0000 UTC 10/2/2003 TROPICAL STORM LARRY FORECAST DISCUSSION #1

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

Model guidance is unusually divergent, with the landfall ranging from Tampa Florida to the Yucatan Peninsula. Therefore, the track forecast is of a low confidence. The CMC and BAMD and BAMM indicate a track toward the coast of Mexico, near the Tampico area, followed by a turn to the north, then NE, toward Florida. I cannot see what it is that these models are seeing. There is a trough as indicated by water vapor imagery at the upper levels approaching the coast of California; however, this trough does not appear deep enough to create a NE turn. The GFDL brings the system inland in about 2 days, while UKMET and NOGAPS keeps the system over the water for about 5 days, before drifting the center inland over the Bay of Campeche coast of Mexico. There is an upper trough digging to the east of Larry; thus, some ridging may build to the north of the system, which would force the storm to move slowly to the west. This forecast reflects this, though it does not move the system onshore through 5 days due to the uncertainty.

Initial intensity is being set to 45KT, which is about 80 percent of the maximum flight level winds that were found by recon. GFDL indicates some intensification, as does CMC. CMC has been the only model that has consistently been indicating development; therefore, it definitely cannot be discounted. I will go with slow development through the period, to a hurricane in 72 hours, assuming that the system remains over the water for that long. This represents a slower rate of development that has been observed today, where recon has reported a 3mb pressure drop in the last few hours.

It should be noted that in these slow moving, formative systems, the center can jump around significantly. Therefore, the track forecast verification is subject to error due to center reformations.

Forecasts Verify Starting at 0900 UTC.

Initial: 20.9N 93.5W 45KT
12 Hour: 21.1N 93.8W 50KT
24 Hour: 21.4N 94.0W 55KT
36 Hour: 21.6N 94.3W 55KT
48 Hour: 21.9N 94.7W 60KT
72 Hour: 22.5N 95.3W 65KT
USE WITH EXTREME CAUTION AS FOLLOWING IS SUBJECT TO LARGE ERROR
96 Hour: 22.5N 95.3W 70KT
120 Hour: 22.8N 97.0W 75KT

Next Discussion 0300 UTC

Forecaster: Ortt

0300 UTC 10/2/2003 TROPICAL STORM LARRY FORECAST DISCUSSION #2

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

Larry is remaining stationary this evening, as has been expected. One change in the guidance is that more of the 0Z tropical guidance now indicates a more northerly and easterly component to the eventual motion. Therefore, this track is being adjusted slightly to the right of the previous track. Larry is not expected to make landfall within the next 5 days.

Will keep the initial intensity at 45KT for this update and keep the same intensity forecast as the previous one. I was tempted to increase the intensity at later periods based upon the convective burst this evening; however, this is south and west of the center; thus, the system still remains somewhat disorganized. However, with the system remaining over water, it should continue to intensify slowly.

Initial: 20.8N 93.5W 45KT
12 Hour: 21.0N 93.7W 50KT
24 Hour: 21.4N 93.9W 55KT
36 Hour: 21.8N 94.1W 55KT
48 Hour: 22.2N 94.3W 60KT
72 Hour: 22.9N 94.7W 65KT
USE WITH EXTREME CAUTION AS FOLLOWING IS SUBJECT TO LARGE ERROR
96 Hour: 23.5N 95.3W 70KT
120 Hour: 24.0N 96.5W 75KT

Next Discussion: 1500 UTC

Forecaster: Ortt

1500 UTC 10/3/2003 TROPICAL STORM LARRY FORECAST DISCUSSION #3

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

Oh where, oh where could that center be? Visible imagery indicates that the center is very hard to find, suggesting that the system may be degenerating back into a broad area of low-pressure. However, that determination will have to wait until recon investigates later today. More guidance than last evening suggests a track farther south; therefore, this track will be adjusted to the left of the previous track.

Initial intensity remains at 45KT and will do so until recon investigates. Due to the lack of organization, the intensity forecast will back off and now peak the system at 65KT in 120 hours.

Initial: 20.5N 93.5W 45KT
12 Hour: 20.5N 93.5W 45KT
24 Hour: 20.5N 93.9W 50KT
36 Hour: 20.6N 94.3W 50KT
48 Hour: 20.7N 94.6W 55KT
72 Hour: 20.9N 95.5W 60KT
USE WITH EXTREME CAUTION AS FOLLOWING IS SUBJECT TO LARGE ERROR
96 Hour: 21.2N 96.5W 60KT
120 Hour: 21.5N 97.5W 65KT

Next Discussion: 0300 UTC

Forecaster: Ortt

0300 UTC 10/3/2003 TROPICAL STORM LARRY FORECAST DISCUSSION #1

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

The latest recon fixes show a slow westerly drift, enough to declare the motion to the west. Whether or not this is temporary or not is another question. The center remains broad; therefore, there may be further relocations. Therefore, the first 12 hours will indicate a stationary system, followed by a slow drift to the west in agreement with the recon fixes form tonight. This remains a low confidence forecast as model guidance is divergent.

Initial intensity is being set to 55KT, based upon 64KT flight level winds and a surface estimate of 60KT from the recon crew. This evening, some of the convection has decreased. In addition, the pressure has risen from 993 to 994mb and there are indications of westerly shear on satellite imagery. Therefore, the forecast will continue to go with slow development, though making the system into a hurricane in 24 hours.

Initial: 20.5N 94.2W 55KT
12 Hour: 20.5N 94.2W 60KT
24 Hour: 20.5N 94.6W 65KT
36 Hour: 20.5N 95.0W 65KT
48 Hour: 20.5N 95.6W 70KT
72 Hour: 20.5N 97.0W 75KT
USE WITH EXTREME CAUTION AS FOLLOWING IS SUBJECT TO LARGE ERROR
96 Hour: 20.5N 98.2W 65KT (inland)
120 Hour: 20.5N 100.0W 25KT (inland and dissipating)

Next Discussion: 1500 UTC

Forecaster: Ortt

1500 UTC 10/3/2003 TROPICAL STORM LARRY FORECAST DISCUSSION #5

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

Larry remains nearly stationary. Model guidance also remains divergent, which is hardly surprising given the weak to non-existent steering currents. The latest recon fixes indicate a meandering. This is forecast through the period and the system is expected to remain over the Gulf for the period, though any deviation would bring the system inland at any time.

Initial intensity is being lowered to 45KT based upon the maximum flight level winds from recon only being 54KT and a pressure rise to 997mb. Satellite imagery indicates some shear over the system. With this in mind, no intensification is being forecast through the next 36 hours, followed by slight intensification through 72 hours. Afterwards, upwelling may cause some weakening and this is reflected in the forecast.

Initial: 20.1N 94.5W 45KT
12 Hour: 20.1N 94.5W 45KT
24 Hour: 20.1N 94.7W 45KT
36 Hour: 20.1N 94.8W 45KT
48 Hour: 20.1N 95.0W 50KT
72 Hour: 20.1N 95.5W 55KT
USE WITH EXTREME CAUTION AS FOLLOWING IS SUBJECT TO LARGE ERROR
96 Hour: 20.1N 95.5W 55KT
120 Hour: 20.0N 95.3W 50KT

Next Discussion: 0300 UTC

Forecaster: Ortt

0300 UTC 10/3/2003 TROPICAL STORM LARRY FORECAST DISCUSSION #6

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

Larry has been drifting very slowly to the south. The majority of the guidance indicates somewhat of a south drift, with only AEMI and LBAR indicating a NE motion. The flow is mainly zonal in the northern Gulf as the winds are straight out of the west in the mid and upper levels. This is preventing any deep troughs from picking the system up. Therefore, the NE solution is being discounted and this forecast is being adjusted to the south of the previous one.

Initial intensity remain at 45KT and will do so until recon arrives. This is despite some satellite estimates as high as 55KT. I have chosen the lower intensity due to the fact that the convection is not concentrating around the center, but is extended in a curved band well to the NE of the center. This forecast basically updates the previous intensity forecast, going with little change through 24 hours, followed by slow intensification. The system is now expected to be inland; therefore, upwelling is not being factored into this forecast.

Initial: 19.7N 94.9W 45KT
12 Hour: 19.5N 95.0W 45KT
24 Hour: 19.3N 95.2W 45KT
36 Hour: 19.0N 95.5W 50KT
48 Hour: 18.9N 96.0W 55KT
72 Hour: 18.8N 96.5W 60KT
USE WITH EXTREME CAUTION AS FOLLOWING IS SUBJECT TO LARGE ERROR
96 Hour: 18.7N 97.5W 40KT (inland)
120 Hour: 18.6N 98.5W 25KT (inland and dissipating)

Next Discussion: 1500 UTC

Forecaster: Ortt

1500 UTC 10/4/2003 TROPICAL STORM LARRY FORECAST DISCUSSION #7

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

Larry continues to be nearly stationary in the Bay of Capmeche. However, the center appears to have reformed about 1 full degree to the east of where it was last evening. Most guidance suggests that the current SE drift will soon end and revert back to a WSW motion; therefore, this forecast will be similar to the previous.

Satellite imagery indicates that Larry is starting to intensify; however, I prefer to wait for recon data before raising the initial intensity from 45KT. Will go with intensification until the storm makes landfall, though at a slow rate.

Initial: 19.3N 93.7W 45KT
12 Hour: 19.1N 93.7W 50KT
24 Hour: 18.9N 93.9W 55KT
36 Hour: 18.7N 94.3W 60KT
48 Hour: 18.5N 94.8W 60KT
72 Hour: 18.4N 95.5W 50KT (inland)
USE WITH EXTREME CAUTION AS FOLLOWING IS SUBJECT TO LARGE ERROR
96 Hour: 18.3N 96.0W 30KT (inland)
120 Hour: 18.3N 97.0W 25KT (inland and dissipating)

Next Discussion: 0300 UTC

Forecaster: Ortt

0300 UTC 10/5/2003 TROPICAL STORM LARRY FORECAST DISCUSSION #8

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

Larry has continued to drift to the south and is now nearly inland and is expected to mvoe inland in a couple of hours.

Initial intensity remains 45KT. Weakening is now forecast as the system is making landfall. This forecats does not bring Larry into the eastern pacific as it is expected to dissipate over the high mountains.

Initial: 18.5N 93.7W 45KT
12 Hour: 18.0N 93.7W 35KT (inland)
24 Hour: 17.6N 93.9W 25KT (inland and dissipating)
36 Hour: Inland and Dissipated

This is the final forecast discussion on Larry, unless it remains over the water at 1500 UTC tomorrow.

Forecaster: Ortt