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Hurricane Humberto Forecast Discussion Number 26

2019-09-19 04:55:28| National Hurricane Center (Atlantic)

Issued at 1100 PM AST Wed Sep 18 2019 000 WTNT44 KNHC 190255 TCDAT4 Hurricane Humberto Discussion Number 26 NWS National Hurricane Center Miami FL AL092019 1100 PM AST Wed Sep 18 2019 Normal communications with the Bermuda Weather Service have been restored. However, the weather radar on Bermuda is currently down. The center of Humberto made its closest approach to Bermuda a few hours ago, with many weather stations on the island reporting sustained hurricane force winds and gusts near or over 100 kt. Since that time, an Air Force Reserve Hurricane Hunter aircraft has arrived at the storm and reported little change in strength despite a decaying appearance in satellite imagery. The SFMR surface wind estimates were in the 100-105 kt range to the west of the center, and the central pressure was near 952 mb. Based on these data, the initial intensity is held at a possibly conservative 105 kt. The decay in the satellite signature is due to Humberto starting to undergo extratropical transition, a process that the global models forecast to be complete by 36 h. Those models forecast that the cyclone should steadily weaken during and after the transition until it is absorbed by another low pressure system between 96-120 h, and the intensity forecast follows this scenario. The new intensity forecast is basically an update of the previous forecast, with a slightly faster decrease in intensity during the first 48 h. The initial motion is now 055/20. Humberto is forecast to turn north-northeastward as it becomes extratropical, followed by a turn back toward the east-northeastward as the extratropical low is steered by the mid-latitude westerlies. The track guidance remains tightly clustered, and the new forecast track has only minor adjustments from the previous forecast. Key Messages: 1. Tropical-storm conditions on Bermuda should subside during the next several hours. 2. Storm surge and dangerous breaking waves, while diminishing, could cause coastal flooding tonight and Thursday along the coast of Bermuda. 3. 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 19/0300Z 34.0N 63.9W 105 KT 120 MPH 12H 19/1200Z 35.8N 61.6W 95 KT 110 MPH 24H 20/0000Z 38.5N 59.8W 85 KT 100 MPH 36H 20/1200Z 40.7N 58.8W 70 KT 80 MPH...POST-TROP/EXTRATROP 48H 21/0000Z 42.4N 56.1W 55 KT 65 MPH...POST-TROP/EXTRATROP 72H 22/0000Z 45.0N 41.7W 45 KT 50 MPH...POST-TROP/EXTRATROP 96H 23/0000Z 50.0N 25.5W 45 KT 50 MPH...POST-TROP/EXTRATROP 120H 24/0000Z...DISSIPATED $$ Forecaster Beven

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Tropical Storm Mario Forecast Discussion Number 7

2019-09-19 04:53:26| National Hurricane Center (East Pacific)

Issued at 900 PM MDT Wed Sep 18 2019 000 WTPZ44 KNHC 190253 TCDEP4 Tropical Storm Mario Discussion Number 7 NWS National Hurricane Center Miami FL EP142019 900 PM MDT Wed Sep 18 2019 Mario's convection had mostly collapsed around the time of the previous advisory. However, a 1911 UTC GPM microwave pass indicated that the storm still had a tight circulation with a well-defined center, and a new burst of convection began around 2300 UTC. There is a wide range of intensity estimates with 45 kt from TAFB at the low end and 65 kt from the UW-CIMSS at the high end. Given this large spread, the initial intensity is held at 55 kt in the middle of the range. Mario's future still depends on Lorena. At the moment, the storm is moving northwestward, or 320/9 kt. The track models continue to show varying degrees of interaction between Mario and Lorena. On the one hand, the GFS and HWRF models show the smaller Mario becoming enveloped into Lorena's larger circulation, making a backwards-S track as it moves generally northward. On the other hand, since the ECMWF dissipates Lorena inland over Mexico, it allows Mario to move northward or northwestward unabated with not much wiggle in its track. Visible satellite images showed quite a bit of southwesterly flow feeding from near Mario toward Lorena, which leads me to believe that there will at least be some interaction between the two cyclones. Given that, the NHC track forecast has been shifted eastward a bit, but not as far to the east as some of the consensus aids or the HCCA model. Intensity-wise, it appears that Mario will get into a more favorable upper-level environment during the next 24-36 hours, which should foster some strengthening. Mario is forecast to become a hurricane in about 24 hours, and this scenario lies between the IVCN intensity consensus and the HCCA model. Weakening is likely to occur after 48 hours due to an increase in easterly shear, lower oceanic heat content, and possible interaction with Lorena. Because of this possible interaction, confidence in both the NHC track and intensity forecasts is lower than normal. FORECAST POSITIONS AND MAX WINDS INIT 19/0300Z 15.4N 112.2W 55 KT 65 MPH 12H 19/1200Z 16.2N 112.4W 60 KT 70 MPH 24H 20/0000Z 17.1N 112.2W 65 KT 75 MPH 36H 20/1200Z 17.6N 112.0W 70 KT 80 MPH 48H 21/0000Z 18.2N 112.0W 65 KT 75 MPH 72H 22/0000Z 20.2N 113.4W 50 KT 60 MPH 96H 23/0000Z 22.7N 115.8W 45 KT 50 MPH 120H 24/0000Z 24.8N 117.1W 40 KT 45 MPH $$ Forecaster Berg

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Hurricane Lorena Forecast Discussion Number 7

2019-09-19 04:44:26| National Hurricane Center (East Pacific)

Issued at 1000 PM CDT Wed Sep 18 2019 000 WTPZ45 KNHC 190244 TCDEP5 Hurricane Lorena Discussion Number 7 NWS National Hurricane Center Miami FL EP152019 1000 PM CDT Wed Sep 18 2019 Earlier microwave imagery showed that Lorena's structure has continued to improve, with a well-defined low-level ring noted in the 37-GHz channel. The convective signature in infrared satellite imagery is somewhat ragged, although it appears that a warm spot may be developing near the estimated center. Objective SATCON and ADT intensity estimates are 66 kt and 75 kt, respectively, which is higher than the 55-kt subjective estimates from TAFB and SAB. However, given the improved microwave pattern, the initial intensity hedges toward the objective numbers, making Lorena a 65-kt hurricane. Both the track and intensity forecast hinge on whether Lorena survives its fly-by of the coast of Mexico. If the center stays just offshore, which several of the models show, then a strengthening ridge over northern Mexico should steer the cyclone northwestward and west-northwestward away from west-central Mexico after 24 hours, heading in the general direction of the southern tip of the Baja California peninsula. The ECMWF is the only model at the moment that shows Lorena's center moving inland, or interacting with the high terrain enough, to dissipate within the next 12-24 hours. All that being said, the NHC track forecast assumes that Lorena will survive the next 24 hours, and it has been nudged southwestward beyond 36 hours, close to the multi-model consensus aids and the HCCA model. Based on this track, environmental conditions appear favorable for further strengthening during the next couple of days. Weakening should commence by day 3 once the system encounters areas of higher shear and significantly lower oceanic heat content values. As already insinuated above, due the potential for land interaction within the next 12-24 hours, there is greater than usual uncertainty in both the track and intensity forecast for Lorena through day 5. Key Messages: 1. Lorena will be dangerously close to the coast of southwestern Mexico tonight and on Thursday. 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 more uncertain due to the potential for land interaction tonight and Thursday. Residents should ensure that their hurricane plan is in place as watches may be required on Thursday. FORECAST POSITIONS AND MAX WINDS INIT 19/0300Z 18.7N 104.7W 65 KT 75 MPH 12H 19/1200Z 19.7N 105.5W 70 KT 80 MPH 24H 20/0000Z 20.5N 106.6W 75 KT 85 MPH 36H 20/1200Z 21.0N 107.8W 80 KT 90 MPH 48H 21/0000Z 21.4N 109.1W 80 KT 90 MPH 72H 22/0000Z 22.6N 111.5W 75 KT 85 MPH 96H 23/0000Z 24.6N 113.7W 55 KT 65 MPH 120H 24/0000Z 26.4N 115.3W 35 KT 40 MPH $$ Forecaster Berg

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Tropical Storm Jerry Forecast Discussion Number 7

2019-09-19 04:40:56| National Hurricane Center (Atlantic)

Issued at 1100 PM AST Wed Sep 18 2019 000 WTNT45 KNHC 190240 TCDAT5 Tropical Storm Jerry Discussion Number 7 NWS National Hurricane Center Miami FL AL102019 1100 PM AST Wed Sep 18 2019 Jerry is gradually becoming better organized, with a small circular CDO and some banding features over its northwestern quadrant. Although the storm has some modest upper-level outflow, there is evidence of west-northwesterly winds undercutting the system just below the outflow layer. An upper-level cyclone is located a few hundred miles to the northwest of Jerry, as confirmed by synoptic surveillance observations taken recently by the NOAA G-IV jet. However, the global models suggest that this feature should remain far enough to the north of the tropical cyclone so that its shearing influence will be minimal in the short term. The current intensity estimate is 55 kt based on Dvorak classifications from TAFB and SAB. Since the environment is likely to be modestly conducive during the next day or so, strengthening is predicted for the next 24 hours. Thereafter, the dynamical guidance shows some increase in shear, which should result in a leveling off of Jerry's intensity. Later in the forecast period, the global models predict a significant increase in shear, so some weakening is likely. The official intensity forecast is close to the multi-model consensus. The storm remains on track with the motion continuing around 290/13 kt. There are no important changes to the track forecast from the previous advisory. Jerry should move along the southwestern periphery of a subtropical ridge over the next couple of days. In 3-5 days, the tropical cyclone is likely to turn northwest, north-northwest, and eventually north following a weakness in the ridge near 70-75W longitude. The official track forecast is close to the latest corrected multi-model consensus guidance. 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 19/0300Z 15.4N 51.8W 55 KT 65 MPH 12H 19/1200Z 16.2N 53.9W 65 KT 75 MPH 24H 20/0000Z 17.3N 56.7W 75 KT 85 MPH 36H 20/1200Z 18.5N 59.7W 75 KT 85 MPH 48H 21/0000Z 19.7N 62.7W 75 KT 85 MPH 72H 22/0000Z 22.4N 67.3W 70 KT 80 MPH 96H 23/0000Z 25.7N 70.0W 65 KT 75 MPH 120H 24/0000Z 29.0N 69.0W 65 KT 75 MPH $$ Forecaster Pasch

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Tropical Storm Kiko Forecast Discussion Number 27

2019-09-19 04:31:57| National Hurricane Center (East Pacific)

Issued at 800 PM PDT Wed Sep 18 2019 000 WTPZ43 KNHC 190231 TCDEP3 Tropical Storm Kiko Discussion Number 27 NWS National Hurricane Center Miami FL EP132019 800 PM PDT Wed Sep 18 2019 Kiko's appearance has not changed substantially during the past 6 hours. Although the wind shear is very light, at least some dry air appears be getting into the inner core of the tropical storm, limiting Kiko's deep convection. The intensity remains 55 kt based on the most recent UW-CIMSS SATCON and subjective Dvorak current intensity estimates. Both dynamical intensity models (HWRF and HMON) show that Kiko will eventually reform an inner convective core and strengthen, but do so several days apart. It seems likely, given the light shear and warm SSTs beneath the tropical storm, that Kiko will restrengthen at some point. That said, determining the exact timing is probably beyond our current ability to forecast tropical cyclone intensity. The NHC intensity forecast calls for slow strengthening during the next several days, as shown by HCCA, but I would not be surprised if Kiko is nearly steady-state for a day or two, and then strengthens at a faster rate than expected. Confidence in the intensity forecast is therefore somewhat low. The initial motion is now 265/5 kt. Little change was made to the NHC track forecast. Oscillations in the strength of a mid-level ridge to the north Kiko should cause the cyclone to turn northwestward in a day or so, and then back toward the west another day after that. After Kiko reaches the crest of its curvy path, it is expected to turn southwestward yet again by the weekend. The model guidance is in remarkably good agreement for such an unusual track and the NHC forecast remains near the multi-model consensus, with a little extra emphasis placed on the ECMWF which has thus far handled the forecast of Kiko quite well. FORECAST POSITIONS AND MAX WINDS INIT 19/0300Z 15.8N 127.8W 55 KT 65 MPH 12H 19/1200Z 15.9N 128.5W 55 KT 65 MPH 24H 20/0000Z 16.2N 129.3W 60 KT 70 MPH 36H 20/1200Z 16.7N 130.0W 65 KT 75 MPH 48H 21/0000Z 17.2N 130.6W 65 KT 75 MPH 72H 22/0000Z 17.1N 132.1W 75 KT 85 MPH 96H 23/0000Z 16.1N 134.5W 80 KT 90 MPH 120H 24/0000Z 17.0N 137.0W 65 KT 75 MPH $$ Forecaster Zelinsky

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