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Tropical Depression Nine-E Forecast Discussion Number 1
2021-07-30 22:37:29| National Hurricane Center (East Pacific)
Issued at 200 PM PDT Fri Jul 30 2021 000 WTPZ44 KNHC 302037 TCDEP4 Tropical Depression Nine-E Discussion Number 1 NWS National Hurricane Center Miami FL EP092021 200 PM PDT Fri Jul 30 2021 An area of low pressure that NHC has been monitoring during the past several days over the eastern Pacific, has developed a well-defined surface center, as indicated in a recent scatterometer overpass, and has acquired sufficient organized convection to be classified as a 25-kt tropical depression. The northwesterly shear which has been curtailing genesis over the past couple of days has diminished just enough to allow the system to become better organized, particularly, in the east and south portions of the cyclone. The depression is embedded in weak easterly steering currents created by a deep-layer cut-off low and associated trough situated along 125W. As a result, the depression is temporarily drifting west-southwestward, or 255/4 kt. Large-scale models indicate that the cut-off feature will lift northward during the next 24-36 hours allowing a mid-tropospheric ridge to build in over the eastern Pacific. Accordingly, the cyclone should track generally westward at an increased forward speed beyond mid period. The official forecast follows suit and is based on a blend of the top forecast track performers, HFIP Corrected Consensus Approach (HCCA) and the multi-model consensus TVCN. Now that the shear is weakening and the upper tropospheric winds are predicted to become more favorable, (easterly, and little more diffluent) steady strengthening is expected while the cyclone traverses deep, warm oceanic temperatures. The NHC intensity forecast is near the HFIP Corrected Consensus Approach (HCCA) and the IVCN intensity aid and is below the Decay-SHIPS statistical-dynamical guidance beyond the 72-hour period. FORECAST POSITIONS AND MAX WINDS INIT 30/2100Z 12.3N 125.8W 25 KT 30 MPH 12H 31/0600Z 12.0N 126.4W 30 KT 35 MPH 24H 31/1800Z 11.7N 126.9W 30 KT 35 MPH 36H 01/0600Z 11.7N 127.9W 35 KT 40 MPH 48H 01/1800Z 11.8N 129.5W 35 KT 40 MPH 60H 02/0600Z 12.1N 131.1W 40 KT 45 MPH 72H 02/1800Z 12.5N 132.6W 40 KT 45 MPH 96H 03/1800Z 13.2N 135.8W 45 KT 50 MPH 120H 04/1800Z 13.9N 138.9W 50 KT 60 MPH $$ Forecaster Roberts
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