A request from Nouska has reminded me to start up the annual thread for tropical weather.

Usually it's about the Atlantic in particular, but this years season is looking to be a quiet one, while the East Pacific looks to be active, so I figure a thread covering both those regions - and more - is warranted 

Currently, there's a system just east of Florida, and the models are really starting to see development of this into a tropical storm or even hurricane that runs up the East U.S. Coast or very close to it.

I'll have a look at it a bit more later if I find a spare moment 

I definitely think it will be a quiet season this year, even if an El Nino event doesn't develop Tropical Atlantic SST's are below average.

I reckon there will be an ACE value of 30-50 this year in the Atlantic, I thought last year would be very active but unusually low humdity and dry air off NE Brazil seriously hampered things. Cold winters in Southern Brazil, Argentina etc appears to coincide with an increase in dry air in this region. 2007 was a very good example of this also with a very strong La Nina and above average SSTs ACE was still limited to 72, the long term average is 96.

The Atlantic is interesting because it shows a response to increased SST's but this relationship is far from simple due to ENSO, dry air and Saharan rainfall.

Despite these complexities forecasts of ACE are pretty accurate and I'm pretty sure this year will be a quiet one, I find this area particularly interesting as it's what I studied for my undergrad dissertation.

Additionally I think the analogues for this year are 1972, 1982, 1991, 1994 and 2002. All of these years had below average hurricane activity in the Atlantic

Nice analysis there Yorkshirelad 

Looking at 91L (the potential tropical storm or hurricane), it's still drifting about just east of Florida, with little overall momentum to speak of.

According to the models, anything from a tropical depression to nearly a category 2 hurricane is possible:

http://derecho.math.uwm.edu/models/al912014_inten.png

A fair bit of dry air is close to the storm, restricting development somewhat. I guess that the higher-intensity forecasts see the storm managing to exploit quite low wind shear (5-10 knots) to wall-off the dry air with a central dense overcast (a tight cluster of very deep thunderstorms which can draw moisture from the sea surface - low wind shear needed for the vertical lifting to be effective).

Thanks, James.

Now confirmed as TD1 and looking much better with plenty of convection. A few 4th of July activities will have to be rescheduled and make do with a natural fireworks display. Track shifting slightly east and looking less likely to reach full hurricane status.

http://i.imgur.com/a0YNEsC.png

The Atlantic temperature anomalies are like what what we saw in cold PDO, definite horseshoe shape to it. I've only been looking at these charts for about ten years or so but have not seen such a pattern before. Is this in response to the frequent diving of troughs way down to the N. African coast?

http://imgur.com/O6Rd36K

Graphs from Tropical Tidbits.

http://i.imgur.com/gorZOvR.png

All things equal, I would agree with your comments about a quiet season but sometimes weather never works as anticipated.

Yeah, I think the unusual storm behaviour over the winter (intense jet and frequent storms yet still tracking well south of normal) had a large role in the current SST anomaly pattern.

http://www.ssd.noaa.gov/PS/TROP/floaters/01L/imagery/vis-animated.gif

Arthur could be a real troublemaker - the structure on the northern side has improved massively over the past 6 hours, and this is acting to wall off the dry air that was causing issues. The low level circulation appears to be drifting south to mee the mid-level circulation as it edges NW... that's bad news as it means the storm could become vertically stacked very soon.

Recon is in the storm as I type, and has found evidence of an eyewall developing.

In the worst case scenario, that eyewall wraps around the low level circualtion just as alignment with the mid-level circulation occurs. Then, with low wind shear and warm SSTs that aren't being depleted due to the Gulf Stream feeding more in from the south, there won't be much to stop Arthur from bombing out into a notable hurricane.

In short, something historical is possible over the next 24 hours. It's far from certain though - I've seen many a storm suffer sudden hiccups as a slice of dry air manages to cut through the outer bands and strike at the core.

The official NHC foreast doesn't feature such dramatic events, as it figured the dry air would continue to interfere over the next few days, slowing development. That could still happen, but recent developments have sown some seeds of doubt.

Dry air is still interfering with Arthur's development, but offset this with an improving environment and Arthur should become the first Atlantic hurricane as he approaches the Carolina coast Friday.
Not forecast to be stronger than a borderline Cat 2 at this stage but the first storms of the season always seem to kick-up some dust as it were.

http://radblast.wunderground.com/cgi-bin/radar/WUNIDS_map?station=JAX&brand=wui&num=10&delay=15&type=L20&frame=0&scale=0.46956521739130436&noclutter=0&showstorms=0&mapx=400&mapy=240&centerx=214.72222222222217&centery=225.09259259259255&transx=-185.27777777777783&transy=-14.907407407407447&showlabels=1&severe=0&rainsnow=0&lightning=Hide&smooth=0&rand=23405682&lat=0&lon=0&label=you

Hanging around so close to the East Florida Coast, Arthur has been captured nicely by radar throughout his lifetime to date. 

The most recent development of note is that of the band on the north side of the storm. This area had been relatively lacking in convection until quite recently, but now Arthur is finally gaining the sort of highly symmetrical appearance that suggests a well stacked (low and mid-levels more or less aligned on top of one another) and intensifying hurricane.

The storm also seems to be drifting west a bit, which is of great concern to those along the East Coast (or at least should be - some of the media coverage has been a bit lacking in places), particularly around Maine, for example. The model projections have also trended west a bit. 

Something like this could occur:

http://www.tropicaltidbits.com/analysis/models/hwrf/2014070218/hwrf_mslp_uv850_01L_12.png

Which would be unpleasant to say the least.

http://i201.photobucket.com/albums/aa102/boyohio02/TropStormArthur1-7-03-14-0400.gif

After battling with another dry air incursion overnight - that being the one restraint I pointed out that could hold him back - Arthur has taken huge steps in the past hour or so; deep convection has wrapped right around the eye, the wall looks strong and there are hints of a smaller eye developing in the final few frames of the animation.

As Arthur tracks almost due north and then NNE, the most probable path tracks the Gulf Stream rather well, which is bad news for East Coast residents (particularly northward of around South Carolina as things currently stand), as that means the storm may continue to intensify until close to landfall (should landfall occur in the first place - probable but not certain).

http://www.dailymail.co.uk/news/article-2678897/Brooklyn-Bridge-damaged-parts-New-York-flooded-nasty-storm-ahead-hurricane-expected-wreak-havoc-East-Coasters-Fourth-July-festivities.html

Its all kicking off on the US east coast Lucky buggers.

Whatever the rest of the season brings, the first of the Atlantic basin is an impressive system.

I think the Fail is a bit out of date with the offshore statement - midday models trending westward with a bit more of NC coast under the eye.

Don't know if we are allowed pics in here so I'll jut post a wee thumbnail with the link to a full size saved satellite image.

http://i.imgur.com/BLGa2ZQ.jpg

A glancing blow for North Carolina in the end, from a hurricane with maximum sustained winds of 100mph - but these being on the eastern side, meaning largely over the ocean in this case, as the storm tracked across the eastern fringes of the state.

A number of wildlife reserves will have had a bit of a blast through the night, but reports suggest that damage isn't too bad really.

Arthur has since turned east somewhat, and at the moment is tracking further out into the Atlantic, away from the land:

http://radblast.wunderground.com/cgi-bin/radar/WUNIDS_map?station=MHX&brand=wui&num=40&delay=15&type=N0R&frame=0&scale=0.500&noclutter=0&lat=0&lon=0&label=you&showstorms=5&map.x=400&map.y=240&centerx=179&centery=470&transx=-221&transy=230&showlabels=1&severe=0&rainsnow=1&lightning=1&smooth=1

There are weather warning for parts of the Philippines as a typhoon the first proper one this season with wind speeds up to 112 mph arrives.

We are working in Palawan and there is just cloud with rain and no wind to speak of which is typical for this island province  when a typhoon hits other parts. PAGASA give typhoons and tropical storms a local name as well as the international one which can be a tad confusing.

Nick

Thanks for your report Nick 

I was keeping an eye on the storm last night, and saw a minimal typhoon nearing landfall. This morning, I was met by images of a storm with an impressive eye and central structure, which appeared to be intensifying rapidly 

It has since made landfall as a Category 3 typhoon with 125mph winds. The storm's central pressure reportedly fell 20mb in just 3 hours prior to landfall... just imagine what it could have become without land interaction to disrupt it! 

I see that while JMA call it 'Rammasun' (Thunder God), the PAGASA call it 'Glenda'... curious that they do this.

It is interesting that they give it a local name. I suppose one could argue that instead of getting an average of 20 typhoons a year you have 40.

Where we are in Palawan there is virtually no wind just light airs with occasionally heavy rain from the south west monsoon. Pleasantly cool this morning with temps this morning about 23.8C and humidity of 70%. A contrast to the later part of the dry season when night time temps rarely fall below 28C and daytime highs are in the low to mid thirties.

PAGASA is under attack like the UK met Office for poor forecasts or no warnings. One reason is the lack of experienced forecasters with several moving to other countries (Middle East) because of poor pay in the Philippines.

It also apparently relies on a Chinese satellite for up to date images and although it might just be a coincidence, these images are not always available on the PAGASA site especially when you want to know the position of a shower or spell of rain. Some call it a kind of cold war because of the South China Sea situation…

Nick

Typhoons Ramasun and Matmo causing problems in the Pacific around Taiwan and the Philippines, but mostly because of heavy rainfall, not high winds. 

Suggestion of some development in the Atlantic just off W Africa, but may not come to much as there's a lot of dry air around

http://www.weather.com/news/tropical-update-atlantic-pacific-hurricane-season-20140513

I've been watching hurricanes for a while, I use wunderground tropical because their quality is very good. Can someone explain this:

http://www.wunderground.com/hurricane/atlantic/2014/Invest-92L?map=sat

Invest 92L has not been catogarised but it has a clearly visible eye, surely it deserves to be a tropical depression at the very least? 

There's a tropical thread for this you know... moving promptly.

Edit: Quantum's post and Arcus' informative reply have now been added into this thread 

http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=2732

"Morning VIS imagery shows a well defined low level closed circulation has formed about 1,200 NM east of the CARIB near 11.6N / 42.6W and is westbound (280ᵒ) at 20Kts – and is now being carried by NHC as INVEST 92L."

- it appears there is indeed a circulation, but an apparent 'eye' can sometimes be an illusion created by a dry air pocket, and this may be the case with what Quantum saw earlier.

"Global models still have not resolved this system, but after manual initialization by NHC, Early Track and Intensity model forecasts call for the system to become a Depression today and possibly reach Tropical Storm intensity during the next 48-72 hours once the system moves over waters that are warm enough to support storm formation."

- the system is so small that the global models simply don't see it. This does happen from time to time. Good thing is, a system of such tiny influence isn't going to impact the broad scale progression of events around it, so the global models are as valid as always for everywhere away from the invest itself.

Meanwhile in the Pacific...

MATMO (always given in capitals for some reason) has achieved category 1 intensity and appears to be headed for category 2 or 3 prior to landfall inTaiwan. 

The official forecast track looks like this:

http://icons.wxug.com/hurricane/chrisburt/MATMO-OFC-TRACK-3.jpg

Looks like two landfalls on the cards. The major city of Shanghai might see a miserable day out of it, with winds gusting to around 60mph and large rainfall amounts.

Sorry :S I tend to miss them especially if they are stickied.

Invest 93-L given a serious chance of development as it nears the Antilles this week

http://www.weather.com/news/tropical-update-atlantic-pacific-hurricane-season-20140513

Tropical storm Bertha now named

http://www.weather.com/weather/hurricanecentral/tracker

but not a storm predicted to be of any great consequence

http://www.ssd.noaa.gov/PS/TROP/floaters/03L/imagery/ft_lalo-animated.gif

Bertha's trying to ramp up a bit at the moment, but the emphasis is on 'trying'; the low level circulation isn't quite aligned with the deep convection at the moment.

If it does align, a moderate to strong tropical storm might manifest in the next 24-48 hours.

Otherwise, it'll be a good rainbringer for some of the Caribbean Islands that have been seeing anomalously dry conditions lately.

Meanwhile in the Pacific:

http://web.pagasa.dost.gov.ph/weather/daily-weather-forecast

Another typhoon Halong with local name Bagyong Juan to confuse everyone is poised to arrive in the Philippines next week perhaps. Weather forecasts here can be hit and miss that makes the UK Met Office a star performer.

Forecast:  Metro Manila, Central Luzon, Ilocos Region CALABARZON and MIMAROPA will experience occasional rains. The rest of the country will be partly cloudy to cloudy with isolated rainshowers or thunderstorms. Moderate to strong winds blowing from the southwest will prevail throughout the entire archipelago and the coastal waters will be moderate to rough.

And there you have the forecast for the whole of this huge archipelago. Today has been calm or with light airs from the SW and mainly cloudy with a heavy shower around midday and a high of about 29C and a low of 25C.  

We are supposed to be flying tomorrow. Just hope Halong stays out over the ocean.

Nick.