CIMSS TPARC Support Blog

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.

Links:

ECMWF,Met Office,NOGAPS,GFS

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

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.

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.

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.

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).

Links:

ECMWF

Met Office

NOGAPS

GFS

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.

As of 12Z on the 24th, 19W was analyzed near 12.6N 136.3E according to JTWC. It is moving 295 degrees at 10 kts with max sustained winds at 045 kts and gusts to 55 kts. The current Satcon (as of 07Z) analyzes its intensity at 46 kts. The 12:30Z ADT gives an intensity of 47 kts.

The attached IR/upper level AMV and analyzed divergence plot shows the organized circulation, well defined outflow and divergence:

The attached MIMIC animation shows some of the convection organizing to its south as it is trying to develop an eyewall:

The shear over the center is still pretty low (around 5kts) although the surrounding shear is still fairly large (nearly 30 to 40 kts to the southwest).

So what about the future? JTWC has it intensifying by 10 kts every 12 hours or so, with intensities of 120 kts by 12Z on the 19th.

In terms of track, the models are in reasonable agreement, bringing 19W to the northwest close to Taiwan by 00Z on the 29th. JTWC has it to the southeast of Taiwan at that time: closer to the Met Office and NOGAPS solution. The GFS and ECMWF have it much closer to Taiwan.

Over the long term, the ECMWF brings 19W into the Chinese mainland as it moves westward. It also develops TCS048 over the long term, bringing along a similar track as 19W. It’s done fairly well with these genesis cases, so it is worth watching.

The ECMWF ensemble probability predicts strong vorticity along its deterministic track to be quite likely. It is a little less certain over the long range.

Links:

ECMWF, Met Office, NOGAPS, GFS 850 hpa vorticity.

ECMWF 850 vorticity probabilities.

The following two images suggest that TCS047 has sustained winds near 25 kts:

Surface observations and IR Image for TCS047. The ship VNVR is reporting a wind speed of 25kts

Quikscat Analysis and IR images for TCS047. The analysis shows a clear surface circulation

The divergence is fairly strong over some of the larger convective areas, although it hasn’t yet developed an anticyclonic flow aloft:

Although the shear is strong around the storm, it has weakened a great deal over the storm center:

What is driving this development? Well, TCS047 has been under the influence of a weak upper-level low to its north. In the attached animation of upper-level AMVs you can see the weak low travel slowly northwest, perhaps allowing TCS047 better outflow and development. In this animation, 47 is at about 10N 140E:

22SEP2008-upperwinds_anim.gif

And what about the model forecasts:

In terms of track, the models are remarkably similar, even through 120 hours.

The GFS and ECMWF bring this, by then, well developed storm just to the east of Taiwan.

The Met Office model and the NOGAPS bring it farther south, with the Met Office model a bit to the west.

All of the major models have some form of intensification.

What’s going on in the upper-levels?

The ECMWF 200 hPa forecast quickly (00Z on the 25th) erodes the upper level low and develops anticylonic flow over TCS047 as it tracks northwestward, steered by an upper level anticyclone to the west. It eventually stalls it out as this ridge moves out to the east. Hopefully this will remain around long enough for some interesting flights.

The 12Z EC run is very different than the 00Z run. The 00Z run had TCS043 develop and then recurve and shear out. The 12Z run has TCS043 developing, and then turning directly west towards Taiwan.

It seems to be coming in line in track with some of the other models. It will be worth watching as the ECWMF has been very consistent throughout this experiment.

TCS047 is the next TCS invest of interest.

Attached is the 12Z IR image, Scatt data and surface observations available nearby:

IR Image, surface, ship, buoy reports, Scatt data and low-level AMVs for potentially developing system TCS047.

TCS047 is not very well developed or organized. Most of the surface winds above are easterly, although there are hints of southwest winds from the scatt images and a few ship reports.

Although there is some weak divergence aloft and a low level vorticity center. It’s just to the south of an upper low, and that may be causing the shear surrounding the invest. The shear is fairly weak over the invest center, but it is quite strong to the west and north.

See the attached divergence image, and vorticity/shear image:

Upper level divergence and AMVS (top) and deep shear and low-level vorticity (bottom). AMVs and analyses are valid 16Z on 22 September. The IR images are valid at 11 Z.

Of course the big question is when and if this system will develop.

The Met Office model weakens it through 00Z on the 24th and then slowly strengthens it, moving it to the northwest at about 18N 130E by 00Z on the 27th.

The ECMWF model analyzes the storm fairly well. It’s 12 hour forecast matches pretty well with the cloud pattern seen above. It develops this storm over the next few hours and begins to recurve it by around 12Z on the 26nd. By the end of the forecast period: October 02, the ECMWF has a very sheared system located to the south of Japan.

The GFS doesn’t really develop it at all past the short term. As it moves it north and west it kills it off, merging it with some other convective elements up near the Phillipeans. The 12Z run seems to be developing it a bit more actually.  The convection seems a bit more organized. Is this a trend?

It seems there are some differences in the long term shear. See the 00z run here and the 12z shear/850 vorticity here. Look at the forecasts at 00Z on the 26th. The 12Z has a more organized system that is farther to the west than the 00Z run. It’s also under an area of lower shear. Perhaps this is encouraging it’s development.

The NOGAPS that never made it a disturbance it didn’t like, develops it steadily throughout the forecast period and brings it up east of the Phillipeans by 00Z on the 28th.

Taking a quick look at the upper levels in the two models as shown here implies that the 12Z forecaster has a weaker upper level jet, perhaps contributing to the weaker easterly flow.