Home › discussion
 

Keywords :   


Tag: discussion

Hurricane LESTER Forecast Discussion Number 10

2016-08-27 04:50:18| National Hurricane Center (East Pacific)

Issued at 800 PM PDT FRI AUG 26 2016 000 WTPZ43 KNHC 270250 TCDEP3 HURRICANE LESTER DISCUSSION NUMBER 10 NWS NATIONAL HURRICANE CENTER MIAMI FL EP132016 800 PM PDT FRI AUG 26 2016 The satellite presentation has been gradually improving during the past few hours, and an eye became evident on the 0200 UTC night visible image. A convective ring was also observed on the last SSMI microwave pass at 2344 UTC. On this basis, and a Dvorak estimate from TAFB, the initial wind speed has been increased to 65 kt. Additional intensification is anticipated during the next 2 to 3 days while the cyclone continues to move over warm waters and is embedded within light shear. By the end of the forecast period, Lester will probably begin to weaken due to entrainment of drier air. The NHC forecast follows very closely the model consensus, and shows Lester as a hurricane moving into the Central Pacific in about 5 days. The best estimate of the initial motion is toward the west or 280 degrees at 8 kt. Lester is embedded within a deep-layer easterly flow on the south side of an amplifying subtropical ridge extending from the Baja California peninsula westward across the Pacific. This pattern strongly favors the continuation of a westward motion for the next five days with some increase in forward speed. The steering flow is forecast to be so well established that track models are basically on top of each other, increasing the confidence in the forecast. The NHC forecast is in the middle of the tighter-than- normal guidance envelope, and does not deviate much from the previous NHC prediction. FORECAST POSITIONS AND MAX WINDS INIT 27/0300Z 17.9N 116.5W 65 KT 75 MPH 12H 27/1200Z 18.0N 117.7W 65 KT 75 MPH 24H 28/0000Z 18.1N 119.8W 70 KT 80 MPH 36H 28/1200Z 18.2N 122.0W 75 KT 85 MPH 48H 29/0000Z 18.2N 124.5W 80 KT 90 MPH 72H 30/0000Z 18.5N 130.0W 80 KT 90 MPH 96H 31/0000Z 18.5N 136.0W 75 KT 85 MPH 120H 01/0000Z 18.0N 140.8W 70 KT 80 MPH $$ Forecaster Avila

Tags: number discussion forecast hurricane

 

Tropical Depression FOURTEEN-E Forecast Discussion Number 1

2016-08-26 22:34:01| National Hurricane Center (East Pacific)

Issued at 200 PM PDT FRI AUG 26 2016 000 WTPZ44 KNHC 262033 TCDEP4 TROPICAL DEPRESSION FOURTEEN-E DISCUSSION NUMBER 1 NWS NATIONAL HURRICANE CENTER MIAMI FL EP142016 200 PM PDT FRI AUG 26 2016 Visible satellite imagery indicates that the area of low pressure in the western part of the eastern North Pacific basin has developed a well-defined center and has sufficient convective organization to be considered a tropical cyclone. The convective pattern displays a CDO feature near and to the west of the estimated center location due to some east-northeasterly shear, and the initial intensity is set to 30 kt based on the latest SAB Dvorak estimate. The cyclone will be moving over SSTs above 27C and in a low-to-moderate easterly shear environment for the next 2 to 3 days. This should allow for steady intensification, and the NHC forecast shows the cyclone becoming a hurricane in about 3 days. Later in the forecast period the SSTs cool and the mid-level atmosphere dries out, which should result in some weakening. The official intensity forecast is close to or a little below the IVCN consensus through the period. The initial motion estimate is a somewhat uncertain 295/10 given the recent formation of the center. The depression is currently situated on the southwestern flank of a subtropical ridge centered near 125W. A west-northwestward motion is expected during the first couple of days of the forecast period as the cyclone moves around the edge of the ridge. Late in the period a new ridge builds north of the Hawaiian Islands, which should result in a westward motion at days 3 through 5. The track model guidance is in generally good agreement on this scenario, however there is some spread, with the GFS slower and farther south by day 5, while the ECMWF is faster and farther north. The NHC forecast is near the center of the guidance envelope and is a little south of the TVCN consensus and is north of a blend of the GFS and ECMWF. It is too early to determine what, if any, impacts this cyclone could have on the Hawaiian Islands near the end of the forecast period. It is important to remind users that the average 5-day track forecast error for eastern Pacific tropical cyclones is about 170 miles. FORECAST POSITIONS AND MAX WINDS INIT 26/2100Z 13.3N 136.5W 30 KT 35 MPH 12H 27/0600Z 14.2N 137.6W 35 KT 40 MPH 24H 27/1800Z 15.2N 138.9W 40 KT 45 MPH 36H 28/0600Z 15.8N 140.2W 50 KT 60 MPH 48H 28/1800Z 16.6N 141.5W 60 KT 70 MPH 72H 29/1800Z 18.0N 144.5W 65 KT 75 MPH 96H 30/1800Z 19.0N 148.0W 65 KT 75 MPH 120H 31/1800Z 19.0N 152.0W 60 KT 70 MPH $$ Forecaster Brennan

Tags: number discussion tropical depression

 
 

Tropical Storm GASTON Forecast Discussion Number 17

2016-08-26 22:32:40| National Hurricane Center (Atlantic)

Issued at 500 PM AST FRI AUG 26 2016 000 WTNT42 KNHC 262032 TCDAT2 TROPICAL STORM GASTON DISCUSSION NUMBER 17 NWS NATIONAL HURRICANE CENTER MIAMI FL AL072016 500 PM AST FRI AUG 26 2016 The hostile vertical shear from an upper low to Gaston's southwest appears to be dropping with the SHIPS and CIMSS shear analyses down to about 15 kt. The deep convection, however, is still mainly north of the center and lacks significant banding features. SAB and TAFB Dvorak current intensity estimates range from 45 to 55 kt, down slightly from earlier today. In deference to the 1330Z ASCAT scatterometer pass and the very robust low-level circulation evident in the visible imagery during the day, the maximum winds are kept at 55 kt. As Gaston moves away from the upper-level low, the shear should continue to drop to values between 5 and 10 kt by tomorrow. The shear should then stay low through about 72 h while the cyclone traverses over quite warm waters. A key uncertainty in the intensity forecast is from the environmental low-level moisture, which may decrease substantially during the next few days. This could reduce the otherwise quite conducive conditions that Gaston should soon experience. After about three days, Gaston is likely to encounter strong mid-latitude upper-level westerlies and a return of hostile shear while SSTs steadily drop. The official NHC forecast is for steady intensification between days one and three, with gradual weakening thereafter. This forecast is based upon a blend of the tightly packed HWRF/COAMPS/SHIPS/LGEM models and is the same as in the previous advisory. Gaston's center is just tucked in on the southern edge of the deep convection, allowing for a confident assessment of the initial position. The tropical storm is moving toward the northwest at a 15-kt clip, as it is being steered between the strong upper low and a subtropical ridge to its northeast. Around 72 h, Gaston should slow to a crawl as it reaches a weak steering pattern. But by the end of the forecast period, the system should be accelerating northeastward as it enters the mid-latitude westerlies. The track forecast is based upon a blend of the GFS and ECMWF global models and is nearly the same from that in the previous advisory. The initial 34- and 50-kt wind radii were only slightly tweaked based upon the ASCAT scatterometer pass and the wind radii forecast is similar to the RVCN consensus technique. FORECAST POSITIONS AND MAX WINDS INIT 26/2100Z 26.2N 49.7W 55 KT 65 MPH 12H 27/0600Z 27.4N 51.5W 55 KT 65 MPH 24H 27/1800Z 28.6N 53.5W 65 KT 75 MPH 36H 28/0600Z 29.7N 54.8W 75 KT 85 MPH 48H 28/1800Z 30.4N 55.8W 85 KT 100 MPH 72H 29/1800Z 31.5N 56.0W 95 KT 110 MPH 96H 30/1800Z 32.5N 53.5W 90 KT 105 MPH 120H 31/1800Z 34.5N 49.0W 80 KT 90 MPH $$ Forecaster Landsea

Tags: number discussion storm tropical

 

Tropical Storm LESTER Forecast Discussion Number 8

2016-08-26 16:39:16| National Hurricane Center (East Pacific)

Issued at 800 AM PDT FRI AUG 26 2016 000 WTPZ43 KNHC 261439 TCDEP3 TROPICAL STORM LESTER DISCUSSION NUMBER 8 NWS NATIONAL HURRICANE CENTER MIAMI FL EP132016 800 AM PDT FRI AUG 26 2016 It appears that northwesterly shear and dry air entrainment is continuing to prevent Lester from strengthening. The deep convection associated with the tropical cyclone continues to burst, but there is little evidence of banding features at this time. Subject Dvorak intensity estimates range from 45 to 55 kt from SAB and TAFB, and the earlier ASCAT data suggests that the intensity was around 45 to 50 kt, so the initial wind speed will remain 50 kt for this advisory. The shear is expected to decrease very soon, which favors some intensification while Lester remains over warm water during the next few days. Nearby dry air could occasionally interrupt the intensification process during this time, so only gradually strengthening is anticipated through 72 hours. After that time, slightly cooler waters and a more stable airmass near the track could cause some weakening by the end of the forecast period. Lester is moving westward or 280/6. A strong mid- to upper-level ridge centered well west of the Baja California is expected to remain intact through the middle of next week. This ridge should steer Lester westward at a little faster forward speed throughout the entire forecast period. The guidance is in very good agreement with this scenario, and the new NHC track is essentially an update of the previous advisory, and lies near the middle of the guidance envelope. FORECAST POSITIONS AND MAX WINDS INIT 26/1500Z 17.1N 115.0W 50 KT 60 MPH 12H 27/0000Z 17.3N 116.0W 55 KT 65 MPH 24H 27/1200Z 17.4N 117.6W 60 KT 70 MPH 36H 28/0000Z 17.4N 119.7W 70 KT 80 MPH 48H 28/1200Z 17.5N 122.1W 75 KT 85 MPH 72H 29/1200Z 17.5N 127.6W 80 KT 90 MPH 96H 30/1200Z 17.5N 132.8W 80 KT 90 MPH 120H 31/1200Z 17.2N 137.5W 75 KT 85 MPH $$ Forecaster Brown

Tags: number discussion storm tropical

 

Tropical Storm GASTON Forecast Discussion Number 15

2016-08-26 10:51:42| National Hurricane Center (Atlantic)

Issued at 500 AM AST FRI AUG 26 2016 000 WTNT42 KNHC 260851 TCDAT2 TROPICAL STORM GASTON DISCUSSION NUMBER 15 NWS NATIONAL HURRICANE CENTER MIAMI FL AL072016 500 AM AST FRI AUG 26 2016 Gaston is right in the thick of 20-25 kt of southwesterly shear, and the low-level center appears to be near or just inside the southern edge of a ragged central dense overcast. Because Dvorak Current Intensity estimates from TAFB and SAB remain 3.5, the initial intensity is held at 55 kt. With Gaston now moving around the northeastern side of a mid- to upper-level low, the vertical shear is expected to quickly decrease to below 10 kt within the next 12-24 hours. In addition, sea surface temperatures are forecast to increase by another degree or two. Therefore, Gaston is likely to begin strengthening later today, and it should reintensify to a hurricane by tonight or on Saturday. Strengthening is anticipated to continue through days 3 and 4, with Gaston nearing or possibly reaching major hurricane intensity, followed by some weakening on day 5 due to an increase in westerly shear. The reliable intensity models are all within 10-15 kt of each other for the entire forecast period, and the NHC forecast is therefore very close to the ICON intensity consensus. Gaston continues to move northwestward, or 320 degrees at 15 kt. The cyclone is expected to maintain a generally northwestward track but slow down considerably during the next few days after it moves north of the aforementioned mid- to upper-level low and enters a break in the subtropical ridge. After 72 hours, Gaston is expected to reach the mid-latitude westerlies, and a sharp recurvature with acceleration is forecast at the end of the forecast period. While all the track models agree on this scenario, there continue to be differences in the sharpness of Gaston's turn and its forward speed, especially after the turn. Still, the updated NHC track forecast is not too different from the previous one, and it is closest to a clustering of models that includes the GFS, the Florida State Superensemble, and the TVCN multi-model consensus. FORECAST POSITIONS AND MAX WINDS INIT 26/0900Z 23.9N 47.6W 55 KT 65 MPH 12H 26/1800Z 25.5N 49.5W 60 KT 70 MPH 24H 27/0600Z 27.0N 52.1W 65 KT 75 MPH 36H 27/1800Z 28.2N 54.2W 70 KT 80 MPH 48H 28/0600Z 29.2N 55.7W 85 KT 100 MPH 72H 29/0600Z 30.8N 57.1W 95 KT 110 MPH 96H 30/0600Z 32.2N 55.8W 95 KT 110 MPH 120H 31/0600Z 34.0N 51.5W 90 KT 105 MPH $$ Forecaster Berg

Tags: number discussion storm tropical

 

Sites : [845] [846] [847] [848] [849] [850] [851] [852] [853] [854] [855] [856] [857] [858] [859] [860] [861] [862] [863] [864] next »