Home › discussion
 

Keywords :   


Tag: discussion

Subtropical Storm Beryl Forecast Discussion Number 21

2018-07-15 22:34:43| National Hurricane Center (Atlantic)

Issued at 500 PM AST Sun Jul 15 2018 763 WTNT42 KNHC 152034 TCDAT2 Subtropical Storm Beryl Discussion Number 21 NWS National Hurricane Center Miami FL AL022018 500 PM AST Sun Jul 15 2018 Beryl is less organized than 24 h ago, with the cyclone currently comprised of a swirl of low- to mid-level clouds and occasional puffs of convection in the southeastern quadrant. The low-level center has also become completely detached from a large-scale cloud band farther to the east. The initial intensity of 35 kt is based mainly on earlier scatterometer data, and this data was also used to revise the initial wind radii. Beryl has been moving slowly eastward most of the day. However, the last few satellite images suggest a more northward motion is beginning, so the initial motion is an uncertain 075/5. A broad deep-layer mid-latitude trough moving eastward across eastern Canada and the northeastern United States should cause the cyclone to turn northeastward with some acceleration tonight, with a faster northeastward motion expected on Monday and Monday night. The track guidance has shifted to the east on this advisory, so the new forecast track has been adjusted in that direction. However, the new track lies to the west of the center of the guidance envelope and the various consensus models. The new forecast track again keeps the center over the Gulf Stream for 12 h, and the intensity forecast maintains the initial intensity during that time. After that, a quick decay over cold water should occur, and the new intensity forecast now calls for Beryl to dissipate completely between 36-48 h in agreement with the dynamical guidance. The low-level center is still under strong northwesterly vertical shear, and microwave data suggests that dry air has wrapped around the circulation. If these factors prevent the quick re-development of convection, the system could dissipate even earlier than currently forecast. FORECAST POSITIONS AND MAX WINDS INIT 15/2100Z 38.2N 63.8W 35 KT 40 MPH 12H 16/0600Z 39.2N 62.3W 35 KT 40 MPH 24H 16/1800Z 41.3N 59.7W 30 KT 35 MPH...POST-TROP/REMNT LOW 36H 17/0600Z 44.0N 56.8W 25 KT 30 MPH...POST-TROP/REMNT LOW 48H 17/1800Z...DISSIPATED $$ Forecaster Beven

Tags: number discussion storm forecast

 

Subtropical Storm Beryl Forecast Discussion Number 20

2018-07-15 16:36:13| National Hurricane Center (Atlantic)

Issued at 1100 AM AST Sun Jul 15 2018 370 WTNT42 KNHC 151436 TCDAT2 Subtropical Storm Beryl Discussion Number 20 NWS National Hurricane Center Miami FL AL022018 1100 AM AST Sun Jul 15 2018 Overall, Beryl has become less organized since yesterday, with the cyclone currently comprised of a swirl of low- to mid-level clouds with minimal convection in the southeastern quadrant. While the low-level center remains over the Gulf Stream, GOES-16 airmass imagery indicates that the center is now west of the associated upper-level trough and that significant northerly vertical shear is occurring. The initial intensity of 35 kt is based on a subtropical intensity estimate from TAFB, and it could be a little generous. The storm has drifted east-northeastward during the past 12 h, with the initial motion now 075/3. A deep-layer mid-latitude trough moving eastward across eastern Canada and the northeastern United States should cause the cyclone to resume a northeastward motion by tonight, with a faster northeastward motion expected on Monday and Tuesday. The new forecast track is nudged a little to the east of the previous track and lies near the various consensus models. Since the new forecast track keeps the center over the Gulf Stream for another 12 h, the intensity forecast calls for little change in strength during that time. After that, a quick decay over cold water should occur, and the new intensity forecast is the same as the previous forecast in calling for Beryl to dissipate completely by 72 h. It should be noted that if the convection does not increase above its current level, the system could weaken and dissipate earlier than currently forecast. FORECAST POSITIONS AND MAX WINDS INIT 15/1500Z 38.1N 64.7W 35 KT 40 MPH 12H 16/0000Z 39.0N 63.4W 35 KT 40 MPH 24H 16/1200Z 40.8N 61.1W 30 KT 35 MPH...POST-TROP/REMNT LOW 36H 17/0000Z 43.2N 58.6W 25 KT 30 MPH...POST-TROP/REMNT LOW 48H 17/1200Z 45.9N 55.9W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 18/1200Z...DISSIPATED $$ Forecaster Beven

Tags: number discussion storm forecast

 
 

Subtropical Storm Beryl Forecast Discussion Number 19

2018-07-15 10:35:08| National Hurricane Center (Atlantic)

Issued at 500 AM AST Sun Jul 15 2018 149 WTNT42 KNHC 150835 TCDAT2 Subtropical Storm Beryl Discussion Number 19 NWS National Hurricane Center Miami FL AL022018 500 AM AST Sun Jul 15 2018 Water vapor imagery indicates that Beryl has become fully entangled with and embedded within an upper-level cold low, causing the small cyclone to slow down considerably over the warm waters of the Gulfstream. Beryl's appearance in satellite imagery consists of a small donut ring of shallow to moderate convection that fully encircles an eye-like feature. Most of the cloud tops in the ring are around -15C to -20C with a few overshooting towers of -35C to -45C, or about 28,000 to 38,000 ft, in the southeastern quadrant. Although that doesn't sound very impressive, those cloud heights are fairly typical for a subtropical cyclone given the low altitude of the tropopause in the inner core of cold upper-lows at high latitudes. The initial intensity is being maintained at 35 kt based on the tight ring appearance and a subtropical classification of T2.5/35 kt from TAFB. The initial motion estimate is slowly northeastward or 050/03 kt. Now that Beryl has become embedded within the upper-low, its future motion depends heavily on the motion of the now parent upper-low. For the next 48 hours, the new NHC models guidance shows Beryl and the upper-low moving northeastward toward Newfoundland within the mid-latitude westerlies, accompanied by a gradually increasing forward speed of about 10-15 kt by 36 and 48 hours. The new NHC forecast track is again slower than the previous advisory track, and lies between the HCCA and FSSE consensus track forecast models. The center of Beryl is moving slowly over North Atlantic Gulfstream waters of about 27.5C and the entire cyclone lies between the 26-deg-C isotherms, which are only about 60 nmi apart from north to south. The new forecast track keeps Beryl over these warmer waters a little longer than previous forecasts, which could result in the regeneration of convection a slight delay in Beryl weakening and eventually degenerating into a remnant low pressure system than what is currently forecast. But for now, the new NHC intensity forecast maintains continuity with the previous advisory, and closely follows a blend of the HCCA, FSSE, and IVCN intensity consensus models, which have Beryl dissipating just before reaching Newfoundland in about 72 hours. FORECAST POSITIONS AND MAX WINDS INIT 15/0900Z 38.3N 65.2W 35 KT 40 MPH 12H 15/1800Z 39.1N 64.0W 35 KT 40 MPH 24H 16/0600Z 40.5N 62.0W 30 KT 35 MPH...POST-TROP/REMNT LOW 36H 16/1800Z 42.6N 59.6W 25 KT 30 MPH...POST-TROP/REMNT LOW 48H 17/0600Z 45.0N 57.0W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 18/0600Z...DISSIPATED $$ Forecaster Stewart

Tags: number discussion storm forecast

 

Subtropical Storm Beryl Forecast Discussion Number 18

2018-07-15 04:41:38| National Hurricane Center (Atlantic)

Issued at 1100 PM AST Sat Jul 14 2018 580 WTNT42 KNHC 150241 TCDAT2 Subtropical Storm Beryl Discussion Number 18 NWS National Hurricane Center Miami FL AL022018 1100 PM AST Sat Jul 14 2018 Shear and dry air appear to have taken a toll on Beryl this evening as deep convection associated with the system has dissipated. Beryl now consists of a tight swirl of low- to mid-level clouds. The initial wind speed remains 35 kt for this advisory, which is based on a ST2.5 classification from TAFB and earlier ASCAT data, but this could be generous. Beryl will be traversing marginally warm waters of the Gulf Stream during the next 12-18 h, however the system appears to be ingesting a drier and more stable airmass from the northwest which is likely to prevent strengthening. After that time, the cyclone will be moving over much cooler water and into less favorable thermodynamic conditions, which is likely to cause the system to become a remnant low in about 24 hours. The updated NHC forecast assumes that deep convection will re-develop in with the cyclone overnight, but if that does not occur Beryl could become a remnant low much sooner. The global models suggest that the remnant low will dissipate southwest of Newfoundland within 72 hours. Beryl has moved northward this evening, but the longer-term initial motion estimate is north-northeast or 025/11. The storm should move slowly north-northeastward to northeastward around the western periphery of a mid-level ridge centered over the central Atlantic during the next couple of days. The track guidance remains in good agreement on this scenario, but there has been a significant reduction in the predicted forward speed of Beryl in the various dynamical models which has required an adjustment to the official forecast. The new NHC track is slower than, and to the left of, the previous advisory, but is in good agreement with the TVCA and HCCA consensus models. FORECAST POSITIONS AND MAX WINDS INIT 15/0300Z 38.1N 65.4W 35 KT 40 MPH 12H 15/1200Z 39.6N 64.5W 35 KT 40 MPH 24H 16/0000Z 41.1N 62.7W 30 KT 35 MPH...POST-TROP/REMNT LOW 36H 16/1200Z 42.5N 60.7W 30 KT 35 MPH...POST-TROP/REMNT LOW 48H 17/0000Z 44.3N 58.3W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 18/0000Z...DISSIPATED $$ Forecaster Brown

Tags: number discussion storm forecast

 

Subtropical Storm Beryl Forecast Discussion Number 17

2018-07-14 22:52:07| National Hurricane Center (Atlantic)

Issued at 500 PM AST Sat Jul 14 2018 007 WTNT42 KNHC 142052 TCDAT2 Subtropical Storm Beryl Discussion Number 17 NWS National Hurricane Center Miami FL AL022018 500 PM AST Sat Jul 14 2018 While the overall coverage and intensity of convection associated with Beryl has decreased in the past few hours, the remaining convection has become better organized into a curved band. There are also indications that the center may be reforming to the north in response to this band. The initial intensity of 35 kt is based on continuity from the previous advisory and a subtropical intensity estimate of 35-40 kt from TAFB. Beryl remains embedded in an upper-level trough that is well defined in GOES-16 airmass imagery, and thus is still a subtropical cyclone rather than a tropical cyclone. The initial motion is 035/12, which is somewhat uncertain due to the possible reformation of the center. Otherwise, there is little change in the forecast philosophy from the previous advisory. Beryl is in relatively light southwesterly flow between the subtropical ridge and the mid-latitude westerlies, and this pattern should steer the cyclone generally northeastward for the next two to three days. The guidance has shifted a little to the left of that of the previous advisory, and the new forecast track is also nudged in that direction. The new track is generally a blend of the HCCA and TVCN consensus models. The intensity guidance is showing little additional development, and the new intensity forecast will reflect this in keeping the intensity at 35 kt for 24 h. However, the center of Beryl will be passing over the Gulf Stream during the next 12-18 h, so it would not surprising if some intensification occurred. After that, the system should decay over cold water with little or no extratropical transition. The new forecast now calls for dissipation before the 72 h point in agreement with the dynamical models. FORECAST POSITIONS AND MAX WINDS INIT 14/2100Z 37.3N 65.2W 35 KT 40 MPH 12H 15/0600Z 38.8N 64.2W 35 KT 40 MPH 24H 15/1800Z 40.8N 62.5W 35 KT 40 MPH 36H 16/0600Z 43.0N 60.0W 30 KT 35 MPH 48H 16/1800Z 44.9N 57.3W 30 KT 35 MPH...POST-TROP/REMNT LOW 72H 17/1800Z...DISSIPATED $$ Forecaster Beven

Tags: number discussion storm forecast

 

Sites : [574] [575] [576] [577] [578] [579] [580] [581] [582] [583] [584] [585] [586] [587] [588] [589] [590] [591] [592] [593] next »