Issued at 1100 PM AST Thu Aug 14 2025
525 WTNT45 KNHC 150250 TCDAT5 Tropical Storm Erin Discussion Number 15 NWS National Hurricane Center Miami FL AL052025 1100 PM AST Thu Aug 14 2025 Erin has intensified tonight. The first NOAA-P3 reconnaissance mission into the storm found that the center was a little more embedded in the deep convection than earlier with a compact wind field particularly strong on the eastern flank. Tail Doppler Radar data from the aircraft indicated the center is starting to become better aligned, though some residual southward tilt with height still exists, which can also be seen on a 2339 UTC GMI microwave pass. In the most recent leg, peak 700-mb flight level winds from the NOAA aircraft were 69 kt in the northeast quadrant. This value reduces to surface wind near 60 kt, just shy of hurricane intensity. Erin is now starting to move west-northwestward at 285/15 kt. An extensive mid-level ridge stretched from off the eastern United States coast all the way to the eastern Atlantic remains in place helping to steer the storm generally west-northwestward for at least the next 2 to 3 days with it gradually slowing down. During this time-span, a mid-latitude trough moving into the northwestern Atlantic is expected to dig equatorward to the northeast of Bermuda, with another reinforcing shortwave moving into Atlantic Canada towards the end of the forecast period. These features should create a weakness in the subtropical ridge that Erin is expected to turn northwestward and north-northwestward into. The latest track guidance was quite similar to the prior cycle, just a little faster than before towards the end of the forecast period, and only small adjustments were made to the NHC forecast track. This track roughly splits the latest forecast from the Google Deep Mind (GDMI) and HCCA consensus aid. Still, there is a healthy amount of spread in the guidance and uncertainty remains about what impacts Erin may bring to portions of the Bahamas, the east coast of the United States, and Bermuda in the long range. With Erin's core structure improving this evening, the storm appears poised to intensify more quickly in the short term. Rapid intensification probabilities have increased in SHIPS guidance, with now a 38-40 percent chance of a 30 kt increase in the next 24 h. The environment continues to become more thermodynamically favorable, with Erin crossing into 28C and warmer sea-surface temperatures, and mid-level moisture increasing over the forecast time period. Thus, the NHC intensity forecast will show more intensification over the next 48-60 hours, and Erin is now forecast to become a major hurricane earlier and peak at 115 kt, category 4 intensity. After that time, there remains evidence in both SHIPS guidance and model fields that northwesterly vertical wind shear could increase over the system. In addition, there is a good chance Erin may begin to undergo inner-core structural changes, like eyewall replacement cycles, that could broaden its wind field but also cause its intensity to plateau. Thus, the NHC intensity forecast now shows some gradual weakening after a peak intensity in 72 h, though the models show the wind radii expanding quite dramatically in the day 3-5 period. The latest NHC intensity forecast is a little on the high side of the guidance, especially in the short-term, but ends up near the consensus aids HCCA and IVCN towards the end of the forecast period. KEY MESSAGES: 1. Heavy rainfall across the northernmost Leeward Islands, the U.S. and British Virgin Islands, as well as southern and eastern Puerto Rico, may lead to isolated flash and urban flooding, along with landslides or mudslides this weekend into early next week. 2. Tropical storm conditions are possible for portions of the northern Leeward Islands, where Tropical Storm Watches are in effect, beginning on Saturday as the core of Erin passes north of those islands. Tropical storm conditions could also occur in portions of the Virgin Islands and Puerto Rico later in the weekend, and additional watches may be required tonight or on Friday. 3. While there is still uncertainty in what impacts might occur in portions of the Bahamas, the east coast of the United States, and Bermuda next week, the risk of dangerous surf and rip currents across the western Atlantic basin next week continues to increase. FORECAST POSITIONS AND MAX WINDS INIT 15/0300Z 17.1N 52.7W 60 KT 70 MPH 12H 15/1200Z 17.8N 55.2W 70 KT 80 MPH 24H 16/0000Z 18.6N 58.3W 80 KT 90 MPH 36H 16/1200Z 19.4N 61.0W 90 KT 105 MPH 48H 17/0000Z 20.3N 63.3W 100 KT 115 MPH 60H 17/1200Z 21.3N 65.4W 110 KT 125 MPH 72H 18/0000Z 22.4N 67.0W 115 KT 130 MPH 96H 19/0000Z 25.0N 69.4W 110 KT 125 MPH 120H 20/0000Z 28.0N 70.4W 105 KT 120 MPH $$ Forecaster Papin