Why is GFS so persistent on low development in Caribbean

[boca]

Run after run they have been consistently developing a low for a week now that so far has not materialized yet. What gives with this model. I thought they made positive modifications to the model.

[hial2]

If computers were infallible,there'd be no need for weather people, just computer geeks...

[NDG]

Because it sucks,
Seriously, I just think it needs to be adjusted, it might be picking up the right surface conditions but is not picking up the right mid & upper level conditions which are not just right for development.It has been forecasting lowet shear levels in the Caribbean and it has not materialized.

[Steve]

Well all the other major global models that I looked at (UKMet, NOGAPS, CMC) all pretty much develop a storm with a lot of isobars and slam it into the Massachusetts to Maine coasts at the end of their runs. I only ran the models and didn't do any other research on the system (height in the atmosphere, cold core vs. warm core, etc.) .

NOGAPS leaves something back in the western Caribbean and slams it into Latin America, while the low-res MM5 spins something up there that sits and the CMC nudges whatever it is toward the Yucatan.

JMO

Steve

[Steve]

http://weather.unisys.com/ecmwf/ecmwf_500p_4panel.html

European Model (ECMWF) impacts the US Coastline a little farther south. I don't know about who thinks which models suck, but ordinarilly when a bunch of different global models without ties to one another start spinning up a storm (whatever it is they spin up be it cold low, hybrid or tropical), people in the potentially affected areas should at least be taking notice of the possibilities.

Steve

[MGC]

Models spin up phantom lows all the time. Some come to pass some don't. That is why I place little confidence on the models. Until there is a cloud pattern that looks like it has some potential I don't get worked up.....MGC

[Berwick Bay]

Models spin up phantom lows all the time. Some come to pass some don't. That is why I place little confidence on the models. Until there is a cloud pattern that looks like it has some potential I don't get worked up.....MGC

MGC I totally agree with you! I don't depend on models. Once in awhile i will check one that has been posted on this board, but I place no credence on anything until I can see something which matches what the model is trying to portray. I rely more on my own intuition and experience in observing these storms.

[HURRICANELONNY]

I POSTED THIS ON THE "CARRIBEAN LOW SUBJECT". BUT I THOUGHT I WOULD POST IT HERE TO. THERE IS A WEAK LOW AROUND 18N83W. LOOK CLOSE ON THE VIS. LOOP.
http://www.ssd.noaa.gov/goes/east/carb/loop-vis.html

[Tampa Bay Hurricane]

Perhaps the GFS is sensing below normal pressures in
the Caribbean and is thus eager to spin up storms?

[Steve]

>>Models spin up phantom lows all the time. Some come to pass some don't. That is why I place little confidence on the models. Until there is a cloud pattern that looks like it has some potential I don't get worked up.....MGC

Yeah, I hear ya MGC. But there is a bunch of energy north of the Bahamas. The globals have impact in the 3-5 day period. Whether it turns into a surge of tropical moisture, a nontropical low, something classified or whatever, we're not going to have to wait 2 weeks to find out.

Steve

[tailgater]

Ramsdis site now has floater on this area and 1 on the area off the SE coast.
http://www1.cira.colostate.edu/ramm/rms ... _menu.html

[Steve]

The ramsdis loop makes it looks like there are two possible systems sitting there (+/- a spin and a moisture surge). Is the MJO juiced in the WC right now - it kind of has that look.

Steve

[boca]

I love to see one of these phantom lows verify so Lake Okeechobee can fill up.

[flwxwatcher]

The ramsdis loop makes it looks like there are two possible systems sitting there (+/- a spin and a moisture surge). Is the MJO juiced in the WC right now - it kind of has that look.

Steve

Steve... Yep, it looks like the MJO is juiced in the Caribbean

http://www.cpc.ncep.noaa.gov/products/p ... rimjo.html

[Nimbus]

The longer range models must be figuring in climatology. This time of year you often see a low level trough down near Panama. There is a lot of forecast shear just north of that area and until that forecast changes I doubt anything can get going.

http://www.nlmoc.navy.mil/mdl/aor/ngpsh ... wndshr.gif

If a circulation did get started near Panama with high pressure building over it things could change, but then the shear forecast would also need to change.

[Berwick Bay]

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.

I too (independent) of any of the models you are talking about, am beginning to sense improving conditions for a tropical formation near the western tip of Cuba. I "see" conditions improving for development of an upper level high and a stabilizing air mass in this area. There may be enough moisture left over from the low near Nicaragua to instigate some TS activity under the Upper level High. Right now conditions are totally hostile to any formation. But I see conditions changing in about 5-7 days. If I'm right, there could be something approaching Depression status near the western tip of Cuba in the time frame of May 28-May 31st. So I'm going to book this one and call for tropical formation (Depression) near the western tip of Cuba covering the NW Caribbean and Southern Gulf, just SW of Key West.

[wxman57]

Run after run they have been consistently developing a low for a week now that so far has not materialized yet. What gives with this model. I thought they made positive modifications to the model.

Because it's the GFS, and that's what the GFS tends to do. The former MRF did the same thing for many years -- developing about 100 hurricanes per season. The hard part is figuring out which 5-6 of those 100 actually WILL develop.

[Berwick Bay]

I know exactly what you mean about these tropical formation models (very unreliable). And I'm not really concerned what this one is saying. I'm looking at water vapor imagery and present shear conditions and seeing a big change coming in about 5-7 days. This is based on my own "senses" if you will. I'm going to stand by this call of Tropical Depression formation near the western tip of Cuba (NW Carribean-Southern Gulf of Mexico just SW of Key West) in the May 28th-May 31st time frame.

[Nimbus]

This morning the Navy 96 hour shear model hinted at the possibility of a break in the shear near Cuba late in the week. Tonight the 96 hour shear forecast shows a big split west of Cuba. Maybe its just the weekend crew?

http://www.nlmoc.navy.mil/mdl/aor/ngpsh ... wndshr.gif

[Berwick Bay]

Well there you go. I'm glad you posted that Navy Model Nimbus. Makes me feel less lonely out here on the limb. My "senses" tell me upper level conditions changing at about the west tip of Cuba. I'm still not sure about the thunderstorm activity. But I think that will come with the stabilized atmosphere on top providing a cap for any shower activity that may develop. But like I said, "I'm booking this one" for Depression status around the end of the month.