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Tropical Storm Pamela Forecast Discussion Number 7
2021-10-11 22:56:59| National Hurricane Center (East Pacific)
Issued at 300 PM MDT Mon Oct 11 2021 000 WTPZ41 KNHC 112056 TCDEP1 Tropical Storm Pamela Discussion Number 7 NWS National Hurricane Center Miami FL EP162021 300 PM MDT Mon Oct 11 2021 Entrainment of dry mid-level air along with some modest north-northwesterly mid-level shear has caused Pamela's low-level circulation to become slightly exposed just northwest of the somewhat ragged inner-core convection. Upper-level outflow, however, has improved in all quadrants, with a narrow equatorward outflow channel having developed in the eastern semicircle since the previous advisory. Pamela's intensity was increased to 60 kt at 1800 UTC based on satellite current-intensity estimates of T4.0/65 kt from TAFB and T3.7/59 kt from UW-CIMSS ADT. However, 60 kt might be a little generous at the 2100 UTC advisory time, given that the low-level center has recently become partially exposed. The motion estimate is northwestward or 320/06 kt. There is no significant change to the previous forecast track or reasoning. This current slow northwestward motion should continue this afternoon and evening as Pamela approaches the western periphery of a deep-layer subtropical ridge. Later tonight, the cyclone is expected to turn slowly northward, followed by a faster northeastward motion by Tuesday night as Pamela gets caught up in moderate southwesterly flow ahead of a deep-layer mid-latitude trough approaching from the northwest and west. This developing flow pattern is depicted quite well by all of the global and regional models, and should result in Pamela accelerating northeastward on Wednesday right up until the storm makes landfall along the west-central coast of Mexico. The new NHC forecast track has been shifted a little to the right again, and is close to the middle of the tightly packed TCVE, GFEX, NOAA-HCCA, and FSSE consensus track-model envelope. The global and regional models are in very good agreement that the current slight southeastward tilt to the vortex column should abate within the next 6 hours or so, along with the dry mid-level air mixing out. As a result, deep convection should re-fire near the center later tonight, resulting in the development of an eyewall, which will create the necessary chimney effect to allow Pamela to resume its earlier rapid intensification trend. In fact, all of the models now show strengthening right up until the cyclone makes landfall on Wednesday due to the upper-level outflow pattern expanding, along with the development of poleward and equatorward outflow channels by late Tuesday. The new official intensity forecast is basically the same as the previous advisory, and lies near the upper-end of the intensity guidance. Pamela is still expected to become a dangerous major hurricane prior to landfall. After landfall occurs, rapid weakening is forecast due to the cyclone moving over the rugged terrain of west-central Mexico. However, the higher elevations of north-central Mexico could still receive tropical-storm force winds after Pamela moves well inland. Furthermore, deep moisture associated with Pamela will gradually overspread much of north-central and northeastern Mexico late on Wednesday, and then move into southern and central Texas on Thursday, enhancing the rainfall potential in those areas. An Air Force Reserve Hurricane Hunter aircraft is scheduled to investigate Pamela on Tuesday during the late morning and early afternoon to provide a better estimate of the cyclone's intensity. Key Messages: 1. Pamela is forecast to be a major hurricane when it reaches the coast of west-central mainland Mexico on Wednesday, and life-threatening storm surge and dangerous hurricane-force winds are possible within the Hurricane Watch area. Residents in this area should monitor the progress of Pamela and follow any advice given by local officials. 2. Pamela is expected to pass near or south of the southern tip of the Baja California peninsula as a hurricane Tuesday night and early Wednesday, and tropical-storm conditions are possible within the Tropical storm Watch area. 3. Heavy rains associated with Pamela are expected to move into the Mexican States of Sinaloa and western Durgano along with southern portions of Baja California Sur Tuesday and Wednesday. This will pose a threat of significant and life-threatening flash flooding and mudslides. 4. Heavy rains associated with Pamela are expected across portions of central Texas and southeastern Oklahoma late Wednesday and Thursday. This may result in flash and urban flooding. FORECAST POSITIONS AND MAX WINDS INIT 11/2100Z 17.2N 108.5W 60 KT 70 MPH 12H 12/0600Z 18.3N 109.0W 70 KT 80 MPH 24H 12/1800Z 20.0N 108.9W 85 KT 100 MPH 36H 13/0600Z 22.0N 107.8W 100 KT 115 MPH 48H 13/1800Z 24.3N 105.8W 45 KT 50 MPH...INLAND 60H 14/0600Z 27.4N 102.1W 30 KT 35 MPH...POST-TROP/INLAND 72H 14/1800Z 31.2N 97.7W 20 KT 25 MPH...POST-TROP/INLAND 96H 15/1800Z...DISSIPATED INLAND $$ Forecaster Stewart
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Tropical Storm Pamela Forecast Discussion Number 6
2021-10-11 17:13:22| National Hurricane Center (East Pacific)
Issued at 900 AM MDT Mon Oct 11 2021 000 WTPZ41 KNHC 111513 CCA TCDEP1 Tropical Storm Pamela Discussion Number 6...Corrected NWS National Hurricane Center Miami FL EP162021 900 AM MDT Mon Oct 11 2021 Corrected to update Key Messages Pamela's convective pattern has undergone a pronounced bursting phase since the previous advisory, including significant lightning activity in the inner-core region near the center, with formation of a Central Dense Overcast (CDO) now evident. However, the lightning ceased about 5 h ago and the CDO has recently become a little disheveled looking along with pronounced warming of the cloud tops compared to the much colder cloud tops colder than -85C just a few hours ago. The advisory intensity has been increased to 55 kt based on an average of satellite intensity estimates of T4.0/65 from TAFB, T3.0/45 kt from SAB, and T3.5/55 kt from UW-CIMSS ADT. Pamela has slowed down significantly since the previous advisory, and the motion estimate is now northwestward or 320/07 kt. A northwestward motion should continue today as Pamela approaches an east-to-west-oriented subtropical ridge axis situated along 19-20N latitude. By late tonight, the storm is forecast to turn slowly northward, followed by a motion toward the northeast at a faster forward speed by Tuesday night. As Pamela gets caught up in the moderate southwesterly flow between the subtropical ridge to its south and an approaching mid-latitude trough to the northwest, the cyclone should continue to accelerate northeastward on Wednesday until Pamela makes landfall along the southwest coast of Mexico. The new NHC forecast track is a tad to the right of and slightly faster than the previous advisory track, and close to the middle of the tightly packed simple- and corrected-consensus track model envelope. The recent disruption in Pamela's convective pattern has likely been due the cyclone having entrained a slug of dry air. However, this convective hiatus will likely be short-lived due to the robust inner-core wind field noted in earlier ASCAT wind data, which should allow for Pamela to mix out any dry air. Moderate northerly shear is forecast to subside over the next 24 hours, giving way to the development of an upper-level anticyclone over the storm, along with an impressive outflow pattern developing in the northern semicircle. The combination of a tight inner-core wind field, low vertical shear, very warm sea-surface temperatures, and a moist mid-level environment should allow for Pamela to rapid intensify for the next 36 hours -- possibly even right up until Pamela reaches the coast of Mexico. The latest official intensity forecast is very similar to the previous advisory, and is an average of the consensus intensity models IVCN and NOAA-HCCA, an remains at the high end of the intensity guidance. Pamela is expected to become a dangerous major hurricane prior to landfall. After inland occurs, rapid weakening is expected as the storm moves over the rugged terrain of west-central Mexico. However, higher elevations could still receive tropical-storm force winds after Pamela moves well inland. An Air Force Reserve Hurricane Hunter aircraft is scheduled to investigate Pamela Tuesday late morning and early afternoon. Key Messages: 1. Pamela is forecast to be a major hurricane when it reaches the coast of west-central mainland Mexico on Wednesday, and life-threatening storm surge and dangerous hurricane-force winds are possible within the Hurricane Watch area. Residents in this area should monitor the progress of Pamela and follow any advice given by local officials. 2. Pamela is expected to pass near or south of the southern tip of the Baja California peninsula as a hurricane Tuesday night and early Wednesday, and tropical-storm conditions are possible within the Tropical storm Watch area. 3. Heavy rains associated with Pamela are expected to move into the Mexican States of Sinaloa and western Durgano along with southern portions of Baja California Sur Tuesday and Wednesday. This will pose a threat of significant and life-threatening flash flooding and mudslides. FORECAST POSITIONS AND MAX WINDS INIT 11/1500Z 16.8N 108.1W 55 KT 65 MPH 12H 12/0000Z 17.8N 108.9W 70 KT 80 MPH 24H 12/1200Z 19.3N 109.3W 85 KT 100 MPH 36H 13/0000Z 21.1N 108.8W 100 KT 115 MPH 48H 13/1200Z 23.3N 107.1W 105 KT 120 MPH 60H 14/0000Z 25.7N 104.9W 35 KT 40 MPH...INLAND 72H 14/1200Z 29.1N 100.8W 25 KT 30 MPH...POST-TROP/INLAND 96H 15/1200Z...DISSIPATED $$ Forecaster Stewart
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Tropical Storm Pamela Forecast Discussion Number 6
2021-10-11 17:01:56| National Hurricane Center (East Pacific)
Issued at 900 AM MDT Mon Oct 11 2021 000 WTPZ41 KNHC 111501 TCDEP1 Tropical Storm Pamela Discussion Number 6 NWS National Hurricane Center Miami FL EP162021 900 AM MDT Mon Oct 11 2021 Pamela's convective pattern has undergone a pronounced bursting phase since the previous advisory, including significant lightning activity in the inner-core region near the center, with formation of a Central Dense Overcast (CDO) now evident. However, the lightning ceased about 5 h ago and the CDO has recently become a little disheveled looking along with pronounced warming of the cloud tops compared to the much colder cloud tops colder than -85C just a few hours ago. The advisory intensity has been increased to 55 kt based on an average of satellite intensity estimates of T4.0/65 from TAFB, T3.0/45 kt from SAB, and T3.5/55 kt from UW-CIMSS ADT. Pamela has slowed down significantly since the previous advisory, and the motion estimate is now northwestward or 320/07 kt. A northwestward motion should continue today as Pamela approaches an east-to-west-oriented subtropical ridge axis situated along 19-20N latitude. By late tonight, the storm is forecast to turn slowly northward, followed by a motion toward the northeast at a faster forward speed by Tuesday night. As Pamela gets caught up in the moderate southwesterly flow between the subtropical ridge to its south and an approaching mid-latitude trough to the northwest, the cyclone should continue to accelerate northeastward on Wednesday until Pamela makes landfall along the southwest coast of Mexico. The new NHC forecast track is a tad to the right of and slightly faster than the previous advisory track, and close to the middle of the tightly packed simple- and corrected-consensus track model envelope. The recent disruption in Pamela's convective pattern has likely been due the cyclone having entrained a slug of dry air. However, this convective hiatus will likely be short-lived due to the robust inner-core wind field noted in earlier ASCAT wind data, which should allow for Pamela to mix out any dry air. Moderate northerly shear is forecast to subside over the next 24 hours, giving way to the development of an upper-level anticyclone over the storm, along with an impressive outflow pattern developing in the northern semicircle. The combination of a tight inner-core wind field, low vertical shear, very warm sea-surface temperatures, and a moist mid-level environment should allow for Pamela to rapid intensify for the next 36 hours -- possibly even right up until Pamela reaches the coast of Mexico. The latest official intensity forecast is very similar to the previous advisory, and is an average of the consensus intensity models IVCN and NOAA-HCCA, an remains at the high end of the intensity guidance. Pamela is expected to become a dangerous major hurricane prior to landfall. After inland occurs, rapid weakening is expected as the storm moves over the rugged terrain of west-central Mexico. However, higher elevations could still receive tropical-storm force winds after Pamela moves well inland. An Air Force Reserve Hurricane Hunter aircraft is scheduled to investigate Pamela Tuesday late morning and early afternoon. Key Messages: 1. Pamela is forecast to be a major hurricane when it reaches the coast of west-central mainland Mexico on Wednesday, and it could bring life-threatening storm surge and dangerous winds to a portion of that area. Residents in this area should monitor the progress of this system and ensure they have their hurricane plan in place. Hurricane watches will likely be required later this morning. 2. Pamela is expected to pass near or south of the southern tip of the Baja California peninsula as a hurricane Tuesday night or early Wednesday, and could bring strong winds to the extreme southern portion of the peninsula. Watches could be required for portions of this area later today. 3. Heavy rains associated with Pamela are expected to move into the Mexican States of Sinaloa and western Durgano along with southern portions of Baja California Sur Tuesday and Wednesday. This will pose a threat of significant and life-threatening flash flooding and mudslides. FORECAST POSITIONS AND MAX WINDS INIT 11/1500Z 16.8N 108.1W 55 KT 65 MPH 12H 12/0000Z 17.8N 108.9W 70 KT 80 MPH 24H 12/1200Z 19.3N 109.3W 85 KT 100 MPH 36H 13/0000Z 21.1N 108.8W 100 KT 115 MPH 48H 13/1200Z 23.3N 107.1W 105 KT 120 MPH 60H 14/0000Z 25.7N 104.9W 35 KT 40 MPH...INLAND 72H 14/1200Z 29.1N 100.8W 25 KT 30 MPH...POST-TROP/INLAND 96H 15/1200Z...DISSIPATED $$ Forecaster Stewart
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Tropical Storm Pamela Forecast Discussion Number 5
2021-10-11 10:32:51| National Hurricane Center (East Pacific)
Issued at 300 AM MDT Mon Oct 11 2021 000 WTPZ41 KNHC 110832 TCDEP1 Tropical Storm Pamela Discussion Number 5 NWS National Hurricane Center Miami FL EP162021 300 AM MDT Mon Oct 11 2021 The tropical storm has been relatively steady in strength during the past several hours. A large area of deep convection continues, but the center is located near the northern edge of the thunderstorms due to northerly shear. An ASCAT-A pass from several hours ago showed maximum winds in the 40-45 kt range in the northeastern quadrant, and all of the latest Dvorak estimates are 3.0/45 kt. Based on this satellite data, the initial intensity is held at 45 kt. Pamela is moving west-northwestward at 10 kt, and a west-northwest to northwest motion should continue for about another 12 hours as the storm moves in the flow on the southwest side of a mid-level ridge. By tonight and early Tuesday, Pamela should reach the western periphery of the ridge, which should cause a turn toward the north. A faster motion to the northeast is expected beginning Tuesday night when the storm becomes embedded in the flow on the southeast side of a broad mid- to upper-level trough, and that should bring the cyclone inland over west-central Mexico on Wednesday. The new NHC track forecast is a little to the right of the previous one, to be in better agreement with the latest consensus aids. Pamela has been gradually strengthening despite moderate northerly shear. The upper-level pattern is expected to become more favorable for the storm later today. These favorable winds aloft combined with warm SSTs and a moist environment should promote steady to rapid strengthening until Pamela reaches the coast of Mexico. The NHC intensity forecast lies at the high end of the model guidance and continues to show Pamela becoming a dangerous major hurricane prior to landfall. After Pamela moves inland, rapid weakening is expected as the storm moves over the rugged terrain of west-central Mexico. Key Messages: 1. Pamela is forecast to be a major hurricane when it reaches the coast of west-central mainland Mexico on Wednesday, and it could bring life-threatening storm surge and dangerous winds to a portion of that area. Residents in this area should monitor the progress of this system and ensure they have their hurricane plan in place. Hurricane watches will likely be required later this morning. 2. Pamela is expected to pass near or south of the southern tip of the Baja California peninsula as a hurricane Tuesday night or early Wednesday, and could bring strong winds to the extreme southern portion of the peninsula. Watches could be required for portions of this area later today. 3. Heavy rains associated with Pamela are expected to move over the Mexican States of Sinaloa and western Durgano along with southern portions of Baja California Sur Tuesday and Wednesday. This will pose a threat of significant and life-threatening flash flooding and mudslides. FORECAST POSITIONS AND MAX WINDS INIT 11/0900Z 16.2N 107.6W 45 KT 50 MPH 12H 11/1800Z 16.9N 108.5W 55 KT 65 MPH 24H 12/0600Z 18.2N 109.4W 70 KT 80 MPH 36H 12/1800Z 19.9N 109.3W 85 KT 100 MPH 48H 13/0600Z 21.8N 108.3W 100 KT 115 MPH 60H 13/1800Z 24.2N 106.4W 75 KT 85 MPH 72H 14/0600Z 26.9N 103.3W 35 KT 40 MPH...INLAND 96H 15/0600Z...DISSIPATED $$ Forecaster Cangialosi
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Tropical Depression Sixteen-E Forecast Discussion Number 1
2021-10-10 10:59:00| National Hurricane Center (East Pacific)
Issued at 400 AM CDT Sun Oct 10 2021 000 WTPZ41 KNHC 100858 TCDEP1 Tropical Depression Sixteen-E Discussion Number 1 NWS National Hurricane Center Miami FL EP162021 400 AM CDT Sun Oct 10 2021 The system we have been monitoring over the last several days off the southern coast of Mexico has been gradually improving in organization. An earlier ASCAT-A pass at 0257 UTC indicated that a closed surface vortex was developing, especially after investigating the ambiguity wind solutions from the instrument. In addition, the 0600 UTC subjective Dvorak from TAFB was at T2.0/30 kt, which is in good agreement with the peak winds (29 kt) from the earlier scatterometer data. Since that time, convection near the estimated center has only increased in coverage and intensity. Therefore, advisories are being initiated on TD16-E, the first tropical cyclone in the East Pacific basin in nearly a month. The initial intensity has been set at 30 kt in agreement with the scatterometer and satellite intensity estimate. The current motion of the depression is estimated at 290/15 kt, though some uncertainty exists given the system is in its formative stages. At present, the cyclone is situated on the equatorward side of an expensive mid-level ridge centered over Mexico that stretches westward into the East Pacific. This ridge should continue to steer the tropical cyclone to the west-northwest over then next day or so. Thereafter, a strong shortwave trough is forecast to dig into the western United States, creating a pronounced weakness in the mid-level ridge steering the system. The net result of this synoptic pattern change is that the tropical cyclone will likely bend sharply right as the ridge becomes oriented to its east, leading to a turn north to then northeastward in the 48-72 hour forecast. This track evolution would likely steer the system to the mainland Mexican coast in around 96 hours. The latest track guidance is in pretty good agreement on the general track, though investigating the GFS and ECMWF ensembles solutions reveals significant uncertainty in the along-track spread of the current forecast track. The initial NHC track forecast has been chosen to lie near the consensus aids, splitting the difference between the TVCA and HCCA solutions. The environment over the depression appears quite favorable for intensification, with low shear (around 10 kt) high mid-level moisture (around 70 percent) and warm sea-surface temperatures (29-30 C) expected to persist for the next three days. It may take 12-24 hours for an inner core to become established, but after this structural change occurs, the system appears poised for substantial intensification. In fact, the latest GFS-SHIPS guidance indicates a 44 percent chance of a 65 knot increase in intensity over the next 72 hours. The first NHC intensity forecast follows suit, showing a peak intensity of 95 kt in 72 hours. It is worth noting that this intensity forecast is less than some of the more bullish guidance, including the latest HFIP corrected consensus approach (HCCA) and this initial forecast could be conservative. FORECAST POSITIONS AND MAX WINDS INIT 10/0900Z 14.3N 102.9W 30 KT 35 MPH 12H 10/1800Z 15.1N 105.0W 35 KT 40 MPH 24H 11/0600Z 15.8N 107.2W 45 KT 50 MPH 36H 11/1800Z 16.6N 108.6W 60 KT 70 MPH 48H 12/0600Z 17.8N 109.6W 75 KT 85 MPH 60H 12/1800Z 19.0N 109.8W 85 KT 100 MPH 72H 13/0600Z 20.7N 109.4W 95 KT 110 MPH 96H 14/0600Z 25.2N 106.4W 75 KT 85 MPH...INLAND 120H 15/0600Z...DISSIPATED $$ Forecaster Papin
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