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Tropical Depression NINETEEN-E Forecast Discussion Number 1
2016-09-26 16:45:18| National Hurricane Center (East Pacific)
Issued at 800 AM PDT MON SEP 26 2016 000 WTPZ44 KNHC 261445 TCDEP4 TROPICAL DEPRESSION NINETEEN-E DISCUSSION NUMBER 1 NWS NATIONAL HURRICANE CENTER MIAMI FL EP192016 800 AM PDT MON SEP 26 2016 Scatterometer data from around 0600 UTC indicated that the area of low pressure located near 140W had a well-defined circulation, with peak reliable wind vectors of 28 kt. Deep convection associated with this system has since become much better organized. Satellite classifications are T2.0 and T2.5, and the low is designated as a tropical depression based on these satellite data. Light northwesterly shear, warm waters of around 28 deg C and an increasingly diffluent flow aloft over the cyclone support intensification during the next 2 to 3 days. The large divergence expected over the depression is related to a mid-level cyclone seen in water vapor imagery near 18N 140W that is forecast to retrograde. The only negative factor is marginal mid-level moisture that is forecast to decrease further. Once the system gains sufficient latitude after 72 hours, it is likely to become vulnerable to much stronger westerly flow aloft. In fact, with 30 to 40 kt of westerly shear forecast over the cyclone by day 4, rapid weakening should occur, and the system is forecast to be a remnant low by that time. The NHC intensity forecast is a blend of the statistical and dynamical guidance through 72 hours and is below both sets of output after that time. The low was moving just south of due west during the last 24 hours, but appears to have recently turned toward the northwest. Given the sudden change in heading, the initial motion estimate of 305/04 is rather uncertain. Global models show the cyclone turning northward within 24 hours and then moving north-northeastward after that for the next few days while it rotates around the mid-level low to the northwest of the cyclone. Once the cyclone weakens appreciably after 72 hours, a turn toward the west is likely when the remnant low is steered by the trade wind flow. The NHC track forecast is a left of the multi-model consensus, close to a consensus without the GFDL model. FORECAST POSITIONS AND MAX WINDS INIT 26/1500Z 11.6N 139.6W 30 KT 35 MPH 12H 27/0000Z 12.0N 139.8W 40 KT 45 MPH 24H 27/1200Z 12.8N 139.5W 45 KT 50 MPH 36H 28/0000Z 13.6N 138.8W 50 KT 60 MPH 48H 28/1200Z 14.4N 138.2W 55 KT 65 MPH 72H 29/1200Z 16.1N 138.0W 50 KT 60 MPH 96H 30/1200Z 17.2N 139.5W 35 KT 40 MPH...POST-TROP/REMNT LOW 120H 01/1200Z 17.3N 142.3W 20 KT 25 MPH...POST-TROP/REMNT LOW $$ Forecaster Kimberlain
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