Hurricane Maria: NNW Of Bermuda Hurricane Watch Issued

[GaWx]

1) The 12Z Euro, just like the 12Z GFS, appears to want to delay establishing sig. ridging along the US east coast vs. its earlier runs. Prior to the 12Z runs, these two models had suggested on several runs that strong ridging would get established near 9/15, which would mean a better chance for 95L to get trapped. Is rainstorm in charge of input for these models lol?

2) As of 2 PM EDT (6 hour map), the 12Z GFS has 95L near 11.5N, 39.5W (and at ~1011 mb) whereas the 12Z Euro has it near 10.0N, 35.5W and slightly stronger at 1010 mb. Also, the 2 AM EDT Wed. 12 Euro position (18 hour Euro map) is almost right on top of the 12Z GFS' 2 PM Tue. (6 hour) map and is ~2 mb stronger. (It is actually ~30 miles south of that GFS map.)

Any opinion on which model is closer to the actual position and actual strength? I think the Euro is clearly closer in position, but want others' opinions. It will be interesting to see where the NHC has the TD.

[Srain]

If you notice, the euro suggests a piece of energy (vort) is left behind in the Eastern Caribbean. My hunch is that guidance has yet to latch onto any kind of agreement.

[GaWx]

If you notice, the euro suggests a piece of energy (vort) is left behind in the Eastern Caribbean. My hunch is that guidance has yet to latch onto any kind of agreement.

With the Tue 12Z Euro and 12Z GFS being so different regarding the overall pattern by day 7 vs. their Tue 0Z (and 6Z) counterparts, I figure the Wed. 0Z runs have a better than average chance to change significantly from these 12Z runs.

[dpwozney]

2) As of 2 PM EDT (6 hour map), the 12Z GFS has 95L near 11.5N, 39.5W (and at ~1011 mb) whereas the 12Z Euro has it near 10.0N, 35.5W and slightly stronger at 1010 mb. Also, the 2 AM EDT Wed. 12 Euro position (18 hour Euro map) is almost right on top of the 12Z GFS' 2 PM Tue. (6 hour) map and is ~2 mb stronger. (It is actually ~30 miles south of that GFS map.)

Any opinion on which model is closer to the actual position and actual strength? I think the Euro is clearly closer in position, but want others' opinions. It will be interesting to see where the NHC has the TD.

From the satellite map at 1915 GMT, I think the eye is just slightly northwest of 11N, 36W.

[phil882]

Again, I still don't like the prospects for this storm beyond 12-24 hours. Its got a nice banding setup right now, but you can see on visible how the surface circulation is starting to speed up. If this continues, we could be looking at a sheared storm by tomorrow.

[blazess556]

1) The 12Z Euro, just like the 12Z GFS, appears to want to delay establishing sig. ridging along the US east coast vs. its earlier runs. Prior to the 12Z runs, these two models had suggested on several runs that strong ridging would get established near 9/15, which would mean a better chance for 95L to get trapped. Is rainstorm in charge of input for these models lol?

2) As of 2 PM EDT (6 hour map), the 12Z GFS has 95L near 11.5N, 39.5W (and at ~1011 mb) whereas the 12Z Euro has it near 10.0N, 35.5W and slightly stronger at 1010 mb. Also, the 2 AM EDT Wed. 12 Euro position (18 hour Euro map) is almost right on top of the 12Z GFS' 2 PM Tue. (6 hour) map and is ~2 mb stronger. (It is actually ~30 miles south of that GFS map.)

Any opinion on which model is closer to the actual position and actual strength? I think the Euro is clearly closer in position, but want others' opinions. It will be interesting to see where the NHC has the TD.

You may be right. Huge difference in the 18z GFs initialization compared to the 12z GFS 6 hr forecast. Seems to have initialized more like the 12z euro. Will be interesting to see if it has an effect on the track.

[MJO812]

5pm update

[Plokoon111]

Wow it is very similar to Irene's beginning track.

[Siberian Express]

5pm update

Right through a Herbert Box 2pm Saturday.

[HurricaneJosh]

The NHC's first forecast track is encouraging-- doesn't look like an autofish.

[donsutherland1]

Some historical climatology data with respect to the region in which TD 14 formed (11.8N 37.0W):

Since 1950, 8 tropical cyclones formed in the region bounded by 9.8N-13.8N/34.0W-40.0W on September 6 +/- 20 days. A day outside that range was Hurricane Chris (1988), which peaked at Category 1 and recurved and Hurricane Andrew (1992), which made U.S. landfall as a devastating Category 5 hurricane.

Of the eight relevant storms, 3 (37.5%) made U.S. landfall. Those storms were Inez (1966), David (1979), and Frances (2004). 5 (62.5%) avoided U.S. landfall. The landfall percentage is 50% higher than that for all tropical cyclones that formed in the 34W-40W region on September 6 +/- 20 days. IMO, from that pool of eight storms, there are five analog candidates at this time (shown chronologically):

1. Flossie (1978)

2. David (1979)

3. Danielle (1998) **the solution closest to that shown on the 9/6 18z GFS**

4. Erin (2001)

5. Frances (2004)

In terms of peak intensity, 87.5% of the eight storms grew into hurricanes and 62.5% were major hurricanes. 50% were either Category 3 or 4 storms at their peak. From the smaller analog pool, 40% of the tropical cyclones made U.S. landfall and all five storms were hurricanes. 60% of the possible analog storms were major hurricanes. Based on this information, historic climatology suggests that TD 14 will likely peak as a major hurricane. There is some chance albeit a smaller one than had been the case for Katia that the storm will peak at Category 4 strength.

[HurricaneJosh]

Don, do you see this threatening the USA?

[Eyewall2005]

The NHC's first forecast track is encouraging-- doesn't look like an autofish.

Oh its definately looking fishy to me based on what the models are showing. 18z GFS has a yet another trof swooping through and weakening what ever ridge theres been this season and recurves the cyclone.

[donsutherland1]

Don, do you see this threatening the USA?

Josh,

Unless it slows down or tracks generally westward, there's probably a somewhat greater chance at recurvature. Having said that, I believe there is a greater chance of U.S. landfall with what is now TD 14 than had been the case with Katia.

[bluewave]

Here's the GFS EnKF guess...

http://www.esrl.noaa.gov/psd/forecasts/gfsenkf/control/

[HurricaneJosh]

Oh its definately looking fishy to me based on what the models are showing. 18z GFS has a yet another trof swooping through and weakening what ever ridge theres been this season and recurves the cyclone.

But it's not an automatic fish is all I'm saying.

Josh,

Unless it slows down or tracks generally westward, there's probably a somewhat greater chance at recurvature. Having said that, I believe there is a greater chance of U.S. landfall with what is now TD 14 than had been the case with Katia.

That makes sense, and that's what my hunch is as well: more than likely a fish, but definitely not for sure.

[phil882]

I'm definitely not as optimistic as the NHC on this one... The storm should become a tropical storm in the next 24 hours, but after that it will be a constant battle as there is a lot of shear in the path of this storm, first by the fast low level flow, and then later one due to a strong shear axis that gets set up in the wake of Katia's outflow.

http://philstropicalweatherblog.wordpress.com/2011/09/06/katia-moving-slowly-northwestward-td14-forms-invest-96l-forms/

[OSUmetstud]

Phil, I generally agree. However, i was looking at the SHIPS shear values which give me some pause on thinking this is just going to be a weak POS for awhile.

SHEAR (KT) 6 6 8 10 12 15 18 18 14 9 5 10 10SHEAR ADJ (KT) 11 11 8 11 16 8 7 0 2 0 5 2 6SHEAR DIR 257 246 228 225 242 243 233 238 225 235 316 344 317

[dan88]

Phil, I generally agree. However, i was looking at the SHIPS shear values which give me some pause on thinking this is just going to be a weak POS for awhile.

SHEAR (KT) 6 6 8 10 12 15 18 18 14 9 5 10 10SHEAR ADJ (KT) 11 11 8 11 16 8 7 0 2 0 5 2 6SHEAR DIR 257 246 228 225 242 243 233 238 225 235 316 344 317

Intensity wise the SHIPS is in great agreement with the NHC forecast, a generally slow intensification, peaking at 66kt in 120 hours. Though generally with the light to moderate shear, by far the single most significant negative parameter during the forecast is VERTICAL SHEAR DIR, which really keeps the intensity forecast in check.

[gkrangers]

Intensity wise the SHIPS is in great agreement with the NHC forecast, a generally slow intensification, peaking at 66kt in 120 hours. Though generally with the light to moderate shear, by far the single most significant negative parameter during the forecast is VERTICAL SHEAR DIR, which really keeps the intensity forecast in check.

Probably more accurate to say the NHC forecast is in great agreement with the SHIPS guidance.

[k***]

I hope that it stays weak until it's far enough along to make a solid landfall.

[CUmet]

Phil, I generally agree. However, i was looking at the SHIPS shear values which give me some pause on thinking this is just going to be a weak POS for awhile.

SHEAR (KT) 6 6 8 10 12 15 18 18 14 9 5 10 10SHEAR ADJ (KT) 11 11 8 11 16 8 7 0 2 0 5 2 6SHEAR DIR 257 246 228 225 242 243 233 238 225 235 316 344 317

The low 850-200 mb shear is deceptive though. Look at the large shear adj. magnitudes, which accounts for shear in layers other than 850-200 mb. The accelerated low-level flow and the anomalous westerly flow below 200 mb undercutting the outflow are contributing to this.

[phil882]

Phil, I generally agree. However, i was looking at the SHIPS shear values which give me some pause on thinking this is just going to be a weak POS for awhile.

SHEAR (KT) 6 6 8 10 12 15 18 18 14 9 5 10 10SHEAR ADJ (KT) 11 11 8 11 16 8 7 0 2 0 5 2 6SHEAR DIR 257 246 228 225 242 243 233 238 225 235 316 344 317

SHIPS is a great tool, but I wonder if it reliance on the GFS background conditions limits its forecasting ability somewhat. Now that the government pays out a lot of money to receive the ECWMF, why can't we create a statistical/dynamical tool based upon the Euro's background conditions? I say this with the observations last week that the GFS seemed to have difficulty that there was going to be a mid-latitude trough affecting Katia last week while the ECWMF had been well aware of the threat and southwesterly 200mb flow accordingly.

[phil882]

The low 850-200 mb shear is deceptive though. Look at the large shear adj. magnitudes, which accounts for shear in layers other than 850-200 mb. The accelerated low-level flow and the anomalous westerly flow below 200 mb undercutting the outflow are contributing to this.

A quick glance at the 300mb flow reveals the westerly flow you mentioned undercutting the low level flow near the circulation in 24 hours.

[HurricaneJosh]

Like kush was suggesting, there's a big silver lining to this system remaining shallow for the next few days.

[phil882]

Like kush was suggesting, there's a big silver lining to this system remaining shallow for the next few days.

Sure there is... the thing that bugs me here though is the the ECWMF suggests that the current shearing pattern may continue until the system interacts with Hispaniola. If that transpires... well we already saw it once with Emily in early August.

[phil882]

looks pretty decent this morning... should get the upgrade at 11am.

[dtk]

SHIPS is a great tool, but I wonder if it reliance on the GFS background conditions limits its forecasting ability somewhat. Now that the government pays out a lot of money to receive the ECWMF, why can't we create a statistical/dynamical tool based upon the Euro's background conditions? I say this with the observations last week that the GFS seemed to have difficulty that there was going to be a mid-latitude trough affecting Katia last week while the ECWMF had been well aware of the threat and southwesterly 200mb flow accordingly.

Not going to happen. First, we have an agreement with the ECMWF for limited data exchange (we do not pay to receive ECMWF data, but only receive a specific subset of their earliest output with agreement not to distribute; or something along those lines). Additionally, I don't believe that creating an operational product (model) based on something that is completely out of their control (non operational, non-NOAA) is something that is going to happen.

There are technical issues involved as well, such as data timeliness, the necessary training data (for the statistical regression) [this would be especially important for anytime they would do an upgrade], and finally, they (ECMWF) would have to give us permission to create such a product/model.

[OSUmetstud]

The low 850-200 mb shear is deceptive though. Look at the large shear adj. magnitudes, which accounts for shear in layers other than 850-200 mb. The accelerated low-level flow and the anomalous westerly flow below 200 mb undercutting the outflow are contributing to this.

oh cool...I didn't know what that was describing. That makes a bit more sense now.

[Eyewall2005]

12z updated best track brings this to TS strength.