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Hurricane Humberto Forecast Discussion Number 27

2019-09-19 10:53:30| National Hurricane Center (Atlantic)

Issued at 500 AM AST Thu Sep 19 2019 000 WTNT44 KNHC 190853 TCDAT4 Hurricane Humberto Discussion Number 27 NWS National Hurricane Center Miami FL AL092019 500 AM AST Thu Sep 19 2019 Flight-level and surface wind observations reported by Air Force Reserve Hurricane Hunter aircraft exiting Humberto a couple of hours ago indicated that the maximum sustained winds have increased to 110 kt. However, weakening is expected to commence soon. Humberto's extratropical transition continues as a high amplitude PV tongue, noted in the GOES-16 water vapor imagery, and associated dry air, digs into the backside of the cyclone. The large-scale models, as well as the FSU Cyclone Phase Evolution forecast, indicate that the process will be completed in less than 36 hours. Afterward, gradual weakening is expected until the extratropical low is absorbed by another larger low pressure system, moving out of Atlantic Canada, by the end of the forecast period. The NHC intensity forecast is basically an update of the previous forecast and is based on a blend of the global models beyond the 36 hour period. The initial motion is estimated to be northeastward, or 045/19 kt. Humberto is forecast to turn north-northeastward as the cyclone completes its extratropical transition, followed by a turn back toward the east-northeast within the strong deep-layer mid-latitude westerlies. The NHC forecast is nudged a little to the left of the previous advisory between the 36 and 72 hour periods, and is close to the NOAA HFIP HCCA consensus model. Key Messages: 1. Storm surge and dangerous breaking waves, while diminishing, could cause coastal flooding today along the coast of Bermuda. 2. Swells will continue to affect the northwestern Bahamas and the southeastern coast of the United States from east-central Florida to North Carolina during the next couple of days, creating life- threatening surf and rip current conditions. FORECAST POSITIONS AND MAX WINDS INIT 19/0900Z 35.2N 62.2W 110 KT 125 MPH 12H 19/1800Z 37.4N 60.0W 95 KT 110 MPH 24H 20/0600Z 39.9N 58.9W 75 KT 85 MPH 36H 20/1800Z 41.8N 57.4W 60 KT 70 MPH...POST-TROP/EXTRATROP 48H 21/0600Z 43.2N 53.4W 50 KT 60 MPH...POST-TROP/EXTRATROP 72H 22/0600Z 46.3N 36.4W 45 KT 50 MPH...POST-TROP/EXTRATROP 96H 23/0600Z...DISSIPATED $$ Forecaster Roberts

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Tropical Storm Jerry Forecast Discussion Number 8

2019-09-19 10:51:59| National Hurricane Center (Atlantic)

Issued at 500 AM AST Thu Sep 19 2019 000 WTNT45 KNHC 190851 TCDAT5 Tropical Storm Jerry Discussion Number 8 NWS National Hurricane Center Miami FL AL102019 500 AM AST Thu Sep 19 2019 A fortuitous 0531 UTC AMSR2 microwave overpass indicated that Jerry's inner core has significantly become better organized this morning. The image revealed a nearly enclosed banding eye feature with the curved band wrapping around the east portion of the cyclone. Based on the much improved cloud pattern and a blend of the subjective and objective satellite intensity estimates, the initial intensity is increased to 60 kt for this advisory. Jerry is expected to strengthen further in the short term and become a hurricane later today. Afterward, the statistical-dynamical intensity models show some moderate northwesterly shear impinging on the northern half of the cyclone, which should arrest the early period intensification. Beyond the 48 hour period, a majority of the large-scale models indicate increasing westerly vertical shear as Jerry moves northwest of an upper anti-cyclone situated to the north of Hispaniola. Therefore, a weakening trend is expected through the remaining portion of the forecast. The NHC forecast is slightly below the previous advisory after the 48 hour period, but above the HFIP HCCA and IVCN consensus models, and as well as the HWRF. The initial motion is estimated to be west-northwestward, or 290/14 kt. There are no significant changes to the forecast track philosophy. The cyclone is forecast to be steered by the southeasterly flow generated by a subtropical ridge to the northeast of Jerry through the 48 hour period. Around day 3, Jerry is likely to turn northwest to north-northwest, in response to a growing weakness in the aforementioned mid-tropospheric ridge along 70-75W longitude. The official track forecast is based on a blend of the various consensus aids. Key Messages: 1. Jerry is expected to become a hurricane before it moves close to the northern Leeward Islands Friday. Although the core of Jerry is currently expected to pass north of the islands, tropical-storm- force winds and locally heavy rainfall are possible, and tropical storm watches have been issued for a portion of this area. FORECAST POSITIONS AND MAX WINDS INIT 19/0900Z 16.0N 53.2W 60 KT 70 MPH 12H 19/1800Z 16.8N 55.2W 70 KT 80 MPH 24H 20/0600Z 17.8N 57.9W 70 KT 80 MPH 36H 20/1800Z 18.9N 60.9W 65 KT 75 MPH 48H 21/0600Z 20.1N 63.7W 65 KT 75 MPH 72H 22/0600Z 22.9N 68.2W 60 KT 70 MPH 96H 23/0600Z 26.0N 70.0W 65 KT 75 MPH 120H 24/0600Z 29.5N 68.5W 65 KT 75 MPH $$ Forecaster Roberts

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Tropical Storm Mario Forecast Discussion Number 8

2019-09-19 10:51:35| National Hurricane Center (East Pacific)

Issued at 300 AM MDT Thu Sep 19 2019 000 WTPZ44 KNHC 190851 TCDEP4 Tropical Storm Mario Discussion Number 8 NWS National Hurricane Center Miami FL EP142019 300 AM MDT Thu Sep 19 2019 Deep convection has persisted around the center of Mario over the past several hours. However, the improved appearance of the cyclone has not yet resulted in an increase in surface wind speeds, as confirmed by an ASCAT overpass a few hours ago. The initial advisory intensity remains at 55 kt and this is in agreement with the latest objective Dvorak estimates from both TAFB and SAB. With the recent increase in organized convection, Mario is likely starting a phase of intensification while over warm waters and in a moist atmospheric environment. However, this strengthening should be limited due to northeasterly shear being aided by outflow from Hurricane Lorena near the Mexico coast. After 36 hours, Mario is forecast to begin moving into a drier and more stable atmospheric environment while still undergoing shear from nearby Lorena. This should cause a gradual weakening trend through 96 hours. After that time, the cyclone is forecast to move over cooler waters in the same hostile environment, which should cause it to degenerate to a remnant low by the end of the forecast period. The official forecast is near the previous one and is on the higher end of the consensus aids. Mario has turned to the north and the initial motion is now 355/6 kt. The combination of weak steering currents, and a possible subtle interaction between Mario's and Lorena's circulation should induce a slow north to north-northeast motion over the next couple of days. After that time, mid-level ridging is expected to develop over northern Mexico which should cause Mario to turn northwestward with an increase in forward speed. The official forecast is near the ECMWF and lies just a little to the right of the previous forecast through the first few days, and very near it thereafter. FORECAST POSITIONS AND MAX WINDS INIT 19/0900Z 15.9N 111.9W 55 KT 65 MPH 12H 19/1800Z 16.6N 111.7W 60 KT 70 MPH 24H 20/0600Z 17.4N 111.5W 70 KT 80 MPH 36H 20/1800Z 17.9N 111.3W 65 KT 75 MPH 48H 21/0600Z 18.4N 111.3W 60 KT 70 MPH 72H 22/0600Z 20.9N 113.1W 45 KT 50 MPH 96H 23/0600Z 23.2N 115.7W 35 KT 40 MPH 120H 24/0600Z 25.0N 117.5W 30 KT 35 MPH...POST-TROP/REMNT LOW $$ Forecaster Latto

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Tropical Storm Kiko Forecast Discussion Number 28

2019-09-19 10:49:31| National Hurricane Center (East Pacific)

Issued at 200 AM PDT Thu Sep 19 2019 000 WTPZ43 KNHC 190849 TCDEP3 Tropical Storm Kiko Discussion Number 28 NWS National Hurricane Center Miami FL EP132019 200 AM PDT Thu Sep 19 2019 Water vapor satellite imagery as well as satellite-derived winds indicate that there is some southwesterly shear undercutting Kiko tonight, with a large upper level trough digging several hundred miles to the northwest of the cyclone. This flow is likely feeding some dry air into the system, and these factors could explain why Kiko has not been intensifying recently. The objective Dvorak estimate from TAFB as well as subjective intensity estimates suggest that the initial advisory intensity remains at 55 kt. Despite the forecast for shear to be generally relaxed, Kiko will have to overcome dry and stable air to its north and west that may keep entraining into the cyclone's circulation in the coming days. The majority of the intensity guidance only show some slight strengthening over the next several days. And, due to the mixed positive and negative signals for intensification, the official forecast agrees with this scenario and gradually brings Kiko to hurricane strength in about 36 hours, and intensifies it just a little more after that time. The official forecast intensity is very near the HFIP corrected consensus HCCA. The initial motion is westward at 5 kt. A developing weakness in the ridge to the northwest of Kiko will allow for a west-northwest to northwest motion over the next couple of days. Ridging will rebuild to the northwest of Kiko after that time, which will induce a west-southwestward motion. Late in the forecast period, that ridge will weaken, resulting in a turn back to the northwest. The main change to the official forecast track was to nudge it a little to the right, as the well performing ECMWF has shifted quite a bit northward on the latest run. The official forecast now lies on the southern edge of the clustered consensus guidance. FORECAST POSITIONS AND MAX WINDS INIT 19/0900Z 15.9N 128.2W 55 KT 65 MPH 12H 19/1800Z 16.1N 128.9W 55 KT 65 MPH 24H 20/0600Z 16.6N 129.7W 60 KT 70 MPH 36H 20/1800Z 17.3N 130.4W 65 KT 75 MPH 48H 21/0600Z 17.7N 131.1W 65 KT 75 MPH 72H 22/0600Z 17.1N 132.9W 70 KT 80 MPH 96H 23/0600Z 16.3N 135.4W 75 KT 85 MPH 120H 24/0600Z 17.6N 137.5W 70 KT 80 MPH $$ Forecaster Latto

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Hurricane Lorena Forecast Discussion Number 8

2019-09-19 10:43:28| National Hurricane Center (East Pacific)

Issued at 400 AM CDT Thu Sep 19 2019 000 WTPZ45 KNHC 190843 TCDEP5 Hurricane Lorena Discussion Number 8 NWS National Hurricane Center Miami FL EP152019 400 AM CDT Thu Sep 19 2019 Satellite imagery and surface observations from Mexico indicate that the center of Lorena is either inland or hugging the coast. A large portion of the eastern semicircle is interacting with the high terrain. Given the microwave presentation showing a small mid-level eye a few hours ago, and the fact that Dvorak numbers have not changed much, the initial intensity has been kept generously at 65 kt in this advisory. However, Lorena is a very small cyclone and these winds are limited to a very small area near the center. Since a large portion of the cyclone is over land, some weakening is anticipated during the next 12 hours. However, once the center reaches the warmer waters between Cabo Corrientes and the southern portion of the Baja California peninsula, strengthening is indicated. After 2 or 3 days, the environment will be less favorable and weakening should commence. By then, Lorena should be over water or very near the west coast of the Baja California peninsula. One complicating factor which makes this forecast highly uncertain is the possibility that Lorena interacts with the circulation of Tropical Storm Mario which is located not too far to the southwest. Some global models combined the circulations of the two cyclones into one. At this time, the NHC forecast assumes that Lorena will continue as a separate system through five days. The best estimate of the initial motion is toward the north- northwest or 330 degrees at 7 knots. The cyclone is being steered by a persistent subtropical high over Mexico, but the easterly flow around Mario should force Lorena on a more west-northwest track. Beyond 3 days, track models diverge significantly, with some bringing the cyclone west of the peninsula and others to the east. The NHC forecast follows the previous one, and brings Lorena as a weakening cyclone along the west coast of the peninsula. This forecast is highly uncertain at this time. Key Messages: 1. Lorena will be moving over or close to the coast of southwestern Mexico today. A hurricane warning is in effect, and preparations to protect life in property should have been completed. 2. Lorena is forecast to cause heavy rain over portions of the Mexican states of Michoacan, Colima, and Jalisco during the next few days. This rainfall may produce life-threatening flash flooding and mudslides. 3. Lorena could threaten the southern portion of the Baja California peninsula as a hurricane this weekend, but the forecast is highly uncertain due to the potential for the land interaction currently occuring. Residents should ensure that their hurricane plan is in place as watches may be required on Thursday. FORECAST POSITIONS AND MAX WINDS INIT 19/0900Z 19.6N 105.0W 65 KT 75 MPH 12H 19/1800Z 20.5N 105.8W 55 KT 65 MPH 24H 20/0600Z 21.2N 107.0W 65 KT 75 MPH 36H 20/1800Z 21.7N 108.3W 80 KT 90 MPH 48H 21/0600Z 22.2N 110.0W 80 KT 90 MPH 72H 22/0600Z 24.0N 111.5W 60 KT 70 MPH 96H 23/0600Z 26.0N 113.0W 40 KT 45 MPH 120H 24/0600Z 28.0N 114.5W 30 KT 35 MPH $$ Forecaster Avila

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