Hurricane Season 2015 #1: Orkanen & cyclonen wereldwijd

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Op maandag 10 augustus 2015 08:14 schreef aloa het volgende:
Hilda op weg naar Hawaï.

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David vs. Goliath? 96L fights the El Niño factor
As of 2:00 pm EDT Monday, Invest 96L was located near 10°N and 31°W, moving west at about 10 mph. Located along a broad monsoon trough that coincides with the Intertropical Convergence Zone, 96L remains only loosely organized, with a large but unconsolidated area of showers and thunderstorms. Vertical wind shear is light (less than 10 knots), and 96L will encounter warmer sea-surface temperatures as it moves west-northwest (up to 28°C, or 82°F, by later this week), so the large-scale conditions favor gradual strengthening. The National Hurricane Center has been increasing the odds that 96L will develop: in its 8:00 am and 2:00 pm EDT updates, NHC gave the system a 50% chance of becoming a tropical depression in the next 48 hours and a 70% chance over the next 5 days. The RAMMB/CIRA Tropical Genesis Index is also maintaining high odds for development. Among the favored models for intensity, the 1200 GMT Monday runs of the statistics-based LGEM and SHIPS models, which rely heavily on climatology, bring 96L to Category 2 strength by Thursday. The dynamics-based HWRF and GFDL models, which simulate tropical systems within nested high-resolution grids, diverge on the future of 96L. The HWRF develops 96L into a Category 1 hurricane by Thursday, while the GFDL fails to develop 96L significantly. As we discussed in last week’s post on tropical cyclone modeling, HWRF features a dramatic increase in resolution this year, so it will be interesting to see if it correctly pegs the fate of 96L.

While it seems that 96L has a reasonable shot at becoming a tropical storm (which would be named Danny), it also faces some obstacles. Foremost is a huge area of dry air and Saharan dust that extends across the tropical Atlantic just north of 96L's path. As the system grows in size and strength, it would become more likely to ingest some of the dry, dusty air, which would hinder shower and thunderstorm activity. 96L may also encounter an increasing amount of vertical wind shear as it approaches the longitude of the Leeward and Windward Islands this weekend, assuming it survives up to that point. Over the northern Caribbean, shear has actually lessened from the near-record values observed earlier this summer, although shear values of 20 to 40 knots continue to prevail across the southern Caribbean. The ever-strengthening El Niño favors westerly wind at upper levels across this region, though it's possible that the relative lull in shear over the northern Caribbean will continue as 96L approaches. A weak upper-level low is forecast to become pinched off near the Bahamas, south of a building ridge over the northwest Atlantic; this low could become a growing influence on 96L's track and intensity as it moves west of longitude 60°W.

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Lichte aardbeving treft Bay area

De Bay Area nabij de Californische stad San Francisco is gisteren door een aardbeving getroffen. Dat hebben het Amerikaanse Geofysisch Instituut USGS en het Europese aardbevingscentrum EMSC gemeld.
Volgens het USGS deed de beving met magnitude 4,0 zich voor om 15.19 uur Belgische tijd op 1 km van het Californische Piedmont. Het epicentrum bevond zich op 5,4 km diepte, volgens het EMSC 18 km ten noordoosten van San Francisco.

Luidens de krant San Francisco Chronicle is de beving in die stad, in Oakland en verder landinwaarts van de Bay Area gevoeld.

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Eastern Atlantic / Africa

There are more systems in the pipeline, coming off of Africa.

NHC is already highlighting the western one and has upped the probability of becoming at least a tropical depression within the next five days.

If this observation from earlier this afternoon is correct, there's already a northwest wind around that side of the disturbance, meaning it has or is getting close to having a "closed" (fully circular) surface circulation already, and models predict that if it doesn't yet, it will soon.

And then latest model runs are consistent in showing it taking a track next week not too far from Danny's.

The one after that will come off the African coast this weekend, and looks to be healthy and have some chance to further develop too. Models are vacillating between a quickly out-to-sea track and one farther west.

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Op dinsdag 25 augustus 2015 12:02 schreef aloa het volgende:
EC brengt Erika dicht bij de oostkust.
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Op dinsdag 25 augustus 2015 12:14 schreef aloa het volgende:

[..]

Klopt! Het is nu nog wel het enige model wat het laat zien.

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00z run of the ECMWF is very concerning. It agrees with the HWRF and has a Category 4 hurricane off the SE Coast.

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Ignacio may threaten Hawaii early next week

Residents of Hawaii need to keep close tabs on Hurricane Ignacio, which was packing top sustained winds of 90 mph as of 5:00 pm HST (11:00 pm EDT) Thursday. Now located just under 1000 miles east-southeast of Hilo, Ignacio is on a fairly straightforward west-northwest course that should continue over the next several days. Simply extrapolating Ignacio’s track would bring the hurricane very close to Hawaii by Monday or Tuesday. Hurricanes on such a course typically weaken before they reach the islands, traveling over surface waters near the threshold for tropical development of around 26°C (79°F). In this case, Ignacio is getting a boost from favorable upper-level conditions as well as unusually warm sea-surface temperatures, roughly 2°C (3.8°F) above average for this time of year. NHC intensifies Ignacio to just short of Category 3 strength by this weekend, then gradually weakens it starting on Monday. The official forecast calls for Hurricane Ignacio to pass about 100 miles north of Hilo on Tuesday as a Category 1 storm with sustained winds of 80 - 90 mph. No hurricane has ever been officially recorded on the Big Island of Hawaii--the strongest event on record was Tropical Storm Iselle in 2014--so today’s forecast is noteworthy in itself. Beyond the five-day period, models are tending to bend Ignacio’s track slightly leftward, as upper-level ridging strengths to the north. The predicted steering currents and the very warm SSTs make Ignacio a force to be reckoned with, and all of the Hawaiian islands should take this hurricane seriously. Large swells will become a near-certainty over the next few days.