Major Hurricane Norbert

[Somerset Squall]

Invest 91E has finally become sufficiently organised to be classified as a tropical depression. TD15E is meandering off the south coast of southern Mexico, and is actually drifting eastwards. However, a west-northwestward motion if forecast to materialise soon as a subtropical steering ridge builds to the north over Mexico. The timing of the west-northwest turn is uncertain and it is currently unclear whether this motion will persist: bottom line is TD15E needs to be closely watched as it may well threaten Mexico with a landfall if it deviates from it's forecast track.

TD15E is currently under some shear. Convection has been displaced west of the LLC. However, shear is expected to ease and as the depression will be over waters of around 29C for the next three days, intensification is expected, and the NHC seem keen to make this one a hurricane. Time will tell, but shear will be the main factor in future intensity changes for 15E.

Some models, particularly GFS, are forecasting development of another tropical depression to the east of 15E in a few days time. There is nothing of note there currently, but if this was to occur then 15E may not intensify as much as forecast due to competing for resources with the new depression. This is only a possibility though.

[Somerset Squall]

15E has not become any better organised today, with convection still being sheared away from the centre. Therefore, the system still remains a 30kt tropical depression.

15E is drifting slowly westwards in weak steering currents. Future track is still uncertain. Interaction with the developing disturbance (invest 92E) could be a factor along with how dominant the steering ridge becomes over Mexico. GFS is still forecasting invest 92E to develop and absorb 15E. If the subtropical steering ridge remains weak over Mexico, and invest 92E doesn't get too close, the system may drift north-northwestwards towards the coast of Mexico. At third scenario is the subtropical steering ridge to the north being the dominant steering influence which would send 15E west-northwestward into open waters. The third scenario will allow 15E to strengthen the most. I wouldn't like to say which one will occur- the NHC are having a nightmare trying to forecast track and intensity at the moment, largely because it's unclear when or if invest 92E will develop.

Shear is currently prohibiting 15E from strengthening. If 15E manages to push more quickly westwards then it will escape the shear and being over very warm waters, 15E should strengthen. NHC are prediciting a more conservative peak of 60kts (mainly because of 15E's failure to quickly organise at present). However, as I mentioned above, if 15E pushes northwards towards the coast then it won't have much time to strengthen, and if the invest to the east develops then it may not strengthen much either. You can clearly see what a nightmare NHC are having with this system at the moment!

[Cookie]

something to keep an eye on then!

[Somerset Squall]

15E has intensified over night, and is now a 35kt tropical storm, named Norbert. Convection has become more concentrated over the centre as shear has eased, which has facilitated the strengthening. Norbert is forecast to continue to head west-northwestward in a low shear, warm sea environment, and the NHC are forecasting him to become a hurricane once more. The complications I mentioned yesterday are still there- but the further Norbert pushes westward and the slower the disturbance develops to the east decreases the chance of negative interaction between the two. In fact, the NHC now seem to be discounting the absorption scenario. NHC expect a peak of 65kts from Norbert, but he may well become stronger than that as he has several days over toasty waters yet. Shear will largely govern the strength of Norbert, at least for the next 4 days.

[Somerset Squall]

Norbert has continued to intensify this morning, and is now at 40kts. NHC have adjusted the intensity forecast upwards, suggesting now a peak of 75kts. However, the NHC say this could be conservative, and there may be potential for rapid strengthening as shear remains low and sea temps remain very high (29-30C). Norbert is expect to become a hurricane in 36hrs, perhaps sooner if the storm continues to get it's act together like it is currently.

[Somerset Squall]

Norbert is maintaining some deep, concentrated convection over the centre which is aiding some quick development. Norbert is now a 50kt tropical storm. Further intensification is forecast, but it's unclear just how much Norbert will intensify before reaching cooler waters and a more stable atmosphere in a few days time.

Satellite image of east Pacific (Marie around 122W 19N slowly weakening, Norbert to the east of that near the coast of Mexico and invest 92E to the far right of the image):

Edited October 5, 2008 by Somerset Squall

[Cookie]

thanks for posting the sat image. :lol:

[Somerset Squall]

Norbert continues to strengthen, and is now at 55kts, according to the NHC, though Norbert may well be a touch stronger than that looking a latest satellite imagery. Norbert has some impressive banding features as you can see in the image above, and impressive central convection. I reckon Norbert may become a hurricane later tonight or early tomorrow. A northwestward track should continue until around 72hrs where Norbert could be picked up by a trough and dragged northwards into a more stable atmosphere. Until then, Norbert will probably remain in a favourable environment which should encourage further strengthening. Just how strong Norbert will get is still open to question, but NHC are plumping for 80kts currently.

[Cookie]

how strong do you reckon mate?

[Somerset Squall]

how strong do you reckon mate?

It's hard to say but believe it or not Norbert may have behave the opposite to Marco. Norbert is now a 70kt hurricane but it is a fairly large hurricane which makes rapid intensification unlikely. A bit of a guess but I'd go for 90kts being the peak. Let's wait and see if I'm anywhere near the mark .

So yes, Norbert has slowly intensified into a hurricane. Banding features are excellent along with central convection. Norbert is set to strengthen some more with NHC estimating a peak of 80kts. Norbert is forecast to bend to the north and may end up making landfall in Baja California. However, Norbert should've weakened a little by then as stable air and cooler waters should induce weakening beyond 48hrs.

[Cookie]

update

Storm Alert issued at 7 Oct, 2008 21:00 GMT

Hurricane NORBERT is forecast to strike land to the following likelihood(s) at the given lead time(s):

Yellow Alert Country(s) or Province(s)

Mexico

probability for CAT 1 or above is 10% in about 93 hours

probability for TS is 20% in about 69 hours

Yellow Alert City(s) and Town(s)

La Poza (25.9 N, 112.0 W)

probability for CAT 1 or above is 10% in about 93 hours

probability for TS is 20% in about 93 hours

Note that

Yellow Alert (Elevated) is CAT 1 or above to between 10% and 30% probability, or TS to above 50% probability.

CAT 1 means Hurricane strength winds of at least 74 mph, 119 km/h or 64 knots 1-min sustained.

TS means Tropical Storm strength winds of at least 39 mph, 63 km/h or 34 knots 1-min sustained.

Edited October 7, 2008 by cookie

[londonsnow]

looks like norbert may reach cat 4 before weakening as it approaches baja. still it will probably make a big impact on landfall. currently it has v good organisation and a distinctive eye

[Cookie]

it got strong this system

Intense Hurricane NORBERT is forecast to strike land to the following likelihood(s) at the given lead time(s):

Yellow Alert Country(s) or Province(s)

Mexico

probability for CAT 1 or above is 20% in about 69 hours

probability for TS is 40% in about 69 hours

Yellow Alert City(s) and Town(s)

La Poza (25.9 N, 112.0 W)

probability for CAT 1 or above is 15% in about 93 hours

probability for TS is 35% in about 69 hours

Green Alert City(s) and Town(s)

La Paz (24.2 N, 110.3 W)

probability for TS is 35% in about 69 hours

Note that

Yellow Alert (Elevated) is CAT 1 or above to between 10% and 30% probability, or TS to above 50% probability.

Green Alert (Low) is TS to between 31% and 50% probability.

CAT 1 means Hurricane strength winds of at least 74 mph, 119 km/h or 64 knots 1-min sustained.

TS means Tropical Storm strength winds of at least 39 mph, 63 km/h or 34 knots 1-min sustained.

[Somerset Squall]

Indeed, Norbert has intensified more than predicted and is now a cat 3 major hurricane with intensity now at 110kts. Cat 4 status is easily within reach. Congratulations to the HMRF model which has been consistantly forecasting a major hurricane whilst the other models were having none of it.

Norbert has another day of good environmental conditions which should allow some more intensification. NHC calling for a peak of 115kts, though it's possible Norbert may go a little higher than that. Beyond 24hrs, Norbert should weaken as dry stable air, increasing shear and decreasing sea temps have a negative impact on the hurricane. Still expected to be a hurricane when it reaches Baja California though, so they should keep a close eye on Norbert.

Norbert is now the strongest storm this year in the east Pacific, having just surpassed Hernan's 105kt winds. Odd to think of an October hurricane to be stronger than all the rest!

[Somerset Squall]

Intensity has been increased to 115kts, making Norbert a dangerous cat 4. Forecast remains the same, still looks headed for Baja California, it is still uncertain just how much Norbert will weaken prior to landfall though...

[Cookie]

new update

Storm Alert issued at 8 Oct, 2008 21:00 GMT

Intense Hurricane NORBERT is forecast to strike land to the following likelihood(s) at the given lead time(s):

Yellow Alert Country(s) or Province(s)

Mexico

probability for CAT 1 or above is 15% in about 69 hours

probability for TS is 45% in about 69 hours

Yellow Alert City(s) and Town(s)

Rosarito (26.5 N, 111.7 W)

probability for CAT 1 or above is 10% in about 69 hours

probability for TS is 45% in about 69 hours

Don (26.5 N, 109.0 W)

probability for CAT 1 or above is 10% in about 69 hours

probability for TS is 40% in about 69 hours

La Poza (25.9 N, 112.0 W)

probability for CAT 1 or above is 10% in about 69 hours

probability for TS is 45% in about 69 hours

La Paz (24.2 N, 110.3 W)

probability for CAT 1 or above is 10% in about 69 hours

probability for TS is 45% in about 69 hours

Green Alert City(s) and Town(s)

San Lucas (22.9 N, 109.9 W)

probability for TS is 45% in about 69 hours

Los Mochis (25.8 N, 109.0 W)

probability for TS is 40% in about 69 hours

Navojoa (27.6 N, 109.5 W)

probability for TS is 40% in about 69 hours

Guaymas (28.0 N, 111.0 W)

probability for TS is 35% in about 69 hours

Note that

Yellow Alert (Elevated) is CAT 1 or above to between 10% and 30% probability, or TS to above 50% probability.

Green Alert (Low) is TS to between 31% and 50% probability.

CAT 1 means Hurricane strength winds of at least 74 mph, 119 km/h or 64 knots 1-min sustained.

TS means Tropical Storm strength winds of at least 39 mph, 63 km/h or 34 knots 1-min sustained.

[londonsnow]

norbert now a cat 4 as forecast. still v good organisation. weakening before landfall, but how much is debateable

[Somerset Squall]

Norbert has weakened today, but remains a major hurricane with intensity as 100kts. NHC are blaming a possible eye wall replacement on the weakening, which is common for hurricanes as intense as Norbert is. Norbert will likely begin weakening proper tomorrow as cooler waters and a more stable environment greet him. Baja California is still likely however to experience Norbert at hurricane strength.

[Somerset Squall]

Norbert has been downgraded to a cat 1 hurricane now with an intensity of 80kts. Dry, stable air seems to be attacking the hurricane from the north and Norbert's eye looks slightly rugged. It appears a weakening trend may be underway. Landfall intensity predictions have therefore fallen and Norbert may make landfall in Baja as a minimal hurricane or more likely a strong tropical storm. It's still not entirely clear or set in stone so we need to keep an eye on Norbert.

[Cookie]

thanks for the updates mate :lol:

[Somerset Squall]

Norbert is a case when satellite imagery alone should be ignored. Looking at the imagery, Norbert appears a lot stronger than the current intensity of 75kts. Norbert still has a well defined eye and some good banding features. However, data from recon aircraft don't support an intensity higher than 75kts. Norbert is now moving northwards and will cuve northeastwards soon towards Baja, as has been consistently forecast. An increase in shear and land interaction will likely quickly dissipate Norbert over Baja or mainland Mexico. Norbert may still make landfall as a hurricane after some additional weakening.

[Somerset Squall]

Norbert is just completing an eye wall replacement cycle, and is re-intensifying. Intensity is now at 85kts, making Norbert a cat 2 again. Recon are flying into Norbert this evening to get a better idea of current intensity. It's very likely that Baja California will receive a landfall at hurricane intensity so there is a hurricane warning in force. This intensification will be brief as shear is expected to increase before Norbert reaches land which should take the hurricane down to cat 1 before landfall. However, both Baja and Mexico should still be very aware of damaging winds and torrential rains, which will cause severe flooding and possible mudslides of the mountainous terrain.

[londonsnow]

Norbert is now a cat 3 dangerous hurricane less than 200miles off the baja coast according to the noaa. sustained winds of 115mph and additional strengthening forecast before landfall. this is a bit of a beast, and may still be a hurricane when it makes second landfall in mexico. the satellite loop is very impressive

[londonsnow]

Norbert is now a cat 3 dangerous hurricane less than 200miles off the baja coast according to the noaa. sustained winds of 115mph and additional strengthening forecast before landfall. this is a bit of a beast, and may still be a hurricane when it makes second landfall in mexico. the satellite loop is very impressive

edit. now weakened v slightly to cat 2 with winds sustained at 110. still a worry for baja.

[Somerset Squall]

Indeed LS, Norbert has outdone expectations again, and is currently making landfall in Baja as a 90kt, cat 2 hurricane, which is higher than estimated yesterday. Water temps are above average in the area which no doubt helped Norbert regain major hurricane status earlier. Norbert is still a very dangerous hurricane for both Baja and Mexico, and even when it starts to dissipate over land it's very likely to brings some serious rains to southwest USA early next week.