Atlantic Tropical Action 2011

[David Reimer]

[Srain]

TWD:

CARIBBEAN SEA...

AN UPPER LEVEL ANTI-CYCLONIC CIRCULATION SITS OVER THE CARIBBEAN

SEA AND NORTHERN SOUTH AMERICA THIS MORNING. THIS FLOW IS

KEEPING FAIR WEATHER CONDITIONS OVER MUCH OF THE CARIBBEAN...

EXCEPT FOR THE SW BASIN...WHERE BROAD SURFACE CYCLONIC TURNING

IS NOTED IN THIS REGION. LOW LEVEL MOISTURE REMAINS QUITE HIGH

IN THIS REGION...NOTICED ON TPW PRODUCT. SCATTERED SHOWERS AND

TSTMS ARE S OF 18N W OF 73W. WITHIN THIS AREA OF CONVECTION...A

SURFACE TROUGH IS ANALYZED FROM THE COAST OF COSTA RICA NEAR

10N83W NE TO 14N76W. MODEL GUIDANCE IS IN BETTER AGREEMENT

SUGGESTING THE ACTIVITY IN THE SW BASIN WILL INCREASE OVER THE

NEXT 24 HOURS...AS CYCLOGENESIS IN THE FORM OF A WEAK LOW

PRESSURE CENTER DEVELOPS IN THE 36 TO 72 HOUR WINDOW ACROSS THE

SW CARIBBEAN SEA WATERS.

The Euro and the GFS are suggesting a breakdown of the upper ridge across the Western Gulf in the medium/long range. Perhaps a chance something could slip up from the W Caribbean during that timeframe, but would likely be weak and offer increased rain chances to drought parched TX/MX.

[Ed Lizard]

Image removed, 372 hour GFS, Eastern Gulf TC.

I generally find that beyond the resolution reduction the ensembles may be more useful than the 2 week operational GFS. The spaghetti is a mess, a TC in 2 weeks in the Eastern Gulf is possible, but at this point, in my amateur opinion, not probable.

[bluewave]

It looks like the models want to develop a broad area of low pressure over the Western Caribbean with the potential to be a big rainmaker as it lifts slowly north.

[flwxwatcher45]

I generally find that beyond the resolution reduction the ensembles may be more useful than the 2 week operational GFS. The spaghetti is a mess, a TC in 2 weeks in the Eastern Gulf is possible, but at this point, in my amateur opinion, not probable.

It's going to be a long few weeks with this system it seems. Like you said, the Spaghetti is a mess ,which is not a surprise. The EURO at day 10 has the system just south of Eastern Cuba, while the 10 day GFS position has it south of Western Cuba. I suspect weather weenies from Texas to Florida will have a model run or two that gets them excited the next several days.:mapstorm:

[wxmx]

Looks like some real possibility for real rain in our region Jun 5-12. Cyclogenesis probabilities in the Atlantic will enhance above climo as well.

No change in my thoughts... confidence even goes up a notch. Nice wave/westerly surge in the W Caribbean/GOM during this period, classic early activity setup.

In a somewhat related note, I haven't issued my Atlantic basin hurricane season forecast because of above climo work, but I'm having second thoughts on my already above average numbers (16/9/4), looks like we'll have a favorable neutral ENSO signature (2005 is a poster child year for this), where Niña like shear and heavily modulated MJO wave activity are looking like the main key factors for the season. Hopefully I can get my thoughts together before June 1st.

[rainstorm]

No change in my thoughts... confidence even goes up a notch. Nice wave/westerly surge in the W Caribbean/GOM during this period, classic early activity setup.

In a somewhat related note, I haven't issued my Atlantic basin hurricane season forecast because of above climo work, but I'm having second thoughts on my already above average numbers (16/9/4), looks like we'll have a favorable neutral ENSO signature (2005 is a poster child year for this), where Niña like shear and heavily modulated MJO wave activity are looking like the main key factors for the season. Hopefully I can get my thoughts together before June 1st.

that will be an awesome season.

[wxmx]

that will be an awesome season.

r you sure?

[kab2791]

The CMC is LOLz...

[am19psu]

The CMC is LOLz...

/voltron'd

[CooL]

Charley Redux?

its always nice to see the cmc showing life, because if its not, then you know things are really dead in the tropics

[Srain]

lol...

[HurricaneJosh]

Charley Redux?

its always nice to see the cmc showing life, because if its not, then you know things are really dead in the tropics

Bingo. As absurd as it is, the CMC showing something is sort of a baseline pre-req for *anything* to happen.

[CUmet]

I think the chances of TC genesis in the Western Caribbean sometime over the next 10 days are pretty good, especially relative to climatology. The ECMWF's bullishness on the disturbance as well as the GFS's lowering pressures and occasional hints at TC genesis bode pretty well. An atmospheric Kelvin wave currently over the central Pacific will cross into northern South America during the first few days of June. The area of enhanced low-level westerlies following this passage appears to enhance the background low-level vorticity, providing an environment more favorable for TC genesis.

There are a lot of remaining skeptics regarding Kelvin wave influence on Atlantic TC genesis, and the relationship is far from conclusive. Some of the research that I've seen, not only from the existing literature but also stuff that is yet/soon to be published, suggests that Atlantic TC genesis is much more likely to occur (if I recall correctly, something like 2-3 times more likely) in the few days following a KW passage than before. The scientists involved with the upcoming NASA HS3 campaign have shown a lot of interest in this as well, and may make it an objective to capture a KW passage and subsequent TC genesis event.

[am19psu]

I think the chances of TC genesis in the Western Caribbean sometime over the next 10 days are pretty good, especially relative to climatology. The ECMWF's bullishness on the disturbance as well as the GFS's lowering pressures and occasional hints at TC genesis bode pretty well. An atmospheric Kelvin wave currently over the central Pacific will cross into northern South America during the first few days of June. The area of enhanced low-level westerlies following this passage appears to enhance the background low-level vorticity, providing an environment more favorable for TC genesis.

I agree with everyone else for the most part. The only thing that really concerns me in the modeling is the lack of central convection. It still looks like a lot of the monsoon crap from last year in modelworld.

There are a lot of remaining skeptics regarding Kelvin wave influence on Atlantic TC genesis, and the relationship is far from conclusive. Some of the research that I've seen, not only from the existing literature but also stuff that is yet/soon to be published, suggests that Atlantic TC genesis is much more likely to occur (if I recall correctly, something like 2-3 times more likely) in the few days following a KW passage than before. The scientists involved with the upcoming NASA HS3 campaign have shown a lot of interest in this as well, and may make it an objective to capture a KW passage and subsequent TC genesis event.

I'm really not sure why there is so much skepticism in the community. It just makes sense that increased westerlies, even in small amounts, will make the environment more favorable for genesis. I know the Roundy and Schreck paper couldn't find anything statistically significant, but it makes intuitive sense and you can see it happen empirically in every basin.

[wxmeddler]

Constantly Making Cyclones

[Srain]

I'd be cautious pinning down any point at this time regarding future development. As we saw last year with a monsoonal trough/gyre, anywhere from the W Caribbean to the entire Gulf region could see rainfall. I'm not sold yet on anything close to a Hurricane, but an early season TS is certainly not out of the question. Another point regarding the Euro, that model suggests a TUTT traversing the Gulf that would be located in the W Gulf regions by next weekend. Kudos to the Euro seasonals for sniffing out the pattern a couple of months ago.

[shaggy]

Any thoughts or speculation on what dr gray is gonna come out and say on the 1st? My hope is he holds with the 5 analogs years he previously talked about because all had a landfalling TC on the NC coast.

[Wannabehippie]

A rainmaker will be much welcomed by Florida, texas, other areas along the gulf.

It looks like the models want to develop a broad area of low pressure over the Western Caribbean with the potential to be a big rainmaker as it lifts slowly north.

[CUmet]

I'm really not sure why there is so much skepticism in the community. It just makes sense that increased westerlies, even in small amounts, will make the environment more favorable for genesis. I know the Roundy and Schreck paper couldn't find anything statistically significant, but it makes intuitive sense and you can see it happen empirically in every basin.

I agree. Here's a relevant presentation on the topic (Slide 39 is the most important one, posted below): http://www.espo.nasa..._Thorncroft.pdf

Although it's not shown in the above, the Hovmoller composite I've seen shows this as well, with a relative max in TC genesis propagating to the east right behind the Kelvin wave.

[Amped]

Maybe this will be the next Subtropical storm Nichole. Big area of Low pressure on the models for days. Produced a lot of rain, but no real organized center.

[Superstorm93]

GFS develops this in about 57 hours:

180 hours. Goes on to hit Florida twice after this as a decent TC

[Amped]

I agree. Here's a relevant presentation on the topic (Slide 39 is the most important one, posted below): http://www.espo.nasa..._Thorncroft.pdf

Although it's not shown in the above, the Hovmoller composite I've seen shows this as well, with a relative max in TC genesis propagating to the east right behind the Kelvin wave.

You can also see the area of wind shear lift to the north and a right entrance region in the 200MB fields. I think if you can correlate either of those events to the Kelvin Wave you might be able to show it had an influence.

[CUmet]

You can also see the area of wind shear lift to the north and a right entrance region in the 200MB fields. I think if you can correlate either of those events to the Kelvin Wave you might be able to show it had an influence.

Vertical wind shear decreases substantially following the passage of a Kelvin wave. I've seen Hovmoller composite KW plots that show this in the Atlantic, and this is shown in other studies of KW in other basins as well. The expansion of the upper-troposphere ridge in the Caribbean is consistent with the Kelvin wave passage creating anticyclonic upper-trosphere gyres in its wake both to the north and south.

This appears to be one of the more impressive KW events judging from Paul Roundy's Hovmoller plots.

[metalicwx366]

2011 Long-Range Weather Forecast for Florida

JUNE 2011: temperature 79 ° (2 ° below avg.); precipitation 14.5" (8" above avg.); Jun 1-3: Heavy t-storms, cool; Jun 4-9: Sunny north, a few t-storms south; Jun 10-13: Hurricane threat; Jun 14-20: Sunny north, t-storms south; cool; Jun 21-24: Hurricane threat; Jun 25-30: Scattered t-storms, warm.

Wow.....farmers almanac was really close with the 2011 long range forecast if the models are right about the possible tropical threat for florida. Just a few days off while predicting this at the beginning of 2011.

http://www.almanac.com/weather/longrange/region/us/5

[Srain]

The models have backed off regarding a deeper low emanating from the SW Caribbean. The general trend is a much weaker, broad area of low pressure confined S of Cuba in the near to meduim range. There is a weak wave that is approaching from W of the Windward Islands, but the wave axis is rather weak, and lacks deep convection. My hunch is this area of disturbed weather will simmer for several days without much development and be very typical of what we see this time of year with a semi permanent low pressure area in that region. Until a stronger wave comes along, which is not currently on the horizon, this will likely be nothing more than a passing interest...

HPC:

AS A MID TO UPPER LEVEL LOW RETROGRADES ACROSS THE GULF OF MEXICO

TOWARDS TEXAS THIS PERIOD UNDER THE MIDWESTERN/MID-SOUTH

RIDGE...THE DETERMINISTIC AND ENSEMBLE GUIDANCE ALL AGREE ON A

CONVECTIVE LOW PRESSURE AREA FORMING NORTH OF PANAMA WHICH SLOWLY

LIFTS NORTHWARD ALONG/NEAR THE 80TH MERIDIAN WITH TIME.

CONVECTIVE LOW DEVELOPMENT IN THE WESTERN CARIBBEAN SHOULD BE A

SLOW PROCESS CONSIDERING THE LARGE UPPER LOW RETROGRADING TO ITS

NORTHWEST...THE SLOW EXPANSION OF THE UPPER HIGH WESTWARD FROM THE

CENTRAL CARIBBEAN ANTICIPATED...AND ITS FAIRLY LARGE SIZE AS SHOWN

IN THE GUIDANCE.

[Srain]

Surface data suggests a weak 1008mb low has formed E of Nicaragua

[Srain]

Meh...

HPC Final Update:

AS A MID TO UPPER LEVEL LOW RETROGRADES TO SOME DEGREE ACROSS THE

GULF OF MEXICO UNDER THE MIDWESTERN/MID SOUTH RIDGE...THE

DETERMINISTIC AND ENSEMBLE GUIDANCE ALL AGREE ON A CONVECTIVE LOW

PRESSURE AREA FORMING NORTH OF PANAMA WHICH SLOWLY LIFTS NORTHWARD

NEAR THE 80TH MERIDIAN WITH TIME. CONVECTIVE LOW DEVELOPMENT IN

THE WESTERN CARIBBEAN SHOULD BE A SLOW PROCESS CONSIDERING THE

LARGE UPPER LOW RETROGRADING TO ITS NORTHWEST CAUSING VERTICAL

WIND SHEAR EARLY ON WITH A SUBSEQUENT SLOW EXPANSION OF THE UPPER

HIGH WESTWARD FROM THE EASTERN AND CENTRAL CARIBBEAN ANTICIPATED.

THE SYSTEM ALSO APPEARS TO BE OF FAIRLY LARGE SIZE PER THE

GUIDANCE. THE POINTS FOR THIS LOW WERE COORDINATED WITH NHC AT

17Z.

[k***]

Just read DT's hurricane season forecast. It's pretty lame that he can't issue his own forecast without bashing other groups.

[am19psu]

Just read DT's hurricane season forecast. It's pretty lame that he can't issue his own forecast without bashing other groups.

Cliffs notes? I'm not going to spend the time navigating through his garbage.