Akash and Gonu thread

[somethingfunny]

Whoa, that's a beast of a cyclone! I've never witnessed an Arabian Sea cyclone nearing Oman so the next few days will be fascinating from our observers' POV.....but it's going to rain like the days of Noah over the Arabian Peninsula, isn't it? What's the average yearly rainfall in that part of the world?

[wxmann_91]

No problem...

I posted the link to the website on storm2k early today.

Guess I missed it... oops.

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North Indian Ocean Basin is not quite active, but it produces some very strong hurricanes that have killed many in South Asia. Indian Ocean tropical cyclones were not monitored as much. I would not be surprised that a Cat. 3 tropical cyclone has formed in the Arabian Sea more often, but went unrecorded. I notice Gonu might make landfall as a tropical cyclone or equivalent as a Category 1 hurricane on Oman. I wonder if an Indian Ocean tropical cyclone has made landfall on the Arabian Peninsula before as a hurricane of Category 1 or greater. I know the dry air kills it.

The reason that the Arabian Sea is usually very quiet (though I agree that there almost certainly has been other major TC's in that area that aren't recorded), is b/c of the geography and climate. The dry monsoon in the winter kills all convection. The wet monsoon in the summer enhances convection that faces 70-80 kt of shear. Only during the spring and fall, can storms form. And even during that time, there can still be sig. shear. In this case, there is significant shear to the north, to the south (from the monsoonal trough), and it just so happens it is in a sweet spot that isn't sheared but is enhanced by the shear, which increases outflow, as Derek mentioned.

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Raw T numbers indicate that GONU may be closer to 130knots. It certainly has that look to it. I would think that as it gets closer to Oman, it will weaken because precipitable waters are pretty low close to the coast (30-35mm) as the airmass is more characteristic of continental desert. As dry low level air gets drawn into the core of the Gonu, it will really weaken quickly.

Also, the JTWC track is quite a bit farther N than the GFS or ECMWF guidance as both models have a ridge building to the N that will turn Gonu more toward the W. Both indicate a landfall further S which will keep the cyclone over higher ocean heat content. If this more southerly track verifies, this may offset some of the dry air that will work into the core, and Oman could be looking at a significant cyclone striking the coast, but from my brief glance at Google Earth, the coastline seems very sparsely populated. Still, a very unusual event for this part of the world.

Current trends indicate a more northerly movement. I really don't trust in the GFS or ECM. The GFS is not initializing this well, and is keeping this storm fairly weak, thus a more southern track. I haven't seen the ECM initialization though, however, it does show landfall just to the south of where JT shows it. But it is important to note that most of the major global models, excluding the ECM, dissipated the storm initially. The lack of data inputed from this area does hurt model performance somewhat. I guess we'll see what happens. Agree that this will start weakening rapidly in about 36 hr as it nears the Arabian Peninsula.

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Whoa, that's a beast of a cyclone! I've never witnessed an Arabian Sea cyclone nearing Oman so the next few days will be fascinating from our observers' POV.....but it's going to rain like the days of Noah over the Arabian Peninsula, isn't it? What's the average yearly rainfall in that part of the world?

According to Wikipedia, the coasts average about 20 to 100mm of rain per year.

[btangy]

What's the average yearly rainfall in that part of the world?

For Muscat (N Oman), the average June rainfall is 0.6mm (.02in)
For Salalah (S Oman), the average June rainfall is 8.1mm (.32in)

Any way you slice it, just plain arid, so Gonu has the potential to give them way more than their mean yearly rainfall (100-130mm).

(Source: WMO)

[wxmann_91]

What's the average yearly rainfall in that part of the world?

For Muscat (N Oman), the average June rainfall is 0.6mm (.02in)
For Salalah (S Oman), the average June rainfall is 8.1mm (.32in)

Any way you slice it, just plain arid, so Gonu has the potential to give them way more than their mean yearly rainfall.

(Source: WMO)

That's average June rainfall, not average yearly rainfall.

Beautiful storm:

[wxmann_91]

The latest SSMI data does not look impressive at all, with a precip-filled eye. Interesting...

Also, the latest PW loop from the site on the last page, shows some very dry air advecting southward, and has already nearly reached the Gulf of Oman. If that dry air gets even close to Gonu, Gonu will be shredded.

[btangy]

Current trends indicate a more northerly movement. I really don't trust in the GFS or ECM. The GFS is not initializing this well, and is keeping this storm fairly weak, thus a more southern track. I haven't seen the ECM initialization though, however, it does show landfall just to the south of where JT shows it. But it is important to note that most of the major global models, excluding the ECM, dissipated the storm initially. The lack of data inputed from this area does hurt model performance somewhat.

I do agree that the lack of observations hurts the model performance greatly in this region. However, the overall synoptic pattern can be revealing. I've uploaded an image courtesy Plymouth State's interface of the forecasted 500mb heights at 12Z Wed 6/6 around the time Gonu is forecasted to make landfall from the 6/3 12Z run of the ECMWF (color-filled contours) and the 6/4 00Z run of the GFS (white contours): http://web.mit.edu/btangy/Public/GonuECMWFGFS.gif . Both models are in good agreement with the 500mb pattern showing a 589dm ridge to the ENE of Gonu and a 590-591dm ridge to the W of Gonu with a weakness to the N of Gonu. Just like many examples in the Atlantic that we have and will fuss over, the question is if the weakness is strong enough to pull Gonu further N. Arguments for this include what you've mentioned, i.e. that Gonu is much stronger than the models indicate and is being steered by a deeper layer flow which will impart more of a poleward motion (NOGAPS and GFDN guidance). However, note that heights are still projected to be 587-588dm N of Gonu which are quite high. Also, the trough to the N is quite flat and has nearly passed the longitude of Gonu. Both of these argue for a more southerly track, and I would hedge in this direction as the ridging to the N doesn't appear to be consistent with Gonu maintaining the NW-ly motion all the way to the coast. Rather, a turn more toward the W/WNW is, in my opinion, more consistent (ECMWF and GFS guidance).

Oftentimes, the JTWC takes the consensus of the models as their official track, but when the distribution is bi-modal like it is with Gonu, the consensus has a very low probability of verifying.

[Chacor]

04/0230 UTC 18.9N 65.2E T6.5/6.5 GONU -- Arabian Sea

[Chacor]

Small system...

[HurricaneRobert]

It'll be a suprise when it hits. I can only find one article about Gonu through Google. No one's really paying attention, though I think the Cat1 landfall is very possible.

[wxmann_91]

Current trends indicate a more northerly movement. I really don't trust in the GFS or ECM. The GFS is not initializing this well, and is keeping this storm fairly weak, thus a more southern track. I haven't seen the ECM initialization though, however, it does show landfall just to the south of where JT shows it. But it is important to note that most of the major global models, excluding the ECM, dissipated the storm initially. The lack of data inputed from this area does hurt model performance somewhat.

I do agree that the lack of observations hurts the model performance greatly in this region. However, the overall synoptic pattern can be revealing. I've uploaded an image courtesy Plymouth State's interface of the forecasted 500mb heights at 12Z Wed 6/6 around the time Gonu is forecasted to make landfall from the 6/3 12Z run of the ECMWF (color-filled contours) and the 6/4 00Z run of the GFS (white contours): http://web.mit.edu/btangy/Public/GonuECMWFGFS.gif . Both models are in good agreement with the 500mb pattern showing a 589dm ridge to the ENE of Gonu and a 590-591dm ridge to the W of Gonu with a weakness to the N of Gonu. Just like many examples in the Atlantic that we have and will fuss over, the question is if the weakness is strong enough to pull Gonu further N. Arguments for this include what you've mentioned, i.e. that Gonu is much stronger than the models indicate and is being steered by a deeper layer flow which will impart more of a poleward motion (NOGAPS and GFDN guidance). However, note that heights are still projected to be 587-588dm N of Gonu which are quite high. Also, the trough to the N is quite flat and has nearly passed the longitude of Gonu. Both of these argue for a more southerly track, and I would hedge in this direction as the ridging to the N doesn't appear to be consistent with Gonu maintaining the NW-ly motion all the way to the coast. Rather, a turn more toward the W/WNW is, in my opinion, more consistent (ECMWF and GFS guidance).

Oftentimes, the JTWC takes the consensus of the models as their official track, but when the distribution is bi-modal like it is with Gonu, the consensus has a very low probability of verifying.

Baa, I forgot about Plymouth! That's a great map... thanks for posting it. I really haven't been looking at this in too much detail, so haven't really gotten into looking at what's going to steer it, wv loops, etc. Looks like steering patterns are going to be complicated with this one. Looking at the map, I'd agree with you - it's either going to go north or it's going to go west.

Great post!

[Cyclenall]

That's now one of the best looking tropical cyclone's of the 2007 year. I would peg it as a Super Cyclonic Storm by now. I also believe it's the equivalent of a category 5 hurricane right now going just by looks and no data. I'm not sure though on the last IR shot taken though.

[Chacor]

TROPICAL STORM “GONU” ADVISORY NO. FIFTEEN ISSUED AT 0500 UTC OF 4TH JUNE, 2007 BASED ON 0300 UTC CHARTS OF 4TH JUNE 2007. THE VERY SEVERE CYCLONIC STORM “GONU” OVER EASTCENTRAL AND ADJOINING WEST CENTRAL ARABIAN SEA LAY CENTRED AT 0300 UTC OF 4TH JUNE 2007 NEAR LAT. 18.50N AND LONG 65.00E, ABOUT 600 KMS NEARLY WEST OF DWARKA (42731).

CURRENT INTENSITY T5.0 RPT T5.0. SATELLITE IMAGERIES SHOW VISIBLE “EYE” WITH SOLID INTENSE TO VERY INTENSE CONVECTION ASSOCIATED WITH THE SYSTEM. ESTIMATED CENTRAL PRESSURE 960 HPA. MAXIMUM SURFACE SUSTAINED WIND SPEED 90-100 KTS.

FORECAST: THE SYSTEM IS LIKELY TO INTENSIFY FURTHER AND MOVE IN A NORTHWESTERLY DIRECTION. 24 HOURS FORECAST INTENSITY IS T6.0 RPT T6.0. SEA CONDITION WILL BE PHENOMENAL.

[HurricaneBill]

I notice Gonu might make landfall as a tropical cyclone or equivalent as a Category 1 hurricane on Oman. I wonder if an Indian Ocean tropical cyclone has made landfall on the Arabian Peninsula before as a hurricane of Category 1 or greater. I know the dry air kills it.

I was reading an article on Google that said that the Masirah Cyclone in June 1977 did. Although JTWC had the storm peaking at 60KT sustained winds, the article said Masirah Island received sustained winds of 90KT and gusts to 120KT. The island also received 431 mm of rain in 24 hours.

BTW, Masirah Island is located about 15 km off the eastern coast of Oman. The wind speeds of the 1977 cyclone were recorded at a weather station at an airport on the island.

The cyclone damaged 98% of the buildings on Masirah Island and also caused damage on the mainland of Oman. In all, 110 people were killed.

[Weatherfreak000]

Impressive...

[Scorpion]

Looks to have weakened significantly in the past few hours

[Chacor]

Looks to have weakened significantly in the past few hours

Uh... trying to make this sound as friendly as possible, what are you looking at? It's strengthened in the past few hours... and according to the IMD will strengthen further. T6.0 from AFWA, JTWC; T6.2 is the CIMSS 0430Z CI, and SAB has gone with T6.5...

[Cyclenall]

Looks to have weakened significantly in the past few hours

All I see is just a hint of dry air entering the cyclone. Hardly any change in strength if any.

Uh... trying to make this sound as friendly as possible, what are you looking at? It's strengthened in the past few hours... and according to the IMD will strengthen further. T6.0 from AFWA, JTWC; T6.2 is the CIMSS 0430Z CI, and SAB has gone with T6.5...

Agree.

[Typhoon Hunter]

My word this looks wonderful on satellite. Real stadium effect I bet in the eye!

Here's hoping the dry air protects Oman and reduces any potential damge from this beauty.

[wxmann_91]

The satellite presentation of this storm reminds me of Cimaron last year. Do you guys agree?










EDIT: 130 kt on NRL

[Matt-hurricanewatcher]

Looking at satellite it appears its close to "cat5" strength right now. Around 135-140 knots, this is one very powerful system.