1500 UTC 6/29/2003 TROPICAL STORM BILL FORECAST DISCUSSION #1

This is an independent product and not from the National Hurricane Center

The center of Bill is currently moving to the NW near 5KT. This is a bit uncertain as the center is broad and diffuse. Computer models want to bring the system to the NNW over the next couple of days and indicate either a western Louisiana or a Texas landfall. This seems like a reasonable scenario with an upper low to the SW of Bill as well as an approaching weakness to the NW. However, this forecast will be slightly slower than the guidance due to the fact that the center is shallow. However, the forecast track of the center is not all that imnportant here, since the effects spread out considerably from the center to the north and east.

The initial intensity is being set to 35KT. This is based upon a ship report from near the circulation. Bill is of a hybrid nature as dry air is near the center and all of the convection is well to the north and east of the center. This is similar to how Allison formed 2 years ago; however, another Allison is not eexpected at this time. The key to intensification is whether or not the convection can either wrap around or form over the center. With the dry air from the upper low to the south and shear to the north, I am not sold on this scenario. SHIPS intensifies this to a near hurricane in 60 hours, about when the system is expected to be onshore. However, I prefer to be a bit conservative and only forecast 45KT at landfall, due to the environment. Recon will provide a better assessment of the situation this afternoon and it is possible that future forecasts will be revised upwards.

Initial: 22.5N 91.0W 35KT
12 Hour: 23.8N 92.0W 40KT
24 Hour: 25.2N 93.1W 40KT
36 Hour: 26.6N 94.1W 45KT
48 Hour: 28.1N 95.0W 45KT
72 Hour: 32.0N 95.1W 30KT (inland)
SUBJECT TO LARGE ERRORS, USE WITH EXTREME CAUTION
96 Hour: 35.0N 90.0W 15KT(inland, remnant low)

Next Discussion: 2100 UTC

Forecaster: Ortt

2100 UTC 6/29/2003 TROPICAL STORM BILL FORECAST DISCUSSION #2

This is an independent product and not from the National Hurricane Center

Recon has been finding west winds to the north of previous center estimates. This represents a center reformation and not a true rapid northerly motion. However, the center is very broad at this time and the center could easily reform farther to the south. Therefore, this forecast has a lot of uncertainty associated with it. The upper low to the south should still force this on a NW track as previously expected. However, in about 36 hours, the global models are in good agreement about the subtropical ridge moving to the east. In addition, water vapor imagery indicates that there is an upper trough to the NW of the system. Therefore, a more northerly turn should occur before landfall. With the system being farther to the north, this turn should begin sooner than previously anticipated; thus, the greatest threat of landfall would shift from Texas to Louisiana. However, it cannot be emphasized enough that the effects are spread far to the north and east of the center; therefore, the exact forecast track is not as important as it is in a major hurricane. One thing that can throw this forecast for a loop is if the center were to reform again farther to the south

The initial intensity is being set at 40KT. This is based upon recon observations of a large area of tropical storm force winds. Satellite imagery indicates convection near the new center. In addition, the upper winds appear to be more favorable for development with the outflow patter becoming better defined to the north and west of the system. Outflow is basically non-existent to the south due to shear and dry air from the upper low. Satellite imagery indicates westerly winds to the NW of the syste,. probably associated with the upper trough. despite this, SHIPS brings this to near hurricane intensity is a mere 24 hours. GFDL is of no use due to improper initialization as is the global models. With the possible shear present, I will forecast slightly lower than SHIPS and go with 55KT at landfall. However, a good convective burst over a well defined center could result in Bill becomming much stronger than indicated here.

Note: No watches or warnings will be recommended with this package. However, updates will be every 3 hours this evening. A tropical storm warning will likely be recommended either later this evening or tomorrow morning for a portion of the northern Gulf Coast. If Bill intensifies more than anticipated, hurricane watches or warnings may be recommended.

Initial: 24.6N 90.9W 40KT
12 Hour: 26.0N 91.9W 45KT
24 Hour: 27.5N 92.8W 50KT
36 Hour: 29.1N 93.1W 55KT
48 Hour: 31.0N 92.5W 35KT (inland)
72 Hour: 35.0N 88.0W 15KT (inland, remnant low)

Next Discussion: 900 UTC

Forecaster: Ortt

1500 UTC 6/30/2003 TROPICAL STORM BILL FORECAST DISCUSSION #4

This is an independent product and not from the National Hurricane Center

Bill continues to the north. Not much time for a turn and the model are in agreement with a track to the north through 12 hours. Afterwards, the system should turn to the NE as it is caught in the westerlies. The landfall location is about .5 degrees east of where it was at 0900.

Recon has found that Bill has intensified as the pressure fell to 1002mb. Flight level winds do not appear to have increased. Therefore, for now, the winds will remain at 45KT, but in the updates the winds will be increased from 50 m.p.h. to 55 m.p.h.. Little change in intensity is expected before the center reaches the coast with rapid weakening once inland to a remnant low by this time tomorrow.

After writing the package, recon reported 66KT at flight level; thus, surface winds are now being set to 55KT. This is not reflected in the intensity graphic. With the system now on the verge of becomming a hurricane, there is still a chance that it will intensify a little more and reach hurricane intensity before landfall

Initial: 28.7N 91.6W 55KT
12 Hour: 31.0N 91.2W 30KT (inland)
24 Hour: 34.0N 89.0W 15KT (inland and remnant low)

Forecaster: Ortt

900 UTC 6/30/2003 TROPICAL STORM BILL FORECAST DISUCSSION #3

This is an independent product and not form the National Hurricane Center

Bill has resumed a NW motion. Guidance is in good agreement that this track should continue until landfall, which is expected in about 12 hours along the southern coast of Louisiana. The main track problem with this forecast is the recurvature. The trough to its north should pick the system up and begin to recurve it. However, the precise time of recurvature and speed of the motion is in question. Will follow consensus of the guidance and should a gradual acceleration to the NE after landfall.

Initial intensity remains 45KT based upon satellite estimates. However, Bill appears to be as well organized as it has been; therefore, I would not be surprised if recon finds stronger winds when they investigate this morning. SHIPS has backed off a near hurricane intensity at landfall that it has been insisting in recent runs and now only calls for 52KT in 12 hours. This forecast will be a but more aggressive, in calling for a 55KT landfall due to the satellite signature. However, it would not be impossible for Bill to reach hurricane intensity just prior to making landfall, as has been stated in the storm updates.

Initial: 27.4N 91.6W 45KT
12 Hour: 29.5N 92.1W 55KT (near land)
24 Hour: 32.0N 91.0W 25KT (inland)
36 Hour: 35.0N 88.0W 15KT (inland, remnant low)

Next Discussion: 1500 UTC

Forecaster: Ortt

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