El Niño is done; Haiti at risk of heavy rains next week; oil spill update

By: Dr. Jeff Masters , 20:09 GMT le 19 mai 2010

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El Niño rapidly weakened during late April and early May, with sea surface temperatures over the tropical Eastern Pacific in the area 5°N - 5°S, 120°W - 170°W, also called the "Niña 3.4 region", falling a significant 0.65°C in just one month. Temperatures in the region are now in the "neutral" range, just 0.18°C above average, and well below the 0.5°C threshold to be considered an El Niño, according to the Australian Bureau of Meteorology. The speed of the collapse of El Niño makes it likely that a La Niña event is on its way this summer. This is what happened during the last strong El Niño event, in 1998--El Niño collapsed dramatically in May, and a strong La Niña event developed by hurricane season. Six of the sixteen El Niño models (updated as of April 15) are predicting La Niña conditions for hurricane season, and I expect more models will jump on the La Niña bandwagon when the May data updates later this week. The demise of El Niño, coupled with sea surface temperatures in the tropical Atlantic that are currently at record levels, have prompted two major hurricane forecasting groups (tropicalstormrisk.com and Colorado State University) to predict a significantly above average 2010 Atlantic hurricane season. Over the full 160-year period we have records of Atlantic hurricanes, La Niña years have typically had more hurricanes, and more strong hurricanes, compared to neutral years. However, since 1995, there hasn't been any difference between neutral and La Niña years in terms of hurricane activity. La Niña conditions typically cause cool and wet conditions over the Caribbean in summer, but do not have much of an impact on U.S. temperatures or precipitation.


Figure 1. Oil spill edge over the Gulf of Mexico on Wednesday, May 19, as seen from NASA's M ODIS instrument. Note that a band of cumulus clouds formed along the edge of the oil spill. I theorize this is because the low level wind flow out of the southeast moves faster over the oil, since the oil suppresses wave action. As the winds cross the spill boundary into rougher, clean water, they slow down, forcing the air to pile up and create updrafts that then spawn cumulus clouds. See my post on what oil might do to a hurricane for more information on how oil reduces wave action.

Oil spill update
Clouds over the Gulf of Mexico have again foiled satellite imaging of the extent of the Deepwater Horizon oil spill, though through breaks in the clouds it appears that a significant amount of the oil that was pulled southwards towards the Loop Current is now caught in a counter-clockwise rotating eddy just to the north of the Loop Current. However, some oil has escaped this eddy and is on its way south towards the Florida Keys. According to the latest trajectory forecasts from NOAA, the tongue of oil flowing southwards has at most "light" concentrations. The oil will grow more dilute as it travels the 500 miles to the Florida Keys. My present expectation is that the oil entering the Loop Current this week will cause only minor problems in the Keys next week. However, there is a lot of uncertainty about what the oil may do to the fragile Keys ecosystem. See my post yesterday for answers to many of the common questions I get about the spill.

Oil spill resources
My post on the Southwest Florida "Forbidden Zone" where surface oil will rarely go
My post on what oil might do to a hurricane
NOAA trajectory forecasts
Deepwater Horizon Unified Command web site
Oil Spill Academic Task Force
University of South Florida Ocean Circulation Group oil spill forecasts
ROFFS Deepwater Horizon page
Surface current forecasts from NOAA's HYCOM model
HYCOM ocean current forecasts from LSU


Figure 2. Precipitation forecast from today's 8am EDT run of the NAVY NOGAPS model, valid 7 days from now. Precipitation amounts in excess of 70 mm (2.8") in 12 hours are predicted over Haiti, due to a tropical disturbance in the Western Caribbean. Image credit: U.S. Navy.

Potential serious rainfall threat to Haiti next week
Long-range forecasts from the GFS and NOGAPS models over the past few days have consistently been predicting an increase in moisture and decrease in wind shear over the Western Caribbean 5 - 7 days from now, and I expect that a tropical disturbance with heavy rains will develop in the Western Caribbean early next week. A strong subtropical jet stream over the southern Gulf of Mexico will steer the disturbance to the north and east, and the NOGAPS model shows heavy rains in excess of six inches impacting Haiti Wednesday through Thursday of next week. Rains of this magnitude are capable of causing a serious emergency with high loss of life in earthquake-shattered Haiti, and all interests in that nation should closely monitor the situation over the coming week. It is too early to speculate on the possibility of the disturbance becoming a tropical depression. The wunderblogs of StormW and Weather456, who are now featured bloggers for the coming hurricane season, have more information on this potential development, plus the possible development of a subtropical storm between Florida and Bermuda next week.

Major severe weather outbreak over Oklahoma expected tonight
NOAA's Storm Prediction Center has put much of Oklahoma in its High Risk region for severe weather today, warning that "The setup appears most favorable for large, relatively slow moving intense storms with large hail. A couple strong tornadoes also may occur."

I'll be back with a new post Thursday morning.

Jeff Masters

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Quoting MiamiHurricanes09:
Can you post the link for the 18z?


Link
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Member Since: 15 juillet 2006 Posts: 176 Comments: 55446
Quoting WaterWitch11:


yep me too hope their not too tight! lol

sorry i thought it was funny but the mind can be a crazy place!


Tell me about it...it's pretty damned funny in mine!
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Quoting Levi32:
18z NOGAPS out to 108 hours getting more aggressive with the Bahamas low.

Can you post the link for the 18z?
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The 18z NOGAPS depicts a rather large and elongated surface trough of low pressure off the SE coast in 5 days, but after all, 12 hours ago there was absolutely nothing here on the model.

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Quoting Weather456:


I do not believe this disturbance will have a role in the Caribbean because upper winds are too fast there. It however, plays a role as it heads east-northeast into the SW Atlantic.

Expect moderate scattered showers today and tomorrow as it does so.
Thanks W456..moderate & scattered showers here in Cayman now.Much rain out East End today Stormwatcher?
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This will be the radar to watch this evening as this major severe weather outbreak unfolds.

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Quoting atmoaggie:

Seriously. Just about impossible for the tar balls found at Key West yesterday (or the day before?) to have come from BP's problem.

At least 5 actual ocean scientist-types have said in the media that we/Florida/the Keys do commonly get tar balls from various sources and have said things like "it is exceedingly unlikely that..." and you guys just know you're somehow right?

Okay, enjoy that. Hey, could you apply that logic to the IPCC? No, that one suits an agenda. So everyone wants to listen to the scientists...sometimes.

L8R.


AMEN
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Don't know if ya'll saw this. My wife just showed it to me. whoa
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The NOGAPS 18z is showing lighter wind shear in the vicinity of our hybrid low as a result of a more pronounced reflection of the trough-split at 200mb.

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Member Since: 3 juillet 2005 Posts: 427 Comments: 129323
Quoting Bordonaro:

Here are the SPC map indicating the current warnings. These supercells are mean and they mean BUSINESS!!!


Boy do they ever mean business. Been watching the Weather Channel coverage and its been just amazing to watch the storm cells come together so rapidly. Its not gonna be a good evening for folks in that area.
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Quoting Acemmett90:

my radar has two tornados on the ground

they are 28 miles apart and the cells are converging its gonna be an intersting night
Quoting stormwatcherCI:
Expert opinions please. If something does form from the Yucatan disturbance would it be anything more than a rainmaker for Cayman ? Not worried or anything, just curious.


I do not believe this disturbance will have a role in the Caribbean because upper winds are too fast there. It however, plays a role as it heads east-northeast into the SW Atlantic.

Expect moderate scattered showers today and tomorrow as it does so.
Member Since: 24 juillet 2005 Posts: 407 Comments: 19076
18z NOGAPS out to 108 hours getting more aggressive with the Bahamas low.

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Quoting DestinJeff:
any update on the T-Team .... tornadotude and tornadoseeker?

my radar has two tornados on the ground
Quoting Weather456:
I'm not all that satisfied with the GFS runs. It seems every run shows something different. Not consistent enough.
Yeah, I would stick with the Euro in this situation.
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18z GFS Day 7....still quite a mess.

What I am taking away from this run is the overall continued trend westward, more towards the Euro solution, which I believe right now is the most reasonable.

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Quoting cchsweatherman:
Been watching the severe weather across Oklahoma over the past hour and must say that the SPC definitely was right in issuing a PDS (Particularly Dangerous Situation) Tornado Watch. Over the past hour, the dry line coming across Western Oklahoma has really become established moving perpendicular to the warm front moving northbound across Oklahoma. You can clearly see it in the visible satellite image below.



As the evening progresses, this dry line will meet the really unstable airmass coming from the front moving northward and could definitely trigger some monster supercells across the Central Oklahoma area including Oklahoma City. In looking at sounding observations from the region, CAPE values have risen to near 3500 and shear profile has become quite favorable for rotating storms.

In fact, there are three distinct cells having already developed across Northern Oklahoma riding the warm front. For all those in Oklahoma, please heed all warnings and have your weather radios ready. This is a really dangerous situation.

Here are the SPC map indicating the current warnings. These supercells are mean and they mean BUSINESS!!!
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Quoting Weather456:
I'm not all that satisfied with the GFS runs. It seems every run shows something different. Not consistent enough.


I agree. The Euro routinely does a far better job handling these complicated trough-split situations.
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Quoting lickitysplit:
SkyTruth is collecting report of oil on the beach. Go here

No oil on Florida beaches, except for 'tar balls" which are a different thing entirely. They could have come from Curacao....
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Expert opinions please. If something does form from the Yucatan disturbance would it be anything more than a rainmaker for Cayman ? Not worried or anything, just curious.
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Quoting Weather456:
I'm not all that satisfied with the GFS runs. It seems every run shows something different. Not consistent enough.

For what its worth, I agree....
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I'm not all that satisfied with the GFS runs. It seems every run shows something different. Not consistent enough.
Member Since: 24 juillet 2005 Posts: 407 Comments: 19076
235. DEKRE
Quoting Floodman:


The find was way too soon. Tarballs form from tanker fuel, petro products dumped into storm drains, and even (dare I say it) naturally occurring oil oozing from the seabed...now that having been said, the seabed rarely oozes a few million gallons of oil in a month


Tarballs are weathered fuel, the residue when everything else has evaporated. The only way tarballs could have formed in the short time available would be from residue left over after the in situ burning.
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Quoting Weather456:


That is actually the feature over the Yucatan. It merges with the hybrid low in this run.
Wow, I'll post the 18z NOGAPS when it comes out.
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233. xcool
CFS DO VERY POOR JOB ON MJO imo
Member Since: 26 septembre 2009 Posts: 2 Comments: 15684
We may be dealing with 2 trough-splits here. Due to the 24-hour intervals on the ECMWF it was not as easy to see, but an amplified shortwave that moves over the Great Lakes here at 72 hours actually digs southeastward and splits off the eastern seaboard near the Carolinas by 120 hours. This all occurs after the longwave trough splits and leaves, and the GFS and Euro seem to have their main disagreement as to the exact location of the splits and how they interact with each other, either by merging or dancing. The latter makes for more of a mess at the surface.

72 hours:



120 hours:


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Been watching the severe weather across Oklahoma over the past hour and must say that the SPC definitely was right in issuing a PDS (Particularly Dangerous Situation) Tornado Watch. Over the past hour, the dry line coming across Western Oklahoma has really become established moving perpendicular to the warm front moving northbound across Oklahoma. You can clearly see it in the visible satellite image below.



As the evening progresses, this dry line will meet the really unstable airmass coming from the front moving northward and could definitely trigger some monster supercells across the Central Oklahoma area including Oklahoma City. In looking at sounding observations from the region, CAPE values have risen to near 3500 and shear profile has become quite favorable for rotating storms.

In fact, there are three distinct cells having already developed across Northern Oklahoma riding the warm front. For all those in Oklahoma, please heed all warnings and have your weather radios ready. This is a really dangerous situation.
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230. xcool



Member Since: 26 septembre 2009 Posts: 2 Comments: 15684
Quoting MiamiHurricanes09:
Interesting to see a 1005 MB low over Jamaica/Cuba. Let's see if any other models jump aboard with this. I doubt it though.


That is actually the feature over the Yucatan. It merges with the hybrid low in this run.
Member Since: 24 juillet 2005 Posts: 407 Comments: 19076
Quoting Levi32:
18z GFS 120 hours....looks rather odd.



Now not only do we have 2 system, but 3. I wonder if any other models will jump unboard with this.

*1006 MB low in the SW Caribbean.
*1006 MB low over the Bahamas.
*1006 MB low over the Atlantic (hybrid)

GFS 18z 132 Hours

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SkyTruth is collecting report of oil on the beach. Go here
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Quoting hurricanejunky:


Wow! What an amazing coincidence. I'm not buying it...


The find was way too soon. Tarballs form from tanker fuel, petro products dumped into storm drains, and even (dare I say it) naturally occurring oil oozing from the seabed...now that having been said, the seabed rarely oozes a few million gallons of oil in a month
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Multiple energy centers on the GFS....the Euro seems to phase all these shortwave disturbances together into a more organized low while the GFS keeps them separate which really results in a mess.

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Quoting hurricanejunky:


Wow! What an amazing coincidence. I'm not buying it...

Why not??
Well, that just goes to show something or the other.
LOL
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Quoting Jeff9641:


Hey Pat, I hope Nola has the levi situation under control this year.


yep me too hope their not too tight! lol

sorry i thought it was funny but the mind can be a crazy place!
Member Since: 11 août 2008 Posts: 3 Comments: 1704
Here in Ft.Myers,FL it has been overcast all day, no sunshine at all. But also, not one drop of rain. Looking at those radar images, it looks like we should be getting hammered. But, nothing doing.
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Quoting Weather456:
18Z GFS out 5 days

Interesting to see a 1005 MB low over Jamaica/Cuba. Let's see if any other models jump aboard with this. I doubt it though.
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220. xcool


18z
Member Since: 26 septembre 2009 Posts: 2 Comments: 15684
18z GFS 120 hours....looks rather odd.



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Conditions at 42056(Yucatan Basin) as of
(4:50 pm CDT)
2150 GMT on 05/19/2010:
Unit of Measure: Time Zone:

Click on the graph icon in the table below to see a time series plot of the last five days of that observation.
5-day plot - Wind Direction Wind Direction (WDIR): NE ( 50 deg true )
5-day plot - Wind Speed Wind Speed (WSPD): 13.6 kts
5-day plot - Wind Gust Wind Gust (GST): 17.5 kts
5-day plot - Wave Height Wave Height (WVHT): 4.3 ft
5-day plot - Dominant Wave Period Dominant Wave Period (DPD): 6 sec
5-day plot - Average Period Average Period (APD): 4.6 sec
5-day plot - Mean Wave Direction Mean Wave Direction (MWD): E ( 95 deg true )
5-day plot - Atmospheric Pressure Atmospheric Pressure (PRES): 29.80 in
5-day plot - Pressure Tendency Pressure Tendency (PTDY): -0.04 in ( Falling )
5-day plot - Air Temperature Air Temperature (ATMP): 78.8 °F
5-day plot - Water Temperature Water Temperature (WTMP): 83.1 °F
5-day plot - Dew Point Dew Point (DEWP): 76.5 °F
5-day plot - Heat Index Heat Index (HEAT): 82.6 °F
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18Z GFS out 5 days

Member Since: 24 juillet 2005 Posts: 407 Comments: 19076
Quoting atmoaggie:

Seriously. Just about impossible for the tar balls found at Key West yesterday (or the day before?) to have come from BP's problem.

At least 5 actual ocean scientist-types have said in the media that we/Florida/the Keys do commonly get tar balls from various sources and have said things like "it is exceedingly unlikely that..." and you guys just know you're somehow right?

Okay, enjoy that. Hey, could you apply that logic to the IPCC? No, that one suits an agenda. So everyone wants to listen to the scientists...sometimes.

L8R.

Good shot!
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Quoting MiamiHurricanes09:

Hmm, boundary collision...
...right...
...about...
...now.

(really leaving, now)
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Quoting RitaEvac:
Let me know if you think the map site is slick or not weather456, be sure to turn off radar and temps, and loop about .10 second animation


Actually I have been using it in the past and find it quite useful for getting quick weather obs for a system affecting land.
Member Since: 24 juillet 2005 Posts: 407 Comments: 19076
From cnn.com. Dr.Masters was quoted.

Weather Underground meteorologist Jeff Masters said Tuesday that based on satellite imagery, "the oil is definitely in the Loop Current. ... The only question is how much oil made it in."
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Quoting MiamiHurricanes09:
I thought it was. Thanks.


upper level forcing kept amplifying the surface trough and eventually amplified enough you could see spinning in the low levels.
Member Since: 24 juillet 2005 Posts: 407 Comments: 19076

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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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