CIMSS TPARC Support Blog

Attached is an IR animation for TCS043:

Taking a look at a two day animation (focus on TCS043 at about 15N 142E) you can see dirunal variation, as TCS043 strengthens around 12Z (22:00 Guam time) and weakens around 00Z (10 am Guam time). The short animation above is from 10Z - 15Z: near the convective maximum.

At this point, however, shear is the primary factor influencing TCS043:

The above plots show the shear (top) and divergence (bottom) over TCS043. The shear is consitently pushing the convection south. You can see this with the IR images, and with the location of maximum divergence. It’s unlikely to develop while under such strong shear.

The models are in two camps with this invest. The NOGAPS and GFS model have TCS043 developing and then recurving around (NOGAPS) and past (GFS) 140 E longitude. The 12Z ECWMF still has TCS043 moving west and interacting with the monsoon near the Philippians. Unlike the previous run, this run suggest hints of recurvature towards the end of the forecast period. The Met Office model, always the most reluctant developer, brings TCS043 westward and has a weaker interaction with that Phillipean convection.

The key to the recurve/no recurve difference seems to stem from a trough coming off of the China coast from the 20th-21st. The models with a deeper trough seem to be recurving the storm. The models without it seem to allow TCS043 to progress westward. We’ll have to keep an eye on this track difference in future runs.

An overview of the T-PARC domain on 13Z, Sept. 16, 2008:

MTSAT Upper level AMVs and Water-Vapor image valid 13Z, September 16th, 2008

T-PARC’s primary focuses are TCS043 and Tropical Storm Sinlaku. Sinlaku is forecast to move Northeast and begin extra-tropical transition. TCS043 has the potential to develop into another depression, although the models disagree on this. The next two posts will focus on these individual systems.

As of 12Zm September 12th, JTWC has Sinlaku near 23.7N 123.6E. It was moving 310 degrees at 5 kts

with max sustained winds of 100 kts and gusts of 125.

IR image, upper-level AMVs and JTWC track for Typhoon Sinlaku. Valid 13Z, September 12, 2008.

The above image shows Sinlaku’s solid outflow, reasonably well defined and large eye, and slightly assymetric circulation. Dry air to Sinlaku’s west may be hindering it’s outflow to that direction. It is still under fairly low shear, although there are some 20kt shear zones in the northern edges of Sinlaku.

The forecast:

The models are still uncertain about when/if Sinlaku will recurve.

The NOGAPS model that had been the least progressive, is still mostly moving Sinlaku to the northwest. By the end of the forecast cycle, however, there is a hint of Sinlaku moving northeast. It is no longer bringing Sinlaku back down across Taiwan.

The GFS forecast brings the recurvature at T+72 hours (00Z on the 15th) and then brings a slightly weakened Sinlaku into Japan by 00Z on the 17th.

The ECMWF model, which has far been the most progressive in the recurvature, is a bit to the east and north of the GFS in it’s track across Taiwan. Then, it begins the recurvature a little bit earlier, turning it to the east by 12Z on the 14th. It then bring it across the east coast of Japan: a bit to the east of the GFS.

The Met Office Global model once again sits in between the NOGAPS camp and the EC/GFS camp. It slowly moves Sinlaku up across Taiwan and then into China, but begins the recurvature much earlier than the NOGAPS by +96 (00Z on the 16th). It then moves Sinlaku much more slowly to the northeast barely bringing Sinlaku across the China coast by +120 (00Z on the 17th).

These models seem to vary when they interact with the mid-latitude westerlies. When does the ridge to the north of Sinlaku break down? Examining how observations influence the model and its subsequent track will be of interest.

Sinlaku is still an intense typhoon, but has weakened slightly. According to JTWC, as of 12Z on Sept. 11th, Sinlaku, at 22N, 124.8E has max sustained winds of 120 kts with gust up to 145 kts, which is down from about 125 kts at 18Z yesterday. This could be some diurnal fluctuation. It also looks like Sinlaku is going through secondary eyewall formation, as shown in the Mimic microwave animation below:

MIMIC microwave animation for Typhoon Sinlaku. Sinlaku develops a solid secondary eyewall and it's inner eyewall appears to collapse a bit. It does not seem to dissapear totally by the end of the animation.

Sinlaku is forecasted to intensify to about 130 kts by 00Z on the 12th, maintain that intensity until 00Z on the 13th, and then weaken. Sinlaku still has a clear, well defined eye, strong outflow to the northeast, large upper-level divergence, and a well defined, fairly symmetric rotation as seen by the IR/upper level AMV animation included below:

MTSAT IR Image an upper-level AMVs for Typhoon Sinlaku. AMVs Valid 13Z September, 11, 2008.

There was some mention yesterday about drier air working its way into Sinlaku, but this does not seem to have made a huge impact. As mentioned in the JTWC discussion, there has been some resctriction of outflow to the northwest, but this also appears to be waning. Sinlaku is in a region of low shear (5kts) although it is surrounded by high shear on all sides.

Its track is still in question. JTWC still has it creeping slowly to the northwest before moving out to the east, but the timing of this re-curvature is still uncertain. Sinlaku is surrounded by a ridge on each side countering each other’s flow. The interactions with these ridges and the trough to Sinlaku’s north will determine it’s future track. If it does reach that flow, it will move east-northeastward. The timing of that turn is not well resolved by the models.

Quick overview of the models:

GFS: Moves Sinlaku slowly northwest across Taiwan until the 16th. Then slowly begins drifting it northeast after it makes landfall on China coast.

NOGAPS: From now through  Sept. 17, the Sinlaku essentially spins in place around Taiwan. Not good for Taiwan at all.

Met Office: Similar to the GFS. It moves slowly north/northwestward with a hint of westward motion by the end of the forecast period.

ECMWF:   This is the most progressive of the models. It brings Sinlaku through Taiwan, then brings it westward by the 15th of September (+96). In the long-range, it misses Japan entirely, unlike previous forecasts.

This one is a challenge.

Plans to investigate TCS037 fizzled. There was some debate this morning, and at the map discussion last night about investigating TCS035 as an alternative. As of right now, neither of these systems is being flown.

Below is a large-scale water-vapor image, with upper-level AMVs plotted above. The two systems of interest are annotated.

MTSAT WV Image and upper-level AMVs annotated with T-PARC invests. The image and AMVs are valid 12Z, September 5, 2008.

Attached as well are close-up satellite images of TCS037 and TCS035. TCS035 has divergence plotted above.

MTSAT IR image and analyzed upper-level divergence valid 13Z, September 05, 2008. Although the divergence for this system is large, a low level circulation hasn't really developed.

IR image and analyzed deep-layer shear for TCS037. Valid 14Z Sept. 05, 2008. This system hasn't held together particularly well over the last few hours. This strong westerly shear seems particularly hard on it.

The ECWMF model’s 850 vorticity, linked here has TCS037 analyzed fairly well in terms of position. TCS035, in terms of vorticity, is not particularly strong in the model or in the observations. The model does intensify 037 and over the very long term brings it directly into Japan.

The EC doesn’t really develop TCS035, but it does hint at something developing near the Philapeans in the long term.

The Met Office model does something similar with TCS037, although it seems to keep it slightly weaker. It, however, doesn’t really analyze TCS037 at all. TCS037 seems like a better bet in the long run, particularly if it intensifies and moves near Japan. We’ll have to keep an eye on the track and see how it changes in the next few days as well. If TCS035 does develop a low-level circulation, it will be worth watching as well.

As nothing is particularly imminent, I’ll do a brief map discussion.

Upper level AMVs and MTSAT IR Image. TCS invests are annotated. Valid 13z 27 Aug, 2008

In this image, you can see the three T-PARC invests and Tropical Depression 14W. TCS025 has been the focus of the experiment for the past few days. It’s currently pretty close to Guam and is predicted to strengthen a bit and potentially threaten Japan over the next few days.

Comparing this analysis with the GFS 12-hour forecast (initialized from the 00 UTC run):

Annotated 12-hour GFS forecast of 850 hPa vorticity and streamlines.

One can see that the GFS forecast has most of the general features. TD 14W is placed fairly well within the model.  TCS027 is analyzed a bit too far south as compared to the satellite image. TCS025 and TCS028 are fairly well represented here in the forecast.

The GFS is continuing to develop this system over the next day or so before sending it off northwestward and weakening it. The GFS also brings the remnants of TD14 up along the China coast and eventually merging with a midlatitude disturbance near Japan. The model has been consistent with the development of TCS025, but not with its future track and landfall. Japan looks like the place to watch over the weekend.

You can see this 00z run of the GFS here.