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Tropical Storm DARBY Forecast Discussion Number 5

2016-07-12 22:35:41| National Hurricane Center (East Pacific)

Issued at 300 PM MDT TUE JUL 12 2016 000 WTPZ45 KNHC 122035 TCDEP5 TROPICAL STORM DARBY DISCUSSION NUMBER 5 NWS NATIONAL HURRICANE CENTER MIAMI FL EP052016 300 PM MDT TUE JUL 12 2016 Although there is still some northeasterly shear present, the low-level center of Darby has been migrating closer to the deep convection during the day. Recent ASCAT data indicate that maximum winds are now near 45 kt, and this is supported by T3.0 Dvorak classifications from TAFB and SAB. The ocean near Darby is very warm, with SSTs on the order of 29-30 degrees Celsius, but vertical shear is expected to be 10-15 kt for another 24 hours or so. Therefore, steady strengthening is anticipated, with Darby possibly becoming a hurricane on Wednesday. The cyclone will likely reach its maximum intensity around day 3 before it reaches cooler waters and begins to weaken. Because Darby is starting out about 10 kt stronger than previously estimated, the NHC intensity forecast has been bumped up during the entire forecast period, and it is very close to the SHIPS and LGEM guidance. Darby has been moving just south of due west, or 265/10 kt. The subtropical ridge to the north of the cyclone is expected to strengthen during the next 2-3 days, which will force Darby on a westward course during that time. The GFS continues to erode the western extent of the ridge more than the ECMWF and UKMET models on days 4 and 5, allowing Darby to make a stronger northwestward turn at the end of the forecast period. The NHC track forecast favors the ridge remaining strong and only shows a slight west- northwestward motion on days 4 and 5. This forecast is a little south of the TVCE model consensus and not too different from the previous forecast. FORECAST POSITIONS AND MAX WINDS INIT 12/2100Z 15.7N 109.8W 45 KT 50 MPH 12H 13/0600Z 15.6N 111.3W 55 KT 65 MPH 24H 13/1800Z 15.5N 113.5W 65 KT 75 MPH 36H 14/0600Z 15.4N 115.8W 75 KT 85 MPH 48H 14/1800Z 15.6N 118.2W 80 KT 90 MPH 72H 15/1800Z 16.2N 122.7W 85 KT 100 MPH 96H 16/1800Z 17.0N 126.5W 75 KT 85 MPH 120H 17/1800Z 18.0N 130.5W 65 KT 75 MPH $$ Forecaster Berg

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Hurricane CELIA Forecast Discussion Number 25

2016-07-12 22:34:44| National Hurricane Center (East Pacific)

Issued at 200 PM PDT TUE JUL 12 2016 000 WTPZ44 KNHC 122034 TCDEP4 HURRICANE CELIA DISCUSSION NUMBER 25 NWS NATIONAL HURRICANE CENTER MIAMI FL EP042016 200 PM PDT TUE JUL 12 2016 The cloud pattern consists of a large ragged eye surrounded by a ring of moderate convection and a convective curved band to the east of the eye. The overall amount of convection has been decreasing during the past 12 hours. The Dvorak T-numbers have decreased slightly during the day, and the best estimate of the current intensity is 70 kt. The circulation of Celia has continued to move over increasingly cooler waters, and SHIPS guidance indicates a gradual increase in shear. On this basis, the NHC forecast calls for weakening, and Celia is forecast to be a tropical depression in about 3 days or sooner. The best estimate of the initial motion is toward the west-northwest or 300 degrees at about 11 kt. Global models continue to show a persistent moderate subtropical ridge north of Celia. This pattern will continue to steer the cyclone on a west-northwesterly track for the next 2 to 3 days. After that time, Celia should have become a shallow cyclone, and will likely move on a westward track steered by the low-level flow. The track guidance continues to be in very good agreement, and there is high confidence in the forecast. FORECAST POSITIONS AND MAX WINDS INIT 12/2100Z 17.4N 129.5W 70 KT 80 MPH 12H 13/0600Z 18.4N 130.9W 65 KT 75 MPH 24H 13/1800Z 19.6N 133.0W 55 KT 65 MPH 36H 14/0600Z 20.5N 135.2W 45 KT 50 MPH 48H 14/1800Z 21.3N 137.0W 35 KT 40 MPH 72H 15/1800Z 22.5N 141.5W 30 KT 35 MPH 96H 16/1800Z 23.0N 146.0W 25 KT 30 MPH 120H 17/1800Z 24.0N 150.0W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Avila

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Tropical Storm DARBY Forecast Discussion Number 4

2016-07-12 16:32:45| National Hurricane Center (East Pacific)

Issued at 900 AM MDT TUE JUL 12 2016 000 WTPZ45 KNHC 121432 TCDEP5 TROPICAL STORM DARBY DISCUSSION NUMBER 4 NWS NATIONAL HURRICANE CENTER MIAMI FL EP052016 900 AM MDT TUE JUL 12 2016 Recent microwave data indicate that the depression has a well- defined circulation with the center located to the northeast of the strongest convection. Subjective Dvorak intensity estimates are T2.0 from TAFB and T3.0 from SAB, and the latest ADT estimate is right at the tropical storm threshold. A consensus of these values supports upgrading the depression to a tropical storm, with the initial intensity set at 35 kt. After starting off May and June very quietly, the eastern North Pacific season has already caught up to where it should be climatologically in terms of named storms. Darby appears to have turned westward with an initial motion of 270/9 kt. A subtropical ridge extending westward from northern Mexico is expected to strengthen during the next three days, which will steer Darby westward, or even a little south of due west, during that time. The model fields continue to show differences in the strength of the ridge at the end of the forecast period. The ECMWF maintains a stronger ridge, with Darby possibly continuing a westward motion, while the GFS erodes the ridge and allows Darby to gain some latitude. The track model envelope has again shifted southward on this cycle, and the updated NHC track forecast has been nudged in that direction close to a consensus of the GFS and ECMWF. Darby will be moving over a warm pool of SSTs around 29.5 degrees Celsius during the next 24 hours, and the northeasterly vertical shear affecting the cyclone should abate a bit. Depending on its exact track, Darby could move over the cold wake left behind by Hurricanes Blas and Celia in a couple of days. Some shear could also persist for a few days, therefore only steady strengthening is expected through 72 hours. Colder water should then cause weakening on days 4 and 5. There is still a lot of spread among the intensity models, so for now no significant changes are being made to the previous NHC intensity forecast. This scenario is a little above the intensity consensus during the first three days and then close to the consensus on days 4 and 5. FORECAST POSITIONS AND MAX WINDS INIT 12/1500Z 16.0N 108.5W 35 KT 40 MPH 12H 13/0000Z 15.9N 110.0W 40 KT 45 MPH 24H 13/1200Z 15.7N 112.3W 50 KT 60 MPH 36H 14/0000Z 15.5N 114.5W 60 KT 70 MPH 48H 14/1200Z 15.4N 116.8W 65 KT 75 MPH 72H 15/1200Z 15.9N 121.1W 75 KT 85 MPH 96H 16/1200Z 16.5N 125.0W 65 KT 75 MPH 120H 17/1200Z 17.5N 128.5W 55 KT 65 MPH $$ Forecaster Berg

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Hurricane CELIA Forecast Discussion Number 24

2016-07-12 16:32:42| National Hurricane Center (East Pacific)

Issued at 800 AM PDT TUE JUL 12 2016 000 WTPZ44 KNHC 121432 TCDEP4 HURRICANE CELIA DISCUSSION NUMBER 24 NWS NATIONAL HURRICANE CENTER MIAMI FL EP042016 800 AM PDT TUE JUL 12 2016 Although the cloud pattern remains well organized, the convection has weakened considerably during the past several hours while the circulation moves over cooler waters. The eye, or what is left of it, has become large and ragged with the deepest convection located within a curved band to the east. Given that the numbers from both TAFB and SAB have decreased to 4.0 on the Dvorak scale, the initial intensity is lowered to 80 kt, which is an intensity higher than one can expect from these numbers. However, due to continuity and Dvorak constraints, this is probably a good estimate at this time. Celia is moving toward increasingly cooler waters, and beyond 2 days, the shear is expected to increase. These two factors should result in weakening. Most of the models call for gradual weakening and so does the NHC forecast, which in fact, is very close to the SHIPS model. Celia is now moving toward the northwest at 10 kt around the subtropical ridge. Global models forecast the ridge to amplify a little, and this could force Celia on a more west-northwesterly track later today or Wednesday. By the end of the forecast period, Celia should have become a shallow cyclone, and will likely move on a westward track steered by the low-level flow. The NHC forecast is very near the multi-model consensus and continues to be very similar to the previous forecast. Since the track guidance is in good agreement, there is high confidence in the forecast. FORECAST POSITIONS AND MAX WINDS INIT 12/1500Z 16.8N 128.5W 80 KT 90 MPH 12H 13/0000Z 17.8N 129.9W 70 KT 80 MPH 24H 13/1200Z 18.9N 131.8W 60 KT 70 MPH 36H 14/0000Z 19.9N 133.8W 50 KT 60 MPH 48H 14/1200Z 21.0N 136.0W 40 KT 45 MPH 72H 15/1200Z 22.1N 140.2W 30 KT 35 MPH 96H 16/1200Z 22.5N 145.0W 25 KT 30 MPH 120H 17/1200Z 23.5N 149.5W 25 KT 30 MPH $$ Forecaster Avila

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Tropical Depression FIVE-E Forecast Discussion Number 3

2016-07-12 10:49:39| National Hurricane Center (East Pacific)

Issued at 300 AM MDT TUE JUL 12 2016 000 WTPZ45 KNHC 120849 TCDEP5 TROPICAL DEPRESSION FIVE-E DISCUSSION NUMBER 3 NWS NATIONAL HURRICANE CENTER MIAMI FL EP052016 300 AM MDT TUE JUL 12 2016 Satellite images indicate little overall change to the depression during the past several hours. Convection has been flaring up and down without any apparent increase in organization. A pair of ASCAT passes showed maximum winds of 25 to 30 kt, so the initial wind speed will stay 30 kt. The initial motion has turned west-northwestward, and recently the depression may even be moving due westward. A westward or west- southwestward course is expected for the next 2-3 days due to a building ridge over the eastern Pacific. Thereafter the system should resume a track toward the west or west-northwest, with some differences noted in the strength of the ridge at long range. Overall, the model consensus has generally shifted southward by about 30 n mi at most time intervals, and the official forecast will follow that trend. The intensity forecast is tricky since it is becoming more related to the track forecast. While the overall environment looks conducive for strengthening for a few days, the southward shift in the cyclone's predicted path increases the chances that the system encounters the cool wake of Blas and Celia. For now it is expected to stay just to the north, so only a slight reduction is made to the previous official forecast. The latest forecast is similar to the intensity consensus for the first couple days, and remains above that at longer range, mostly out of respect for a rather low-shear environment forecast by the global models by late week. It is worth noting, and probably should be no surprise, that the intensity guidance has a rather wide range for this forecast, with the GFS-based COAMPS-TC model showing no significant strengthening and the HWRF model making the cyclone a hurricane in 36 hours. FORECAST POSITIONS AND MAX WINDS INIT 12/0900Z 15.8N 107.6W 30 KT 35 MPH 12H 12/1800Z 15.9N 108.9W 35 KT 40 MPH 24H 13/0600Z 15.7N 110.9W 45 KT 50 MPH 36H 13/1800Z 15.5N 113.1W 55 KT 65 MPH 48H 14/0600Z 15.5N 115.4W 65 KT 75 MPH 72H 15/0600Z 15.9N 119.8W 75 KT 85 MPH 96H 16/0600Z 16.6N 123.6W 65 KT 75 MPH 120H 17/0600Z 17.5N 127.0W 55 KT 65 MPH $$ Forecaster Blake

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