TCS049…the next TPARC target

October 2nd, 2008

TCS049 is a potential flight target for today. If they flew, the P3 would fly from 21Z on the 2nd - 05Z on the 3rd.

The animation shown below gives some sense of its structure:

It has some decent convection to the north and moderate upper level divergence.  You can see signs of anticyclonic outflow to the northeast of the storm. You can also see a fairly strong TUTT low to the storm’s northeast limiting its development.

What about a low level center? The attached image shows the quikscatt analysis and available surface obs:

You can see a cyclonic circulation on its northeast side, but there is no sign of westerly winds on the east side.

And the shear?

The image above, valid at 11:30 Z on Oct. 2, 2008 shows the shear surrounding TCS049. You can see the southerly shear from the associated TUTT cell to its northwest and the ridge to its east. The shear is currently preventing significant development.

And for its future?

The EC model is the only one that really does something with this system. It sort of splits, with one system moving north and quickly recurving and a second , weaker system moving westward towards the Phillipeans.

Both of those happen in the long term though. It does not seem to be a system with a bright future.



Jangmi fades after ET

October 1st, 2008

The last warning for Jangmi from JTWC was issued at 21Z on the 30th of September. Jangmi had

max sustained winds at 35 kts with gusts to 45 kts. As it moved into the midlatitude westerlies it completed

extra-tropical transition. Attached is an IR image with overlayed divergence and upper-level AMVs. The animation ends on 13Z on October 1st:

You can see how sheared the system is and that it’s lost any symmetry. According to the GFS phase diagram Jangmi has already fully undergone extra-tropical transition. It still has some anticyclonic outflow to the south, but it is impeded to its north from the midlatitude jet.

Unfortunately, the C-130 has finished flying for the experiment and the P-3 has been down due to an AC problem. But, we will have flight data from the Falcon (and perhaps the DOTSTAR too) which will be vital for AMV validation.

Attached is the planned route for the Falcon at 00Z on the 1st of October, plotted over ECMWF forecast upper-level winds and low-level vorticity:

As you can see they are attempting to sample Jangmi’s outflow and interaction with the midlatitude jet.  The model output shown above agrees fairly well with the 200 hPa streamlines from the AMVs

And what about future development?

The ECMWF does not do much with it in terms of development. The GFS hints at Jangmi merging with another disturbance and developing something downwind. The NOGAPS and Met Office model hint at something as well. These should be well out of range for the research aircraft, but perhaps the data we’ve obtained from the experiments will help downstream forecasts.

TCS048 is now Tropical Storm Twenty-One

September 29th, 2008

As of 12Z TCS048 became  tropical storm 21W,  upgraded from tropical depression 21W.
At 12Z, according to JTWC it was analyzed near 8.9N 129.6E moving 280 degrees at 15 kts. They analyzed it’s strength at 35 kts with gusts to 45.

The system is still a bit sheared, as shown in the IR image and shear analysis shown below:

The shear is more intense to the south and west of the storm but the convection has gotten a bit more organized.  A previous quikscatt analysis shows a closed circulation, but it is only hinted at with surface and ship obs at this time. The AMV/IR and divergence animation shown below shows some weak but widespread divergence over the deepest convection:

An anticyclonic outflow hasn’t developed as of yet, although there are some hints of poleward outflow to its west.

The models are reasonably similar in their track for 21W, at least for the short term. They all bring it to the northwest up and across the Philippines through about 12Z on the 29th, steered by a subtropic ridge to its east. As this ridge weakens, the storm is expected to take a slightly more northerly/northeasterly turn. The models seem to weaken the storm as it crosses land and then re-intensify after it goes through the South China Sea.

Models: ECWMF, Met Office, GFS, NOGAPS

Tropical Storm Jangmi 12Z September 29th, 2008

September 29th, 2008

At 12Z, September 29th JTWC analyzed Jangmi at  27.2N 122.1E, moving 09 kts at 065 degrees with an intensity of 055 kt, and gusts of 070 kts.

Attached is the IR, upper-level AMV, and analyzed divergence animation valid at 14Z:

Jangmi has been hit hard by shear from the upper-level westerlies off of China. These westerlies  have enhanced the outflow and divergence to Jangmi’s northeast, but the associated shear has helped weaken the storm significantly as well.

As of 13Z the ADT analyzed an intensity of 39 kts, and the 08Z AMSU and SATCON had an intensity of 45 kts. The 12Z TMI image shows some convection to the northeast as well, but no organized eyewall.

Looking at the phase diagrams, the GFS diagram shows ET is underway, loosing its symmetric representation already, and then becoming cold-core by the 2nd of October. The Met Office diagram has similar timing. The NOGAPS analysis is similar early on, but then becomes more symmetric before becoming cold core.

The models are moving the system eastward, well south of Japan, and shearing it out quickly. They vary a bit in their frontal development and placement, however. By 00Z on the 3rd, all of the models except the NOGAPS analyze the system around 30N, 140E. The NOGAPS, the most symmetric of the analyzed systems, is also the slowest; bringing it to 30N 130E by that same time. The ECMWF seems the most sheared.

Model forecasts: ECMWF,Met Office,GFS, NOGAPS.

Either way, in the shorter term, this system is likely to weaken in the near time. The recurvature is interesting, because it was only recently predicted by the models. Looking back, the model consensus forecast on the 26th still shows Jangmi heading into China. By the 27th, the 12Z run began forecasting recurvature. This may be a good potential case to look at the effect of observations to see if the track prediction can be improved.

Jangmi continued to intensify through 18Z on the 27th

September 29th, 2008

On 06Z on the 25th of Septebember, Jangmi was named a Typhoon. 48 hours later: by 06Z on the 27th, Jangmi was a Super Typhoon with reported 135 knot winds, according to the working best track on the Unisys website. Jangmi intensified very quickly. By  00Z on the 29th Jangmi had weakened to a Tropical Storm. It continues to weaken.

Attached is the SATCON intensity plot for the storm:

SATCON shows Jangmi’s clear intensification and weakening. What is also shows is the very successful performance of the satellite-intensity techniques. The SATCON (and corresponding ADT and AMSU) are very close to the best track. The C-130 recon , however, had also reported nearly 140 kt winds, implying an even better performance for the algorithms that will have to be analyzed post-storm.

The MIMIC animation from 00Z on the 26th - 00Z on the 27th linked here shows Jangmi’s intensification and organization. The animation shown here from 00Z on the 27th - 00Z on the 28th shows its annular status as it holds its intensity for nearly 24 hours and begins to weaken.

The animation below shows the strong analyzed divergence, anticyclonic outflow from the upper-level AMVs, and clear, well-defined eye near the Jangmi’s peak intensity:

Jangmi quickly began to weaken after it neared cooler Sinlaku and Hagupit cooled waters and crossed Taiwan. Its current status and future track will be the subject of a future blog post.

Rapid Intensification of Jangmi 20Z September 26th, 2008

September 26th, 2008

Here is the MIMIC animation showing this intensification (as of 18Z it had 120 kts).

Here is the IR animation. You can see the very strong outflow and clear eye:

TCS048…the next storm? 21Z, September 26th, 2008

September 26th, 2008

TCS048 has been trying to develop over the past few days. Attached are the upper-level AMV divergence plots and the shear plots over the disturbance:

The divergence plot shows some organization and two weak centers of divergence over the distrubance. The AMVs don’t show much of a sign of any coherent, anticyclonic outflow.

The shear plot:

Shows 15-20 kts of northerly shear over the center, with stronger shear toward its edges. A fairly strong TUTT low lies to its northeast, potentially hindering its development.  The surface and ship observations show no sign of a closed circulation, particularly on the southern side. Quikscatt/ASCAT passes aren’t available.

So what are the models doing with this storm?

Only the ECMWF and NOGAPS (no real surprise there) develop this sytem to any degree. And although the EC develops a rather large system, by the end of its run, it is not particularly strong. The GFS develops it a little at first, but by 00Z on the 30th it has begun to dissapate. The Met Office model develops the system to a medium sized but fairly weak disturbance.

The ECMWF seems to be weakening the upper-level northeasterly winds slightly, perhaps allowing for this system to develop. The GFS, on the other hand, has strong upper-level easterlies over the disturbance.

The EC model has been pretty solid for this experiment. It is still the one to watch.

Jangmi Strengthens: 12Z, September 26th, 2008

September 26th, 2008

As of 12Z, JTWC has analyzed Jangmi at 17.7N 127.9E.

It is moving  310 DEGREES AT 12 KTS with an intensity of 095 kts and gusts of 115 kts.

The satcon image below shows Jangmi’s steady intensification:

The animated IR image with overlayed AMVs and analyzed divergence is shown below:

It shows a very well developed upper-level pattern with strong outflow to the north and south. The analyzed divergence is quite strong. This is a very healthy storm.

The attached MIMIC animation shows a very complex and changing eyewall structure:

The 200 hPa streamlines shown below shows the general synoptic set up dominating Jangmi:

Jangmi’s outflow is enhanced by the upper-level low to its east along with the anticyclone above it. The intensity forecast has increased since yesterday: it’s forecast to intensify to 120 kts by 00Z on the 28th and then weaken quickly after that, mostly likely due to Taiwanese interaction.

The consensus track from yesterday, put Jangmi by 12Z at 16.3N 129.1E, a bit to the south and east of it’s current position (17.7N 127.9E). It’s steering is predominantly driven by a subtropical ridge to it’s north, particularly as the upper level trough from the westerlies moves eastward. As this ridge builds, Jangmi is expected to have a more westerly track.

By 00Z on the 29th, ECMWF and NOGAPS bring Janmi directly over Taiwan. The Met Office model is a bit more progressive, moving Jangmi across Taiwan about 12 hours earlier. It is no longer south of the other models as it was previously. The GFS is similar to the Met Office, although it slows Jangmi down a bit after the Taiwanese landfall. None of the models are showing signs of recurvature.

Typhoon Jangmi: 12Z September 25th 2008

September 25th, 2008

As of 06Z on the 25th, Jangmi was upgraded to a Typhoon.

JTWC’s 12Z analysis:Position: near 14.5N 131.4E

Movement: 275 DEGREES AT 11 KTS

Intensity: max sustained winds - 070 KT, GUSTS 085 KT

The 11:30 Z ADT has analyzed its intensity at 57 knots with its CDO. The most recent satcon analysis was at 20Z on the 24th, with an intensity of 56 knots.

Attached below is an animated IR image with upper-level AMVs and analyzed divergence:

It’s got fairly healthy divergence aloft and reasonable outflow to its northeast and southwest. Outflow is somewhat restricted to the north. There are hints of dry air to the north and northeast, possible due to an upper-level low.

The MIMIC animation below shows the development of an eye over most of Jangmi’s eastern side:

The 12Z AMSU-B image, shown here (courtesy of NRL) does imply a fully closed eye:

The quikscatt 09Z analysis has a fully developed low level circulation around Jangmi. It is a healthy storm. It’s under reasonably low shear (about 10kts) but still surrounded by high shear to the east and south.

And what’s in it’s future:

JTWC has it intensifying to 115 kts by 12Z on the 27th and maintaining that intensity through the 28th. As it approaches Taiwan it is forecasted to weaken.

Its track is being influenced by the subtropical ridge to its west and north, driving Jangmi to the west more than previously forecasted. The T-PARC consensus forecast had predicted it to be at: 15.3N 132.2E. It’s current position is to the south and west of this forecast.

The models are again reasonably consistent with each other bringing Jangmi in some form across Taiwan, but their timing and placement are slightly different. The ECMWF and NOGAPS have it striking Taiwan at about 12Z on the 28th. The Met Office model by that time has it south of Taiwan, but west of the other models. The GFS is a bit to the east of other models, but closer in latitude ot the EC and NOGAPS. They seem to be moving a bit more slowly, in general, today than previous model runs, but not by much.

Jangmi is named. Models amazingly consistent on its future

September 24th, 2008

The models are amazingly consistent on Jangmi’s forecast over the next few days. Out to 120 hours they all put Jangmi over Taiwan (with a few minor details).



Met Office



Attached is an animation of Jangmi with its outflow plotted above:

A current C-130 flight observed a maximum wind speed of 55 kts. Satcon (as of 16Z) analyzes the intensity at 53 kts.