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Tropical Depression SIX-E Forecast Discussion Number 1

2016-07-15 16:58:31| National Hurricane Center (East Pacific)

Issued at 900 AM MDT FRI JUL 15 2016 000 WTPZ41 KNHC 151458 TCDEP1 TROPICAL DEPRESSION SIX-E DISCUSSION NUMBER 1 NWS NATIONAL HURRICANE CENTER MIAMI FL EP062016 900 AM MDT FRI JUL 15 2016 The eastern North Pacific July tropical cyclone outbreak continues. Visible satellite and overnight ASCAT data indicate that the large low pressure area located southwest of the coast of Mexico has acquired a well-defined circulation and enough convective banding to classify the system as a tropical cyclone. This marks the fifth tropical cyclone formation in the eastern Pacific this month. The earlier ASCAT data showed maximum winds of 25 to 30 kt, and this is the basis for the initial wind speed of 30 kt. The depression is forecast to remain over warm water and in a low-shear environment during the next few days, but the large size and current lack of inner-core convection will likely result in only gradual strengthening through tonight. After that time, steady strengthening is forecast, and the cyclone is forecast to become a tropical storm by early Saturday, and reach hurricane strength in a couple of days. After that time, the system is expected to move over water that has been cooled by the previous couple of hurricanes, and only a little additional intensification is predicted. The NHC intensity forecast is a little lower than the SHIPS guidance, and follows the multi-model intensity consensus closely. The initial motion of the depression is a somewhat uncertain 290/7 kt. A climatological west-northwestward heading is forecast through the entire forecast period, to the south of a strong mid- to upper-level ridge extending westward from northern Mexico. The track guidance is in very good agreement, and the NHC forecast is near the middle of the model envelope. FORECAST POSITIONS AND MAX WINDS INIT 15/1500Z 14.0N 106.3W 30 KT 35 MPH 12H 16/0000Z 14.8N 107.8W 35 KT 40 MPH 24H 16/1200Z 15.2N 109.6W 45 KT 50 MPH 36H 17/0000Z 15.6N 111.2W 55 KT 65 MPH 48H 17/1200Z 15.9N 112.9W 65 KT 75 MPH 72H 18/1200Z 16.8N 116.1W 75 KT 85 MPH 96H 19/1200Z 17.8N 119.4W 80 KT 90 MPH 120H 20/1200Z 18.5N 123.0W 75 KT 85 MPH $$ Forecaster Brown

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Hurricane DARBY Forecast Discussion Number 16

2016-07-15 16:52:39| National Hurricane Center (East Pacific)

Issued at 800 AM PDT FRI JUL 15 2016 000 WTPZ45 KNHC 151452 TCDEP5 HURRICANE DARBY DISCUSSION NUMBER 16 NWS NATIONAL HURRICANE CENTER MIAMI FL EP052016 800 AM PDT FRI JUL 15 2016 Darby's eye became a little better defined earlier this morning, with an elongated tail of convection developing within the eastern portion of the circulation. Dvorak final-T numbers are now 4.5/77 kt from TAFB, 5.0/90 kt from SAB, and 5.1/92 kt from the UW-CIMSS ADT, so the initial intensity is raised to 85 kt on this advisory. The eye appears to have opened up a bit on the latest satellite pictures, so it's possible that Darby may have reached its peak intensity. The hurricane is now moving over sea surface temperatures a little less than 27C, and the ocean beneath the hurricane is expected to be colder than 26C within the next 24-36 hours. Since vertical shear continues to gradually decrease, Darby is forecast to maintain its intensity or only gradually weaken during the next day or two. After 48 hours, more marked weakening is anticipated due to SSTs getting as cold as 24-25C. No changes to the NHC intensity forecast, which is essentially a blend of the SHIPS model and Florida State Superensemble early and the IVCN intensity consensus late, were required from the previous advisory. Darby appears to have turned west-northwestward and slowed down, and the initial motion estimate is 285/8 kt. An amplifying mid- to upper-level trough along the west coast of the United States is expected to weaken the subtropical ridge during the next day or two. This should allow the hurricane to continue moving west-northwestward for the next 36 hours, but thereafter a westward turn is anticipated when a weaker Darby comes under the influence of lower-level steering winds. There continues to be high confidence in Darby's future path due to a tightly packed model suite, and the updated NHC track forecast is shifted slightly northward only during the first 36 hours to account for the recent west-northwestward turn. FORECAST POSITIONS AND MAX WINDS INIT 15/1500Z 16.5N 120.5W 85 KT 100 MPH 12H 16/0000Z 17.0N 121.9W 85 KT 100 MPH 24H 16/1200Z 17.5N 123.8W 80 KT 90 MPH 36H 17/0000Z 17.9N 125.5W 75 KT 85 MPH 48H 17/1200Z 18.1N 127.3W 70 KT 80 MPH 72H 18/1200Z 18.6N 131.6W 60 KT 70 MPH 96H 19/1200Z 19.0N 136.5W 50 KT 60 MPH 120H 20/1200Z 19.0N 141.5W 45 KT 50 MPH $$ Forecaster Berg

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Tropical Storm CELIA Forecast Discussion Number 35

2016-07-15 10:40:59| National Hurricane Center (East Pacific)

Issued at 200 AM PDT FRI JUL 15 2016 000 WTPZ44 KNHC 150840 TCDEP4 TROPICAL STORM CELIA DISCUSSION NUMBER 35 NWS NATIONAL HURRICANE CENTER MIAMI FL EP042016 200 AM PDT FRI JUL 15 2016 Enhanced infrared imagery and a recent SSMIS microwave overpass show all that remains of Celia's deep convective cloud pattern is a fragmented curved band displaced about 60 nm north-northeast of the exposed circulation center. The initial intensity is lowered to 40 kt, but is quite a bit higher than the subjective satellite intensity estimates out of respect for the 45-50 kt winds that were depicted in the earlier 14/1912 UTC ASCAT pass. Celia should continue to gradually spin down, due to the sub-24C SSTs and the surrounding stable air mass, and become a post-tropical cyclone by tonight. Although the latest Remote Sensing System's latest SST analysis indicates slightly warmer SSTs of 25-26C ahead of Celia, the global models still show increasing westerly shear in 36 hours, which is expected to hamper any regeneration potential. The intensity forecast is an update of the previous advisory and is hedged toward the multi-model consensus and the GFS/ECMWF large-scale models. Celia has been moving west-northwestward or 285/11 kt. The cyclone is forecast to turn westward later today as it weakens further, becoming a shallow system, and is steered by the low-level trades. The model guidance reflects this scenario well and the official NHC forecast splits between the previous forecast track and the multi-model consensus. Celia has moved into the Central Pacific basin. Therefore, this is the last advisory on this system by the National Hurricane Center. Subsequent advisories will be issued by the Central Pacific Hurricane Center in Honolulu, Hawaii. FORECAST POSITIONS AND MAX WINDS INIT 15/0900Z 22.0N 140.2W 40 KT 45 MPH 12H 15/1800Z 22.2N 142.0W 35 KT 40 MPH...POST-TROPICAL 24H 16/0600Z 22.4N 144.5W 30 KT 35 MPH...POST-TROP/REMNT LOW 36H 16/1800Z 22.7N 146.7W 30 KT 35 MPH...POST-TROP/REMNT LOW 48H 17/0600Z 23.2N 148.8W 30 KT 35 MPH...POST-TROP/REMNT LOW 72H 18/0600Z 24.1N 153.2W 30 KT 35 MPH...POST-TROP/REMNT LOW 96H 19/0600Z 25.0N 158.1W 30 KT 35 MPH...POST-TROP/REMNT LOW 120H 20/0600Z 26.3N 163.4W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Roberts

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Hurricane DARBY Forecast Discussion Number 14

2016-07-15 04:46:27| National Hurricane Center (East Pacific)

Issued at 800 PM PDT THU JUL 14 2016 000 WTPZ45 KNHC 150246 TCDEP5 HURRICANE DARBY DISCUSSION NUMBER 14 NWS NATIONAL HURRICANE CENTER MIAMI FL EP052016 800 PM PDT THU JUL 14 2016 Darby has become a little better organized during the past 6 hours with a ragged 30-nmi-diameter eye having appeared within the central dense overcast. Upper-level outflow has continued to expand in all quadrants. The initial intensity has been increased to 80 kt based on a blend of consensus subjective intensity estimates of T4.5/77 kt from TAFB and SAB, and UW-CIMSS objective intensity estimates of 83 kt and 85 kt from AMSU and ADT, respectively. Darby's initial motion estimate is 280/11 kt after smoothing through some wobbles in the track. Otherwise, there is no significant change to previous track or philosophy. The latest model guidance remains in excellent agreement on Darby moving west-northwestward to westward for the next 48 hours, followed by a turn to a more due west motion after that as the ridge to the north of the hurricane builds slightly southward and westward. The new NHC track forecast is basically just an extension of the previous advisory track, and remains near the southern edge of the guidance suite, following the consensus of the GFS and ECMWF models. Although the vertical wind shear is expected to remain 10 kt or less throughout the 5-day forecast period, SSTs decreasing below 27C and the large eye of Darby argue against any significant strengthening during the next day or so. After that, SSTs decreasing to less than 26C should induce gradual weakening by 36 h and beyond. However, the aforementioned weak wind shear conditions should act to prevent a more typical rapid weakening trend from occurring. This is similar to the slower-than-normal weakening trend noted with Tropical Storm Celia during the past couple of days while that cyclone has been moving through a similar environment of low shear and cool waters near 25C. The official NHC intensity forecast is above the IVCN intensity consensus model, and closely follows a blend of the SHIPS and LGEM models. FORECAST POSITIONS AND MAX WINDS INIT 15/0300Z 16.0N 119.1W 80 KT 90 MPH 12H 15/1200Z 16.4N 120.7W 85 KT 100 MPH 24H 16/0000Z 16.9N 122.7W 85 KT 100 MPH 36H 16/1200Z 17.4N 124.7W 80 KT 90 MPH 48H 17/0000Z 17.6N 126.5W 75 KT 85 MPH 72H 18/0000Z 18.1N 130.4W 65 KT 75 MPH 96H 19/0000Z 18.3N 135.1W 55 KT 65 MPH 120H 20/0000Z 18.6N 140.0W 50 KT 60 MPH $$ Forecaster Stewart

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Tropical Storm CELIA Forecast Discussion Number 34

2016-07-15 04:42:27| National Hurricane Center (East Pacific)

Issued at 800 PM PDT THU JUL 14 2016 000 WTPZ44 KNHC 150242 TCDEP4 TROPICAL STORM CELIA DISCUSSION NUMBER 34 NWS NATIONAL HURRICANE CENTER MIAMI FL EP042016 800 PM PDT THU JUL 14 2016 Deep convection within Celia has been steadily deteriorating with only a few patches of moderately cold cloud tops existing in the northern semicircle. Consistent with this downward trend, the SAB and TAFB subjective Dvorak classifications have dropped to current intensity numbers of 2.0 and 2.5, respectively, suggesting an intensity of 30-35 kt. However, a recent ASCAT-A scatterometer pass indicated that peak winds near 50 kt were still occurring. Assuming some weakening since that time, the initial intensity is assessed at 45 kt. Despite the resilience of the vortex today, Celia should soon succumb to the effects of cool 24-25 deg C SSTs, a stable atmosphere, and convergent upper-level flow. Thus it is anticipated the the system will lose its deep convection and become a post-tropical cyclone on Friday and degenerate to a remnant low by Saturday. Due in part to the strong synoptic-scale pressure gradient to Celia's north, the system should be able to maintain peak winds of about 30 kt for the next few days. The NHC intensity forecast is based upon the IVCN consensus, in which the statistical models dissipate Celia more quickly, while the dynamical models hold on to Celia perhaps too robustly. Celia is moving toward the west-northwest at about 12 kt due to the steering influence of a strong subtropical ridge to its northeast. As the cyclone decays, it should be carried along in the low-level easterly trade wind flow toward the west at about the same forward speed. The NHC track forecast is based upon the TVCN consensus, which shows a tight packing of its individual members. On the forecast track, Celia is expected to move into the Central Pacific basin tomorrow morning. The scatterometer pass indicated that the tropical-storm-force wind radii were somewhat larger than earlier analyzed. Consistent with a larger-sized circulation, an altimeter pass showed that the extent of 12-ft seas was also substantially larger than indicated in the last advisory. FORECAST POSITIONS AND MAX WINDS INIT 15/0300Z 21.8N 139.1W 45 KT 50 MPH 12H 15/1200Z 22.2N 140.9W 40 KT 45 MPH 24H 16/0000Z 22.3N 143.3W 35 KT 40 MPH...POST-TROPICAL 36H 16/1200Z 22.4N 145.7W 30 KT 35 MPH...POST-TROP/REMNT LOW 48H 17/0000Z 22.8N 148.0W 30 KT 35 MPH...POST-TROP/REMNT LOW 72H 18/0000Z 23.8N 152.6W 30 KT 35 MPH...POST-TROP/REMNT LOW 96H 19/0000Z 24.5N 157.3W 30 KT 35 MPH...POST-TROP/REMNT LOW 120H 20/0000Z 25.4N 162.4W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Landsea

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