Tropical Development at Bahamas / GOM in comming days?

[cycloneye]

12z EURO



Tracks towards Mexico/Texas border.

[ROCK]

12z EURO



Tracks towards Mexico/Texas border.

very similar to a previous run......I think once a system gets going the models will narrow down the track some......The EURO had TD10 going west also but the actual surface low formed more north than progged......

[hial2]

12z EURO



Tracks towards Mexico/Texas border.

very similar to a previous run......I think once a system gets going the models will narrow down the track some......The EURO had TD10 going west also but the actual surface low formed more north than progged......

Where is the surface low?? Thanks

[ROCK]

12z EURO



Tracks towards Mexico/Texas border.

very similar to a previous run......I think once a system gets going the models will narrow down the track some......The EURO had TD10 going west also but the actual surface low formed more north than progged......

Where is the surface low?? Thanks

this is no surface low yet as looking at the vis loops.....this is some low level convergence ......give it some time to brew.....


http://cimss.ssec.wisc.edu/tropic/real- ... 8conv.html

[wxman57]

OK, let's take a real look at some model data - not just what they're saying about surface features. Let's look at the whole picture all on one graphic. I've zoomed in on the Gulf and plotted 200mb winds (39,000ft) in pink, 200mb streamlines in yellow, and a 1mb surface analysis (0.5mb for Euro) in blue. I looked at the GFS (valid 18Z Wed), the ECMWF (valid 12Z Wed), and the NOGAPS (Valid 12Z Wed) to see just what each model shows happening at the surface and aloft over the central Gulf at mid week.

First, look at the GFS. Note the surface low right on the upper-level trof axis, surrounded by 40-60kt NE winds on one side and 40-60kt SW winds on the other side. There's a fairly strong upper level high over northern Mexico and another over eastern Cuba. This is not an environment favorable for tropical development at all, but it could favor a non-tropical (subtropical low). By Friday, the GFS has the low (upper & sfc) inland into Texas and the high over Cuba building west over the Gulf in its wake.



Now let's compare that to the 12Z NOGAPS. Just about an identical pattern with the exception of the jet core only goes up to 50 kts and not 60 kts on either side of the upper level trof axis. Again, unfavorable for tropical development. Also, the NOGAPS moves both the upper low and surface low inland into TX by Friday with the upper high over Cuba building west into the Gulf by next weekend.



Finally, the 12Z ECMWF. We don't have the very high-res dataset, but what we have shows an almost identical pattern to the GFS and NOGAPS. Exceptions are that the Euro develops the surface low west of the upper trof axis (which would be quite strange/unlikely). Also, the EURO only sees a 40kt jet west and east of the upper trof axis.



So what might we conclude from the latest model runs? All agree that the surface low will be a reflection of the upper level low/trof. There will be no upper-level ridge building over the low. The ridge builds over the Gulf only after the low moves inland. This is a good setup for the development of a subtropical depression or a subtropical storm, not a tropical cyclone. Winds north of the low out over the coastal waters could be in the 25-40 kt range in squalls. Chances of a strong TS or a hurricane developing are low.

[srainhoutx]

Thanks wxman57 for your input. Indications have show this to be a sub tropical setup for a while now. You have comfirmed it.

[Tampa Bay Hurricane]

i'd take a nice weak subtropical storm anyday
At least with a subtropical system there is much less
chance of hurricane conditions.

Thanks for that analysis Wxman57!

And wxman57 do you think the florida
peninsula will get windy rains out of this?

[wxman57]

i'd take a nice weak subtropical storm anyday
At least with a subtropical system there is much less
chance of hurricane conditions.

Thanks for that analysis Wxman57!

And wxman57 do you think the florida
peninsula will get windy rains out of this?

Sure, the peninsula will get rain as it moves across, but not much in the way of sustained wind inland (10-15 kts). Winds will be about twice as strong over water as over land.

[Tampa Bay Hurricane]

i'd take a nice weak subtropical storm anyday
At least with a subtropical system there is much less
chance of hurricane conditions.

Thanks for that analysis Wxman57!

And wxman57 do you think the florida
peninsula will get windy rains out of this?

Sure, the peninsula will get rain as it moves across, but not much in the way of sustained wind inland (10-15 kts). Winds will be about twice as strong over water as over land.

Thanks! Awesome because today even though it is breezy it is too
hot to go outside without the sun angle getting you...so I am looking
forward to some rain

A good breeze with rain is what I like!!!

[robbielyn]

well wxman57 you sure know how to knock the wind out of the sails but sometimes the truth hurts

[Derek Ortt]

for about the 100th time this season

The global models really do not need a center to be accurate. They have the ability to actually develop a circulation

The EURO was flat out wrong with TD 10... there is a reason why I do not use that model

[Tampa Bay Hurricane]

I'll tell you one thing...it looks like this has
some heavy rains with it, and quite
an expanse of convection
http://www.goes.noaa.gov/ECIR3.html

Or:


ULL near SE FL and another low near the bahamas
fighting for dominance.

[chadtm80]

for about the 100th time this season

The global models really do not need a center to be accurate. They have the ability to actually develop a circulation

The EURO was flat out wrong with TD 10... there is a reason why I do not use that model

Which I just do not get.. ERUO was wrong so you don't use it.. But you love using the GFDL and it has been wrong numerous times

[AJC3]

i'd take a nice weak subtropical storm anyday
At least with a subtropical system there is much less
chance of hurricane conditions.

Thanks for that analysis Wxman57!

And wxman57 do you think the florida
peninsula will get windy rains out of this?

Sure, the peninsula will get rain as it moves across, but not much in the way of sustained wind inland (10-15 kts). Winds will be about twice as strong over water as over land.

And to add to this...we'll often see gradient winds associated with a strong high to the north produce the worst of the winds/seas/surf and otherwise squally weather BEFORE any surface trough or low forms to the S/SE. What can wind up happening is that the low or trough that forms becomes fairly broad and puts a significant enough dent in the gradient to weaken the gradient wind flow.

The formation of Tammy just off our coast in Oct 2005 is a good example of a case where the weather actually IMPROVED along the east coast once the low (a TC in this case) formed.

http://www.hpc.ncep.noaa.gov/dailywxmap ... 051004.gif
http://www.hpc.ncep.noaa.gov/dailywxmap ... 051005.gif

[bwhorton2007]

Hey guys no model is 100% correct all the time or we wouldn't need all the ones we have.

[Recurve]

17-24 knot NE surface flow bringing showers and some thunderstorms from out over the Straits into SE FL and the upper Keys now, moist atmosphere with the strong S/SW upper flow. Pressures trending down somewhat along the Keys, wondering where the surface low is supposed to be.

[Tampa Bay Hurricane]

Oh nevermind- the low is further east:
http://www.ssd.noaa.gov/goes/east/watl/loop-avn.html

Go and click the NCEP FRONTS and you will see the
1012 mb centered low along a stalled frontal boundary.

[Tampa Bay Hurricane]

i'd take a nice weak subtropical storm anyday
At least with a subtropical system there is much less
chance of hurricane conditions.

Thanks for that analysis Wxman57!

And wxman57 do you think the florida
peninsula will get windy rains out of this?

Sure, the peninsula will get rain as it moves across, but not much in the way of sustained wind inland (10-15 kts). Winds will be about twice as strong over water as over land.

And to add to this...we'll often see gradient winds associated with a strong high to the north produce the worst of the winds/seas/surf and otherwise squally weather BEFORE any surface trough or low forms to the S/SE. What can wind up happening is that the low or trough that forms becomes fairly broad and puts a significant enough dent in the gradient to weaken the gradient wind flow.

The formation of Tammy just off our coast in Oct 2005 is a good example of a case where the weather actually IMPROVED along the east coast once the low (a TC in this case) formed.

http://www.hpc.ncep.noaa.gov/dailywxmap ... 051004.gif
http://www.hpc.ncep.noaa.gov/dailywxmap ... 051005.gif

Thank you for that explanation
I remember tammy it was very windy before it formed then it
formed and moved north and the winds went down to very calm here.

[Recurve]

Oh nevermind- the low is further east:
http://www.ssd.noaa.gov/goes/east/watl/loop-avn.html

Go and click the NCEP FRONTS and you will see the
1012 mb centered low along a stalled frontal boundary.

Thanks. Seems more like we're on the wet side, but I guess we've got the gradient instability. Also anybody see something right off Nassau, SW of the low.

[bwhorton2007]

i see it recurve but since everything now seems to be pointing a subtropical developement it is probably nothing at this point.