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Hurricane GONZALO Forecast Discussion Number 22

2014-10-17 22:57:23| National Hurricane Center (Atlantic)

Issued at 500 PM AST FRI OCT 17 2014 000 WTNT43 KNHC 172057 TCDAT3 HURRICANE GONZALO DISCUSSION NUMBER 22 NWS NATIONAL HURRICANE CENTER MIAMI FL AL082014 500 PM AST FRI OCT 17 2014 Another reconnaissance plane has been in and around the eye of Gonzalo and found no significant change in the structure of the hurricane. Maximum flight-level winds were 124 kt, but the highest SFMR wind was 88 kt. Based on these data, the initial intensity is estimated to be 100 kt. The minimum central pressure remains around 949 mb. Although there has been a slight decrease in the surface winds, no significant change in intensity is expected before the eye crosses Bermuda in a few hours. Due to the large observed differential between the winds at the surface and aloft, a higher than normal gust factor has been used in this advisory. After Gonzalo passes Bermuda, increasing shear and cooler waters along the track of the hurricane should result in a faster weakening. Gonzalo is likely to transition into a post-tropical cyclone by 36 to 48 hours as it moves near or south of Newfoundland. This is the consensus of most of the global models. Aircraft fixes indicate that the hurricane is moving toward the north-northeast or 025 degrees at 14 kt. Gonzalo should accelerate and turn to the northeast once it becomes completely embedded within the faster southwesterly mid-latitude flow ahead of a deepening trough along the east coast of the United States. There has been no change in the guidance, and the NHC forecast is similar to the previous one. Significant coastal flooding on Bermuda is likely. Although specific amounts cannot be forecast for Gonzalo, Hurricane Fabian produced an estimated 10 feet of storm surge when it moved over Bermuda as a major hurricane in 2003, and similar values could occur with Gonzalo. Given the proximity of this dangerous hurricane to Bermuda, NHC will provide hourly position updates until Gonzalo clears Bermuda. FORECAST POSITIONS AND MAX WINDS INIT 17/2100Z 31.7N 65.3W 100 KT 115 MPH 12H 18/0600Z 34.1N 63.8W 95 KT 110 MPH 24H 18/1800Z 38.7N 60.4W 85 KT 100 MPH 36H 19/0600Z 44.7N 54.2W 70 KT 80 MPH 48H 19/1800Z 50.5N 45.5W 60 KT 70 MPH...POST-TROP/EXTRATROP 72H 20/1800Z 56.5N 18.0W 40 KT 45 MPH...POST-TROP/EXTRATROP 96H 21/1800Z...POST-TROP/EXTRATROP $$ Forecaster Avila

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Tropical Depression TWENTY-E Forecast Discussion Number 1

2014-10-17 22:52:55| National Hurricane Center (East Pacific)

Issued at 200 PM PDT FRI OCT 17 2014 000 WTPZ45 KNHC 172052 TCDEP5 TROPICAL DEPRESSION TWENTY-E DISCUSSION NUMBER 1 NWS NATIONAL HURRICANE CENTER MIAMI FL EP202014 200 PM PDT FRI OCT 17 2014 The tropical disturbance south of Mexico has developed deep convection organized in rainbands today. Correspondingly, the subjective Dvorak classifications from SAB and TAFB have come in at 1.5 and 2.0, respectively. Additionally, ship and ASCAT scatterometer observations suggest that a well-defined closed circulation has formed. Thus the system is being started as a tropical cyclone in this advisory. The two ASCAT passes this afternoon suggest peak winds of 30-35 kt, though these are along the edge of the swath and may not be reliable. Finally, a couple of ships at 18Z indicated winds of 30-35 kt. This relative bounty of observations indicates an intensity of 30 kt, though this may be somewhat conservative. The tropical depression appears to be in an environment conducive for further intensification in the short term, as water temperatures are near 30C, vertical shear is very weak, and the atmosphere is quite moist in the low levels and supportive of deep convection. Intensification is shown, quite similar to a blend of the SHIPS statistical model and the GFDL and HWRF dynamical models. A 48 hr point is shown for continuity, but the system is unlikely to exist that long as a tropical cyclone over the high terrain of Mexico. An alternative scenario - supported by the ECMWF and GFDL models - is that the cyclone reaches the coast, but does not press inland, meandering just offshore as a tropical cyclone for a longer time than indicated here. The location and motion of the cyclone's center have substantial uncertainty, though it appears to be moving toward the north at about 7 kt. The tropical depression is being steered primarily due to the interaction of deep-layer southwesterlies equatorward of the cyclone with a weak ridge to its northeast. The system should slow its forward speed during the next couple days as the steering flow weakens. The NHC forecast track is based upon the TVCE multi-model ensemble. The primary threat from this system is expected to be heavy rainfall that will likely produce flash flooding and mudslides in portions of southern Mexico during the next few days, especially near areas of elevated terrain. FORECAST POSITIONS AND MAX WINDS INIT 17/2100Z 15.4N 99.0W 30 KT 35 MPH 12H 18/0600Z 16.1N 99.2W 35 KT 40 MPH 24H 18/1800Z 16.7N 99.3W 45 KT 50 MPH...INLAND 36H 19/0600Z 17.2N 99.4W 30 KT 35 MPH...INLAND 48H 19/1800Z 17.5N 99.4W 20 KT 25 MPH...INLAND 72H 20/1800Z...DISSIPATED $$ Forecaster Landsea

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Hurricane GONZALO Forecast Discussion Number 21

2014-10-17 16:55:23| National Hurricane Center (Atlantic)

Issued at 1100 AM AST FRI OCT 17 2014 000 WTNT43 KNHC 171455 TCDAT3 HURRICANE GONZALO DISCUSSION NUMBER 21 NWS NATIONAL HURRICANE CENTER MIAMI FL AL082014 1100 AM AST FRI OCT 17 2014 Gonzalo is under surveillance by a NOAA hurricane hunter plane and its eye is in the scope of the Bermuda radar. Maximum winds measured so far by the SFMR on board the plane are 104 kt, and on this basis the initial intensity is lowered to 110 kt. This slight weakening is in agreement with the fact that the eye on satellite is not as distinct as it was 12 hours ago, and the Dvorak t-numbers are decreasing. Although it appears that a gradual weakening has begun, Gonzalo is expected to be a dangerous Category 3 hurricane as it moves near or over Bermuda later today. After that time, increasing shear and cooler waters along the track of the hurricane should result in a faster weakening. Gonzalo is likely to transition into a post-tropical cyclone by 36 to 48 hours as it moves near or south of Newfoundland, and become fully extratropical thereafter. Radar and aircraft fixes indicate that the hurricane is moving toward the north-northeast or 025 degrees at 14 kt. Gonzalo should accelerate and turn to the northeast once it becomes completely embedded within the faster southwesterly mid-latitude flow ahead of a deepening trough along the east coast of the United States. The guidance remains tightly clustered, and There is no reason to deviate much from the previous NHC forecast which shows a powerful hurricane passing near or over Bermuda later today, and a post-tropical cyclone passing south of Newfoundland in about 36 to 48 hours. Significant coastal flooding on Bermuda is likely if Gonzalo continues on the current NHC forecast track. Although specific amounts cannot be forecast for Gonzalo, Hurricane Fabian produced an estimated 10 feet of storm surge when it moved over Bermuda as a major hurricane in 2003, and similar values could occur with Gonzalo. FORECAST POSITIONS AND MAX WINDS INIT 17/1500Z 30.4N 66.1W 110 KT 125 MPH 12H 18/0000Z 32.6N 64.9W 100 KT 115 MPH 24H 18/1200Z 36.3N 62.5W 90 KT 105 MPH 36H 19/0000Z 41.5N 58.0W 80 KT 90 MPH 48H 19/1200Z 48.0N 49.0W 70 KT 80 MPH...POST-TROP/EXTRATROP 72H 20/1200Z 55.0N 25.0W 45 KT 50 MPH...POST-TROP/EXTRATROP 96H 21/1200Z...POST-TROP/EXTRATROP $$ Forecaster Avila

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Hurricane GONZALO Forecast Discussion Number 18

2014-10-16 22:31:46| National Hurricane Center (Atlantic)

Issued at 500 PM AST THU OCT 16 2014 000 WTNT43 KNHC 162031 TCDAT3 HURRICANE GONZALO DISCUSSION NUMBER 18 NWS NATIONAL HURRICANE CENTER MIAMI FL AL082014 500 PM AST THU OCT 16 2014 Recent microwave data indicate that Gonzalo has a concentric eyewall structure, with a small open inner ring of convection surrounded by a larger closed ring. The satellite presentation has not changed appreciably since this morning, and the CI estimate from the UW-CIMSS ADT supports maintaining the initial intensity at 125 kt. An Air Force reconnaissance aircraft is scheduled to investigate Gonzalo later this evening and should give us a better handle on the hurricane's current intensity. Light westerly shear has been affecting Gonzalo, but it hasn't been enough to disrupt the hurricane's structure. Vertical shear is forecast to increase slightly during the next 12-24 hours, and then increase substantially after 48 hours. Also, sea surface temperatures along Gonzalo's forecast path are expected to be at least 26C for the next 48 hours. Therefore, only gradual weakening is anticipated during the next couple of days while Gonzalo moves near Bermuda. More rapid weakening should occur after 48 hours once Gonzalo moves north of the Gulf Stream and is affected by 40-50 kt of westerly shear. The NHC intensity forecast closely follows the intensity consensus ICON, and no significant changes were required to the previous forecast. The global models indicate that Gonzalo will likely become extratropical by 72 hours, and that is now indicated in the NHC forecast. Gonzalo has turned north-northeastward and begun to accelerate with an initial motion estimate of 015/8 kt. The hurricane is entering the flow ahead of a deep-layer trough located over the eastern United States, and this pattern is expected to cause Gonzalo to accelerate further toward the north-northeast during the next 48 hours. After 48 hours, the cyclone is forecast to turn northeastward and east-northeastward over the north Atlantic. The track guidance is tightly clustered for much of the forecast period. However, the new models are again a little slower than the previous forecast, and they have shifted northwestward between 48-72 hours. The updated NHC track forecast has also been shifted northwestward during that time toward the TVCA model consensus. Significant coastal flooding on Bermuda is likely if Gonzalo continues on the current NHC forecast track. Although specific amounts cannot be forecast for Gonzalo, Hurricane Fabian produced an estimated 10 feet of storm surge when it moved over Bermuda as a major hurricane in 2003, and similar values could occur with Gonzalo. FORECAST POSITIONS AND MAX WINDS INIT 16/2100Z 27.1N 68.2W 125 KT 145 MPH 12H 17/0600Z 28.7N 67.3W 120 KT 140 MPH 24H 17/1800Z 31.1N 65.9W 110 KT 125 MPH 36H 18/0600Z 34.3N 64.0W 100 KT 115 MPH 48H 18/1800Z 39.0N 60.8W 95 KT 110 MPH 72H 19/1800Z 50.5N 46.0W 65 KT 75 MPH...POST-TROP/EXTRATROP 96H 20/1800Z 55.0N 21.0W 35 KT 40 MPH...POST-TROP/EXTRATROP 120H 21/1800Z...DISSIPATED $$ Forecaster Berg

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Hurricane GONZALO Forecast Discussion Number 16

2014-10-16 10:38:14| National Hurricane Center (Atlantic)

Issued at 500 AM AST THU OCT 16 2014 000 WTNT43 KNHC 160838 TCDAT3 HURRICANE GONZALO DISCUSSION NUMBER 16 NWS NATIONAL HURRICANE CENTER MIAMI FL AL082014 500 AM AST THU OCT 16 2014 The satellite presentation of Gonzalo has improved during the past few hours, with the eye warming and becoming more distinct since the last advisory. The 0600 UTC Dvorak estimate from TAFB was T6.0/115 kt and the 0715 UTC ADT was T6.2/120 kt. The initial intensity is set to 120 kt for this advisory based on the improving satellite appearance. The next Hurricane Hunter aircraft will be investigating Gonzalo around 1200 UTC to provide more information on the storm's intensity. Given the recent satellite trends, it seems that Gonzalo has completed the earlier eyewall replacement cycle. Some additional fluctuations in intensity are possible during the next 12 hours while Gonzalo remains over SSTs around 29C. Gradual weakening is forecast through 36 hours while SSTs slowly cool along the track and the shear begins to increase, and Gonzalo is expected to remain a dangerous hurricane as it passes near Bermuda on Friday. After 36 hours, faster weakening is shown as Gonzalo becomes post-tropical and then gradually decays as an extratropical cyclone late in the period. The new NHC intensity forecast is a little above most of the guidance in the short term and then trends toward the LGEM model while Gonzalo remains a tropical cyclone. The initial motion estimate is 360/08, as Gonzalo is moving northward to the west of a subtropical ridge. The model guidance is in very good agreement on the track forecast scenario, with Gonzalo expected to recurve ahead of a mid-latitude trough moving off the east coast of North America. The guidance this cycle has trended a little to the right through 48 hours and the NHC track has been adjusted 20-30 miles in that direction. This forecast is now a little to the left of the multi-model consensus and brings the center of Gonzalo very close to Bermuda in about 36 hours. Late in the period, post-tropical Gonzalo is expected to pass south of Newfoundland and then accelerate northeastward and eastward across the north Atlantic. At days 3 through 5, the new NHC forecast is largely an update of the previous one. The post-tropical portion of the forecast has been coordinated with the NOAA Ocean Prediction Center. FORECAST POSITIONS AND MAX WINDS INIT 16/0900Z 25.3N 68.7W 120 KT 140 MPH 12H 16/1800Z 26.8N 68.4W 115 KT 130 MPH 24H 17/0600Z 29.2N 67.1W 110 KT 125 MPH 36H 17/1800Z 31.9N 65.4W 100 KT 115 MPH 48H 18/0600Z 35.3N 63.4W 90 KT 105 MPH 72H 19/0600Z 45.5N 53.5W 70 KT 80 MPH...POST-TROPICAL 96H 20/0600Z 52.0N 33.0W 45 KT 50 MPH...POST-TROP/EXTRATROP 120H 21/0600Z 55.0N 10.0W 40 KT 45 MPH...POST-TROP/EXTRATROP $$ Forecaster Brennan

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