Thunder44's Isaac Forecasts: 2pm Update

[Thunder44]

The following post is NOT an official forecast and should not be used as such. It is just the opinion of the poster and may or may not be backed by sound meteorological data. It is NOT endorsed by any professional institution including storm2k.org For Official Information please refer to the NHC and NWS products.

5pm Forecast: No Threat to Land

Discussion:

As of the 5pm Advisory, the NHC placed the center of TD 9 at 26.5N 53.1W and is moving to the NW at 14mph. Maximum sustained winds are at 35mph and the pressure is at 1012mb.

Satellite images indicate that the low pressure area out in Central Atlantic has become Tropical Depression #9. The system has a large- asymmetric appearance and outflow is being restricted over the west and south side of the circulation, as an upper-level low is impacting shear and dry air into the system. As the ULL gradually backs off to the west it should allow the system to slowly strengthen through 72hrs. I expect it to reach tropical storm strength later tonight or tomorrow. Afterwards shear should increase again and it will be moving over cooler waters. The intensity forecast closely follows the SHIPS until 96hrs, which brings the storm to 50kts, then it shows weakening.

TD 9 is currently moving around the subtropical ridge out in the Central Atlantic and it should continue moving to the NW for the next 36hr to 48hrs, until a large trough over the Western Atlantic turns the system to the north then NE into the North Central Atlantic, with an increase in forward speed. The global models show agree with this scenario, but do not show a tropical cyclone. The forecast track is a compromise between the BAMM, BAMD, BAMS statistical models. On my current forecast track the storm should pass well to the east of Bermuda with no impact other than some high surf.

I will have another forecast tomorrow morning.

Forecast Points and Intensity:

Initial 26.5N 53.1W 30kt
12hrs VT 27.8N 54.6W 35kt
24hrs VT 29.0N 56.0W 40kt
36hrs VT 30.4N 56.8W 40kt
48hrs VT 31.5N 57.5W 45kt
72hrs VT 34.5N 58.0W 50kt
96hrs VT 38.0N 56.5W 50kt
120hrs VT 42.5N 52.5W 40kt

[rainstorm]

sounds like a good forecast

[Thunder44]

The following post is NOT an official forecast and should not be used as such. It is just the opinion of the poster and may or may not be backed by sound meteorological data. It is NOT endorsed by any professional institution including storm2k.org For Official Information please refer to the NHC and NWS products.

7am Thurs Forecast: Still a TD

As of the 5am Advisory, the NHC placed the center of TD 9, currently at 27.8N 54.6W and is moving to the NW at 12mph. Maximum sustained winds remain at 35mph with a pressure of 1011mb.

TD 9 has apparently not strengthened much overnight and still has asymmetric appearance on satellite imagery. Convection has increased somewhat and become a little better organized around center. Although it is mostly to the NW of the center, leaving the center partially exposed. Dvorak satellite estimates suggest that it has reached TS strength, but the NHC has decided to wait for more data to confirm, before upgrading the storm.

The forecast reasoning from the previous forecast generally remains the same, except some of the models have shifted their tracks further to the west. The depression should continue moving the NW this morning than WNW later today or tonight as ridge builds back further west temporarily. Then storm should turn the north tomorrow and than NE, as it approaches the large trough in the Western Atlantic. The forecast track has been shifted to the left, and closely follows the GFDL and the CONU. On this forecast track, the storm should still pass safely east of Bermuda, but there is a slight chance further west track, as shown by some models.

TD 9 is expected to become a TS a today, and there has been little change to the intensity forecast or reasoning. Extratropical transition is now it expected to occur between 96hrs and 120hrs.

I will have another forecast out sometime this evening.

Forecast Points and Intensity:

Initial 27.8N 54.6W 30kt
12hrs VT 29.0N 56.0W 35kt
24hrs VT 30.0N 58.0W 40kt
36hrs VT 31.5N 59.0W 40kt
48hrs VT 34.5N 59.0W 45kt
72hrs VT 38.0N 56.5W 50kt
96hrs VT 42.5N 52.5W 50kt...Becoming Extratropical
120hrs VT 47.0N 46.5W 40kt...Extratropical

[Thunder44]

11am Update:

This is just to update the status of this system, which has been declared TS Issac as of 11am Advisory from NHC.

Forecast Points and Intensity:

Initial 28.2N 54.7W 35kt
12hrs VT 29.0N 56.0W 35kt
24hrs VT 30.0N 58.0W 40kt
36hrs VT 31.5N 59.0W 40kt
48hrs VT 34.5N 59.0W 45kt
72hrs VT 38.0N 56.5W 50kt
96hrs VT 42.5N 52.5W 50kt...Becoming Extratropical
120hrs VT 47.0N 46.5W 40kt...Extratropical

[rainstorm]

thanks num 44

[Thunder44]

The following post is NOT an official forecast and should not be used as such. It is just the opinion of the poster and may or may not be backed by sound meteorological data. It is NOT endorsed by any professional institution including storm2k.org For Official Information please refer to the NHC and NWS products

7pm Thurs Forecast: No Threat to Land

As of the 5pm Advisory, the NHC placed the center of TS Isaac currently at 28.9N 54.9W and is moving to the NNW at 8mph. Maximum sustained winds are at 45mph and the pressure is at 1006mb.

Isaac became a TS this morning as satellite estimates and a QS pass that storm reached TS strength of 40kts. On the latest satellite imagery, Isaac appears to suffering from some dry air and shear as convection appears to be meager and fragmented. The storm also appears to have some subtropical characteristics. Although the structure of Isaac appears to be more compact than earlier, which is more typical of a tropical cyclone. Slow strengthening is still expected through 48hrs until the storm moves over cooler waters and becomes extratropical. The intensity forecast is similar to the NHC forecast.

The upper low to the SW of Isaac had induced a NNW movement today and caused Isaac to move to the right of my previous forecast track and this also to the right of most of the dynamical models this afternoon, except the UKMET. Isaac should turn to WNW as the ULL moves further south and the ridge in Central Atlantic builds further west for while. Then as Isaac approaches the large trough in the Western Atlantic it should recurve out to sea. My forecast track has been shifted to the right and mirrors the NHC track, which looks good to me.

I will have another forecast out tomorrow morning


Initial 28.9N 54.9W 40KT
12hrs VT 29.7N 55.6W 45KT
24hrs VT 30.5N 57.0W 45KT
36hrs VT 31.4N 58.1W 50KT
48hrs VT 32.8N 59.2W 50KT
72hrs VT 36.5N 60.0W 50KT... Becoming Extratropical
96hrs VT 42.0N 56.0W 50KT...Extratropical
120hrs VT 47.0N 47.0W 50KT...Extratropical

[rainstorm]

looks quite good to me

[Thunder44]

The following post is NOT an official forecast and should not be used as such. It is just the opinion of the poster and may or may not be backed by sound meteorological data. It is NOT endorsed by any professional institution including storm2k.org For Official Information please refer to the NHC and NWS products

9:30am Fri Forecast

Discussion:

As of the 5am Advisory, the NHC placed the center of TS Isaac at 29.2N 55.6W and is moving toward the NW at 5mph. Maximum sustained winds remain at 40kts and the pressure is at 1006mb.

Isaac has changed little in organization overnight. Convection remains meager and fragmented around center, but these little burst of convection are helping the storm to maintain it’s current intensity of 40kts. This also been confirmed by the latest high-resolution QS pass this morning.

The current movement of Isaac appears to very slow and erratic to the left of the forecast track. The future of Isaac has become a little more uncertain this morning, as many of the global and dynamical models have shifted their tracks further west and the GFS and ECMWF now merge Isaac with another extratropical low developing off the US east coast. Those two models then take this system north, close to Eastern New England and over Nova Scotia apparently as a non-tropical system. The latest GFDL track is further east from it’s 0z run. For now, my forecast track will be close to the 6z CONU, which will be a little further west of the NHC track between 48hrs and 96hrs, and slower to account for the slow and erratic movement this morning.

The intensity forecast not changed. Despite what track Isaac takes, it is expected to slowly strengthen through 48hrs and begin extratropical transition afterwards, as it interacts with the large trough and non-tropical low developing off the east coast.

I will have another forecast out this evening.


Forecast Points and Intensity:

Initial 29.2N 55.6W 40kt
12hrs VT 29.5N 57.0W 45kt
24hrs VT 31.0N 59.0W 45kt
36hrs VT 33.0N 60.5W 50kt
48hrs VT 33.0N 59.5W 50kt
72hrs VT 40.0N 59.5W 50kt...Becoming Extratropical
96hrs VT 46.5N 51.0W 50kt...Extratropical
120hrs VT 49.0N 40.0W 50kt...Extratropical

[rainstorm]

looks better organized

[Thunder44]

11pm Update:

Sorry, for no forecast this evening. I was tired and fell asleep. I will try to have another out early tommorrow morning.

By the way I expect Issac to become a hurricane by tomorrow and to basically follow the NHC track.

[Thunder44]

The following post is NOT an official forecast and should not be used as such. It is just the opinion of the poster and may or may not be backed by sound meteorological data. It is NOT endorsed by any professional institution including storm2k.org For Official Information please refer to the NHC and NWS products.

7am Sat Forecast: Hurricane Soon

Discussion:

As of the 5am Advisory, the NHC placed the center of TS Isaac currently at 30.3N 58.0W and is moving to the WNW at 6kts. Maximum sustained winds are near 60kts and the pressure is at 995mb.

Isaac has been strengthening since yesterday and it’s appearance continues to improve this morning. Latest satellite images show convection increasing around what appears to be large eye, indicating the storm is organizing an eyewall. It appears to me to be a hurricane now, and I expect the NHC to upgrade this storm to hurricane by the next advisory. I expect slow strengthening through the next 36hrs as the storm remains over warm water and low upper-level wind shear. After 36hrs the storm should be moving over cooler water and shear should increase therefore weakening is expected. The SHIPS take the storm to 68kts by 48hrs, and the GFDL takes to about 90kts at 48hrs. The intensity forecast will lean closer to the GFDL, with a peak intensity of 80kts at 36hrs, since I believe it will be a hurricane very soon. After 48hrs, the storm should weaken and become extratropical as it begins to interacts with and becomes absorbed by a mid-latitude system developing off the New England coast.

Most models have continued to shift their tracks to the west and the consensus has the storm coming closer to Bermuda between 24hrs to 36hrs and moving over New Foundland between 72hrs and 96hrs. It appears the ridge will hold on long in the North Central Atlantic to keep the storm from making a sharper recurvature out to sea, in advance of the large east coast trough off and along the US East Coast. The storm should begin to slowly turn to the NNW then north tomorrow than to the NNE on Monday. The forecast track follows the 6z CONU and is also close to the NHC track. On this forecast track, Isaac should still pass far enough east of Bermuda to avoid any significant impacts, and make landfall over New Foundland as a strong extratropical storm. However, this can change and both areas should monitor the progress of this storm closely.

I will have another forecast out sometime this evening.

Forecast Points and Intensity

Initial 30.3N 58.0W 60kt
12hrs VT 31.0N 59.0W 65kt
24hrs VT 32.0N 60.5W 75kt
36hrs VT 35.5N 61.0W 80kt
48hrs VT 39.0N 60.5W 75kt
72hrs VT 47.0N 55.0W 65kt...Extratropical
96hrs VT...Absorbed

[rainstorm]

keep us updated

[Thunder44]

As of 11am Advisory, the NHC has upgraded Isaac to a hurricane with winds of 65kts. There are no changes to the forecast track or intensity.

Forecast Points and Intensity

Initial 30.9N 58.7W 65kt
12hrs VT 31.0N 59.0W 65kt
24hrs VT 32.0N 60.5W 75kt
36hrs VT 35.5N 61.0W 80kt
48hrs VT 39.0N 60.5W 75kt
72hrs VT 47.0N 55.0W 65kt...Extratropical
96hrs VT...Absorbed

[rainstorm]

does it have an eye?

[Thunder44]

The following post is NOT an official forecast and should not be used as such. It is just the opinion of the poster and may or may not be backed by sound meteorological data. It is NOT endorsed by any professional institution including storm2k.org For Official Information please refer to the NHC and NWS products.

8pm Sat Forecast:

Discussion:

As of the 5pm Advisory, the NHC placed the eye of Hurricane Isaac at 31.6N 59.5W and is moving to the NW at 9kts. Maximum sustained winds have increased to 70kts and the pressure is at 989mb.

Isaac became a hurricane this morning and has been slowly intensifying this afternoon. Satellite images this evening show the storm becoming better organized with improving anti-cyclonic outflow aloft in all quads. The eye is bit ragged but becoming better defined on enhanced infrared images. I expect Isaac to strengthen a little more during the next 12 to 24hrs before it upper-level wind shear increases and the system moves over colder water. The intensity forecast from the previous forecast has not changed much. Isaac is expected to transition to an extratropical storm by 48hrs.

Isaac is now moving to the NW at a faster speed. The synoptic reasoning has not changed from previous discussions. The models are still agreement in a recurvature, but how sharp this will be is the question for a pass over or near Newfoundland. The track after 36hrs has been shifted a little east and faster to closely follow the latest CONU and is also close to the NHC track. On the current forecast track, Isaac should move over extreme SE New Foundland as a strong extratropical storm.

Forecast Track and Intensity:

Initial 31.6N 59.5W 70kt
12hrs VT 32.5N 60.3W 75kt
24hrs VT 35.0N 61.0W 80kt
36hrs VT 39.0N 60.5W 75kt
48hrs VT 44.0N 56.8W 65kt...Becoming Extratropical
72hrs VT 47.0N 55.0W 55kt...Extratropical

[Thunder44]

The following post is NOT an official forecast and should not be used as such. It is just the opinion of the poster and may or may not be backed by sound meteorological data. It is NOT endorsed by any professional institution including storm2k.org For Official Information please refer to the NHC and NWS products.

7am Sun Forecast: Threat to Newfoundland

Discussion:

As of the 5am Advisory, the NHC placed the center of Hurricane Isaac at 33.1N 60.1W and is moving to the NNW at 9mph. Maximum sustained winds have increased to 75kts and the pressure is at 985mb.

Isaac continues to slowly strengthen and it will have another 6 to 12hrs to get a little stronger before upper-level shear increases and storm moves over colder water. Therefore weakening should start to occur late this afternoon or this evening. Then extratropical transition should occur between 36hrs and 48hrs.

The forecast track has not changed much. It has been shifted little further east to account for short-term movement and to be closer to the latest model consensus and also is in line with the NHC track. Some of models, such as the GFS and CMC, take the storm further west and have landfall over Western Newfoundland, but it appears that Isaac is already making the turn north. On the current forecast track the storm should be moving over or very close to Avalon Peninsula in New Foundland, tomorrow night.

At this time, the storm is expected to be extratropical as moves over Newfoundland. However as with many of these high-latitude tropical systems as of late, there is a possibility it may still maintain enough tropical characteristics, to be considered a tropical cyclone. Therefore the Canadian Hurricane Center has issued a TS watch for the Avalon Peninsula in New Foundland.

Forecast Points and Intensity:

Initial 33.1N 60.1W 75kt
12hrs VT 35.0N 60.4W 80kt
24hrs VT 39.8N 58.9W 70kt
36hrs VT 44.6N 55.4W 60kt...Becoming Extratropical
48hrs VT 48.5N 50.9W 55kt...Extratropical
72hrs VT 52.5N 42.0W 45kt...Extratropical

[Thunder44]

11am Sun Update:

Shear has increased this morning over Issac and it appears to be already weakening. The current intensity of the storm is at 70kts, and I no longer expect strengthening today.

[Thunder44]

The following post is NOT an official forecast and should not be used as such. It is just the opinion of the poster and may or may not be backed by sound meteorological data. It is NOT endorsed by any professional institution including storm2k.org For Official Information please refer to the NHC and NWS products.

6pm Sun Forecast

Discussion:

As of the 5am Advisory, the NHC placed the center of Hurricane Isaac at 36.3N 60.0W and is moving to the north at 18kts. Maximum sustained winds are at 70kts and the pressure is at 985mb.

Isaac weakened slightly earlier today as shear increased over it. However, the storm has maintained intensity since then at 70kts and has even improved somewhat in satellite appearance. The storm is expected to gradually weaken over the next 24hrs as it moves over cooler water and shear increases, then become extratropical by 36hrs.

Issac has now turned north and should begin to turn to the NNE soon. The model consensus has shifted westward this afternoon, and all models show a landfall over Newfoundland tomorrow night. Therefore forecast track will shift back west and continues to follow the CONU and will be close to the latest NHC track.

On the current forecast track, Issac should pass over SE Newfoundland as an extratropical storm. The CHC continues the TS watch for the Avalon Peninsula, in case the storm doesn’t become extratropical when it nears the area. Regardless, the area will still likely get tropical-storm force winds. Please refer to NHC and CHC products for official information and emergency planning.

Forecast Points and Intensity:

Initial 36.3N 60.0W 70kt
12hrs VT 39.8N 58.9W 65kt
24hrs VT 44.6N 56.0W 60kt...Becoming Extratropical
36hrs VT 48.8N 53.3W 55kt...Extratropical
48hrs VT 52.0N 48.5W 45kt...Extratropical

[rainstorm]

isaac still looks mean

[Thunder44]

The following post is NOT an official forecast and should not be used as such. It is just the opinion of the poster and may or may not be backed by sound meteorological data. It is NOT endorsed by any professional institution including storm2k.org For Official Information please refer to the NHC and NWS products.

8am Mon Forecast: Racing To Newfoundland

Discussion:

As of the 8am Intermediate Advisory, the NHC placed the center of Hurricane Isaac currently at 42.0N 56.7W or 370 miles SSW of Cape Race, Newfoundland and is moving to the NNE at 35mph. Maximum sustained winds are at 65kts and the pressure is at 989mb. The CHC has now issued a Tropical Storm Warning for the Avalon Peninsula and a Tropical Storm Watch for the Burin and Bona Vista Peninsulas in SE New Foundland. Please refer to the NHC and CHC products for official information and emergency planning.

Issac weakened slightly overnight but is still a hurricane and it appears to be very much a tropical cyclone with deep convection around the center. I expect only slow weakening down to just below hurricane strength today and extratropical transition should begin later this afternoon, with further weakening.

The forecast track has changed little, but it has been shifted east to be closer to the latest model consensus and is also close to the NHC and CHC tracks. Basically the center of Isaac, is expected to pass near or over the Avalon Peninsula, late this afternoon and this evening as an extratropical storm. However it is possible it will still be a tropical cyclone as it nears the SE New Foundland coast today.


Forecast Points and Intensity:

Initial 42.0 N 56.7 W 65kt
12hrs VT 45.0N 54.4W 60kt...Becoming Extratropical
24hrs VT 49.8N 50.6W 55kt...Extratropical
36hrs VT 52.5N 41.5W 45kt...Extratropical