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Tropical Depression IDA Forecast Discussion Number 34
2015-09-26 22:32:52| National Hurricane Center (Atlantic)
Issued at 500 PM AST SAT SEP 26 2015 000 WTNT45 KNHC 262032 TCDAT5 TROPICAL DEPRESSION IDA DISCUSSION NUMBER 34 NWS NATIONAL HURRICANE CENTER MIAMI FL AL102015 500 PM AST SAT SEP 26 2015 There continues to be little change associated with Ida. A small area of pulsing convection is lingering to the east of the exposed low-level center. The circulation remains well organized, however, and mainly consists of a swirl of low-level clouds. Earlier ASCAT data indicated that winds were in the 25-30 kt range, and since the cyclone has not changed much since then, the initial intensity is held at 30 kt. The models are quite divergent on the future intensity of Ida. The SHIPS model suggests that the depression could strengthen since the shear is expected to lessen during the next 2-3 days. Conversely, most of the dynamical models show little, if any, strengthening likely due in part to the abundant dry air near the cyclone. In fact, the latest runs of the GFS and ECMWF models show Ida's circulation becoming elongated or degenerating into a trough within the next few days when a frontal boundary stalls just to the north of the system. The official forecast follows the previous couple of advisories in maintaining Ida as a depression through the period, however, it would not be surprising if Ida dissipates before then like the GFS and ECMWF models suggest. Ida is gradually turning to the left as predicted, and the latest initial motion estimate is now 320/7 kt. A continued turn toward the west and then southwest is predicted during the next couple of days as a low- to mid-level ridge builds to the north of the cyclone. Thereafter, Ida, or its remnants, is expected to move generally westward at a slightly faster forward speed. Although there remains some spread in the guidance, most of the models agree on this general theme. The new official track forecast is a little faster than the previous one and remains close to the consensus aids. FORECAST POSITIONS AND MAX WINDS INIT 26/2100Z 24.4N 47.1W 30 KT 35 MPH 12H 27/0600Z 24.8N 47.7W 30 KT 35 MPH 24H 27/1800Z 24.6N 48.5W 30 KT 35 MPH 36H 28/0600Z 24.1N 49.6W 30 KT 35 MPH 48H 28/1800Z 23.6N 51.4W 30 KT 35 MPH 72H 29/1800Z 23.4N 55.8W 30 KT 35 MPH 96H 30/1800Z 23.9N 58.9W 25 KT 30 MPH 120H 01/1800Z 24.2N 61.0W 25 KT 30 MPH $$ Forecaster Cangialosi
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