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Post-Tropical Cyclone Eleven-E Forecast Discussion Number 6
2017-08-05 22:37:49| National Hurricane Center (East Pacific)
Issued at 300 PM MDT Sat Aug 05 2017 000 WTPZ41 KNHC 052037 TCDEP1 Post-Tropical Cyclone Eleven-E Discussion Number 6 NWS National Hurricane Center Miami FL EP112017 300 PM MDT Sat Aug 05 2017 The center of the cyclone has been devoid of deep convection for most of the day. A few convective bursts located well to the west and northwest of the center have been observed periodically during the afternoon, but they are probably not contributing to the maintenance of the circulation, and do not meet the criteria of organized deep convection for a tropical cyclone. On that basis, the cyclone has been declared a remnant low and this is the last advisory. For additional information on the remnant low please see High Seas Forecasts issued by the National Weather Service, under AWIPS header NFDHSFEPI, WMO header FZPN02 KWBC, and on the web at http://www.opc.ncep.noaa.gov/shtml/NFDHSFEPI.shtml. A pair of ASCAT passes around 1636 and 1722 UTC showed max winds of about 25 kt, so the initial intensity has been set to that value. The 1722 ASCAT-A pass also indicated that the circulation may already be opening into a trough. The remnants should continue to gradually spin down over the next day or so before dissipating entirely within about 36 hours, if not sooner, as shown by the ECMWF, GFS, and SHIPS models. The post-tropical cyclone has continued to move a little right of the forecast track, perhaps due to the lack of deep convection that could have forced it farther west with the mid- to upper-level flow. Instead, it should continue to be steered by the weak low-level flow, generally north-northwestward or northwestward, until dissipation. FORECAST POSITIONS AND MAX WINDS INIT 05/2100Z 20.3N 111.7W 25 KT 30 MPH...POST-TROPICAL 12H 06/0600Z 20.9N 112.1W 25 KT 30 MPH...POST-TROP/REMNT LOW 24H 06/1800Z 21.2N 112.3W 20 KT 25 MPH...POST-TROP/REMNT LOW 36H 07/0600Z...DISSIPATED $$ Forecaster Zelinsky
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Tropical Depression Eleven-E Forecast Discussion Number 5
2017-08-05 16:38:16| National Hurricane Center (East Pacific)
Issued at 900 AM MDT Sat Aug 05 2017 000 WTPZ41 KNHC 051438 TCDEP1 Tropical Depression Eleven-E Discussion Number 5 NWS National Hurricane Center Miami FL EP112017 900 AM MDT Sat Aug 05 2017 The tropical depression lost most of its deep convection overnight, but a small burst near the center has occurred this morning. Since that time, the center has become again nearly devoid of convection, but I can't yet rule out that one more burst could occur later today. The intensity has been held at 30 kt, based on earlier ASCAT data, but this could be generous given the lack of convection. No change has been made to the intensity forecast. Vertical wind shear remains high, and cloud-drift winds from GOES-W indicate that upper-level winds near the depression are between 40 and 50 kt from the east-northeast. The upper-level winds are not expected to lessen, and the available moisture should decrease steadily as the depression moves farther away from its parent disturbance and into a much drier environment. Combined, these factors should cause the depression to become a remnant low as early as this afternoon. The forward speed of the depression has slowed since the circulation is mostly limited to the low levels, and the initial motion estimate is 325/7 kt. During the overnight hours that the cyclone lacked deep convection, it moved slowly north or north-northwestward, so the track has been shifted to the right. Otherwise, no significant changes to the track forecast were required, and the cyclone, or its remnants, should be steered generally northwestward in light low-level steering flow until dissipation. FORECAST POSITIONS AND MAX WINDS INIT 05/1500Z 19.6N 111.3W 30 KT 35 MPH 12H 06/0000Z 20.2N 111.9W 25 KT 30 MPH...POST-TROP/REMNT LOW 24H 06/1200Z 20.8N 112.3W 25 KT 30 MPH...POST-TROP/REMNT LOW 36H 07/0000Z 21.0N 112.5W 20 KT 25 MPH...POST-TROP/REMNT LOW 48H 07/1200Z...DISSIPATED $$ Forecaster Zelinsky
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Tropical Depression Eleven-E Forecast Discussion Number 4
2017-08-05 10:34:12| National Hurricane Center (East Pacific)
Issued at 300 AM MDT Sat Aug 05 2017 000 WTPZ41 KNHC 050834 TCDEP1 Tropical Depression Eleven-E Discussion Number 4 NWS National Hurricane Center Miami FL EP112017 300 AM MDT Sat Aug 05 2017 The center of the depression moved over Socorro Island, Mexico between 0400 and 0500 UTC. A Mexican Navy automatic weather station located in that island reported a well defined wind shift associated with the circulation and 20 to 25 kt winds in gusts. A recent ASCAT pass shows a few vectors of 30 kt, and this will be the intensity in this advisory. The depression has been decapitated by strong upper-level easterly winds, and the low-level and mid-level centers are now separated by at least 230 n mi. There are only a few patches of deep convection left. Since the shear environment is forecast to persist or even increase, the NHC forecast calls for the depression to become a remnant low in about 12 hours or so. The low-level swirl associated with the center of the depression is moving toward the northwest or 315 degrees at 8 kt around the periphery of a subtropical ridge. Since no changes in the steering pattern is forecast by global models, this general motion is expected to continue until dissipation in a day or so. FORECAST POSITIONS AND MAX WINDS INIT 05/0900Z 19.2N 111.4W 30 KT 35 MPH 12H 05/1800Z 20.0N 112.3W 25 KT 30 MPH...POST-TROP/REMNT LOW 24H 06/0600Z 20.6N 112.8W 25 KT 30 MPH...POST-TROP/REMNT LOW 36H 06/1800Z 21.2N 113.3W 20 KT 25 MPH...POST-TROP/REMNT LOW 48H 07/0600Z...DISSIPATED $$ Forecaster Avila
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Tropical Depression Eleven-E Forecast Discussion Number 3
2017-08-05 04:34:46| National Hurricane Center (East Pacific)
Issued at 900 PM MDT Fri Aug 04 2017 000 WTPZ41 KNHC 050234 TCDEP1 Tropical Depression Eleven-E Discussion Number 3 NWS National Hurricane Center Miami FL EP112017 900 PM MDT Fri Aug 04 2017 The tropical depression is displaying a well-defined center of circulation east of decaying cold cloud tops as shown in the beautiful 1-minute experimental visible imagery from the new GOES-16 satellite. Dvorak classifications from TAFB and SAB - along with the character of the tight center - suggest that the maximum winds remain about 30 kt. However, the exposed center of this system is symptomatic of a highly sheared environment due to the 30 kt upper-level easterlies impinging upon Eleven-E. These shearing winds should not relent as a strong mid- to upper-level ridge over northwestern Mexico will remain in place. Additionally, the tropical depression will be moving into increasingly dry and stable air. The system should lose all deep convection and become a remnant low in a day or two, which is in agreement with all dynamical and statistical guidance. Eleven-E is moving toward the west-northwest at 11 kt, mainly due to the aforementioned ridge to its north. As the tropical depression loses its deep convection and becomes a shallow vortex, it should drift slowly northwestward or northward in weak low-level flow. The official track forecast is adjusted to the right (northeastward) of the previous advisory and is based upon the HCCA corrected consensus technique. FORECAST POSITIONS AND MAX WINDS INIT 05/0300Z 18.6N 111.0W 30 KT 35 MPH 12H 05/1200Z 19.3N 112.1W 30 KT 35 MPH 24H 06/0000Z 20.3N 113.0W 25 KT 30 MPH 36H 06/1200Z 20.9N 113.5W 20 KT 25 MPH...POST-TROP/REMNT LOW 48H 07/0000Z 21.3N 113.6W 20 KT 25 MPH...POST-TROP/REMNT LOW 72H 08/0000Z...DISSIPATED $$ Forecaster Landsea
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Tropical Depression Eleven-E Forecast Discussion Number 2
2017-08-04 22:39:39| National Hurricane Center (East Pacific)
Issued at 300 PM MDT Fri Aug 04 2017 000 WTPZ41 KNHC 042039 TCDEP1 Tropical Depression Eleven-E Discussion Number 2 NWS National Hurricane Center Miami FL EP112017 300 PM MDT Fri Aug 04 2017 The tropical depression remains strongly sheared from the northeast. Since the last advisory, small vortices have been seen rotating around a larger/primary center that has reformed or consolidated a little closer to the convection. Due to this relocation, Dvorak intensity estimates from both TAFB and SAB have increased to 30 kt. Since there are no in-situ or scatterometer observations available, the initial intensity has been raised accordingly, to 30 kt. There has been no change to the intensity forecast reasoning, and there are still no models that show the cyclone becoming a tropical storm. Based on GFS and ECMWF SHIPS diagnostics, the 850-200 mb shear should increase to near 30 kt by tomorrow, accompanied by a sharp decrease in available moisture. Based primarily on the HWRF and ECMWF models, the forecast calls for Eleven to become a remnant low by 48 h and dissipate by 96 h. Given the hostile environment, it is possible that weakening could occur even quicker, as depicted by the GFS and experimental HMON. The track forecast has been shifted to the west for the first 12 hours due to the relocation of the center in that direction. Other than that, very little change has been made to the official track forecast. The global models remain in good agreement that the depression will continue generally west-northwestward, steered by the low- to mid-level steering flow associated with the ridge to the northeast. Since the low-level winds are weak, the depression should slow substantially before it dissipates. FORECAST POSITIONS AND MAX WINDS INIT 04/2100Z 18.0N 110.2W 30 KT 35 MPH 12H 05/0600Z 18.7N 111.6W 30 KT 35 MPH 24H 05/1800Z 19.5N 112.8W 30 KT 35 MPH 36H 06/0600Z 20.2N 113.6W 25 KT 30 MPH 48H 06/1800Z 20.6N 114.1W 20 KT 25 MPH...POST-TROP/REMNT LOW 72H 07/1800Z 20.8N 114.5W 20 KT 25 MPH...POST-TROP/REMNT LOW 96H 08/1800Z...DISSIPATED $$ Forecaster Zelinsky
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