ATL: DANNY - Remnants - Discussion

[gigabite]

The block dot is a relative position of the moon to give the image perspective. The tidal effect of the on the system is weakening as the latitude moves further south of the system and as the strength of the alignment with the Sun and other 1% bodies fades.

[SouthDadeFish]

Gigabite, how can you distinguish any possible tidal effects from other commonly used environmental controls such as vertical wind shear, thermodynamic instability, etc... ? One could easily argue you are displaying the diurnal cycle of convection or the effects of dry air entrainment.

[CrazyC83]

I'm thinking it goes up to 70/70 at next update.

[beoumont]

gigabite"
This is the location of the moon at 15:15 utc 08/16/15.
Historically a New Moon pass under the an invest within 10 degrees of latitude is generally followed by some tropical development.
Tomorrows pass will fit this criteria also.
Tomorrow is the last day of the New Moon phase & the last day of this data set for this month.

The following URL leads to the only moon phase vs tropical cyclone genesis study I have ever seen (and it shows a tendency for development on new and full moon.) Please, Gigabite, enclose a link to the other study you are referring to; and do explain your statement " New Moon pass under the an invest within 10 degrees of latitude" . How does one assign an earth latitude relative to the moon?

Observed Relations hips Bet ween 1 u nar Tidal Cycles
and Formation of Hurricanes and Tropical Storms’

http://docs.lib.noaa.gov/rescue/mwr/100/mwr-100-06-0451.pdf

* Thanks for the research paper.
* It is a nice searchable .pdf.
* You realize the paper predates the GOES weather satellite program, and no reference more recent than 1972.
* It is basically a frequency study of all tidal periods, and cyclone formation with out the aid of spread sheet analysis or study site selection capability.

The data Partagas used was gathered by him from a decade of arduous searching raw ship reports, ship logs, private journals from island folk, NWS records, and any other source he could find referring to the existence of a tropical system at sea (like wave periods, etc). With this data he completed a statistical study; not based on gravity, etc--although he might have been encouraged to begin his study because he had a hunch the "pull" of the moon has some atmospheric effect, and was one added factor for TS genesis. He did most of this in the 1960s and 1970s; so, of course his data came before then. I happened to sit across from him at the NHC library for several months in 1964, observing him gathering some of this data.

I recall Gil Clark had moon phases, plus apogee and perigee dates, posted on his wall behind his desk at the NHC---so I became a believer, and have noticed, in some years, that the new and full moon "coincided" with many of the TS formations that year. Other years, it doesn't seem to hold.

Most people on another forum (and this one, too, I, assume) are skeptical of the moon phase on TS genesis. Hence, I suggested one skeptical met student do his own statistical study. He did, and he was surprised that there is a statistical increase in TS geneses on new and full moons in the Atlantic Basin. But, it does not hold in the E. or W. Pacific at all. He used data from 1930 something through 2008.

[Gustywind]

Up to 60/80 %

000
ABNT20 KNHC 172323
TWOAT

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT MON AUG 17 2015

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

Showers and thunderstorms associated with an area of low pressure
located several hundred miles southwest of the Cape Verde Islands
are gradually becoming better organized. Environmental conditions
appear conducive for additional development of this system, and a
tropical depression will likely form within the next few days while
the system moves west-northwestward at 10 to 15 mph.
* Formation chance through 48 hours...medium...60 percent
* Formation chance through 5 days...high...80 percent

$$
Forecaster Cangialosi

[tatertawt24]

Wow, they're really confident about this developing... it looks dreadful right now.

[Yellow Evan]

Wow, they're really confident about this developing... it looks dreadful right now.

NHC has been a bit more bullish with TWO %'s as of late.

[Siker]

Wow, they're really confident about this developing... it looks dreadful right now.

Convection is on the increase, and it already had a good structure, so it looks a lot less "dreadful" than it did earlier today.

[gigabite]

Gigabite, how can you distinguish any possible tidal effects from other commonly used environmental controls such as vertical wind shear, thermodynamic instability, etc... ? One could easily argue you are displaying the diurnal cycle of convection or the effects of dry air entrainment.

It is the timing of the event, that I use to develop the slides for the body of work. I'll post a list of the expected attributes from the 400 or so observations I've made, one day. Some of them are more well defined, like when the New Moon's path splits a system that is expected to develop. Coincidence is the explanation that satisfies, it isn't possible as you say to distinguish this phenomena from any other without a gravimetric measurement. That is not in the budget right now, and differential gravimeters don't work at sea which limits the observation sites to the Caribbean Islands. The number system crossings in that range would put the observation time for the study in excess of 30 years to satisfy the minimum requirement of the Central Limit Theory. As the frequency and quality of the coverage improves tracking the gravity shaft will become more realistic. The Earth rotates at 1000 miles per hour capturing that in a single composite image at 2 to 4 frames per hour is a stroke of luck.

[Gustywind]

000
AXNT20 KNHC 172347
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON AUG 17 2015


...SPECIAL FEATURES...
TROPICAL WAVE EXTENDS FROM 09N31W TO 18N33W MOVING W AT 15-20
KT. A 1010 MB LOW IS CENTERED AT THE SOUTHERN EXTENT OF THE WAVE
AXIS EMBEDDED WITHIN THE MONSOON TROUGH NEARLY COLLOCATED WITH A
MAXIMUM IN 850 MB RELATIVE VORTICITY. SCATTERED MODERATE
CONVECTION IS FROM 06N-12N BETWEEN 29W-36W. THE SYSTEM HAS A
MEDIUM CHANCE OF DEVELOPING INTO A TROPICAL CYCLONE DURING THE
NEXT 48 HOURS.

[galaxy401]

A bit late here but it seems weird seeing 60% but it isn't code red.

[Gustywind]

From Dr Jeff Masters

http://www.wunderground.com/blog/JeffMa ... rynum=3074

96L Slowly Organizing

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.

[gigabite]

. ... He did, and he was surprised that there is a statistical increase in TS geneses on new and full moons in the Atlantic Basin. But, it does not hold in the E. or W. Pacific at all. He used data from 1930 something through 2008.

There is a high frequency of tropical storm development at the New Moon, but it mostly depends on the latitude of the New Moon at aphelion. When the latitude of the Moon at aphelion is extremely low there is an el Nino. This limits atmospheric moisture in the Atlantic, maybe globally. ( I'm looking at that, but the time lines for the data collection are very long ) The more moisture in the atmosphere the more pronounced the New Moon effect. There are ranges of latitude where there is more atmospheric moisture. It is not just a high run low run thing.

[Dean4Storms]

Wow, that convective burst is impressive this evening. It's going to have to maintain that for NHC to pull the trigger IMO.

[NCSTORMMAN]

Wow, that convective burst is impressive this evening. It's going to have to maintain that for NHC to pull the trigger IMO.

I have been saying for the last few hours that it is a tropical depression right now. I have seen them get classified looking worse. I understand the NHC being cautious though. They have time to be cautious as others mentioned to me earlier.

[Ntxw]

I'm beginning to change my tune with this disturbance. It has displayed resiliency fighting off the adjacent dry air. The convective burst to the west looks promising. The environment is still far from ideal though.

It has some help with CCKW (kelvin wave). A lot of people mistake dry air from sinking air. Systems can often fight off dry air with a moist envelope especially with size. Sinking air is a bigger problem since it will squash the development of thunderstorms (thus reducing the moist envelope). I think this is a reason why 96L has been able to pulse on and off even with dry air to the north. The rest of this week will be somewhat decent in terms of not so much sinking air as the CCKW will remain in place, the main thing to watch will be shear as it approaches the Carib IMO.

[NCSTORMMAN]

Sure does look good to me right now and during the lowest point for convection to fire across the Atlantic it is doing this.

[cycloneye]

Not budging to the north of 10N yet.

96L INVEST 150818 0000 9.8N 33.2W ATL 30 1011

[Weatherboy1]

I wouldn't be surprised to see this designated a TD by 11 tomorrow morning IF the convection persists overnight; deeper reds (higher tops) near the presumed low center and general persistence of lighter thunderstorms all day tell me this wave is doing much better than all those that came before it (which isn't sayong much. Lol)

[northjaxpro]

Tonight, checking satellite imagery, this is the best presentation of 96L imo to this juncture. Convection is really firing up again and the structure overall continues to look very good. I am inclined to believe that this as of now is a developing full fledged tropical cyclone and this system will likely be Danny quite soon if the current trends I am seeing now continues.

The big, BIG issue later in the week will be if this system will hold together approaching the hostile Caribbean environment. Will the shear ease up some by the weekend in that region? It has been so bad with shear in the Caribbean all sesson long. But, we have a cyclone out there in the MDR which is doing a bit more than holding its own currently, so we will follow the situation in the coming days.