Looks like shear in the Carib

[Derek Ortt]

the latest WV loops do show some shear in the Caribbean and that a large UL is dropping right into the C Carib. Already, the western extent of the outflow is flat

This may be yet another blown GFS shear forecast. Read some of the papers on the NCEP vortex removal technique to understand why GFS ALWAYS blows shear forecasts... they dampen the amplitude of any nearby trough as well as removing the hurricane

[Huckster]

What effect do you think that might have on the track? More along the lines of straight through the shear or gaining latitude?

[Matt-hurricanewatcher]

Take a look at the latest Ir. It shows that a big outflow boundry has shot out of the northeastern quad. Very unfavable for tropical cyclone development.

Here is what the shear maps show...For one out in front of it to the west the shear is 5 to 8 knots...Which is about as favable as you can get. To the north of the system. Which is above 15 to 20 north is increasing shear of 10 knots or 20 to 30 knots. In which the system its self is with an a area of 5 to 10 knots=Upper high...So for one that should act as a outflow channel for the time being. If it where to move 5 or 6 degrees to the south that might be a different storie. The dry air over the eastern caribbean is a problem. In how close this system is to the coast is another factor.

So thats my thinking...Its really going to have problems durning the short term with that outflow boundry.

[Derek Ortt]

shouldnt affect the track much, but may mean this doesnt come close to what the models are saying

[Derek Ortt]

for the system to thrive, the shear needs to go away within the next 12-18 hours

[loon]

for the system to thrive, the shear needs to go away within the next 12-18 hours

I'll see what I can do....

cheers,
loon

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
505 AM AST WED JUL 13 2005

.SYNOPSIS...AT UPPER LEVELS...WHILE A STRONG HIGH PRESSURE REMAINS
ENTRENCHED IN THE GULF OF MEXICO AND THE SOUTHERN UNITED STATES...AN
UPPER LEVEL TROUGH MOVING OVER HISPANIOLA WILL CONTINUE WESTWARD
ACROSS THE CARIBBEAN...BURROWING UNDER THE HIGH PRESSURE AND
DISPLACING IT NORTHWARD. THE TROUGH WILL ARRIVE IN SOUTHERN MEXICO
SUNDAY.


Trough is retograding westward.

[Derek Ortt]

sure doesn't look like it is retrograding.

GFS does tend to mess these up. Kurihara 1995 (the spelling may be off), explains the vortex removal technique and how NCEP removes the trough as well

[Matt-hurricanewatcher]

I see the clouds/outflow getting flatten on the north side. With a large upper low over the western caribbean, with a piece of it droping southwestward. The shear maps do show 25 to 30 knot shear/a increase of 10 durning the time frame to the north. But this system also has a upper high over it. Its main factor is that pool of dry air over the caribbean. Then that outflow boundry. If it races to fast it will run into that ULL at 65 to 70 west.

[Thunder44]

From looking at first visible images I see fairly well-wrapped up system, with a good outflow jet on it's NW side. I don't see the outflow boundaries you are talking about, Matt.

[Matt-hurricanewatcher]

Lok on the Eastern side. You see that band of clouds shooting out?

http://www.ssd.noaa.gov/PS/TROP/DATA/RT ... -loop.html

[vbhoutex]

Definitley an obvious outflow boundary on the Eastern side. You can also see the cluster of storms it came out of starting to collapse or at least see the tops warming significantly.

[HouTXmetro]

Wait, isn't the trough suppose to influence Emily to take a more Northward course?

[vbhoutex]

Wait, isn't the trough suppose to influence Emily to take a more Northward course?

What trough are you talking about?

[Stormcenter]

Wait, isn't the trough suppose to influence Emily to take a more Northward course?

What trough are you talking about?

I think he is referring to the "trough" mention in the N.O. NWS discussion this morning.

This is from this morning's NWS N.O. discussion for 7-13-05

OLD REMNANTS OF DENNIS WILL FINALLY BE PICKED UP IN THE WESTERLIES
STARTING SAT MORNING. BY THIS TIME, EXTENDED MODEL GUID SHOWS
EMILY IN THE CARRIBEAN. AS OLD DENNIS MOVES NE, THE UPPER TROUGH
PICKING IT UP BEGINS TO ERODE THE RIDGE OVER THE GULF CAUSING IT
TO WEAKEN A BIT. THE GFS IS ADVERTISING SOME STRONG MCS FEATURES
SWINGING OUT FROM THE BASE OF THE TROUGH STARTING THIS FRIDAY. THE
UPPER TROUGH IS ALSO ADVERTISED TO STAY PUT OVER OKLAHOMA AND
TEXAS THROUGHOUT THE REMAINDER OF THE RUN. THE GLOBAL SUITES ALSO
SHOW EMILY MOVING ON A WNW COURSE INTO MEXICO. WILL BE INTERESTING
TO SEE LATER SOLUTIONS OF THE GLOBAL SUITES AS A WEAKNESS BEGINS
TO DEVELOP OVER THE WESTERN GULF REGION STARTING SUNDAY. STAY TUNED...

[ncweatherwizard]

Well there was some pretty stiff shear in the Caribbean on Monday, and at that point it looked like it needed to get out by Thursday; didn't see that there weren't too many ways for that to happen, since troughing had to lift out of the Caribbean by Wednesday or Thursday.
So in a nutshell, what was once a possibility seems to be becoming more and more likely. Oh, and that's a good thing.

Scott

[Stormcenter]

Well there was some pretty stiff shear in the Caribbean on Monday, and at that point it looked like it needed to get out by Thursday; didn't see that there weren't too many ways for that to happen, since troughing had to lift out of the Caribbean by Wednesday or Thursday.
So in a nutshell, what was once a possibility seems to be becoming more and more likely. Oh, and that's a good thing.

Scott

A "possibility" for what?

[ncweatherwizard]

Well there was some pretty stiff shear in the Caribbean on Monday, and at that point it looked like it needed to get out by Thursday; didn't see that there weren't too many ways for that to happen, since troughing had to lift out of the Caribbean by Wednesday or Thursday.
So in a nutshell, what was once a possibility seems to be becoming more and more likely. Oh, and that's a good thing.

Scott

A "possibility" for what?

sorry....possibility for shear in the Caribbean when Emily crosses it.