TS Nate

[donsutherland1]

Over the past three hours, Nate has drifted slightly to the northwest. Over the next several days, steering currents will likely remain weak. As a result, Nate could drift slowly to the northward as it grows into a hurricane. However, ridging increasingly appears likely to redevelop afterward. Once that happens, Nate's northward progress will likely come to an end. With building ridging, storms in the vicinity of the Bay of Campeche have had a history of tracking somewhat south of west as they headed for landfall. A west-southwest trajectory is probably the most likely scenario for Nate prior to landfall. Already, a cluster of hurricane models, not to mention the 18z GFS, support just such a scenario.

From the Florida State University site:

Given the historic climatology associated with tropical cyclones forming in the region in which Nate formed, the forecast upper air pattern on both the GFS and ECMWF ensembles, and the cluster of models pointing to a Mexico landfall, I have good confidence that Nate will make landfall in Mexico, probably not far from Tampico.

Estimated Track:

21.5N 93.6W

22.5N 95.0W

22.7N 96.0W

22.3N 97.8W

21.9N 100.0W

Estimated Point of Landfall:

22.298N 97.809W (near Tampico, Mexico)

Estimated Intensity at Landfall:

Maximum sustained winds: 90 mph

[gil888]

Over the past three hours, Nate has drifted slightly to the northwest. Over the next several days, steering currents will likely remain weak. As a result, Nate could drift slowly to the northward as it grows into a hurricane. However, ridging increasingly appears likely to redevelop afterward. Once that happens, Nate's northward progress will likely come to an end. With building ridging, storms in the vicinity of the Bay of Campeche have had a history of tracking somewhat south of west as they headed for landfall. A west-southwest trajectory is probably the most likely scenario for Nate prior to landfall. Already, a cluster of hurricane models, not to mention the 18z GFS, support just such a scenario.

From the Florida State University site:

Given the historic climatology associated with tropical cyclones forming in the region in which Nate formed, the forecast upper air pattern on both the GFS and ECMWF ensembles, and the cluster of models pointing to a Mexico landfall, I have good confidence that Nate will make landfall in Mexico, probably not far from Tampico.

Estimated Track:

21.5N 93.6W

22.5N 95.0W

22.7N 96.0W

22.3N 97.8W

21.9N 100.0W

Estimated Point of Landfall:

22.298N 97.809W (near Tampico, Mexico)

Estimated Intensity at Landfall:

Maximum sustained winds: 90 mph

To the thousandths of a degree? Wow you are good!

[donsutherland1]

To the thousandths of a degree? Wow you are good!

It's not meant to be that precise. I was using Google Maps and just took the numbers from my plotted path.

[wxsmwhrms]

I know I was kind of ranting on here this morning about my rationale for a the 00Z EC solution toward the Gulf Coast. Here is where I guess I am tonight. I can see where if this is a slow developing system that mainly stays where it's at for the next 2-3 days like the GFS EnKF shows, that it would do what it or the GFDL shows were it generally just moves WNW and then W into NE Mexico. Those models basically keep the system S of 23N the entire life cycle. But if it has a much more northward component and moves N or NNW to near 25N like the ECMWF/UK/HWRF show by 72 hours, I think it will be very difficult for it to be missed by the troughing/weakness. I think the op ECMWF missed it because it was just slightly weaker with the trough and more to the left than the previous run, but the EC ensemble remains a bit more robust with the troughing and a bit farther E in the mean. Further, if it deepens as the models generally show the next few days, it should gain more latitude than the GFS models show. I said 60/40 this morning for a US LF and I will stick with it for now, but obviously the next 24-48 hours will be critical for the evolution.

I hope the 40% ends up verifying- the central Gulf coast does not need another dose of heavy rain, TX could use any shot of rain they can get, and Josh would probably be better able to chase in Mexico than in the marshes of LA.

[wxsmwhrms]

Looks like some curved bands now developing E and W of the center. I agree with Don that it looks to have drifted NW or NNW over the last few hours.

[Ed Lizard]

A Northeast Mexico hurricane would have to be pretty big to drop much rain in the burning parts of Texas. Dolly got some rain up here.

I'd feel better if it can get up near 25º or 26ºN.

[wxsmwhrms]

That experimental T254 GFS ensemble is a definite point for the southern solution. The 00Z run had nearly all of the members going to LA, now the 18Z run has all but one going to Mexico. Again, the key seems to be that in the shorter term none of them get the system N of 23N, and they all pretty much show a WNW or NW track which turns W or WSW. They never get the more poleward motion shown by the HWRF/EC/UK/GGEM.

[HurricaneJosh]

I hope the 40% ends up verifying- the central Gulf coast does not need another dose of heavy rain, TX could use any shot of rain they can get, and Josh would probably be better able to chase in Mexico than in the marshes of LA.

Yep-- agreed. The LA bayous ain't easy chase turf. Thanks for thinking of me.

[HurricaneJosh]

Status quo at 10 pm CDT. No changes to initial intensity or forecast. I'm not terrible impressed with the IR presentation tonight. We need to see some convection firing closer to that center:

[SN_Lover]

Dry air is being pulled into NATE. I don't see any strengthening in the near future.

[phil882]

Through 54 hours the 00z GFS is quite a bit further northeast than 18z or 12z...

[wxmx]

Through 54 hours the 00z GFS is quite a bit further northeast than 18z or 12z...

Yep, closer to it's cousin the GFS EnKF... maybe a tad north.

[wxsmwhrms]

Yep, closer to it's cousin the GFS EnKF... maybe a tad north.

Yeah, at 90 hours it's like at 22N, 95W versus 19.5N, 97W on the 18Z run. It is also deeper and slower with the trough over the Arklatex at that time. Like you said, looks much more like the EnKF. Looks like it will still go into Mexico, but it is way closer to getting involved in that trough than its previous runs. Needs to stay as far SW as the model is showing it to keep that track into Mexico.

[phil882]

Starting about 72 hours onward, the 00z GFS is downright scary. Its fairly rare to see such a spectacular outflow pattern depicted by such a small system. Were the GFS to verify, such an outflow regime would be supportive of a Cat 3+ easily. If the thermodynamic environment cooperates, it may get much stronger than that.

[wxsmwhrms]

Starting about 72 hours onward, the 00z GFS is downright scary. Its fairly rare to see such a spectacular outflow pattern depicted by such a small system. Were the GFS to verify, such an outflow regime would be supportive of a Cat 3+ easily. If the thermodynamic environment cooperates, it may get much stronger than that.

yes, it looks very favorable. The GFS basically has no steering flow after the trough lifts out in the day4 timeframe, it basically leaves the system to behind to slowly drift SW, but it is still sitting offshore of Mexico at 132 hours. I have to be honest, I just do not see the ridging in the GFS to drive this system back to SW at least not in the mid levels. If the system is far enough S, the upper level ridging could drive it west, but then again, if upper level flow dominates, it will probably gain more latitude in the early periods. The GFS looks to have it essentially trapped under an upper high at day 5-6 with little movement.

[Frank]

Starting about 72 hours onward, the 00z GFS is downright scary. Its fairly rare to see such a spectacular outflow pattern depicted by such a small system. Were the GFS to verify, such an outflow regime would be supportive of a Cat 3+ easily. If the thermodynamic environment cooperates, it may get much stronger than that.

Thats actually a great point

[wxmx]

0z CMC still scoops Nate to the NNE

[phil882]

yes, it looks very favorable. The GFS basically has no steering flow after the trough lifts out in the day4 timeframe, it basically leaves the system to behind to slowly drift SW, but it is still sitting offshore of Mexico at 132 hours. I have to be honest, I just do not see the ridging in the GFS to drive this system back to SW at least not in the mid levels. If the system is far enough S, the upper level ridging could drive it west, but then again, if upper level flow dominates, it will probably gain more latitude in the early periods. The GFS looks to have it essentially trapped under an upper high at day 5-6 with little movement.

I've done a quick little animation below that shows the evolution of the 500mb flow from the GFS. The peak of the troughing caused by the retrograding upper level low occurs at 48 hours, at the beginning of the animation. While there is no ridge to the north of Nate, there are dual ridges to the left and right of the system are near the same intensity and applying about the same flow both northward and southward on the storm. Thus they contribute little to no motion for the storm. Second, the mid-level westerlies from the upper level low only reach into the northern Gulf and do not seem to "capture" Nate, even on the outer edge of the circulation. If Nate can't be influenced by the westerly flow at this time frame, there needs to be assistance of a subtropical high to give the system the kick of northerly motion to get it into the westerly flow. That's what typically happens with Cape Verde systems, because the subtropical high is almost always stronger to the right of the circulation, so the northerly component of motion is supported by the ridge until the trough gets close enough to capture it.

That's not what we see in the animation below. While the mid-level ridging directly to the north is not present, the mid-level ridge to the west is imparting enough southerly flow to negate most of the northerly motion produced by the mid-level ridge to the east. By 72 hours, its obvious that the mid-level ridging is starting to build back in and the upper level trough has missed its chance to have a significant influence on the system. I'd actually argue based on the animation below that the GFS is probably too slow with Nate beyond 96 hours and we should see a more persistent wsw motion because the southerly flow from the the building subtropical ridge over Texas is starting to have a greater influence on the storm than the subtropical-ridge further east in the Atlantic.

[HurricaneJosh]

Phil, when are you gonna make one of them fancy forecast maps for Nate?

[phil882]

Phil, when are you gonna make one of them fancy forecast maps for Nate?

Patience, Just got to put a few finishing touches

Also might wait for the ECWMF before I present my forecast.

[Cheeznado]

The Euro is slower/more easterly track at first, but looks like it will still hit Mexico south of Brownsville. However, it is awfully close to picking Nate up, just barely misses the trough which is a bit slower/further west. This one is a nail biter.....

[andyhb]

The Euro is slower/more easterly track at first, but looks like it will still hit Mexico south of Brownsville. However, it is awfully close to picking Nate up, just barely misses the trough which is a bit slower/further west. This one is a nail biter.....

Just need to inject a little bit of Autumn depth into that trough and perhaps...

[HurricaneJosh]

Patience, Just got to put a few finishing touches

Also might wait for the ECWMF before I present my forecast.

Patience, indeed!

[phil882]

Patience, indeed!

Ok... enjoy! I don't have enough time for a discussion on my blog, but I can save that for tomorrow. This forecast might look super bullish on intensity, but its hard to go against both the GFS and ECWMF predicting a highly favorable upper level wind environment over 31 degree Celsius waters with enough Oceanic Heat Content. The dry air is only initially an issue until the easterly shear subsides. The storm should have plenty of time to intensify and beyond 72 hours I expect at least one episode of rapid intensification that could occur anywhere from 72-96 hours. Considering that the high resolution ECWMF shows a sub 944mb cyclone at 114 hours out, this forecast is very much in line intensity wise with the ECWMF which I think is handling the synoptic environment well. Note that the storm remains super tiny and the 1008mb isobar doesn't even come close to approaching Texas. This is on the same spacial scale as Karl last year in this region. Beyond 72 hours, there will be a growing probability of an eyewall replacement cycle, and this may never get completed as the storm will also start to feel the effects of the downsloping effect of topography advecting dry air into the core circulation to its east by 96 hours.

Trackwise is a compromise between the ECWMF and GFS, leaning slightly towards the ECWMF because the higher resolution of the model is more likely depicting the mid-level structure of the tropical cyclone more accurately, meaning before the ridge builds in all the way to the north, the storm will likely drift a little more to the north due to stronger winds on the NE side of the system. However, once the ridge builds in all the way, the system will take a turn to the WSW very similar to Karl last year.

[HurricaneJosh]

Ok... enjoy! I don't have enough time for a discussion on my blog, but I can save that for tomorrow. This forecast might look super bullish on intensity, but its hard to go against both the GFS and ECWMF predicting a highly favorable upper level wind environment over 31 degree Celsius waters with enough Oceanic Heat Content. The dry air is only initially an issue until the easterly shear subsides. The storm should have plenty of time to intensify and beyond 72 hours I expect at least one episode of rapid intensification that could occur anywhere from 72-96 hours. Considering that the high resolution ECWMF shows a sub 944mb cyclone at 114 hours out, this forecast is very much in line intensity wise with the ECWMF which I think is handling the synoptic environment well. Note that the storm remains super tiny and the 1008mb isobar doesn't even come close to approaching Texas. This is on the same spacial scale as Karl last year in this region. Beyond 72 hours, there will be a growing probability of an eyewall replacement cycle, and this may never get completed as the storm will also start to feel the effects of the downsloping effect of topography advecting dry air into the core circulation to its east by 96 hours.

Trackwise is a compromise between the ECWMF and GFS, leaning slightly towards the ECWMF because the higher resolution of the model is more likely depicting the mid-level structure of the tropical cyclone more accurately, meaning before the ridge builds in all the way to the north, the storm will likely drift a little more to the north due to stronger winds on the NE side of the system. However, once the ridge builds in all the way, the system will take a turn to the WSW very similar to Karl last year. Beyond 72 hours, there will be a growing probability of an eyewall replacement cycle, and this along with the increasing

Wow-- that is some forecast. Provocative, to say the least. You have a major passing right over Tampico. This would be a big deal if it happened.

Do you expect this to be a microcane all the way through?

[phil882]

Wow-- that is some forecast. Provocative, to say the least. You have a major passing right over Tampico. This would be a big deal if it happened.

Do you expect this to be a microcane all the way through?

First of all, I want to say I actually had no idea I was taking the center directly over Tampico ( I used google earth without all the cities and labels added. You are just gonna have to trust me on that one ). Needless to say there is a lot of uncertainty beyond 72 hours as with most forecasts, so take the plotted track with a grain of salt and focus on the overall cone

As for the size of the storm, the limited RH field in the Gulf of Mexico will likely limit its size. However, the storm might have an opportunity to expand slightly before landfall if an eyewall replacement cycle does take place. That's highly speculative though at this point. The radius of 1008mb pressure isobar, which is the radius of outer closed isobar (ROCI) doesn't seem to increase in size much on the ECWMF and remains around 100mi in radius the storms entire life.

[HurricaneJosh]

The 4 am CDT package is out, and I have to say, this one is like watching paint dry!

No movement, no change in intensity, no change to the forecast or the reasoning behind it. Nada. (Well, there's one small detail of note: the satellite presentation is slowly improving.)

The latest track suggests a Cat-1 landfall between La Pesca and Tampico sometime Tuesday afternoon.

[thewxmann]

The 4 am CDT package is out, and I have to say, this one is like watching paint dry!

No movement, no change in intensity, no change to the forecast or the reasoning behind it. Nada. (Well, there's one small detail of note: the satellite presentation is slowly improving.)

The latest track suggests a Cat-1 landfall between La Pesca and Tampico sometime Tuesday afternoon.

Actually, they lowered the intensity at Days 4 & 5 and added this caveat:

THIS...AND THE RELATIVE LACK OF CONVECTIVE ORGANIZATION...WOULD ARGUE AGAINST ANY SIGNIFICANT INTENSIFICATION IN THE SHORTTERM. LATER IN THE FORECAST PERIOD...SHIPS GUIDANCE STILLINDICATES THE PRESENCE OF A RELATIVELY DRY LOW- TO MID-LEVEL AIRMASS AND A SUDDEN INCREASE IN SOUTHWESTERLY SHEAR ASSOCIATED WITH ATROUGH OVER THE SOUTHEASTERN UNITED STATES. THIS SUGGESTS THAT THESTRONGER DYNAMICAL GUIDANCE...E.G. HWRF...MAY BE IN DOUBT.

Needless to say, liking the Phil-cast more than the [official] Forecast.

[HurricaneJosh]

Actually, they lowered the intensity at Days 4 & 5 and added this caveat:

THIS...AND THE RELATIVE LACK OF CONVECTIVE ORGANIZATION...WOULD ARGUE AGAINST ANY SIGNIFICANT INTENSIFICATION IN THE SHORTTERM. LATER IN THE FORECAST PERIOD...SHIPS GUIDANCE STILLINDICATES THE PRESENCE OF A RELATIVELY DRY LOW- TO MID-LEVEL AIRMASS AND A SUDDEN INCREASE IN SOUTHWESTERLY SHEAR ASSOCIATED WITH ATROUGH OVER THE SOUTHEASTERN UNITED STATES. THIS SUGGESTS THAT THESTRONGER DYNAMICAL GUIDANCE...E.G. HWRF...MAY BE IN DOUBT.

Needless to say, liking the Phil-cast more than the [official] Forecast.

Yes, they lowered it 5 kt for Days 4 and 5, which is nothing significant.

[thewxmann]

BTW, I would not be surprised if the future track of Nate ends up looking somewhat similar to Hattie's in 1961. That might end up being a decent "analog" in terms of the H5 pattern (I haven't checked though, and yeah, I know it was in a different sea and all that).