Home › discussion
 

Keywords :   


Tag: discussion

Tropical Storm SIMON Forecast Discussion Number 18

2014-10-06 04:42:42| National Hurricane Center (East Pacific)

Issued at 800 PM PDT SUN OCT 05 2014 000 WTPZ44 KNHC 060242 TCDEP4 TROPICAL STORM SIMON DISCUSSION NUMBER 18 NWS NATIONAL HURRICANE CENTER MIAMI FL EP192014 800 PM PDT SUN OCT 05 2014 The cloud pattern associated with Simon continues to slowly degrade this evening. The cloud tops have gradually warmed and recent microwave data indicate that the low-level center is located to the southwest of the main convective mass due to moderate southwesterly shear. The latest Dvorak Data T-numbers from SAB and TAFB are 3.5, but current intensity numbers remain higher due to Dvorak weakening constraints. The initial wind speed has been lowered to 60 kt, closer to the data T-numbers and a little below what was supported by the earlier NOAA aircraft data. Increasing southwesterly shear, cooler sea surface temperatures, and drier air should cause continued weakening during the next couple of days. Simon is forecast to become a tropical depression within 36 hours and should degenerate to a remnant low by Tuesday, before the center reaches the Baja California peninsula. The updated NHC intensity forecast is in good agreement with the SHIPS/LGEM guidance and is close to the model consensus. Simon is moving north-northwestward or 345 degrees at about 6 kt. The cyclone should turn northward, then north-northeastward during the next 24 hours around the western side of a mid-level high located near the coast of southwestern Mexico. Although the track guidance generally agrees on this scenario, there continues to be differences in how soon Simon or its remnants will reach the Baja peninsula. The GFS takes the cyclone across the Baja peninsula in about 48 hours, while the ECMWF and UKMET shows this occurring about a day later. The NHC track forecast remains in between these solutions and is close to the multi-model consensus. Even if Simon or its remnant circulation does not make it across the rugged terrain of the Baja California peninsula, moisture associated with this system is expected to spread across the northern Baja California peninsula, northwestern Mexico, and into the U.S. Desert Southwest, which could trigger heavy rains in those regions during the next few days. FORECAST POSITIONS AND MAX WINDS INIT 06/0300Z 23.8N 117.6W 60 KT 70 MPH 12H 06/1200Z 24.6N 117.6W 45 KT 50 MPH 24H 07/0000Z 25.7N 117.3W 35 KT 40 MPH 36H 07/1200Z 26.9N 116.8W 30 KT 35 MPH 48H 08/0000Z 28.1N 115.8W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 09/0000Z 30.0N 114.0W 20 KT 25 MPH...POST-TROP/REMNT LOW 96H 10/0000Z...DISSIPATED $$ Forecaster Brown

Tags: number discussion simon storm

 

Hurricane SIMON Forecast Discussion Number 17

2014-10-05 22:42:42| National Hurricane Center (East Pacific)

Issued at 200 PM PDT SUN OCT 05 2014 000 WTPZ44 KNHC 052042 TCDEP4 HURRICANE SIMON DISCUSSION NUMBER 17 NWS NATIONAL HURRICANE CENTER MIAMI FL EP192014 200 PM PDT SUN OCT 05 2014 A NOAA Hurricane Hunter aircraft investigating Simon has found that the cyclone's maximum winds continue to decrease quickly. The plane measured maximum 700-mb flight-level winds of 73 kt and surface-based SFMR winds as high as 58 kt in the northeastern quadrant. Based on the aircraft data, the initial intensity is lowered to 65 kt, which could be generous. UW-CIMSS analyses and the SHIPS output indicate that southwesterly shear has increased to about 20 kt, and satellite imagery suggests that Simon's circulation is beginning to decouple. With the cyclone expected to remain over 24-25C water and in a highly sheared environment during the next few days, continued rapid weakening is anticipated. The updated NHC forecast is lower than the previous forecast mainly due to the adjusted initial intensity, and Simon is likely to become a tropical depression in 36 hours and a remnant low by 48 hours, before it reaches the Baja California peninsula. Forecast fields from the global models indicate that the cyclone will have dissipated over northwestern Mexico by day 4, which is indicated in the official forecast. Simon has turned north-northwestward with an initial motion of 330/8 kt. The hurricane is currently moving around the western periphery of a mid-level high centered near the west coast of Mexico, and it should turn northward and then northeastward around this feature during the next 48-72 hours. The model guidance is in relatively good agreement on the future track of Simon, but there continues to be disagreement on how fast Simon or its remnants reach the Baja California peninsula. For example, the GFS and ECMWF solutions are about 24 hours apart on when they bring the center of Simon to the coast. The updated NHC track forecast is a little faster than the previous one after 24 hours but is relatively close to the multi-model consensus TVCE. Even if Simon or its remnant circulation does not make it across the rugged terrain of the Baja California peninsula, deep moisture associated with the cyclone is expected to spread across the northern Baja California peninsula, northwestern Mexico, and into the U.S. Desert Southwest, which could trigger heavy rains in those regions in a few days. FORECAST POSITIONS AND MAX WINDS INIT 05/2100Z 23.4N 117.5W 65 KT 75 MPH 12H 06/0600Z 24.2N 117.7W 50 KT 60 MPH 24H 06/1800Z 25.2N 117.5W 40 KT 45 MPH 36H 07/0600Z 26.2N 117.1W 30 KT 35 MPH 48H 07/1800Z 27.5N 116.3W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 08/1800Z 30.0N 114.0W 20 KT 25 MPH...POST-TROP/REMNT LOW 96H 09/1800Z...DISSIPATED $$ Forecaster Berg

Tags: number discussion simon forecast

 
 

Hurricane SIMON Forecast Discussion Number 16

2014-10-05 16:49:09| National Hurricane Center (East Pacific)

Issued at 800 AM PDT SUN OCT 05 2014 000 WTPZ44 KNHC 051449 TCDEP4 HURRICANE SIMON DISCUSSION NUMBER 16 NWS NATIONAL HURRICANE CENTER MIAMI FL EP192014 800 AM PDT SUN OCT 05 2014 Simon continues to weaken. The distribution of deep convection has become more asymmetric during the last 12 hours, and there has been a general warming of cloud top temperatures. The cyclone's cloud canopy has also been expanding over the northern semicircle while eroding some to the south. This transformation of the cloud pattern is primarily related to an increase in southwesterly shear over the hurricane, as diagnosed by UW-CIMSS shear analyses and SHIPS model output. A blend of Dvorak Final-T and CI-numbers from TAFB and SAB is used to reduce the initial intensity to 85 kt. As Simon gains latitude during the next couple of days, a further increase in shear is expected in association with a mid- to upper-level shortwave trough several hundred miles west of the coast of southern California. The abrupt and substantial increase in shear, combined with water temperatures around 25 deg C and other considerably less conducive thermodynamic conditions, should result in a rapid decay of the cyclone. Global models show the low- to mid-level centers of Simon decoupling around 48 hours, and Simon should become a remnant low in 72 hours, if not sooner. The NHC intensity forecast, like the previous one, shows rapid weakening over the next 48 hours and is in excellent agreement with the latest multi-model consensus. The initial motion estimate is 325/09. Simon is moving into a region of weak steering on the western periphery of a subtropical ridge centered near western Mexico. This synoptic pattern should result in the cyclone's gradual turning toward the north with a decrease in forward speed over the next day or so. The previously mentioned shortwave trough should cause Simon to turn northeastward within 48 hours, with Simon or its remnants likely moving over the north-central portion of the Baja California peninsula later in the forecast period. The NHC forecast has not changed much relative to the previous one and remains close to the multi-model consensus, substantially slower than the GFS solution which brings Simon inland over northwestern Mexico in 72 hours. Even if Simon or its remnant circulation does not make it across the rugged terrain of the Baja California peninsula, deep moisture associated with the cyclone is expected to spread across the northern Baja California peninsula, northwestern Mexico, and into the U.S. Desert Southwest, which could trigger heavy rains in those regions in a few days. FORECAST POSITIONS AND MAX WINDS INIT 05/1500Z 22.9N 117.1W 85 KT 100 MPH 12H 06/0000Z 23.6N 117.4W 70 KT 80 MPH 24H 06/1200Z 24.5N 117.5W 55 KT 65 MPH 36H 07/0000Z 25.4N 117.2W 40 KT 45 MPH 48H 07/1200Z 26.2N 116.8W 30 KT 35 MPH 72H 08/1200Z 28.2N 115.4W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 09/1200Z 29.7N 113.8W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 10/1200Z...DISSIPATED $$ Forecaster Kimberlain

Tags: number discussion simon forecast

 

Hurricane SIMON Forecast Discussion Number 15

2014-10-05 10:42:48| National Hurricane Center (East Pacific)

Issued at 200 AM PDT SUN OCT 05 2014 000 WTPZ44 KNHC 050842 TCDEP4 HURRICANE SIMON DISCUSSION NUMBER 15 NWS NATIONAL HURRICANE CENTER MIAMI FL EP192014 200 AM PDT SUN OCT 05 2014 Simon peaked around 0000 UTC based on various satellite intensity estimates and microwave satellite imagery indicating that an eyewall replacement was well underway at that time. Since then, more recent conventional and microwave satellite imagery indicates that the inner-core convection has eroded significantly, especially in the southwestern semicircle, and that the eye is rapidly becoming less distinct. The initial intensity of 100 kt, which could be generous, is based on a blend of subjective and objective satellite intensity estimates from TAFB, SAB, and UW-CIMSS. The initial motion estimate is 320/09 kt. There is no significant change to the previous forecast track or reasoning. A steadily weakening Simon is forecast to move around the western periphery of a deep-layer ridge that extends from central Mexico westward to southern Baja California Sur for the next 48 hours, and then recurve to the northeast as the cyclone comes under the influence of mid-level southwesterly flow ahead of an approaching weak shortwave trough. As the cyclone weakens and becomes more vertically shallow, the system is expected to slow down until it reaches the latitude of recurvature along 24N-25N, after which a gradual increase in forward speed is expected. The official forecast track is just an update of the previous advisory track and is close to the consensus model TVCN. Simon is now located over sub-26C sea-surface temperatures and is heading for cooler water. The cyclone is expected to remain in unfavorable oceanic and thermodynamic conditions for at least the next 72 hours, during which time southwesterly vertical wind shear is forecast to increase to more than 25 kt by 48 hours. These hostile conditions are expected to result in rapid weakening of Simon, with the cyclone becoming a remnant low pressure system by 96 hours, if not sooner. The new intensity forecast is a little lower than the previous advisory, and essentially follows the intensity consensus model IVCN. Even if Simon or its remnant circulation does not make it across the rugged terrain of the Baja California peninsula, deep moisture associated with the cyclone is expected to spread across northern Baja California, northwestern Mexico, and into the U.S. Desert Southwest, which could trigger another heavy rain event in those regions in a few days. FORECAST POSITIONS AND MAX WINDS INIT 05/0900Z 22.1N 116.7W 100 KT 115 MPH 12H 05/1800Z 23.0N 117.3W 85 KT 100 MPH 24H 06/0600Z 24.0N 117.6W 70 KT 80 MPH 36H 06/1800Z 24.9N 117.5W 55 KT 65 MPH 48H 07/0600Z 25.6N 117.1W 40 KT 45 MPH 72H 08/0600Z 27.6N 115.6W 30 KT 35 MPH 96H 09/0600Z 28.9N 114.3W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 10/0600Z 30.6N 112.8W 20 KT 25 MPH...POST-TROP/REMNT LOW $$ Forecaster Stewart

Tags: number discussion simon forecast

 

Hurricane SIMON Forecast Discussion Number 14

2014-10-05 04:33:04| National Hurricane Center (East Pacific)

Issued at 800 PM PDT SAT OCT 04 2014 000 WTPZ44 KNHC 050232 TCDEP4 HURRICANE SIMON DISCUSSION NUMBER 14 NWS NATIONAL HURRICANE CENTER MIAMI FL EP192014 800 PM PDT SAT OCT 04 2014 After the NOAA Hurricane Hunter aircraft left Simon earlier today, satellite images revealed that the eye became quite distinct and surrounded by very deep convection. Dvorak subjective and objective numbers from TAFB, SAB and UW-CIMSS jumped to T6.0 on the Dvorak scale. Based on this data, the initial intensity was adjusted upward to 115 kt. This makes Simon the 6th Category Four Hurricane on the Saffir-Simpson Hurricane Scale this season. Simon reached 115 kt just before entering a region of cool waters, and as we speak, a portion of the circulation is already doing so. Most of the global models increase the shear as the cyclone moves northward toward the mid-latitude westerlies. Based on these two factors, the NHC forecast calls for significant weakening during the next few days. In fact, if Simon reaches Baja California, it is likely to be a weak tropical storm or a tropical depression. Simon is already turning and is now moving toward the northwest or 315 degrees at 9 kt. The ridge that has been steering Simon is forecast to weaken and shift southward. This pattern will move Simon northward until the cyclone encounters the mid-latitude westerlies, and a recurvature toward Baja California will then begin in 48 hours. One large uncertainty is how fast Simon will move after recurvature. The GFS and the ECMWF are now in better agreement in accelerating the cyclone, but many of the other models are not quite so fast. The NHC forecast is not as fast as the GFS/ECMWF pair at this time, but I would not be surprised if a faster motion has to be indicated in the next forecast. The trend of models suggests that moisture from Simon could bring another heavy rain event to the southwestern United States in a few days. FORECAST POSITIONS AND MAX WINDS INIT 05/0300Z 21.4N 115.9W 115 KT 130 MPH 12H 05/1200Z 22.4N 117.0W 100 KT 115 MPH 24H 06/0000Z 23.5N 117.6W 90 KT 105 MPH 36H 06/1200Z 24.4N 117.8W 75 KT 85 MPH 48H 07/0000Z 25.2N 117.5W 60 KT 70 MPH 72H 08/0000Z 27.0N 116.2W 40 KT 45 MPH 96H 09/0000Z 28.5N 114.5W 30 KT 35 MPH 120H 10/0000Z 30.0N 113.0W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Avila

Tags: number discussion simon forecast

 

Sites : [1057] [1058] [1059] [1060] [1061] [1062] [1063] [1064] [1065] [1066] [1067] [1068] [1069] [1070] [1071] [1072] [1073] [1074] [1075] [1076] next »