ATL: BERTHA - Post-Tropical - Discussion

[supercane4867]

AL, 93, 2014072806, , BEST, 0, 103N, 310W, 20, 1013, DB, 34, NEQ, 0, 0, 0, 0, 1015, 150, 60, 0, 0, L, 0, , 0, 0, INVEST, S,


Pre-invest thread

viewtopic.php?f=31&t=116523

[TropicalAnalystwx13]

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
200 AM EDT MON JUL 28 2014

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

A tropical wave located about 550 miles southwest of the Cape
Verde Islands is producing a large area of cloudiness and
thunderstorms. Shower activity has increased and become a little
better organized during the past several hours, and environmental
conditions are expected to be conducive for additional development
of this disturbance over the next several days while it moves
generally westward at 10 to 15 mph.
* Formation chance through 48 hours...medium...30 percent.
* Formation chance through 5 days...high...70 percent.

$$
Forecaster Stewart

[beoumont]

Quickly building muscle mass. Latest run of GFS recurves low at longitude 70; where earlier run was several degrees further east. 200 mb prog. builds high wnw than nw with system.

[Hurricane Alexis]

This should become more organized than TD2, reason being that it's much larger and can sustain itself better. There hasn't been a healthy looking wave like this in the MDR in a while. Should it keep moving westward it could stay south of all that SAL to the north of it. Shear ahead of it seems to be on the low side as well and waters only get warmer the further west it goes.

[Gustywind]

Are things are heating up in the tropics? Hey islanders let's have fun because of weather is wonderfull in the Lesser Antilles ; but keep a small eye on that for the weekend... in case of?

From the Weather Channel http://www.weather.com/news/tropical-up ... n-20140513


ATLANTIC BASIN

Thunderstorms have increased near a tropical disturbance moving westward across the eastern Atlantic. The area of unsettled weather is embedded within a line of converging air (see animation above), with winds coming together to not only produce showers but also a natural area of spin for a low pressure system to form. The spin to the air is limited right now which is some good news in the short term.

The complication comes in a few days when the disturbance hits a more favorable atmosphere. Some of our weather models like the American GFS show a robust tropical storm approaching the Lesser Antilles by the end of the week. Meanwhile, the highly touted European weather model is less enthusiastic, forecasting little if any development.

In this instance a much stronger case can be made for development than against it. The disturbance is a low-running wormburner, so it'll likely stay south of the dry and dusty Saharan air that would otherwise work against development. This also means it'll remain within that region of converging air, which will continue to nourish thunderstorm growth and spin. By mid-week, upper winds are expected to relax noticeably, which will provide further support for organization. (Also worth noting that more recent runs of the European model using different starting conditions do show some development potential when compared to previous runs.)

Bottom line: odds are tilted in favor of tropical development in the upcoming days. It's too early to say how strong a developing system might get but the Lesser Antilles, Leeward Islands, and even Puerto Rico could be impacted by this system by late week into the weekend. Stay tuned.

[cycloneye]

Strong favorable upper divergence that favors lower pressures. Gustywind,post that at the Caribbean Weather thread too.

[Gustywind]

Strong favorable upper divergence that favors lower pressures. Gustywind,post that at the Caribbean Weather thread too.

http://oi61.tinypic.com/k9ghkx.jpg

ok thanks to you

[cycloneye]

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
800 AM EDT MON JUL 28 2014

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

A tropical wave located several hundred miles southwest of the Cape
Verde Islands is producing disorganized cloudiness and
thunderstorms. Environmental conditions are expected to be
conducive for gradual development of this disturbance over the next
several days while it moves generally westward at 10 to 15 mph.
* Formation chance through 48 hours...medium...30 percent.
* Formation chance through 5 days...high...70 percent.

$$
Forecaster Pasch

[Gustywind]

Given accuweather.com, bear watching mode is up

Strong Atlantic Disturbance Bears Watching
July 28, 2014; 5:47 AM

A cluster of showers and storms in the Central Atlantic could organize into Bertha before the end of the week.

http://www.accuweather.com/en/weather-v ... 1683763362

[ouragans]

By the way, floater is up since 6z

http://www.ssd.noaa.gov/PS/TROP/floater ... oater.html

[GeneratorPower]

It has the appearance of a pretty big storm. This might have a larger footprint than the average storm.

[wxman57]

I think that the best chance for development is moving to within 48 hours now. Euro develops it today then slowly weakens it as it moves toward the eastern Caribbean. GFS reaches peak intensity in 2-3 days (1007-1008mb low) then recurves it. Might reach weak TS strength. Doesn't look like it can make it to the Gulf or the East U.S. Coast given the massive upper-level trof that will reside along the East U.S. Coast through this weekend (and resulting weakening western periphery of the Bermuda High).

[NDG]

Per the 06z SHIPS forecast, it keeps 93L in a fairly good moist air environment through at least the next 72 hrs, compared to TD2 which had do deal with average humidity levels in the 40s & 30s % in the 700mb-500mb column.

[NDG]

I think that the best chance for development is moving to within 48 hours now. Euro develops it today then slowly weakens it as it moves toward the eastern Caribbean. GFS reaches peak intensity in 2-3 days (1007-1008mb low) then recurves it. Might reach weak TS strength. Doesn't look like it can make it to the Gulf or the East U.S. Coast given the massive upper-level trof that will reside along the East U.S. Coast through this weekend (and resulting weakening western periphery of the Bermuda High).

According to the latest HD GFS run:

[northjaxpro]

GFS considerably deeper with the system on that run.

[cycloneye]

Note=Model runs are being posted at the 93L models thread,thanks.

[NDG]

:uarrow: GFS considerably deeper with the system on that run.

Yes, its high resolution run on tropicaltidbits has been showing a stronger storm than its low resolution version, 06z run is actually weaker than its previous run which showed peaking at 986mb.

[ronjon]

The one thing 93L has going for it is its southern latitude and connection with moisture from the ITCZ. It will need to separate itself from the ITCZ at some point to develop but its got plenty of ocean to gain latitude to do so. The EC troughiness will probably recurve it but Upper Air forecast out 7-10 days are pretty iffy. The ECM builds ridging in at the surface and 500 mb in the SW Atlantic on its latest run at 7-9 days which leads to a positively aligned trough from new england to the gulf coast with its southern axis out toward the central La coast. Have to check the evolution of this pattern in the coming days to see how far west the system goes.

[tropicwatch]

I don't know if the trough will dig deep enough.

[wxman57]

According to the latest HD GFS run:

http://www.tropicaltidbits.com/analysis/models/gfs/2014072806/gfs_pres_wind_93L_18.png

NDG - I can't seem to find that graphic on Tropical Tidbits. I'm looking at the high-res GFS on my workstation and don't see anything below about 1005 mb.