Ivan Advisories

[PurdueWx80]

The dance has to do with fierce winds interacting w/ the high terrain of the island. Basically, cyclonic rotation and friction will pull a storm cyclonically around an island such as Jamaica or especially Taiwan, which means it is pulled around the northern side. The synoptic flow would take over after the mesoscale interaction w/ land and the "normal" track would continue. If Ivan stays far enough to the south of Jamaica (a brush rather than a full on hit) then this probably won't happen.

[Possum Trot]

I hope they have personal floatation devices.

[x-y-no]

He's interacting more heavily with the ridge now. This is really obvious in both the visible and WV loops if one looks up just over and north of Cuba.

If the ridge were strong, it would accellerate him more westerly. But instead it's weakening, so just slowing him down on his WNW track. The slower he goes, the more time the tip of the ridge has to break down completely. That Atlantic mid to upper low is still headed into the picture and will contribute to that.

Hmmm, because the wind pattern in the ridge is clockwise, I'd expect a conveyor effect to the NNE.
Please help me out with this one.

The problem is the ridge appears to be weakening in front of him. I'll illustrate with the first few frames of the 12Z GFS which is just coming out.

Here's the initialization:

http://www.nco.ncep.noaa.gov/pmb/nwprod ... 0_000s.gif

Note the 588 line just north of him, and the closed low at about 30N 55W.

Now here's 6 hours:

http://www.nco.ncep.noaa.gov/pmb/nwprod ... 0_006s.gif

See how the 588 line has backed off and the low is now outside of it still moving W? Also note the weakness left behind by Frances over Georgia.

Now here's 12 hours:

http://www.nco.ncep.noaa.gov/pmb/nwprod ... 0_012s.gif

The low is still moving W and the ridge still backing off. Steering currents for Ivan are real weak.

Here's 24 hours:

http://www.nco.ncep.noaa.gov/pmb/nwprod ... 0_024s.gif

Now there's a split between the ridges right over FL, and the system MWatkins pointed out yesterday is coming in towards the Great lakes ready to make a connection and pull him north.

[Josephine96]

Good luck to anyone who stays

[HurricaneQueen]

Thank you for understanding. I didn't think those that hadn't experienced this month of horror could appreciate just how emotionally draining it can be. Ivan is just the icing on the cake. I think of myself as a self-reliant, rational person but right now everything has turn to jelly-fortunately I'm going on remote control because I have been so well prepared. I promised myself never again would I go through a CAT 4 but we have so little choices this far south in FL. My husband works at Home Depot so he can't leave and there really is no where to go and no way to get there. Heck, we don't even know if we will get hit. Good luck, everyone and

Thanks,
Lynn

[Anonymous]

Charley and Isidore did it as well. I talked about it once on the show.

[nicdeedoop]

And I thought I was the "only" one that held pieces of paper up to my monitor

[Josephine96]

It's draining even for us inlanders.. About 3 blocks from where i live.. you have to swim to get out the block they're on

[Tri-State_1925]

I know they have the technology and experience, but from my viewing experience, 96 hr wind forcasts are just too far off for me to take seriously. I don't think any machine will ever master the nature of the GOM.

[Josephine96]

Swollen St. Johns River Threatens Homes
Hurricane Fances is gone, but the runoff from the tremendous rain it brought is causing historically severe flooding.

Video


St. Johns River Swollen





The 310-mile long St. Johns River is the spine of east Central Florida's drainage system, WESH NewsChannel 2 reported.

The river channels away water from major rivers like the Econ, the Little Econ and the Wekiva, and it keeps giant lakes, such as Monroe, Jesup, Harney, and Beresford, filled.

After two hurricanes, the river and its tributaries are choked with runoff, and the flood waters are rising.

The swelling river is threatening homes in the areas of Geneva, Sanford, Stone Island, Hontoon Island and River Bluff.

The river is expected to crest over the weekend. Just as bad, once the river level is at its peak, the water will move very slowly toward the Atlantic Ocean.

The National Weather Service predicted it will be several weeks before the flood plain drains and the water recedes.

In a move to try to protect some homes, state and local authorities have imposed -- and promise to enforce -- a no-wake zone from Lemon Bluff to Lake George.

But with docks, walkways and yards already flooded and waters inching upward in the next 48 hours, some homes will unavoidably be flooded.

Residents will have to make a decision about whether or not to stay in their homes or move to dry ground. In the coming days, police in each community along the river will make decisions about voluntary or mandatory evacuations in the interest of resident safety.

[KG4HPN]

Actually, I use a ruler. I wish I'd thought of paper, since the screen is convex and a ruler just doesn't quite cut it. Thanks for the idea!

-Jet
KG4HPN

[x-y-no]

Wow ... slower and slower ...

At 60 hours the GFS still has him over central Cuba.
[/img]

[CaptinCrunch]

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

Straight for Jamaica, better make sure you have enought ganja, man

[Stormtrack03]

The piece of paper doesnt account for the occassional wobbles .

[Josephine96]

Wobble here, wobble there..

[tronbunny]

Wow!
That was an awesome explanation! I get it.
I hope the Mods don't want to pull those graphics on this thread, very enlightening.

Thanks!!!!

Now, let's see how reliable GFS is.

[CaptinCrunch]

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

Ivan's NEW eye, looks good

[Josephine96]

Good link and yes it does.. Maybe strengthening some..?

[charleston_hugo_veteran]

Today's Discussion
POSTED: September 10, 2004 11:37 a.m.


Hurricane Ivan is a dangerous Category 4 hurricane. As of 11:00 a.m. EDT, Ivan was centered at 16.5 north and 75.1 west, or less than 155 miles southeast of Kingston, Jamaica. Ivan is moving west-northwestward at 12 mph. Maximum sustained winds are 145 mph. The central pressure in Ivan is 934 millibars or 27.58 inches. Hurricane-strength winds extend up to 60 miles from the center of Ivan; tropical storm force winds are up to 175 miles from the center.

Ivan was for a time a Category 5 hurricane, but the hurricane is undergoing internal changes that will cause it to go through cycles of strengthening and weakening. This process is called eye-wall replacement and is common with all very strong hurricanes. During this process, the hurricane's eye contracts, causing a second eye wall to form around the smaller eye wall nearer the center. Once the second and larger eye wall forms, the inner eye wall falls apart and pressures within the hurricane rise. The larger second eye wall then slowly contracts and, once again, the pressure falls. Each time the pressure rises, the wind field around the hurricane decreases somewhat. Each time the pressure falls, the wind field around the hurricane tightens and usually increases. This process can take anywhere from 12 to 24 hours. Observing the satellite picture this morning, we see that the western quadrant of Ivan has become somewhat ragged, an indication of the process described above, and perhaps an indication that the hurricane is undergoing a little shear. As Ivan closes in on Jamaica, the wind field around the hurricane will start to interact with the mountains of the island. This could cause Ivan to weaken somewhat. But, historically, most strong hurricanes that have interacted with the 1000- to 7000-foot mountains of Jamaica have re-strengthened. The hurricane will cause heavy rainfall totalling 5.00-10.00 inches, leading to life-threatening mudslides and flooding over the island later today, tonight, into Saturday. Large battering waves and a storm surge of 5-10 feet will pummel coastal areas of Jamaica today and tonight. After leaving Jamaica, Ivan will aim at Cuba. Current computer forecasts diverge once Ivan moves toward Cuba, then north of Cuba. AccuWeather.com meteorologists believe Ivan will pass just west of Key West Monday afternoon, then track very close or make landfall along the west or southwest coast of Florida Monday night. A landfall west of Appalachicola is becoming more and more unlikely, as we look at how the steering pattern is to evolve across the lower 48 states. High pressure to the north should weaken, allowing Ivan to slow; the trough coming into the middle of the U.S. will have a chance to influence the track, and turn it more north and even northeast. Obviously, there is still some uncertainty, but from all the information and data we are looking at now, it seems highly likely that a third hurricane will strike Florida. Anyone with interests in the northern or northwestern Caribbean and the Gulf of Mexico, especially anyone in Florida, should closely monitor the movement of Ivan. Please check back with AccuWeather.com for updates on this life-threatening hurricane.

Elsewhere in the Atlantic basin, there is a tropical wave along 39 west, south of 18 north; fairly strong convection, or thunderstorms, are associated with this wave. A tropical wave is along 54 west, south of 20 north. Yesterday, Tropical Depression number 10 dissipated into an area of disorganized weather. We are also watching an area of low pressure southeast of South Texas. This feature could become better organized in a couple of days.

[dhweather]

Looks like a West wobble too.