING HAS RE-DEVELOPED OVER THE WESTERN QUADRANT. A 242226Z SSMIS 91GHZ MICROWAVE IMAGE DEPICTS TIGHTLY- CURVED BANDING WRAPPING INTO A WELL-DEFINED LOW-LEVEL CIRCULATION CENTER, WHICH SUPPORTS THE INITIAL POSITION WITH HIGH CONFIDENCE. THE INITIAL INTENSITY OF 75 KTS IS BASED PRIMARILY ON THE RJTD DVORAK INTENSITY ESTIMATE AND THE CIMSS ADT ESTIMATE. ENVIRONMENTAL CONDITIONS HAVE IMPROVED AS THE SYSTEM TRACKS AWAY FROM LUZON WITH MODERATE RADIAL OUTFLOW AND LOW VERTICAL WIND SHEAR.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TY 18W IS FORECAST TO TRACK WESTWARD THROUGH THE FORECAST PERIOD UNDER THE STEERING INFLUENCE OF THE STR POSITIONED TO THE NORTH, MAKING LANDFALL NEAR DA NANG, VIETNAM NEAR TAU 48. TY 18W IS FORECAST TO RAPIDLY INTENSIFY FROM TAU 24 TO TAU 48 UNDER IMPROVING UPPER-LEVEL CONDITIONS TO A PEAK OF 110 KNOTS. AFTER TAU 48, THE SYSTEM WILL WEAKEN AS VERTICAL WIND SHEAR INCREASES AND THE SYSTEM TRACKS OVER SOUTHEAST ASIA WITH DISSIPATION EXPECTED BY TAU 96.

MODEL DISCUSSION: WITH THE EXCEPTION OF NAVGEM AFTER TAU 60, NUMERICAL MODEL GUIDANCE IS IN TIGHT AGREEMENT LENDING HIGH CONFIDENCE TO THE JTWC FORECAST TRACK. THE OVERALL CONFIDENCE IN THE JTWC INTENSITY FORECAST IS MEDIUM DUE TO MODERATE UNCERTAINTY IN THE INITIAL INTENSITY AFTER THE SHORT TRANSIT ACROSS LUZON. THE BULK OF THE INTENSITY GUIDANCE INDICATES A RE-INTENSIFICATION PHASE WITH HWRF INDICATING A PEAK OF 115 KNOTS AT TAU 36 AND COAMPS-TC A PEAK OF 115- 120 KNOTS. THE 251800Z COAMPS-TC ENSEMBLE INDICATES A 20 TO 30 PERCENT PROBABILITY OF RAPID INTENSIFICATION OVER THE NEXT 24 TO 48 HOURS, GENERALLY SUPPORTING THE CURRENT FORECAST PHILOSOPHY.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: TROPICAL STORM (TS) 19W HAS CONTINUED TO STEADILY CONSOLIDATE AS INDICATED IN ANIMATED ENHANCED INFRARED SATELLITE IMAGERY, WHICH SHOWS DEEP CONVECTIVE BANDING OVER THE EASTERN SEMICIRCLE WRAPPING INTO THE NORTHERN QUADRANT. A 260024Z MHS 89GHZ MICROWAVE IMAGE PROVIDES CLEAR EVIDENCE THAT A DEFINED LOW-LEVEL CIRCULATION CENTER HAS FORMED WITH EXTENSIVE DEEP CONVECTIVE BANDING LOCATED OVER THE EASTERN SEMICIRCLE. ADDITIONALLY, A 260028Z ASCAT-B BULLSEYE IMAGE SHOWS A SYMMETRIC CIRCULATION WITH A SWATH OF 30-35 KNOT WINDS OVER THE EASTERN SEMICIRCLE, WHICH SUPPORTS THE INITIAL POSITION AND INITIAL INTENSITY WITH HIGH CONFIDENCE. ENVIRONMENTAL CONDITIONS ARE FAVORABLE WITH ROBUST EQUATORWARD AND POLEWARD OUTFLOW CHANNELS AND LOW VERTICAL WIND SHEAR (VWS).

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TS 19W IS FORECAST TO TRACK GENERALLY NORTHWESTWARD THROUGH TAU 24 WITHIN THE COMBINED STEERING INFLUENCE OF THE BROAD STR TO THE EAST AND THE WEAK STR POSITIONED TO THE NORTH. AFTER TAU 24, A DEEP MIDLATITUDE SHORTWAVE TROUGH WILL APPROACH CENTRAL JAPAN AND WEAKEN THE STR TO THE NORTH ALLOWING THE SYSTEM TO TURN POLEWARD THROUGH TAU 36 THEN RECURVE NORTHEASTWARD ALONG THE NORTHWESTERN FLANK OF THE RE-ORIENTED STR TO THE SOUTHEAST. BY TAU 48, TS 19W WILL BEGIN EXTRA-TROPICAL TRANSITION (ETT) AS IT INTERACTS WITH THE MIDLATITUDE WESTERLIES AND BAROCLINIC ZONE. THE SYSTEM WILL COMPLETE ETT BY TAU 72 AS IT GAINS FRONTAL CHARACTERISTICS AND BECOMES EMBEDDED WITHIN THE MIDLATITUDE WESTERLIES. TS 19W SHOULD INTENSIFY STEADILY THROUGH TAU 48 UNDER FAVORABLE CONDITIONS TO A PEAK OF 70 KNOTS. AFTER TAU 48, COOLER SEA SURFACE TEMPERATURE VALUES (26C) AND MODERATE VWS WILL WEAKEN THE SYSTEM. HOWEVER, THE SYSTEM IS EXPECTED TO REMAIN A LARGE STORM-FORCE EXTRA-TROPICAL LOW.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT WITH A SPREAD OF LESS THAN 90NM THROUGH TAU 48. AFTER TAU 48, MODEL GUIDANCE DIVERGES SLIGHTLY WITH NAVGEM THE PRIMARY OUTLIER OVER THE SOUTHERN EDGE OF THE AIDS ENVELOPE. THE REMAINDER OF THE GUIDANCE IS IN GOOD AGREEMENT, THEREFORE, THERE IS HIGH OVERALL CONFIDENCE IN THE JTWC FORECAST TRACK. ADDITIONALLY, THE 251800Z ECMWF ENSEMBLE (EPS) AND GFS ENSEMBLE (GEFS) ARE IN GOOD AGREEMENT SUPPORTING THE JTWC FORECAST TRACK. THE 251800Z COAMPS-TC ENSEMBLE INDICATES A MODERATE PROBABILITY (40 TO 60 PERCENT) FOR RAPID INTENSIFICATION PEAKING IN THE TAU 36 TO TAU 60 TIMEFRAME.

WTNT44 KNHC 260300 TCDAT4 Tropical Storm Ian Discussion Number 12 NWS National Hurricane Center Miami FL AL092022 1100 PM EDT Sun Sep 25 2022 The storm has become better organized-looking on satellite imagery, with strengthening central convection and developing banding features. Upper-level anticyclonic outflow also appears to be increasing over the system. Flight-level winds, Doppler radar velocities, and dropsonde data from a NOAA Hurricane Hunter aircraft indicate that Ian's intensity is now near 55 kt. Ian has turned toward the northwest and the initial motion estimate is now 315/11 kt. During the next 48 hours, the tropical cyclone is expected to turn toward the north as it moves along the western side of a mid-level high pressure area. Later in the forecast period, a broad mid-tropospheric trough over the eastern United States is likely to induce a slightly east of northward motion. However, around 4 days, the steering currents are forecast to weaken as the trough moves to the east of Ian's longitude. Some of the guidance model tracks such as that from the GFS have, again, shifted to the east, mainly after 48 hours. The official track forecast has been shifted somewhat to the east of the previous one and is mainly a blend of the latest ECMWF and GFS predictions. It should again be stressed that there is still significant uncertainty in the track of Ian, especially in the 3-5 day time frame. Users should not focus on the details of the track forecast at longer time ranges. Observations from the aircraft indicate that the tropical cyclone is developing an inner core, so significant intensification is likely to occur during the next couple of days. The SHIPS Rapid Intensification Index indicate a fairly high chance for rapid strengthening during the next 24 to 36 hours, and the official forecast reflects this likelihood, calling for Ian to become a major hurricane over the southeastern Gulf of Mexico. Key Messages: 1. Ian is expected to produce heavy rainfall and instances of flash flooding and possible mudslides in areas of higher terrain, particularly over Jamaica and Cuba. Considerable flooding impacts are possible later this week in west central Florida. Additional flash and urban flooding, and flooding on rivers across the Florida Peninsula and parts of the Southeast cannot be ruled out for later this week. 2. Life-threatening storm surge and hurricane-force winds are expected in portions of western Cuba beginning late Monday, and Ian is forecast to be at or near major hurricane strength when it is near western Cuba. Efforts to protect life and property should be rushed to completion. 3. Ian is expected to be a major hurricane in the eastern Gulf of Mexico during the middle of this week, but uncertainty in the track and intensity forecasts remains higher than usual. Regardless of Ian’s exact track and intensity, there is a risk of dangerous storm surge, hurricane-force winds, and heavy rainfall along the west coast of Florida and the Florida Panhandle by the middle of this week, and residents in Florida should ensure they have their hurricane plan in place. Follow any advice given by local officials and closely monitor updates to the forecast.