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Hurricane Jerry Forecast Discussion Number 15
2019-09-21 04:59:24| National Hurricane Center (Atlantic)
Issued at 1100 PM AST Fri Sep 20 2019 000 WTNT45 KNHC 210259 TCDAT5 Hurricane Jerry Discussion Number 15 NWS National Hurricane Center Miami FL AL102019 1100 PM AST Fri Sep 20 2019 Jerry has been displaying a classic bursting convective pattern with a nearly circular CDO that expanded over the circulation since the last advisory. An Air Force Hurricane Hunter mission that just arrived in Jerry indicated that the center is farther northeast than previously estimated, which appears coincident with the location of the most recent bursts of convection. Since subjective and objective Dvorak intensity estimates range from 61 kt to 77 kt, the initial intensity remains 70 kt. This intensity could be adjusted based on what the plane finds while investigating the circulation. The central pressure is estimated to be 993 mb based on the center drop from the plane. The hurricane is still moving quickly west-northwestward with an initial motion of 295/15 kt. The track forecast is fairly straightforward. Jerry is approaching a break in the subtropical ridge, created by a deep-layer trough currently moving across the northwestern Atlantic. This pattern is expected to cause Jerry to gradually recurve around the ridge during the next 5 days, with its forward motion reaching a minimum between 48-72 hours when it moves near the ridge axis. There is very good agreement among the track guidance on this scenario, and the only notable spread is related to the system's forward speed when it accelerates on day 5. The consensus aids are holding tough on a relatively consistent trajectory, so little change was made from the previous official forecast. Dropsonde data from a NOAA G-IV synoptic surveillance mission indicate that anticyclonic flow continues over the hurricane at the 200-mb outflow level (except it's restricted a bit to the west), but 15-25 kt of northeasterly flow is cutting through the circulation just below 250 mb. Despite this flow, Jerry's structure does not appear to have degraded too much. Since the hurricane appears that it will move beneath an upper-level anticyclone in about 24 hours, its intensity may not decrease too much over the next several days. And despite an increase in westerly shear after 48 hours, enhanced upper-level divergence to the east of an upper-level trough could offset the potential for weakening. Accounting for uncertainties, the NHC intensity forecast maintains a fairly steady strength for the entire forecast period, keeping Jerry as a hurricane for the next 5 days. This forecast is close to the HCCA model and the simple consensus aids, but it's notable that it's up to 20 kt lower than the statistical-dynamical models by the end of the forecast period. Key Messages: 1. Although the core of Jerry is passing north of the northern Leeward Islands, heavy rainfall and flash floods are possible there overnight. FORECAST POSITIONS AND MAX WINDS INIT 21/0300Z 20.5N 62.8W 70 KT 80 MPH 12H 21/1200Z 21.4N 64.4W 65 KT 75 MPH 24H 22/0000Z 22.6N 66.6W 65 KT 75 MPH 36H 22/1200Z 24.0N 68.1W 65 KT 75 MPH 48H 23/0000Z 25.3N 68.7W 70 KT 80 MPH 72H 24/0000Z 27.9N 68.2W 70 KT 80 MPH 96H 25/0000Z 30.8N 66.3W 65 KT 75 MPH 120H 26/0000Z 34.5N 62.1W 65 KT 75 MPH $$ Forecaster Berg
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