1500 UTC 8/19/2004 TROPICAL DEPRESSION 7-E FORECAST #1

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Tropical Depression 7-E has been moving to the west over the last couple of days, under the influence of a large ridge to the north. Guidance suggests that there may be some limited weakening of the ridge in the short term, which would allow for a north of due west track to commence. However, near the end of the period, assuming that there is weakening over the cooler waters and the system becomes more shallow, the system should turn back to the west, possibly even to the south of due west as it is steered by the low-level flow. This is a common track once systems start to weaken near Hawaii. This forecast brings the storm south of Hawaii in 4-5 days.

Dvorak data T numbers are increasing. Satellite imagery shows a very good banding structure with this cyclone. Therefore, intensification is likely over the next couple of days. SHIPS brings 7-E to a strong tropical storm in 36-48 hours, then maintains the intensity. The GFD models bring this depression to a very strong tropical storm or category 1 hurricane in just 24 hours, before weakening the system. Due to the lack of an inner-core, I do not foresee this becoming a strong storm or hurricane in 24 hours; therefore, for the first 36 hours I will follow the trends from SHIPS, before reverting to the GFD models and forecasting a weakening system. It should be noted that if this cyclone tracks farther south than expected, then the system would remain over warmer waters and would have a better chance to intensify.

Initial: 11.6N 132.7W 30KT
12 Hour: 12.0N 135.0W 35KT
24 Hour: 13.0N 137.0W 45KT
36 Hour: 14.0N 139.0W 50KT
48 Hour: 15.0N 141.0W 50KT
72 Hour: 16.0N 145.5W 45KT
USE WITH EXTREME CAUTION AS FOLLOWING IS SUBJECT TO LARGE ERROR
96 Hour: 16.2N 150.5W 40KT
120 Hour: 16.0N 155.5W 35KT

Next Forecast: 0300 UTC

Forecaster: Ortt

0300 UTC 8/20/2004 TROPICAL DEPRESSION 7-E FORECAST #2

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No graphics with this forecast

Guidance now indicates that the ridge will not be as strong as expected in a couple of days. This will allow for the depression to remain farther north and closer to Hawaii. This, along with the current motion being well right of the previous track, means that the new forecast must be right of the previous one. I do not want to make any significant changes; therefore, this forecast will bring the system to 18.0N in 120 hours, passing just south of the big island.

Initial intensity remains near 30KT. Earlier, satellite imagery showed a good convective burst over the small center; however, this is starting to fade. Stll going with the intensity forecast from before, 50KT before weakening over cooler waters.

Initial: 12.9N 135.0W 30KT
12 Hour: 14.0N 137.0W 40KT
24 Hour: 15.1N 139.0W 45KT
36 Hour: 16.2N 141.0W 50KT
48 Hour: 17.0N 143.1W 50KT
72 Hour: 17.5N 147.5W 45KT
USE WITH EXTREME CAUTION AS FOLLOWING IS SUBJECT TO LARGE ERROR
96 Hour: 17.8N 152.0W 40KT
120 Hour: 18.0N 157.0W 35KT

Next Forecast: 1500 UTC

Forecaster: Ortt

1500 UTC 8/20/2004 TROPICAL STORM ESTELLE FORECAST #3

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Estelle has moved ever so slightly faster and left of the previous forecast track. Synoptic reasoning is basically the same. As the ridge builds back in to the north of Estelle, the track will bend back to the west. Models disagree on the strength of the ridge. One factor complicating the track forecast is the intensity of Estelle. A stronger storm would likely move more north than a weaker storm as the low-level flow would steer the storm mainly to the west or WSW while a stronger storm would likely have somewhat of a northward component, mainly due to the trough. The models assuming a deeper system are also more to the north than those indicating a shallow system or an open wave. For now, I will go with a mainly westward track at the end as the system should be weakening at that time.

Initial intensity is set to 35KT based upon satellite estimates. Intensity forecast is reduced slightly to 45KT as Estelle has not intensified quite as much as previously thought. With shear increasing and SST's cooling, there likely is not that much time for intensification to occur.

Initial: 13.9N 137.3W 35KT
12 Hour: 14.9N 139.3W 40KT
24 Hour: 15.8N 141.4W 45KT
36 Hour: 16.5N 143.6W 45KT
48 Hour: 17.0N 145.8W 40KT
72 Hour: 17.7N 150.0W 40KT
USE WITH EXTREME CAUTION AS FOLLOWING IS SUBJECT TO LARGE ERROR
96 Hour: 17.9N 154.5W 35KT
120 Hour: 17.9N 159.0W 35KT

Next Forecast: 0300 UTC

Forecaster: Ortt

0300 UTC 8/21/2004 TROPICAL STORM ESTELLE FORECAST #4

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There are no graphics with this forecast

Estelle is in a rapid intensification phase. Satellite imagery shows well developed bands of convection spiraling into a well-developed inner-core. In addition, water vapor imagery shows a large ridge over the storm, which is being amplified by the large trough that is digging over Hawaii. This may result in less shear than was expected, allowing for more intensification. This forecast will go for rapid intensification through 12 hours, taking the system to 70KT, with some additional intensification afterwards, then leveling off at 80KT. This is even more aggressive than SHIFOR, which brings the system to 75KT. Only a slow weakening is forecast after 72 hours, mainly due to guidance, though my confidence in guidance is low.

With the system being deeper, the chance for a SW track is starting to look unlikely. Guidance is also shifting to the right. If the trough digs much more, it may be hard for Estelle to pass south of Hawaii, unless the system becomes sheared and shallow. This being said, I am only making a slight northward adjustment to the forecast track as I would like to see how the system reacts over the next 12 hours, as well as the surrounding environment and the guidance. This track still keeps the center south of South Point.

Initial: 14.3N 139.3W 55KT
12 Hour: 15.3N 141.3W 70KT
24 Hour: 16.3N 143.3W 75KT
36 Hour: 17.0N 145.4W 80KT
48 Hour: 17.4N 147.6W 80KT
72 Hour: 18.0N 151.8W 80KT
USE WITH EXTREME CAUTION AS FOLLOWING IS SUBJECT TO LARGE ERROR
96 Hour: 18.2N 155.0W 75KT
120 Hour: 18.3N 159.2W 70KT

Next Forecast: 1500 UTC

Forecaster: Ortt

1500 UTC 8/21/2004 HURRICANE ESTELLE FORECAST #5

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Latest Dvorak estimates from SSD and CPHC are now at 65KT. This, along with the very impressive satellite appearance justifies calling Estelle a hurricane at this time with 65KT winds, although based upon the objective T numbers, the intensity may be somewhat higher.

Models continue to forecast a track south of Hawaii. However, two things give me some cause for concern with the models. The first is that the motion over the last 6 hours has been close to 305, while the track models have been initialized at 290. The second is that the models are forecasting a shallow system as it approaches Hawaii. Since this is not the forecast, I have no choice but to disregard the majority of the guidance for now as the guidance is assuming Estelle will be steered by the low-level flow and that the effects from the trough will be minimal. However, I am still not going to forecast a landfall in Hawaii, but instead just make a slight northward adjustment to the forecast track, passing south of South Point at 18.4N instead of 18.2N. There is still time to change the forecast to indicate a landfall if necessary. This track is also slightly slower than the previous one.

The upper environment for Estelle is one of the most favorable patterns that I have ever seen. A large trough is digging to the west near Hawaii and this is allowing for the upper ridge over Estelle to become even better established. This should help to offset some of the effects of the slightly cooler SST that the hurricane will be moving over. I will go with about 12 hours more of rapid intensification, then level the storm off at 85KT in 24 hours. Slow weakening as the system approaches Hawaii due to the possibility of some shear with the trough is indicated in this forecast. It should be noted that if an eye can form today, Estelle may become much stronger than what is indicated here.

Initial: 14.9N 140.9W 65KT
12 Hour: 15.9N 142.5W 80KT
24 Hour: 16.9N 144.3W 85KT
36 Hour: 17.6N 146.3W 85KT
48 Hour: 18.0N 148.3W 85KT
72 Hour: 18.3N 152.3W 80KT
USE WITH EXTREME CAUTION AS FOLLOWING IS SUBJECT TO LARGE ERROR
96 Hour: 18.4N 156.3W 75KT
120 Hour: 18.5N 160.3W 70KT

Next Forecast: 0300 UTC

Forecaster: Ortt

0300 UTC 8/22/2004 TROPICAL STORM ESTELLE FORECAST #6

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No graphics with this forecast

Estelle has become sheared from the SE, leaving the convection NW of the center. CI and data T numbers ar decreasing. Recent satellite imagery shows some cold cloud tops pushing back toward the center, but not enough to justify calling Estelle a hurricane any longer. This forecast will go for little change through for 72 hours, with slow weakening afterwards as satellite imagery shows the trough moving to the west, which should keep the strong SW shear away from Estelle.

With Estelle not being as strong as forecast, the chances for a WSW track are becoming more likely. For now, I will not make any significant changes to the track, but instead will just adjust the track .5 degrees south as it passes by South Point. Reasoning for this southward adjustment is that Estelle should be influenced more by the low-level flow than previously anticipated.

Initial: 15.8N 141.6W 60KT
12 Hour: 16.8N 143.0W 60KT
24 Hour: 17.6N 144.6W 60KT
36 Hour: 18.0N 146.6W 60KT
48 Hour: 18.2N 148.6W 60KT
72 Hour: 18.2N 152.6W 60KT
USE WITH EXTREME CAUTION AS FOLLOWING IS SUBJECT TO LARGE ERROR
96 Hour: 17.9N 157.0W 50KT
120 Hour: 17.0N 161.5W 40KT

Next Forecast: 1500 UTC

Forecaster: Ortt

1500 UTC 8/22/2004 TROPICAL STORM ESTELLE FORECAST #7

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Estelle has collapsed. There is little, if any, deep convection, and what there is is well away form the low-level center. Water vapor imagery shows that the trough to the west is starting to produce even more shear. Based upon this, the new intensity forecast calls for Estelle to be a remnant low in just 36 hours, if not sooner. However, forecast points will still be provided. This is a faster weakening than the intensity guidance suggests, though the intensity guidance has been initialized at 45KT.

Since the vortex has no depth, the BAMS trend is being followed. This requires this forecast track to be adjusted significantly to the south of the previous one. However, this forecast is somewhat north of BAMS as I do not want to make a 2.5-3 degree southward adjustment from the previous forecast track. Instead, this track is 1.5 degrees south of the previous at 120 hours.

Initial: 16.1N 142.5W 35KT
12 Hour: 16.3N 143.8W 35KT
24 Hour: 16.3N 145.2W 30KT
36 Hour: 16.3N 147.0W 25KT (remnant low)
48 Hour: 16.3N 149.0W 20KT (remnant low)
72 Hour: 16.2N 153.0W 15KT (remnant low)
USE WITH EXTREME CAUTION AS FOLLOWING IS SUBJECT TO LARGE ERROR
96 Hour: 15.9N 157.0W 15KT (remnant low)
120 Hour: 15.5N 161.5W 10KT (remnant low)

Next Forecast: 0300 UTC

Forecaster: Ortt

0300 UTC 8/23/2004 TROPICAL DEPRESSION ESTELLE FORECAST #8

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No graphics with this forecast

Estelle has not produced any deep convection for the past 18 hours. However, visible satellite imagery still shows a very tight circulation. Therefore, the system will be given 12 more hours before the system is declared to be a remnant low. Estelle is forecast to be a remnant low in just 12 hours.

The low-cloud swirl should move mainly to the west then WSW in accordance to the BAMS model and the low-level wind flow.

Initial: 16.4N 143.4W 30KT
12 Hour: 16.5N 144.5W 25KT (remnant low)
24 Hour: 16.3N 145.7W 20KT (remnant low)
36 Hour: 16.1N 147.2W 20KT (remnant low)
48 Hour: 15.8N 149.0W 15KT (remnant low)
72 Hour: Remnant low

Next Forecast: 1500 UTC

Forecaster: Ortt

1500 UTC 8/23/2004 TROPICAL DEPRESSION ESTELLE FORECAST #9

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Estelle has failed to generate any deep convection overnight; therefore the system is being declared to be a remnant low at this time.

The remnant cloud swirl should move to the west and then WSW with the low-level wind flow.

No forecast points provided with this forecast.

This is the final forecast on Estelle

Forecaster: Ortt

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