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Tropical Depression NINETEEN-E Forecast Discussion Number 4
2015-10-15 22:36:32| National Hurricane Center (East Pacific)
Issued at 200 PM PDT THU OCT 15 2015 000 WTPZ44 KNHC 152036 TCDEP4 TROPICAL DEPRESSION NINETEEN-E DISCUSSION NUMBER 4 NWS NATIONAL HURRICANE CENTER MIAMI FL EP192015 200 PM PDT THU OCT 15 2015 Visible satellite images suggest that the depression is not very well organized. The circulation is still somewhat elongated, and the low-level center is located near the eastern edge of a cluster of deep convection. The convection itself also appears to have lost some organization since earlier today. The maximum winds remain 30 kt based on Dvorak CI numbers of 2.0 from TAFB and SAB. Even though environmental conditions appear conducive for strengthening, the depression is not in any hurry to intensify. The hurricane intensity models and the global models all insist that the depression will strengthen soon. However, the one prominent difference in this afternoon's model suite is that the ECMWF model does not deepen the cyclone for another 48 hours or so. Since most of the guidance intensifies the system through 5 days, the NHC intensity forecast remains consistent with the previous forecasts, making the cyclone a hurricane in about 2-3 days. This is also consistent with the latest intensity consensus. However, given the latest ECMWF run and the current structure of the depression, it's possible that intensification could be delayed. The initial motion is 265/11 kt. A mid-level ridge is steering the depression westward, and this motion is likely to continue for at least another 48 hours. After that time, the ridge is forecast to weaken and give way to a broad trough west of the Baja California peninsula. This should allow the cyclone to turn west-northwestward and then northwestward by day 5. Although the track models generally agree on this scenario, the system's weaker representation in the ECMWF during the first few days causes it to continue westward beyond 48 hours and make a more gradual turn compared to the other models. This now places the ECMWF closer to the UKMET model, which was the only outlier on the previous forecast cycle. Based on the new guidance, the NHC track forecast has been shifted westward and is a little bit slower than the previous forecast, especially at days 4 and 5. FORECAST POSITIONS AND MAX WINDS INIT 15/2100Z 10.1N 120.9W 30 KT 35 MPH 12H 16/0600Z 9.9N 122.8W 35 KT 40 MPH 24H 16/1800Z 9.9N 125.1W 45 KT 50 MPH 36H 17/0600Z 9.8N 127.0W 55 KT 65 MPH 48H 17/1800Z 9.9N 128.6W 65 KT 75 MPH 72H 18/1800Z 10.7N 131.3W 80 KT 90 MPH 96H 19/1800Z 12.5N 134.0W 85 KT 100 MPH 120H 20/1800Z 15.0N 137.0W 90 KT 105 MPH $$ Forecaster Berg
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