July 2012: Earth's 4th warmest; update on 94L--a threat to the Antilles

By: Dr. Jeff Masters , 7:19 PM GMT on August 18, 2012

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July 2012 was the globe's 4th warmest July on record, according to the National Oceanic and Atmospheric Administration's National Climatic Data Center (NCDC). NASA rated it the 12th warmest. July 2012 global land temperatures were the 3rd warmest on record, breaking a streak of three months (April, May, and June) when global land temperatures were the warmest on record. July 2012 global ocean temperatures were the 7th warmest on record, and it was the 329th consecutive month with global temperatures warmer than the 20th century average. The last time global temperatures were below average was February 1985. Global satellite-measured temperatures in July for the lowest 8 km of the atmosphere were 7th or 5th warmest in the 34-year record, according to Remote Sensing Systems and the University of Alabama Huntsville (UAH). Wunderground's weather historian, Christopher C. Burt, has a comprehensive post on the notable weather events of July in his July 2012 Global Weather Extremes Summary.



Figure 1. Departure of temperature from average for July 2012. Most areas of the world experienced much higher-than-average monthly temperatures, including most of the United States and Canada. Meanwhile, Australia, northern and western Europe, eastern Russia, Alaska, and southern South America were notably cooler than average. Image credit: National Climatic Data Center (NCDC) .

El Niño watch continues
Sea surface temperatures increased to 0.8°C above average as of August 13 in the equatorial Pacific off the coast of South America. Ocean temperatures have been near or above the 0.5°C above average threshold needed for a weak El Niño event since the beginning of July. However, winds, pressures, and cloud cover over the region have not responded in the fashion typically associated with an El Niño, and NOAA's Climate Prediction Center (CPC) said that "The lack of a clear atmospheric response to the positive oceanic anomalies indicates ongoing ENSO-neutral conditions," in their August 9 El Niño discussion. They have issued an El Niño watch, and give a 71% chance that an El Niño event will be in place by September. El Niño conditions tend to decrease Atlantic hurricane activity, by increasing wind shear over the tropical Atlantic. Wind shear has been close to average over the tropical Atlantic since the beginning of hurricane season in June, though.


Figure 2. Arctic sea ice extent in 2012 (black line) compared to the previous record low year of 2007 (blue line) shows that 2012 is fast approaching all-time record territory. A big Arctic storm with a central pressure of 963 mb affected the ice during the first two weeks of August, causing a temporary downward spike in sea ice extent. Image credit: Danish Meteorological Institute.


Figure 3. View of the North Pole on August 17, 2012 from the North Pole Environmental Observatory shows plenty of melt water pools from the warm summer the North Pole has had.

Arctic sea ice falls to 2nd lowest extent in July, nears all-time record low during August
July 2012 Arctic sea ice extent reached its 2nd lowest July extent in the 35-year satellite record, according to the National Snow and Ice Data Center (NSIDC). During the first half of August, sea ice has undergone a spectacular decline, and we are on pace to break the all-time lowest sea ice extent record set in September 2007. As of August 17, the University of Bremen was showing that sea ice extent has already broken the all-time record; the Danish Meteorological Institute put the ice loss in 2nd place behind September 2007; and the National Snow and Ice Data Center put Arctic ice loss in 3rd place behind September of 2007 and 2011.

Update on 94L
A large tropical wave (Invest 94L) located a few hundred miles southwest of the Cape Verde Islands off the coast of Africa is headed west at 15 - 20 mph. This storm is a threat to develop into a tropical storm that will affect the Lesser Antilles Islands as early as Wednesday. The storm is under moderate wind shear of 10 - 20 knots, and is over waters of 28°C. A large area of dry air lies just to the north of 94L, as seen on the latest Saharan Air Layer (SAL) analysis. Satellite loops show that 94L has increased in organization this afternoon, with a growing amount of heavy thunderstorm activity and spin at middle levels of the atmosphere.


Figure 4. Afternoon satellite image of Invest 94L.

Forecast for 94L
The latest 2 pm EDT run of the SHIPS model predicts that wind shear will be low, 5 - 10 knots, and ocean temperatures will fluctuate around 28°C over the next five days, as 94L tracks westwards towards the Lesser Antilles. As is typical with storms making the crossing from Africa to the Antilles, dry air to the north will likely interfere with development, and the SHIPS model predicts increased dry air as 94L approaches the Lesser Antilles. However, with shear expected to be low, dry air may be less of an issue for 94L than it was for Ernesto or TD 7. The storm should maintain a nearly due west track through Monday night, to a point near 50°W, about 700 miles east of the Lesser Antilles. At that point, a trough of low pressure passing to the north of 94L may be able to pull the storm to the northwest well to the northeast of the Lesser Antilles, as suggested by the latest 12Z (8 am EDT) run of the NOGAPS model. The 12Z UKMET model shows a more west-northwesterly motion resulting in a near miss of the Lesser Antilles on Thursday. Our two best performing models--the GFS and ECMWF--have both been taking 94L through the Lesser Antilles with every run for the past 24 hours, though. The latest 12Z run of both models now agree on the timing, with 94L arriving Wednesday night or Thursday morning. The BAMM model, which performed as well as the ECMWF and GFS at 5-day forecasts in 2011, is also showing a track through the Lesser Antilles. Given this agreement among our top three models for long-range forecasts, I give a 60% chance that 94L will pass through the Lesser Antilles. In their 2 pm EDT Tropical Weather Outlook, NHC gave 94L a 50% chance of developing into a tropical depression by Monday afternoon.

Jeff Masters

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The problem for 94L in the near-term is the abnormally-dry air in the central Atlantic, some of which is already starting to wrap into the circulation in the NW quadrant. Let's not forget all of the very impressive waves we have seen near the Cape Verde islands so far this year that just petered out once they were on their own in the central Atlantic due to this dry air. I wouldn't be surprised at all to see 94L held under hurricane strength until west of 60W.

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Quoting LargoFl:
say palm beach..you folks still street flooding down there?


It's not so bad, the drivers make it every man for themselves.
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Member Since: June 20, 2012 Posts: 0 Comments: 2159
Quoting CybrTeddy:
Still see no reason as to why 94L shouldn't become a potent system.
Forward speed perhaps is the only negative..
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Keep in mind hurricane georges was going 15-20 mph when it reached peak intensity, 155 mph, although conditions were different.
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say palm beach..you folks still street flooding down there?
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Quoting weatherman12345:
you guys have to remeber that it is moving at a good pace. 20 MPH; remeber what happens to storms this season that move too fast
Just what I was thinking... looked at the last TWO and noticed the 20mph, thought "ut oh"....

It would be really whack if the EURO is right...
Member Since: October 25, 2005 Posts: 19 Comments: 22322
Quoting Stormchaser2007:
GFS continues to weaken the system as it moves through the Caribbean, just under Hispaniola.

Very odd and major change.


Looks stronger at 126 hours than it did at 114 hours and 120 hours

also note, this is already further west than the other runs due to it being weaker
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Quoting washingtonian115:
Maybe speed is it's worst enemy right now.
yes for the last 2 but this one has very little sal
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Quoting Stormchaser2007:
GFS continues to weaken the system as it moves through the Caribbean, just under Hispaniola.

Very odd and major change.




IF it keeps showing a weak system that doesn't dissipate....also not good (for Gulf Coast and FL)
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Quoting Tazmanian:
94L and look whats be hid it






all so thew wave be hid 94L looks a little more S then 94L is
yes there is a wave train on africa, one after another
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GFS continues to weaken the system as it moves through the Caribbean, just under Hispaniola.

Very odd and major change.
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Quoting tennisgirl08:


Yes, but only for now. This is also what is causing 94L's high rate of speed...keeping him weak and disorganized.
ok ty
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Maybe speed is it's worst enemy right now.
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Quoting LargoFl:
Is it these 2 HIGHS that will keep it from recurving?


Yes, but only for now. This is also what is causing 94L's high rate of speed...keeping him weak and disorganized.
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433. HadesGodWyvern (Mod)
Japan Meteorological Agency
Tropical Cyclone Advisory #8
TROPICAL DEPRESSION 16
6:00 AM JST August 19 2012
====================================

SUBJECT: Tropical Depression In Sea East Of The Philippines

At 21:00 PM UTC, Tropical Depression (1006 hPa) located at 17.8N 125.0E has 10 minute sustained winds of 30 knots with gusts of 45 knots. The depression is reported as moving southwest slowly.

Dvorak Intensity: T2.0

Forecast and Intensity
========================

24 HRS: 17.8N 125.0E - 35 knots (CAT 1/Tropical Storm)
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94L and look whats be hid it






all so thew wave be hid 94L looks a little more S then 94L is
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Quoting TropicalAnalystwx13:
I don't see any reason to believe this won't be a hurricane before reaching the islands, and eventually a major hurricane.

Wind shear is low, SSTs are warm, and OHC is increasing. The environment is a bit dry, but it shouldn't struggle much with dry air with low wind shear.
YA say a bit dry but the most moist we have seen this year
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Quoting MAweatherboy1:
Look at the storm behind it!

Double whammy for the islands?.I see Kirk to.Wave train is set in motion.
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The changes from yesterday are quite significant from yesterday.

Yesterday the GFS had a 100 knot system in the eastern Caribbean.

On the 18z run NOW, it has a 50-60 knot system.


I'd follow the trends over the next couple of cycles.

This could cause some headaches.
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Quoting Clearwater1:
What do you see that all the models don't?

Just the generally favorable conditions... I'm by no means the only one here who sees strengthening happening, but the models don't see it.
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.50 PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE
NEXT 48 HOURS AS IT MOVES WESTWARD AT ABOUT 20 MPH.

Not much is likely to change for some time. While fast movement does not negate strengthening, it does however delay the process and makes the cyclone more vulnerable to adversity (Shear & Dry Air). Long story short, and as Dr. Masters has indicated in his blog, the Antilles should start regularly monitoring the strength of the cyclone and potentially prepare for a formidable strike mid-late week.
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Quoting WxGeekVA:
ALERT:

A Wishcasting Warning has been issued for the entire Wunderblog area. At 6:04PM EDT recent posts showed a lack of hype and a weaker model run which is failing to meet expectations, prompting westcasting and a general state of disbelief in in the models for the Wunderground community. This warning is in effect until 11 PM EDT tonight, where it will be either discontinued or extended.
ok ok you got 2 points for that
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Quoting CybrTeddy:


I haven't heard your thoughts, do you think the ECMWF is right and this won't even develop or are you against that scenario?


If things don't change too dramatically by 12z tomorrow, I'll have a discussion on 94L.

It all depends how fast this system goes. If it trucks at 20+ mph like Ernesto did, then it will not be a strong system as it approaches the islands due to DAI and inner circulations not being aligned. However, it will be farther west and may not be picked up by a trof until it potentially reaches the central/western Caribbean.
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Look at the storm behind it!

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Quoting MAweatherboy1:
While conditions seem to favor intensification, it is unwise to ignore the fact that the major models are trending considerably weaker with this storm, to the point of not developing it at all by the Euro... They may see something we don't.

Personally I still see strengthening though.
What do you see that all the models don't?
Member Since: August 26, 2006 Posts: 0 Comments: 1548
Quoting txwcc:


SHIPS (18Z) suggests not as moist an environment down the road as he approaches the Lesser Antilles...

Link

TIME (HR) 0 6 12 18 24 36 48 60 72 84 96 108 120

700-500 MB RH 65 65 66 64 66 64 60 56 52 49 49 48 49

"but it shouldn't struggle much with dry air with low wind shear."
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Dear rescueguy,you should go to fema.gov to find out how FEMA works.Around 300 disasters declararations has happened after Katrina and many of those in populated areas (e.g IKE sep 2008 TX) and FEMA assistance is required when local officials have not enough resources and funds to help our citizens .so you better start to worry or concerned about the local and state officials where you live.
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Is it these 2 HIGHS that will keep it from recurving?
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Quoting RitaEvac:


Something has gotta form over the Gulf, but where the rain goes is beyond me. Talking dry air with dewpoints in the 50s and 60s in SE TX behind front, but with possible tropical entity down the road over Gulf, remains to be seen how all this unfolds.

Situation like this a North movement is in the cards



The odds are anything forming in the GOM won't do anything for S Cen TX (due to W -> E movement)
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The models on crack.I don't see what's stopping this from becoming at least a moderate tropical storm when it makes it's approach to the islands.
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GFS aint giving up the remnants of Helene. Turns it west here

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Quoting tennisgirl08:
I'm just gonna go out on a limb here and make some people mad....haha.

I think future Isaac will be a fish storm, may hit Bermuda....and low chance the northern leewards.
Cape Verde storms are fun to track and look beautiful out in the Atlantic...but I just don't think they will hit the East coast this year.

I think the only chance for a CONUS strike this year will be from homegrown mischief....mostly in the GOMEX.

You can quote me on that....I'm a big believer in climatology and precedent. The analog years must be taken into consideration.



And I hope you are 100% right... Except that I don't want any homegrown mischief either.
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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