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Post-Tropical Cyclone Octave Forecast Discussion Number 9
2019-10-19 22:39:43| National Hurricane Center (East Pacific)
Issued at 200 PM PDT Sat Oct 19 2019 000 WTPZ43 KNHC 192039 TCDEP3 Post-Tropical Cyclone Octave Discussion Number 9 NWS National Hurricane Center Miami FL EP182019 200 PM PDT Sat Oct 19 2019 Deep convection has not returned, now being absent for at least 12 hours. The environment around Octave is dry and stable, and it is unlikely that significant convection will come back any time soon. Octave has therefore become a remnant low, and its maximum winds are estimated to be 30 kt based on recent scatterometer data. The remnant low is expected to linger for at least the next 5 days with its intensity holding steady or decreasing due to moderate southeasterly shear and mid-level relative humidities of 30-40 percent. The initial motion remains very slowly east-northeastward, or 070/2 kt. The remnant low is trapped in a weak steering regime, and it is expected to meander for the next 5 days, only moving a net distance of 50-100 n mi during that period. A slight westward adjustment was made to this last NHC official forecast to account for the latest multi-model consensus aids and the ECMWF, which lies along the western edge of the guidance envelope. FORECAST POSITIONS AND MAX WINDS INIT 19/2100Z 11.6N 125.7W 30 KT 35 MPH...POST-TROPICAL 12H 20/0600Z 11.4N 125.7W 25 KT 30 MPH...POST-TROP/REMNT LOW 24H 20/1800Z 11.1N 125.7W 25 KT 30 MPH...POST-TROP/REMNT LOW 36H 21/0600Z 10.8N 125.7W 25 KT 30 MPH...POST-TROP/REMNT LOW 48H 21/1800Z 10.9N 125.7W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 22/1800Z 11.7N 125.8W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 23/1800Z 12.4N 125.4W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 24/1800Z 12.0N 124.6W 20 KT 25 MPH...POST-TROP/REMNT LOW $$ Forecaster Berg
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Post-Tropical Cyclone Nestor Forecast Discussion Number 9
2019-10-19 16:58:40| National Hurricane Center (Atlantic)
Issued at 1000 AM CDT Sat Oct 19 2019 000 WTNT41 KNHC 191458 TCDAT1 Post-Tropical Cyclone Nestor Discussion Number 9 NWS National Hurricane Center Miami FL AL162019 1000 AM CDT Sat Oct 19 2019 Nestor has made the transition to a post-tropical extratropical cyclone. There has been no significant convection near the low-level center for more than six hours, and satellite and surface observations indicate that the cyclone's center has merged with a nearby frontal system that lies along the coast of the Florida panhandle. The overall cloud pattern more closely resembles that of an occluded low pressure system now, including a pre-frontal squall line or convergence zone a few hundred nmi east of the low. Sustained tropical-storm-force winds with gusts to near 50 kt have been reported by some of the buoys and coastal marine stations over the northeastern Gulf of Mexico during the past few hours. The initial intensity of 45 kt is based on Doppler velocity values of 50-55 kt between 4000-6000 ft ASL located over Apalachee Bay, which approximately equals surface winds of 40-44 kt. The now well-defined low-level center made a brief jog toward the northwest early this morning as an upper-level low passed over the larger cyclonic gyre. However, the motion since that time has been slowly eastward, and the initial motion estimate is now east-northeastward or 075/08 kt. Despite the earlier erratic motion, the latest NHC track model guidance remains in very good agreement on post-tropical Nestor moving northeastward and accelerating over the next 36 hours or so, followed by a turn toward the east once the cyclone reaches the North Carolina Outer Banks. By 48 hours, the parent upper-level low is expected to weaken and open up into a shortwave trough, and leave Nestor behind as a weakening extratropical cyclone that dissipates by 96 h east of the U.S. east coast. The new official forecast track was only nudged a little to the west of the previous advisory due to the more westward initial position, and lies close to an average of the deterministic 0000 UTC and 0600Z GFS, ECMWF, and UKMET model runs. No strengthening is anticipated before Nestor moves inland later this afternoon. Some slight weakening will occur after the center moves inland, but gale-force winds are expected develop over the Atlantic waters of northeastern Florida to the Carolinas this afternoon and tonight, and across the mid-Atlantic U.S. coastal waters on Sunday. The extratropical cyclone is expected to dissipate or merge with a cold front in about 4 days or sooner. Given the non-tropical structure of Nestor, dangerous storm surge and tropical-storm-force and gale-force winds will occur along a large portion of the Florida Gulf Coast well east of the track of Nestor's center today. Key Messages: 1. There is a danger of life-threatening storm surge inundation of up to 4 feet above ground level along the Florida Gulf Coast from Indian Pass to Clearwater Beach, where a Storm Surge Warning is in effect. Residents in these areas should follow advice given by local officials. 2. Tropical storm force winds will continue across portions of the Florida Gulf Coast, where tropical storm warnings are in effect. Regardless of the exact track and intensity of the system, these winds will cover a large area, especially east of the center. 3. Isolated flash flooding is possible across the southeastern United States into Sunday morning. 4. Wind and coastal flooding hazards along the U.S. East Coast will be covered by non-tropical watches and warnings issued by local NWS offices, since the system is expected to lose its tropical characteristics after it moves inland along the Gulf Coast. FORECAST POSITIONS AND MAX WINDS INIT 19/1500Z 29.3N 86.3W 45 KT 50 MPH...POST-TROP/EXTRATROP 12H 20/0000Z 31.0N 83.5W 35 KT 40 MPH...POST-TROP/EXTRATROP 24H 20/1200Z 34.1N 79.5W 40 KT 45 MPH...POST-TROP/EXTRATROP 36H 21/0000Z 36.0N 75.1W 40 KT 45 MPH...POST-TROP/EXTRATROP 48H 21/1200Z 36.6N 71.5W 40 KT 45 MPH...POST-TROP/EXTRATROP 72H 22/1200Z 36.4N 66.6W 35 KT 40 MPH...POST-TROP/EXTRATROP 96H 23/1200Z...DISSIPATED $$ Forecaster Stewart
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Tropical Depression Octave Forecast Discussion Number 8
2019-10-19 16:58:12| National Hurricane Center (East Pacific)
Issued at 800 AM PDT Sat Oct 19 2019 000 WTPZ43 KNHC 191458 TCDEP3 Tropical Depression Octave Discussion Number 8 NWS National Hurricane Center Miami FL EP182019 800 AM PDT Sat Oct 19 2019 Octave's last bit of deep convection dissipated about 6 hours ago, around 0900 UTC, leaving the cyclone as a swirl of low-level clouds. The maximum winds are still estimated to be 30 kt based mainly on the CI number from TAFB. Octave could still produce intermittent bursts of convection during the next several days, but increased shear and a dry air mass with mid-level relative humidities of 30-40 percent are likely to keep the activity from being persistent or well organized. If deep convection doesn't redevelop soon, then Octave would be declared a remnant low later today. The cyclone's maximum winds should decrease a little more in the short term, but the remnant low is likely to persist near the Intertropical Convergence Zone for the entire 5-day forecast period. Octave is moving slowly east-northeastward, or 070/2 kt. The depression is caught in a weak steering pattern, and it is likely to meander around for the next 5 days, never reaching speeds any higher than about 3 kt. No significant changes to the NHC track forecast were made from the previous advisory. FORECAST POSITIONS AND MAX WINDS INIT 19/1500Z 11.5N 125.9W 30 KT 35 MPH 12H 20/0000Z 11.6N 125.6W 25 KT 30 MPH...POST-TROP/REMNT LOW 24H 20/1200Z 11.3N 125.5W 25 KT 30 MPH...POST-TROP/REMNT LOW 36H 21/0000Z 10.9N 125.5W 25 KT 30 MPH...POST-TROP/REMNT LOW 48H 21/1200Z 10.8N 125.5W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 22/1200Z 11.4N 125.3W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 23/1200Z 12.5N 124.9W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 24/1200Z 12.6N 124.0W 20 KT 25 MPH...POST-TROP/REMNT LOW $$ Forecaster Berg
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Tropical Storm Nestor Forecast Discussion Number 8
2019-10-19 10:38:42| National Hurricane Center (Atlantic)
Issued at 400 AM CDT Sat Oct 19 2019 000 WTNT41 KNHC 190838 TCDAT1 Tropical Storm Nestor Discussion Number 8 NWS National Hurricane Center Miami FL AL162019 400 AM CDT Sat Oct 19 2019 Nestor is rapidly losing the few tropical characteristics that it once had. The cloud pattern consists of a large circulation of low clouds with a comma-shape convective band well to the east of the circulation. This band is already over a large portion of the Florida peninsula. The center of the system or the area of minimum pressure could be anywhere within this gyre, and the precise location is uncertain. Surrounding data and ASCAT measurements suggest that the winds have decreased to 45 kt. All indications are that no significant strengthening is anticipated before the broad circulation moves inland later today, and guidance suggests that Nestor will lose its tropical characteristics while moving across the southeastern United States. The weaker extratropical cyclone is expected to dissipate or merge with a cold front in about 4 days or sooner. Since the center is not well defined, the initial motion is highly uncertain. It appears that cyclone has slowed down but it should resume a motion toward northeast or 045 degrees at about 15 kt. Most of the track models are in good agreement that this general motion should continue, and the broad circulation will move inland over the Florida Panhandle later today and across portions of Georgia and the Carolinas later tonight and Sunday. Given the non-tropical appearance of Nestor, dangerous storm surge and tropical-storm-force winds will occur along a large portion of the Florida Gulf Coast well east of the track of Nestor's center today. Key Messages: 1. There is a danger of life-threatening storm surge inundation of up to 5 feet above ground level along the Florida Gulf Coast from Indian Pass to Clearwater Beach, where a Storm Surge Warning is in effect. Residents in these areas should follow advice given by local officials. 2. Tropical storm force winds are spreading across portions of the Florida Gulf Coast, where tropical storm warnings are in effect. Regardless of the exact track and intensity of the system, these winds will cover a large area, especially east of the center. 3. Isolated flash flooding is possible across the southeastern United States into Sunday morning. 4. Wind and coastal flooding hazards along the U.S. East Coast will be covered by non-tropical watches and warnings issued by local NWS offices, since the system is expected to lose its tropical characteristics after it moves inland along the Gulf Coast. FORECAST POSITIONS AND MAX WINDS INIT 19/0900Z 29.0N 86.0W 45 KT 50 MPH 12H 19/1800Z 30.7N 84.0W 35 KT 40 MPH 24H 20/0600Z 33.5N 80.0W 35 KT 40 MPH...POST-TROPICAL 36H 20/1800Z 36.0N 76.0W 35 KT 40 MPH...POST-TROP/EXTRATROP 48H 21/0600Z 37.0N 71.5W 35 KT 40 MPH...POST-TROP/EXTRATROP 72H 22/0600Z 37.5N 65.0W 35 KT 40 MPH...POST-TROP/EXTRATROP 96H 23/0600Z...DISSIPATED $$ Forecaster Avila
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Tropical Depression Octave Forecast Discussion Number 7
2019-10-19 10:37:06| National Hurricane Center (East Pacific)
Issued at 200 AM PDT Sat Oct 19 2019 000 WTPZ43 KNHC 190837 TCDEP3 Tropical Depression Octave Discussion Number 7 NWS National Hurricane Center Miami FL EP182019 200 AM PDT Sat Oct 19 2019 Dry air and southeasterly shear are taking their toll on Octave. Small bursts of intermittent convection continue to the northwest of Octave's center, and the lack of persistent deep convection over the center is causing the low to gradually spin down. The latest subjective Dvorak classification from TAFB suggests winds have decreased to 30 kt, with even lower intensity estimates from SAB and UW-CIMSS ADT. Given that the overnight scatterometer missed the system, and the fact it does take time to spin down these lows, the initial intensity is lowered generously to 30 kt. Octave will continue to be in a hostile environment with about 25 kt of southeasterly wind shear and in the presence very dry air for the next few days. This should prevent any deep convection from persisting over the cyclone long enough to maintain the current vortex. Thus, a gradual weakening trend should continue, and Octave may become a remnant low by tonight. Even after the system becomes a remnant low, there could be occasional development of convection. However, at this time it is not believed that this convection will be sufficient enough to cause the cyclone to regenerate. This remnant low is expected to persist through the end of the forecast period. Octave is drifting northeast and it should remain in a weak flow regime for the entire forecast period. The official NHC forecast shows a meandering motion for the next several days, and the forecast track lies near the various consensus aids. FORECAST POSITIONS AND MAX WINDS INIT 19/0900Z 11.5N 126.4W 30 KT 35 MPH 12H 19/1800Z 11.7N 126.0W 25 KT 30 MPH 24H 20/0600Z 11.6N 125.8W 25 KT 30 MPH...POST-TROP/REMNT LOW 36H 20/1800Z 11.2N 125.7W 25 KT 30 MPH...POST-TROP/REMNT LOW 48H 21/0600Z 11.0N 125.8W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 22/0600Z 11.7N 125.2W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 23/0600Z 12.4N 124.8W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 24/0600Z 13.0N 124.4W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Latto
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