Models show a low pressure in the atlantic

[cycloneye]

http://152.80.49.210/CGI/PUBLIC/wxmap_l ... 2003051712

Some models like the very good nogaps are showing a low pressure in the atlantic near bermuda to the east of that island but the question is if this will go to tropical warm core or it will be extratropical and the answer to that will have to wait a few days to see the reallity of what will happen with this low and also we have to wait to see if the models continue to show it on the next runs but it is something to watch.

[Derek Ortt]

Doesnt look to be tropical at this time as it is very spread out. However, these things can become tropical if the dynamics are right, so it should be watched

[cycloneye]

http://152.80.49.210/CGI/PUBLIC/wxmap_l ... 2003051800

I am using the same model NOGAPS to see how the runs change and the latest one shows a low pressure deepening in the central atlantic but again will it be extratropical or it will turn into a warm core tropical system or subtropical but I guess we will have to wait for more runs from this and other models to see if they drop that low or they continue with it.The only thing to do for now is to watch the atlantic in the coming days to see what will this feature do.

[Derek Ortt]

I wouldnt call nogaps on of the better models. It is notorious for spinning up a few phantoms

[cycloneye]

http://152.80.49.210/CGI/PUBLIC/wxmap_l ... 2003051800

Here is another model the GFS that shows that low pressure in the central atlantic deepening to 1000 mbs but again will it be warm core tropical system or an extratropical cold core system well time will tell.

[chadtm80]

I wouldnt call nogaps on of the better models

what one would you call one of the better ones?

[Derek Ortt]

For formation, I have a tendency to hug the Bracknell model, as well as GFS (unfortunately) and UKMET

[Steve]

Good question chad. They all have their known biases. From my experience in model watching - which is only a few years since I've always been a satellite man - different models perform better in different seasons and under different scenarios. Overall, the UK Met does pretty good. The Canadian model (CMC) is okay too. It really just depends. Some people like the AVN/MRF (whatever it's called now), but it's really bad when there is something moving west through the Atlantic. It will try to turn a system north and dig a trof off the east coast until it gives up and finds another solution.

What I recommend is that when there's a tropical threat or potential genesis of a tropical system, look at all the models and see how they figure things out. Many of them change drastically from run to run. If there is extreme dissimilarity, throw out the so-called "outliers" on the E/W or N/S and split the difference with the rest of 'em. Blend the model run in with a long WV loop and see what you get.

Steve

[Steve]

>>For formation, I have a tendency to hug the Bracknell model, as well as GFS (unfortunately) and UKMET

That's an interesting point Derek. A lot of people on the web dig the Bracknell model. I've only followed it a few times and it was pretty off (early in last year's gulf storms particularly). What is it that you like about the Bracknell? Is it the overall performance over a few seasons or the methodology or what?

Thanks.

Steve

[vbhoutex]

Steve,
You use the same methodology I do with respect to using the models. They are only good so far, then you need to see the real thing, the sat loops. They show what is really going on and can give a good hint as to what is to come if you watch them closely. A good case in point is last years FAY. Everyone kept saying she was gonna pop and gain a lot of strength, but she didn't. She didn't because of the dry air sneaking in from the S and SW which no one saw coming save a few. I didn't see it coming, but when I looked back over it, it was right there, on the WV loop, not the models. To really get a handle on what is happening with any system, tropical or otherwise, one must use evrything available to them that they understand. I am still a rank amatuer, but I am learning. It is unfortunate that some of the folks out there, and I am not pointing at anyone here, think since they canread a model they have it down pat.

[chadtm80]

Thanks for the info derek, Steve, and VB

Where can you find the Bracknell?

[Anonymous]

http://www.met-office.gov.uk/sec2/sec2c ... l#guidance

[Derek Ortt]

I like the bracknell because for the most part, it makes sense. I have found that many of its errors are due to forward speed and the intensity errors have quite clear biases; thus, they are easy to compensate for when making a forecast. Others, like GFS and GFDL (intensity only, GFDL has the best track) can be all over the place and are not consistent; thus, their biases are not always easy to figure out quickly

[Derek Ortt]

One interesting note about the Bracknell: it is not widely used in the field of tropical meteorology. I gave a briefing last year and referenced the Bracknell, and the people were wondering what model that was. It is not that widely known for some reason

[cycloneye]

Ok guys as always good discussion this time about the models but let's return to what this thread is about and that is a low pressure forming in the atlantic as the models are suggesting. Warm core tropical low or cold core extratropical is the question pending but all signs point out to a low forming in the central atlantic SE of Bermuda.

[Stormsfury]

I'm a little surprised that no one mentioned the ECMWF model.

[Rainband]

I didn't see it??? Why???

[ColdFront77]

There has been discussion here, that this low pressure is being indicated by other forecast models.

[Anonymous]

Several models are showing a substantial low to develop east of Bermuda in 3-4 days, and have it moving northward at a fair pace. While it does appear the low will be rather vigorous, the chances of it becoming tropical or even subtropical are next to none. To get a warm core, it would have to sit around for a while in supportive ssts away from any frontal systems, and right now I don't see that happening.

[ColdFront77]

That sure looks to be the case, Rob.