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Hurricane Humberto Forecast Discussion Number 25

2019-09-18 22:52:30| National Hurricane Center (Atlantic)

Issued at 500 PM AST Wed Sep 18 2019 000 WTNT44 KNHC 182052 TCDAT4 Hurricane Humberto Discussion Number 25 NWS National Hurricane Center Miami FL AL092019 500 PM AST Wed Sep 18 2019 Normal communications with the Bermuda Weather Service have been disrupted due to a lightning strike. Humberto is taking on more of a hybrid-extratropical structure based on most of the rain shield having been displaced to the left or poleward side of the circulation now as seen in Bermuda weather radar data, and also in conventional and passive microwave satellite imagery. Sustained hurricane-force winds and gusts have been measured by amateur radio operators across the island, with a peak gust to 104 mph having been reported thus far at Ports Island, Bermuda. The initial intensity of 105 kt on the previous advisory has been maintained since little overall change in the structure has occurred since the last aircraft reconnaissance mission 6 hours ago. The initial motion estimate is 060/17 kt. There are no significant changes to the previous forecast track or reasoning. Humberto has basically remained on track during the past 24 hours. The hurricane is expected to continue accelerating toward the east-northeast tonight and Thursday morning, with the center expected to pass about 80 nmi northwest of Bermuda early this evening. A turn toward the northeast and north-northeast is forecast to occur by early Thursday afternoon, followed by a motion toward the east-northeast by 48 hours, with the latter motion continuing through 96 hours. The new official track forecast is similar to the previous advisory track, and lies close to the tightly packed TVCN, NOAA-HCCA, and FSSE consensus track models. Humberto is now fully embedded within an anticyclonically curved right-rear jet entrance region. As a result, some fluctuations in strength could occur during the next 12 hours or so. Thereafter, strong southwesterly vertical wind shear in excess of 50 kt, along with cold upwelling beneath the hurricane, should combine to induce steady weakening. By 48 hours, the global models continue to forecast Humberto to merge with a frontal system, and the NHC intensity forecast calls for extratropical transition around that time. The official intensity forecast follows an average of the global models' intensity forecasts due to Humberto's hybrid nature, which is not being captured properly by the tropical-cyclone-based consensus intensity models. Key Messages: 1. A prolonged period of dangerous winds is expected to continue on Bermuda through Thursday morning, with hurricane-force winds expected during the next several hours. Preparations to protect life and property should be rushed to completion. 2. Storm surge and dangerous breaking waves could cause coastal flooding tonight and Thursday along the southern 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 18/2100Z 33.0N 66.3W 105 KT 120 MPH 12H 19/0600Z 34.6N 63.6W 105 KT 120 MPH 24H 19/1800Z 37.4N 61.0W 95 KT 110 MPH 36H 20/0600Z 39.8N 60.0W 75 KT 85 MPH 48H 20/1800Z 41.6N 58.7W 60 KT 70 MPH...POST-TROP/EXTRATROP 72H 21/1800Z 43.9N 47.0W 45 KT 50 MPH...POST-TROP/EXTRATROP 96H 22/1800Z 49.0N 30.0W 45 KT 50 MPH...POST-TROP/EXTRATROP 120H 23/1800Z...DISSIPATED/ABSORBED $$ Forecaster Stewart

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Tropical Storm Mario Forecast Discussion Number 6

2019-09-18 22:51:28| National Hurricane Center (East Pacific)

Issued at 300 PM MDT Wed Sep 18 2019 000 WTPZ44 KNHC 182051 TCDEP4 Tropical Storm Mario Discussion Number 6 NWS National Hurricane Center Miami FL EP142019 300 PM MDT Wed Sep 18 2019 ASCAT data, including from the new ASCAT-C instrument, was very helpful in analyzing the location, size, and intensity of Mario this afternoon. The tropical storm has contracted substantially, and earlier microwave data suggested that it had developed a mid-level eye-like feature. Since that time, it appears that moderate easterly wind shear, associated at least in part with outflow with Mario's larger sibling (Lorena) to the east, has prevented the tropical storm from strengthening at a faster rate. The intensity is nonetheless increased to 55 kt, and this could be conservative given that the ASCAT data showed maximum winds of 50-55 kt. The track and intensity of Mario will depend largely on what happens with Lorena. If Lorena moves inland and weakens, Mario will likely be located within a very favorable environment for intensification. However, if Lorena stays offshore and strengthens (like shown in the latest NHC forecast), it will likely continue to negatively affect Mario for the next several days. Lorena's forecast may become more clear later tonight, but until then the Mario intensity forecast is, and will likely continue to be, highly uncertain. The NHC forecast is slightly above the intensity consensus, but is still well within the intensity model spread. Mario continues to move northwestward at about 10 kt. Most of the global models forecast that Mario will meander generally northward to northwestward for the next couple of days toward a weakness in the subtropical ridge. After that, if Lorena survives its brush with Mexico and strengthens near the Baja California peninsula, there is a chance that Mario could turn abruptly eastward as it interacts with the other cyclone. That said, most of the global models show no such interaction occuring, and instead show Mario continuing broadly northward through day 5. The NHC forecast follows the bulk of the guidance northward for now, but it should be noted that uncertainty in the track forecast is still high. FORECAST POSITIONS AND MAX WINDS INIT 18/2100Z 15.0N 111.8W 55 KT 65 MPH 12H 19/0600Z 15.8N 112.4W 60 KT 70 MPH 24H 19/1800Z 16.7N 112.5W 65 KT 75 MPH 36H 20/0600Z 17.5N 112.4W 70 KT 80 MPH 48H 20/1800Z 17.9N 112.6W 70 KT 80 MPH 72H 21/1800Z 18.6N 113.4W 55 KT 65 MPH 96H 22/1800Z 21.5N 116.0W 55 KT 65 MPH 120H 23/1800Z 23.5N 117.0W 50 KT 60 MPH $$ Forecaster Zelinsky

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Tropical Storm Kiko Forecast Discussion Number 26

2019-09-18 22:50:25| National Hurricane Center (East Pacific)

Issued at 200 PM PDT Wed Sep 18 2019 000 WTPZ43 KNHC 182050 TCDEP3 Tropical Storm Kiko Discussion Number 26 NWS National Hurricane Center Miami FL EP132019 200 PM PDT Wed Sep 18 2019 Kiko has apparently continued to strengthen. Subjective and objective Dvorak intensity estimates at 1800 UTC were all 55 kt, so the intensity is raised to that value. At least slow additional strengthening is possible during the next few days. Wind shear that previously affected the cyclone seems to have decreased, and Kiko is far enough south that it should remain over fairly warm waters for the next couple of days. The HWRF and HMON models were not available for this forecast, but previous runs showed the potential for possibly significant strengthening during the next couple of days. On the other hand, the statistical guidance is much lower. Without any new dynamical intensity guidance available, it seems wise to make no large changes to the intensity forecast this cycle, but it is slightly higher in the short term to account for the higher initial intensity. In general, the NHC forecast is a little above the intensity guidance at all forecast hours. The initial motion is 250/6 kt, but the tropical storm is still forecast to turn westward within the next few hours. Kiko is still expected to snake its way westward during the next 5 days as a mid-level ridge to the north builds, weakens, and then builds again. The global models all show this general scenario and vary mainly in the forward speed of the cyclone. Very little change was made to the NHC forecast, which is near the middle of the guidance envelope. FORECAST POSITIONS AND MAX WINDS INIT 18/2100Z 15.8N 127.3W 55 KT 65 MPH 12H 19/0600Z 15.6N 128.2W 60 KT 70 MPH 24H 19/1800Z 15.8N 129.0W 65 KT 75 MPH 36H 20/0600Z 16.2N 129.5W 70 KT 80 MPH 48H 20/1800Z 16.7N 130.2W 70 KT 80 MPH 72H 21/1800Z 17.0N 131.8W 70 KT 80 MPH 96H 22/1800Z 16.0N 134.3W 75 KT 85 MPH 120H 23/1800Z 16.0N 136.5W 65 KT 75 MPH $$ Forecaster Zelinsky

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Tropical Storm Lorena Forecast Discussion Number 6

2019-09-18 22:48:54| National Hurricane Center (East Pacific)

Issued at 400 PM CDT Wed Sep 18 2019 000 WTPZ45 KNHC 182048 TCDEP5 Tropical Storm Lorena Discussion Number 6 NWS National Hurricane Center Miami FL EP152019 400 PM CDT Wed Sep 18 2019 Visible satellite imagery has continued to show an improvement in banding around the center of Lorena this afternoon. Bands now wrap completely around the center, but there have been no recent microwave images to see if an eye has developed. The increase in organization has led to higher objective satellite intensity from UW/CIMSS, and a blend of the SAB and ADT estimates yields an initial intensity of 60 kt. Additional strengthening is likely, and Lorena is forecast to become a hurricane tonight while it moves over warm water with low shear conditions. The storm is predicted to move very close to or over the southwestern coast of Mexico later tonight and early Thursday, and the remainder of the intensity forecast will depend on how much land interaction occurs and the eventual structure of the storm afterward. If Lorena moves to the right of the official forecast, more significant weakening is likely and the storm would struggle to re-strengthen later in the period. The new NHC track forecast shows slightly less interaction of the core of the cyclone with land, and assumes Lorena will be able to continue strengthening while the shear remains low and it moves over very warm waters southeast of the Baja California peninsula. Lorena is moving northwestward or 320/11 kt. The track guidance remains about the same as before, with the ECMWF taking the center inland over southwestern Mexico while most of the remainder of the guidance keeps it just offshore. The NHC forecast is slightly west of the previous advisory through 24 hours, but continues to show the center passing very close to southwestern Mexico. After that time, a narrow mid-level ridge is forecast to build to the north of Lorena, and this should lead to a west-northwestward motion with Lorena passing near or just south of the southern tip of the Baja Peninsula. The NHC track forecast is in best agreement with the HFIP corrected consensus. 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 is forecast to become a hurricane and move dangerously close to the coast of southwestern Mexico tonight and Thursday. A hurricane warning is in effect and preparations to protect life in property should be rushed to completion. 2. Lorena is forecast to cause heavy rain over portions of the Mexican states of Guerrero, 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 tonight or Thursday. FORECAST POSITIONS AND MAX WINDS INIT 18/2100Z 17.9N 104.4W 60 KT 70 MPH 12H 19/0600Z 19.2N 105.3W 70 KT 80 MPH 24H 19/1800Z 20.1N 106.2W 70 KT 80 MPH 36H 20/0600Z 20.7N 107.2W 75 KT 85 MPH 48H 20/1800Z 21.2N 108.3W 80 KT 90 MPH 72H 21/1800Z 22.5N 110.8W 85 KT 100 MPH 96H 22/1800Z 24.5N 113.0W 60 KT 70 MPH 120H 23/1800Z 26.6N 115.0W 40 KT 45 MPH $$ Forecaster Brown

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Tropical Storm Jerry Forecast Discussion Number 6

2019-09-18 22:41:26| National Hurricane Center (Atlantic)

Issued at 500 PM AST Wed Sep 18 2019 000 WTNT45 KNHC 182041 TCDAT5 Tropical Storm Jerry Discussion Number 6 NWS National Hurricane Center Miami FL AL102019 500 PM AST Wed Sep 18 2019 Jerry continues to strengthen this afternoon, as indicated by 1-min GOES-16 satellite imagery, with a large burst of convection close to the center. In addition, microwave data show that the central structure has improved, displaying a tightly wrapped band near the center. The initial wind speed is set to 50 kt, on the conservative side of the intensity estimates. The storm should become a hurricane on Thursday while it is moving over very warm waters with light shear. Dropsondes from the NOAA G-IV aircraft this afternoon show that Jerry is surrounded by some very dry air in the lower to mid-levels, and this is likely the main limiting factor on the cyclone's strengthening rate in the near term. By 48 hours, almost all of the models show an increase in northwesterly shear due to flow from an upper-level ridge, which seems likely to cause some weakening. At long range, Jerry is likely to interact with a mid-latitude trough, which is notoriously difficult to forecast. Only small changes were made to the previous wind speed prediction, and this advisory is close to a blend of the various consensus aids. The initial motion continues to be west-northwestward, or 290/13 kt. There's no substantial change to the track forecast on this package, with a subtropical ridge providing a well-defined steering current. This ridge should move Jerry along at a faster forward speed in about the same direction for the next couple of days, taking the center close to but north of the northern Leeward Islands. Afterward, a northwest to northward turn, influenced by a weakness in the aforementioned ridge left behind by Humberto and a new mid-latitude shortwave, is anticipated. The new forecast is very close to the previous one and a blend of the latest ECMWF ensemble mean and the corrected-consensus HCCA. 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 18/2100Z 15.0N 50.5W 50 KT 60 MPH 12H 19/0600Z 15.7N 52.5W 60 KT 70 MPH 24H 19/1800Z 16.7N 55.3W 70 KT 80 MPH 36H 20/0600Z 17.8N 58.3W 70 KT 80 MPH 48H 20/1800Z 19.1N 61.4W 65 KT 75 MPH 72H 21/1800Z 21.5N 66.5W 60 KT 70 MPH 96H 22/1800Z 25.2N 70.0W 60 KT 70 MPH 120H 23/1800Z 28.5N 69.5W 60 KT 70 MPH $$ Forecaster Blake

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