Atlantic Tropical Action 2014

[IsentropicLift]

Seems to be some cyclonic flow out ahead of 93L more towards the area of convection further east, maybe a center relocation?

 

[wxmx]

No, no relocation...there's not even a decent outburst of convection, and the LLC is still very well defined and naked. It's currently under the lowest shear it will be...After the next 12-18 hours, everything will be downhill...until maybe 5-6 days from now, when recurving...but I wouldn't bet on that.

[Roger Smith]

Final reminder, if you're entered in the seasonal contest, post your August monthly forecast by 06z tonight.

 

Contest rules relevant to today's 70% chance possible T.D. 3 ... if it gets a name in July using z time, then its entire history belongs to July. Therefore don't count it in your August forecast in that case. If it gets a name in August (for example at 03z) then its entire history belongs to August. Timing of number designation is not a factor in contest.

 

If these circumstances cause you to wish to edit your already posted forecast for August, feel free, I won't be incorporating them into the table until after 06z, but if you wish to edit after that and take on the 1% hourly penalty, then make a note in your edited post (I check back, no need to repost).

 

Good luck.

[Ground Scouring]

A cell 50 miles or so SSW of the LLC isn't enough to warrant an upgrade. We would need to see storms concentrated much closure to the center of circulation before any real chance of 93L developing any further. The exposed center is racing rather quickly to the W/WNW as well and that  should inhibit much more in the way of development. Look further E across Africa as we enter the month of August. There is some increase in convection along and N 10 that may weaken the  SAL a bit as we move along. We still have a lot of season left.

Meh. There is absolutely no logical reason to expect an uptick in CV activity later this year…everything (Sahel drought, SSTA configuration, etc.) is just negative. Even homegrown development looks increasingly dubious this year, given how dry much of the basin has been. Furthermore, don't expect shear to get better as we enter late August/early September, because seasonal changes in wavelengths, plus the effects of El Niño, will just exacerbate already-high levels of shear. Those factors will just offset seasonal increases in instability. The past few days were instructive. I can almost guarantee that every remaining system will follow a similar evolution: hyped model forecasts, sheared/dried-out husks of naked swirls, drastic underperformance, and/or recurvature. I really wish that someone would design algorithms to account for aerosols in computer models…their performance with 93L (other than that of the ECMWF, which has done impressively well, considering that it doesn't account for the SAL) has been worse than horse manure. I think I'll just stop posting in the Atlantic thread because as far as I'm concerned this season's dead on arrival.

[icebreaker5221]

Meh. There is absolutely no logical reason to expect an uptick in CV activity later this year…everything (Sahel drought, SSTA configuration, etc.) is just negative. Even homegrown development looks increasingly dubious this year, given how dry much of the basin has been. Furthermore, don't expect shear to get better as we enter late August/early September, because seasonal changes in wavelengths, plus the effects of El Niño, will just exacerbate already-high levels of shear. Those factors will just offset seasonal increases in instability. The past few days were instructive. I can almost guarantee that every remaining system will follow a similar evolution: hyped model forecasts, sheared/dried-out husks of naked swirls, drastic underperformance, and/or recurvature. I really wish that someone would design algorithms to account for aerosols in computer models…their performance with 93L (other than that of the ECMWF, which has done impressively well, considering that it doesn't account for the SAL) has been worse than horse manure. I think I'll just stop posting in the Atlantic thread because as far as I'm concerned this season's dead on arrival.

 

July is always peak season for SAL, and also climatologically features the strongest subtropical ridge and the most subsidence.  It's actually quite rare that dry air isn't an issue in July.  And sure, a developing El Nino will not help with development, but there have been plenty of seasons with weak / moderate Ninos that turned out to be at least ok.  I'm also not particularly optimistic about this season, but a dry July and a slowly-developing Nino are no reason to write off Aug-Oct altogether. 

 

I wouldn't be so quick to write-off homebrews either, especially tropical transition, PV-tail, or MCV development.  They're rarely predicted much more than a couple days in advance and only need a small area of favorable conditions near the coast to develop. 

[TropicalAnalystwx13]

Stewart has raised 93L's chances of development up to 80%, stating that thunderstorms have been increasing east of the center and if they continue to expand, advisories will be initiated on Tropical Storm Bertha tonight or tomorrow.

 

But honestly, would it meet the criteria of a tropical cyclone? I personally don't see how a transient burst...much like this morning's...would satisfy the deep, organized portion of NHC's own definition of what a TC is.

 

This should have been designated several nights ago when it had organized convection and spiral banding. I still don't know why it wasn't.

 

[WhiteoutWX]

Meh. There is absolutely no logical reason to expect an uptick in CV activity later this year…everything (Sahel drought, SSTA configuration, etc.) is just negative. Even homegrown development looks increasingly dubious this year, given how dry much of the basin has been. Furthermore, don't expect shear to get better as we enter late August/early September, because seasonal changes in wavelengths, plus the effects of El Niño, will just exacerbate already-high levels of shear. Those factors will just offset seasonal increases in instability. The past few days were instructive. I can almost guarantee that every remaining system will follow a similar evolution: hyped model forecasts, sheared/dried-out husks of naked swirls, drastic underperformance, and/or recurvature. I really wish that someone would design algorithms to account for aerosols in computer models…their performance with 93L (other than that of the ECMWF, which has done impressively well, considering that it doesn't account for the SAL) has been worse than horse manure. I think I'll just stop posting in the Atlantic thread because as far as I'm concerned this season's dead on arrival.

Calm down we haven't even entered climatological peak season

[TropicalAnalystwx13]

BULLETIN
TROPICAL STORM BERTHA ADVISORY NUMBER   1
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL032014
1100 PM AST THU JUL 31 2014

 

...TROPICAL STORM BERTHA DEVELOPS EAST OF THE SOUTHERN LESSER
ANTILLES...
...TROPICAL STORM WARNINGS AND WATCHES ISSUED...

 

SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...12.3N 55.5W
ABOUT 275 MI...445 KM ESE OF BARBADOS
ABOUT 385 MI...620 KM ESE OF ST. LUCIA
MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H
PRESENT MOVEMENT...WNW OR 290 DEGREES AT 20 MPH...31 KM/H
MINIMUM CENTRAL PRESSURE...1008 MB...29.77 INCHES

 

WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY...

 

THE METEOROLOGICAL SERVICE OF BARBADOS HAS ISSUED A TROPICAL STORM
WARNING FOR BARBADOS AND DOMINICA.

 

 

THE GOVERNMENT OF ST. LUCIA HAS ISSUED A TROPICAL STORM WARNING FOR
ST. LUCIA.

A TROPICAL STORM WATCH HAS BEEN ISSUED FOR PUERTO RICO...VIEQUES...
CULEBRA...AND THE U.S. VIRGIN ISLANDS.

 

THE METEOROLOGICAL SERVICE OF BARBADOS HAS ISSUED A TROPICAL STORM
WATCH FOR ST. VINCENT AND THE GRENADINES.

 

A TROPICAL STORM WARNING COULD BE REQUIRED FOR MARTINIQUE FRIDAY
MORNING.

 

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

 

A TROPICAL STORM WARNING IS IN EFFECT FOR...
* BARBADOS
* ST. LUCIA
* DOMINICA

A TROPICAL STORM WATCH IS IN EFFECT FOR...
* PUERTO RICO
* VIEQUES
* CULEBRA
* U.S. VIRGIN ISLANDS
* ST. VINCENT AND THE GRENADINES

 

A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE
EXPECTED SOMEWHERE WITHIN THE WARNING AREA...IN THIS CASE WITHIN
THE NEXT 24 HOURS.

 

A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE
POSSIBLE WITHIN THE WATCH AREA...GENERALLY WITHIN 48 HOURS.

 

INTERESTS ELSEWHERE ACROSS THE NORTHEASTERN CARIBBEAN SEA SHOULD
MONITOR THE PROGRESS OF THIS SYSTEM.

 

FOR STORM INFORMATION SPECIFIC TO YOUR AREA IN THE UNITED STATES...
INCLUDING POSSIBLE INLAND WATCHES AND WARNINGS...PLEASE MONITOR
PRODUCTS ISSUED BY YOUR LOCAL NATIONAL WEATHER SERVICE FORECAST
OFFICE. FOR STORM INFORMATION SPECIFIC TO YOUR AREA OUTSIDE THE
UNITED STATES...PLEASE MONITOR PRODUCTS ISSUED BY YOUR NATIONAL
METEOROLOGICAL SERVICE.

 

DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 1100 PM AST...0300 UTC...THE CENTER OF TROPICAL STORM BERTHA WAS
LOCATED NEAR LATITUDE 12.3 NORTH...LONGITUDE 55.5 WEST. BERTHA IS
MOVING TOWARD THE WEST-NORTHWEST NEAR 20 MPH...31 KM/H...AND THIS
GENERAL MOTION IS EXPECTED TO CONTINUE FOR THE NEXT COUPLE OF DAYS.
ON THE FORECAST TRACK...BERTHA IS EXPECTED TO PASS NEAR BARBADOS
FRIDAY AFTERNOON AND MOVE THROUGH THE CENTRAL LESSER ANTILLES FRIDAY
EVENING.

 

REPORTS FROM AN AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT INDICATE
THAT MAXIMUM SUSTAINED WINDS ARE NEAR 45 MPH...75 KM/H...WITH HIGHER
GUSTS. LITTLE CHANGE IN STRENGTH IS FORECAST DURING THE NEXT 48
HOURS.

 

TROPICAL-STORM-FORCE WINDS EXTEND OUTWARD UP TO 45 MILES...75 KM
FROM THE CENTER.

 

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1008 MB...29.77 INCHES.

 

HAZARDS AFFECTING LAND
----------------------
WIND...TROPICAL STORM CONDITIONS ARE EXPECTED TO FIRST REACH THE
WARNING AREA BY MIDDAY FRIDAY...MAKING OUTSIDE PREPARATIONS
DIFFICULT OR DANGEROUS. TROPICAL STORM CONDITIONS ARE POSSIBLE IN
THE WATCH AREA IN PUERTO RICO AND THE U.S. VIRGIN ISLANDS ON
SATURDAY.

 

RAINFALL...BERTHA IS EXPECTED TO PRODUCE RAINFALL AMOUNTS OF 1 TO
3 INCHES WITH ISOLATED AMOUNTS UP TO 5 INCHES ACROSS PORTIONS OF THE
LEEWARD ISLANDS...PUERTO RICO...AND THE VIRGIN ISLANDS THROUGH
SATURDAY NIGHT.

 

NEXT ADVISORY
-------------
NEXT INTERMEDIATE ADVISORY...200 AM AST.
NEXT COMPLETE ADVISORY...500 AM AST.

 

$$
FORECASTER STEWART

[IsentropicLift]

At least the latest burst of convection is right over the center. I have to say this is probably the most pathetic IR image I've ever seen of a system that has just been upgraded.

 

[phil882]

The ECMWF looks more favorable for Bertha once it makes it north of the greater antilles. If it can survive with its circulation intact (which was shown to be robust in recon earlier, its got a chance for a better life N of 20 degrees. 

 

Speaking of those short fused home brew disturbances, don't sleep on that bit of disturbed weather at 25N and 67W. None of the global models have anything, but the diffluence to the northwest of the decaying TUTT has been helping convection in this region for the last 24 hours. In fact its been helping to significantly weaken the TUTT due to PV distribution of active convection modifying the thermodynamic profile via latent heat release. This region will likely drift to the west slowly, and at the very least will enhance moisture down the road for Florida and the southeastern coastline.

[Srain]

So much for pressure and upgrading on a wind gust or two...

[bluewave]

A new paper that just came out may explain why we have seen the changes in

the hadley circulation and drier conditions across the Tropical Atlantic. The

main culprit seems to be a weakening of the temperature gradient between

the tropics and midlatitudes since 1997. While we have seen a hiatus in 

global temperatures since then, the SST's have been rising from 20-45N

especially in the Pacific relative to the tropics. This is something that 

we typically see during the -PDO/La Nina. So the cooler Atlantic MDR SST's

this year reduce the temperature gradient even more against the

general trend that we have been experiencing in recent years.

The last -PDO/La Nina era featured drying over the Eastern Pacific and

South America but not the Atlantic.We would probably need further

study to isolate the Atlantic region vs other regions but the

general temperature gradient changes looks like a piece

of the puzzle.

 

http://www.oriadam.info/oriadam/HCW_Expansion_2014.pdf

[phil882]

Bertha is coming within the radar range of Barbados if anyone cares. 

 

http://barbadosweather.org/barbados-weather-Radar-SABDriver.php

[Kory]

Recon is finding widespread TS force winds in the eastern part of the storm.  

[IsentropicLift]

LLC is fully exposed again. In any event, intensity has been raised to 45kts.

 

[PSUBlizzicane2007]

I imagine that in the tropical cyclone report, Bertha will be reclassified as a tropical cyclone before the date advisories were initiated.

[TropicalAnalystwx13]

If nothing else, it's impressive how resilient Bertha's circulation has been. The center has spent the better part of the past 4-5 days completely exposed, battling dry air and shear, and yet it remains very well-defined. Before recon left, they reported a minimum barometric pressure of 1006mb, which is 2mb lower than earlier.

 

[Sunny and Warm]

Lots of outflow boundaries in that pic.

[Weathergun]

West wind at 14mph reported at Le Lamentin, Martnique at 3:30pm. Pressure also 1008mb. Will probably be used to keep it a TS at 5pm:

 

http://weather.noaa.gov/weather/current/TFFF.html

[Srain]

I did a bit of quick research and not taking into account of the current ENSO state (La Nina/El Nino be they weak, neutral or strong) AMO, PDO NAO, EPO and AO, but strictly based off the Day 11+ Analogs issued July 31st with the top 10 Analogs years that are somewhat correlated with the current upper air pattern regime expected...and this is what those analogs suggest...tropical cyclone wise. There are some notable Hurricanes within those analog years. The analogs just offer clues to past general weather patterns across North America and what happened during the analog years across the Tropical North Atlantic Basin.

 

CPC July 31st Day 11+ Analogs:

 

 

1975:

 

 

1958:

 

 

1985:

 

 

2005:

 

 

1951:

 

 

2008:

 

 

1983:

 

 

1991:

 

 

1999:

 

 

1961:

 

[icebreaker5221]

Actually, the structure of Bertha has improved quite dramatically over the last 3 hours.  This corroborates well with the CIMSS SAL product, which suggests that the worst of the SAL air has finally mixed out.  That UL low north of the Dominican Republic is probably also helping to ventilate the upper levels. 

 

[Sunny and Warm]

I did a bit of quick research and not taking into account of the current ENSO state (La Nina/El Nino be they weak, neutral or strong) AMO, PDO NAO, EPO and AO, but strictly based off the Day 11+ Analogs issued July 31st with the top 10 Analogs years that are somewhat correlated with the current upper air pattern regime expected...and this is what those analogs suggest...tropical cyclone wise. There are some notable Hurricanes within those analog years. The analogs just offer clues to past general weather patterns across North America and what happened during the analog years across the Tropical North Atlantic Basin.

 

CPC July 31st Day 11+ Analogs:

Except for 1985, 2005, and 2008, the other years had few US hits and what appears to have been a persistent East coast trough.  Very similar to this year I might add.

[IsentropicLift]

Nice blowup again right over the center

 

[icebreaker5221]

Nice blowup again right over the center

 

 

Yes, looks like a decrease in dust/aerosol with an increase in UL divergence are helping with the convection.  However, shear and dry air still remain, so I wouldn't expect anything more than perhaps a modest increase in organization. 

[wxmx]

It looks like it's in a col region in between upper level features...this has reduced dramatically the wind shear to <5kts according to CIMSS analysis. This will be temporary as Bertha heads towards a more hostile region near the Leeward islands/PR/Hispaniola.

[Ground Scouring]

Except for 1985, 2005, and 2008, the other years had few US hits and what appears to have been a persistent East coast trough.  Very similar to this year I might add.

Most years don't have a Cat.-2+ hurricane hitting the U.S. All the years listed--except 1951, 1983, and 1991--had at least one Cat.-2+ hurricane strike in the U.S. (1958 had Helene producing Cat.-3 winds on the Outer Banks.) Technically, that's hardly inactive by any standard. At any rate, I'm not giving those analogs much weight, considering that the pattern at any given point doesn't necessarily indicate what is to come down the road. Other factors this year favor a more inactive season than the analogs suggest. Someone mentioned frontal development off the SE coast or in the Gulf, but long-range forecasts indicate an enhanced ridge off the SE coast in mid to late August, which would make MCV development less likely.

[dtk]

Meh. There is absolutely no logical reason to expect an uptick in CV activity later this year…everything (Sahel drought, SSTA configuration, etc.) is just negative. Even homegrown development looks increasingly dubious this year, given how dry much of the basin has been. Furthermore, don't expect shear to get better as we enter late August/early September, because seasonal changes in wavelengths, plus the effects of El Niño, will just exacerbate already-high levels of shear. Those factors will just offset seasonal increases in instability. The past few days were instructive. I can almost guarantee that every remaining system will follow a similar evolution: hyped model forecasts, sheared/dried-out husks of naked swirls, drastic underperformance, and/or recurvature. I really wish that someone would design algorithms to account for aerosols in computer models…their performance with 93L (other than that of the ECMWF, which has done impressively well, considering that it doesn't account for the SAL) has been worse than horse manure. I think I'll just stop posting in the Atlantic thread because as far as I'm concerned this season's dead on arrival.

I will let them know that they should be considering aerosols. I bet they never thought of that.

[isohume]

I will let them know that they should be considering aerosols. I bet they never thought of that.

 

[LocoAko]

I will let them know that they should be considering aerosols. I bet they never thought of that.

 

[Superstorm93]