05W(GAEMI) making landfall over CHINA// INVEST 95W// 02E(BUD)// 3 Week TC Formation Probability//2509utc

JTWC IS ISSUING 6HOURLY WARNINGS ON 05W. 3HOURLY SATELLITE BULLETINS ARE ISSUED ON 05W AND ON THE REMNANTS OF 04W.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL STORM (TS) 05W (GAEMI) ABOUT 40 NM OFFSHORE OF EASTERN CHINA WITH A QUICKLY DETERIORATING CONVECTIVE STRUCTURE. INSTEAD OF TIGHTLY WRAPPING INTO THE SYSTEM, THE CONVECTIVE BANDING IS STARTING TO DRIFT AWAY FROM THE LOW-LEVEL CIRCULATION CENTER (LLCC). OBSERVATIONS NEAR THE COAST OF CHINA OF AROUND 25 KTS REVEAL THAT THE WIND FIELD OF 05W HAS BECOME VERY LOPSIDED. MUCH WEAKER WINDS ARE PRESENT IN THE NORTHWESTERN QUADRANT THAN ELSEWHERE, SHOWING THE INFLUENCE LAND INTERACTION IS HAVING ON THE SYSTEM. ENVIRONMENTAL CHARACTERISTICS INCLUDE: MODERATE RADIAL OUTFLOW ALOFT, MODERATE VERTICAL WIND SHEAR, AND WARM SEA SURFACE TEMPERATURES. THESE FACTORS ARE HIGHLY OFFSET BY THE EXTENSIVE LAND INTERACTION ON THE VORTEX, CAUSING THE ENVIRONMENT TO BE UNFAVORABLE FOR ANY FURTHER DEVELOPMENT. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE LLCC PEAKING THROUGH THE DRIFTING DEEP CONVECTION AS SEEN IN THE ANIMATED MSI. THE INITIAL INTENSITY OF 60 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE OBJECTIVE AND SUBJECTIVE INTENSITY ESTIMATES LISTED BELOW.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: LANDFALL OF TS 05W IS QUICKLY APPROACHING AND IS EXPECTED TO OCCUR BY 251200Z. 05W IS FORECAST TO CONTINUE TRACKING ALONG THE SOUTHWEST PERIPHERY OF THE STR TO THE NORTHEAST THROUGHOUT THE REMAINDER OF THE FORECAST PERIOD AS IT TRACKS INLAND. 05W IS FORECAST TO DROP BELOW TROPICAL STORM STRENGTH NEAR TAU 24 AS THE TERRAIN WILL HAVE HAD AMPLE TIME TO ERODE THE VORTEX. FURTHER LAND INTERACTION WILL RAPIDLY WEAKEN 05W WITH DISSIPATION FORECAST TO OCCUR NO LATER THAN TAU 48.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN VERY GOOD AGREEMENT REGARDING THE TRACK OF 05W WITH A 120 NM CROSS-TRACK SPREAD AT TAU 36. NAVGEM DEPICTS A SLIGHTLY DIFFERENT TRACK AFTER TAU 36, TRACKING THE SYSTEM ALMOST STRAIGHT NORTHWARD. OTHERWISE, MODELS HIGHLY AGREE WHICH LENDS HIGH CONFIDENCE TO THE JTWC TRACK FORECAST. INTENSITY GUIDANCE IS ALSO IN VERY GOOD AGREEMENT OF A WEAKENING TREND WITH DISSIPATION BY TAU 48. THEREFORE, THE JTWC INTENSITY FORECAST IS PLACED WITH HIGH CONFIDENCE.

AN AREA OF CONVECTION (INVEST 95W) HAS PERSISTED NEAR 6.8N 135.4E, APPROXIMATELY 58.5 NM SOUTHEAST OF PALAU. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A BROAD SLIGHTLY OBSCURED LOW LEVEL CIRCULATION CENTER (LLCC) WITH PERSISTENT CONVECTIVE FLARING ON THE NORTHERN PERIPHERY RESPECTIVELY. ENVIRONMENTAL ANALYSIS SHOWS FAVORABLE CONDITIONS FOR FURTHER DEVELOPMENT OF INVEST 95W WITH WARM (29-30C) SST, WEAK UPPER LEVEL OUTFLOW DUE TO THE DOMINANT PRESENCE OF TY 05W, AND LOW TO MODERATE (15-20KTS) VWS. DETERMINISTIC MODEL GUIDANCE SHOWS POOR AGREEMENT ON DEVELOPMENT CYCLE OF 95W WITH GFS AND NAVGEM SHOWING DISTURBANCE STRENGTH BY TAU 60 WHILE ECMWF LEANING MORE ON THE LOWER SIDE WITH JUST TROUGHING, BUT THERE IS STILL HOPE WITH ALL AGREEING ON A RELATIVELY NORTHWESTWARD TRACK SIMILAR TO 05W. GEFS AND ECENS ENSEMBLES SHOW STRONG MEMBER SIGNATURES THROUGHOUT WITH GOOD AGREEMENT ON A NORTHWESTWARD TRACK AS WELL. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 13 TO 18 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1007 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS LOW.

DETERMINISTIC MODEL GUIDANCE SHOWS POOR AGREEMENT ON DEVELOPMENT CYCLE OF 95W WITH GFS AND NAVGEM SHOWING DISTURBANCE STRENGTH BY TAU 60 WHILE ECMWF LEANING MORE ON THE LOWER SIDE WITH JUST TROUGHING, BUT THERE IS STILL HOPE WITH ALL AGREEING ON A RELATIVELY NORTHWESTWARD TRACK SIMILAR TO 05W. GEFS AND ECENS ENSEMBLES SHOW STRONG MEMBER SIGNATURES THROUGHOUT WITH GOOD AGREEMENT ON A NORTHWESTWARD TRACK AS WELL.

GTH Outlook Discussion Last Updated - 07/23/24 Valid - 07/31/24 - 08/13/24 The Madden Julian Oscillation (MJO) has remained weak since June, staying within the RMM-based unit circle aside from occasional short bursts of activity. Destructive interference with enhanced equatorial Rossby Wave activity has resulted in reduced MJO amplification across the Eastern Hemisphere. Despite this, the global upper-level velocity potential pattern is more organized and resembles a wave-1 asymmetry. Anomalous upper-level divergence is noted across much of Asia and the Pacific, with anomalous convergence over the Americas and Atlantic. Dynamical models predict the MJO to remain weak, although some convective enhancement across the Western Hemisphere is depicted by week-2 in several GEFS and ECMWF ensemble members tied to a Convectively-Coupled Kelvin Wave (CCKW). Tropical Cyclone (TC) activity has increased across the Western Pacific with 2 TCs developing on 7/20, Typhoon Gaemi to the east of the Philippines, and Tropical Storm Prapiroon over the South China Sea. The prevailing pattern favors increased tropical cyclone (TC) activity to continue over the Western Pacific, and expand into the Eastern Pacific. A 20-40 percent chance for TC development is posted across the Western Pacific for week-2, and is shifted northward and eastward compared to current activity. For the Eastern Pacific, the National Hurricane Center is highlighting 2 disturbances for potential TC development in week-1 (20 and 30 percent chances), and several 0z GEFS and ECMWF ensemble members depict continued TC activity in week-2 as the convective environment aloft becomes more favorable due to the aforementioned CCKW. Therefore, a 40-60 percent chance for TC formation is highlighted across the basin in week-2, decreasing to 20-40 percent in week-3. The uptick in TC activity in the Eastern Pacific may spread into the Atlantic as well, although tools are not as robust. However, given the increasing climatology and anomalously warm sea surface temperatures (SSTs), it is plausible that TC development could occur following a quiet period for the better part of July. For week-2, some ECMWF ensemble members depict TC development across the western Atlantic or northern Caribbean, with the GEFS not showing any signal. However, an increasing wave train off of Africa and an increasingly favorable environment support having a 20-40 percent chance of TC formation across the western Atlantic for week-2, with the highlighted area more focused on the Main Development Region during week-3.

The precipitation outlook for weeks 2 and 3 is based on potential TC activity, the anticipated state of El Nino and the MJO, and informed by GEFS, CFSv2 and ECMWF ensemble mean solutions. Enhanced rainfall is forecast across parts of the Eastern Pacific and Central America during weeks 2 and 3, with increased chances for below-normal rainfall over northern South America and the equatorial Atlantic. Above-normal rainfall is favored over parts of southeastern Asia and the western Pacific during week-2, but a shifting convective pattern favors decreasing chances in week-3 with some areas becoming more favored to have below-normal rainfall. Above-normal temperatures along with excessive heat conditions are forecast over much of the continental U.S. during early August.