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

By: Dr. Jeff Masters , 8:09 PM GMT on May 19, 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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161. xcool


examiner.com
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Quoting atmoaggie:
Hmmm, not going to say "I told ya so".

Seemed like a number of folks were just ready to assume...

Florida Keys Tar Balls Not From Gulf Oil Spill
http://www.benzinga.com/press-releases/10/05/b291050/coast-guard-florida-keys-tar-ball s-not-from-gu lf-oil-spill


This is what I was saying yesterday. Tar balls are common in Florida and not unsual to find especially during high ship tracffic time and when dredging is occurring. The media is ready to blame everything on BP. The point being is that when you walk on a beach you are not looking for tar balls but now that this spill is happening you a are looking for them.
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I posted it on your March 17 blog. Why, I have no idea. I thought it worth mentioning, that disturbance being detected by the models in the Caribbean Sea would be very near or over that very warm pool of water showing up on the water temperature map.
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GFS long term has literally started cranking storms out left and right, even past the 2 we are looking at fro early next week.
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Quoting Jeff9641:


SE US and Gulf coast areas are in for a long season.


Way too early to commit to something like that. No idea how the Bermuda High and westerlies will have an impact on the upcoming season. As always, need to stay alert and it only takes one storm to make it a memorable one. 1992 - only seven named storms, but Andrew hit. 2005 - 28 named storms, no landfalling storms from north Florida through entire SC coast.
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Quoting Levi32:


Good for them. That's a forecaster who isn't a slave to the models.


lol
Member Since: July 24, 2005 Posts: 407 Comments: 19076
154. xcool


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Quoting Jeff9641:


SE US and Gulf coast areas are in for a long season.
Yup, I'm going to purchase my generator before June 1st. I'm probably going to need it in Miami, but I hope I don't need to.
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Notice the Low in Carib....
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Link
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NEXRAD Radar
Oklahoma City, Base Reflectivity 0.50 Degree Elevation Range 124 NMI



Kingfisher
Forecasts for Oklahoma Return to U.S. Severe Weather
Current Severe Weather

Tornado Warning

Statement as of 3:56 PM CDT on May 19, 2010

The National Weather Service in Norman has issued a

* Tornado Warning for...
northwestern Kingfisher County in central Oklahoma...
southwestern Garfield County in northern Oklahoma...

* until 445 PM CDT

* at 356 PM CDT... National Weather Service radar indicated a severe
thunderstorm capable of producing a tornado 16 miles southwest of
Bison... moving northeast at 20 mph.

* Locations in the warning include Bison and Lacey.

Precautionary/preparedness actions...

Take cover now. Leave Mobile homes and vehicles. If possible... move
to a basement or storm shelter. Otherwise move to an interior room or
hallway on the lowest floor. Stay away from windows and outside
walls.


Lat... Lon 3612 9781 3605 9820 3617 9820 3617 9815
3617 9811 3618 9810 3631 9797
time... Mot... loc 2056z 232deg 16kt 3611 9815
Member Since: Posts: Comments:
SSTs aren't strong enough to support a hurricane off the FL coast. The 26C threshold is only in the gulfstream, so it appears this system will be mostly subtropical IF it develops. Once it approaches the gulfstream it could then begin to acquire tropical characteristics if conditions permit.
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Quoting CybrTeddy:


About?


Press
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Quoting Jeff9641:
Local news outlets in Orlando weather in house computer models show a very STRONG LOW Sub TS/Hurricane impacting NE FL by next Wednesday!!!!!!!
Very interesting. Looks to be similar to what the ECMWF is showing.
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Quoting Jeff9641:
Local news outlets in Orlando weather in house computer models show a very STRONG LOW Sub TS/Hurricane impacting NE FL by next Wednesday!!!!!!!


I wouldn't be throwing around the "H" word just yet, for either of the two disturbances. There is a lot to be worked out in the upper levels before either system will have a chance of getting that strong.
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Quoting Jeff9641:
Local news outlets in Orlando weather in house computer models show a very STRONG LOW Sub TS/Hurricane impacting NE FL by next Wednesday!!!!!!!


Jeff I must applaud you're call of this hybrid low. Good job.
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Quoting Jeff9641:
Fun In Games begin for Florida!

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MELBOURNE FL
325 PM EDT WED MAY 19 2010

WILL ALSO BE TRACKING TWO FEATURES OF INTEREST THROUGH THIS WEEKEND
...ALONG WITH HOW THE SUBSEQUENT MODEL RUNS CONTINUE TO HANDLE THESE
FEATURES. THE FIRST IS THE AFOREMENTIONED WRN ATLC SHORT WAVE TROUGH
THAT WILL SPIN UP A SFC LOW SOMEWHERE BTWN 25-30N AND 70-75W. THE
SECOND AND MORE IMPACTING FEATURE (EVENTUALLY) WILL BE THE NRN
STREAM SHORT WAVE TROUGH WHICH MOVES ENEWD THROUGH THE MIDWEST AND
GRT LKS RGNS FRI/ SAT...THEN MAKES AN ABRUPT RIGHT HAND TURN ON
SUN...DROPPING EITHER SHARPLY SWD ALONG THE MID ATLC/SERN SEABOARD
(GFS SOLN) OR SSE INTO THE WRN ATLC WHERE IT PHASES WITH THE
TROUGH/LOW ALREADY THERE AND BECOMES VERTICALLY STACKED (ECM SOLN).
GIVEN THE PRONOUNCED UPSTREAM AMPLIFICATION...SIGNIFICANT HGT FALLS
APPEAR LKLY ALONG OR JUST OFFSHORE THE EAST COAST. EXACTLY WHERE
THIS OCCURS WILL DETERMINE THE EXTENT OF INTERACTION BTWN THE TWO
SYS...AND HENCE HAVE HUGE FCST RAMIFICATIONS LCLY...ESPEC FROM MON
ONWARD.

MON-WED...FCST BCMS UNCERTAIN GIVEN THE DISPARITY IN THE GFS/ECM
SOLNS. IT IS IMPORTANT TO NOTE THAT THE LATEST GFS IS STRONGER AND
MORE CUTOFF AT H50 THAN PREV RUNS...AND THUS HAS TRENDED TWD THE
ECM. BRAND NEW 12Z ECM HOT OFF THE PRESSES IS ALMOST IDENTICAL TO
IT`S 00Z SOLN AT BOTH THE SFC AND H50...ALBEIT JUST A BIT FATHER
NORTH WITH WHERE THE STACKED LOW MOVES INTO THE SERN CONUS (CLOSER
TO THE FL/GA BORDER RATHER THAN INVOF SGJ-DAB). WHAT SEEMS MORE
CERTAIN IS THAT THE UPPER SYSTEM WILL BE FAIRLY STOUT AND WILL
RETROGRADE SWWD UNDERNEATH THE STRONG UPPER HIGH TO ITS NORTH...

EVENTUALLY WINDING UP CLOSE ENOUGH TO CTRL/NORTH FL TO PRODUCE
UNSETTLED WX BY TUE/WED. SHOULD CONTINUE TO SEE AN ONSHORE FLOW
REGIME...SOMETHING BTWN ENE AND NE...WITH SUFFICIENT MOISTURE TO
PRODUCE AT LEAST SCT POPS...PSBLY HIGHER


Good for them. That's a forecaster who isn't a slave to the models.
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For those who want to keep an eye on the Severe Weather in OK, KFOR-TV LIVE STREAM below:
Link
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Hook Echo forming
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132. xcool



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Quoting wunderkidcayman:
New surface map new surface map!!!!!!!!!!!!!!

18Z SURFACE MAP



OLD SURFACE MAP 12Z


Yes, but (always a yes, but)

These are not generated by an objective algorithm, but by a human. *Some* things might change from one analysis to the next simply because a different person is conducting the analysis. Sure, there are guidelines for analyzing a low, ITCZ, front, etc., but no hard and fast rules.
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NEXRAD Radar
Oklahoma City, Base Reflectivity 0.50 Degree Elevation Range 124 NMI




Kingfisher
Forecasts for Oklahoma %u2014 Return to U.S. Severe Weather
Current Severe Weather

Tornado Warning

Statement as of 3:56 PM CDT on May 19, 2010

The National Weather Service in Norman has issued a

* Tornado Warning for...
northwestern Kingfisher County in central Oklahoma...
southwestern Garfield County in northern Oklahoma...

* until 445 PM CDT

* at 356 PM CDT... National Weather Service radar indicated a severe
thunderstorm capable of producing a tornado 16 miles southwest of
Bison... moving northeast at 20 mph.

* Locations in the warning include Bison and Lacey.

Precautionary/preparedness actions...

Take cover now. Leave Mobile homes and vehicles. If possible... move
to a basement or storm shelter. Otherwise move to an interior room or
hallway on the lowest floor. Stay away from windows and outside
walls.


Lat... Lon 3612 9781 3605 9820 3617 9820 3617 9815
3617 9811 3618 9810 3631 9797
time... Mot... loc 2056z 232deg 16kt 3611 9815
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Quoting Acemmett90:

gfs has a wacky track though


That is not the current Low your looking at.
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pat,
if i don't see your question on ac's blog in a couple of hours, i'm going to post it. it's a good question and needs to be asked and nobody has asked as of yet.

ok these pecan pies are not going to make themselves. bbl
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125. xcool
lmao
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Quoting Weather456:


Atmospheric pressures are also below climatological mean which is a great way of assessing cyclogenesis.


Yup. They are dipping below normal everywhere from Cape Hatteras south through the Caribbean as of this morning.

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Quoting Floodman:


I always said you were a smart man, atmo!

Let's not get carried away...
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Quoting Floodman:


WUMail me, Teddy...


About?
Member Since: July 8, 2005 Posts: 259 Comments: 24580
Quoting Acemmett90:

1006mb low could that be the one that all the models are picking up on


A Heat Low.
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120. xcool
"So Amazing" how forecasting models work..
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Quoting Acemmett90:

1006mb low could that be the one that all the models are picking up on
That's the Colombian low, it's always there.
Quoting Levi32:


The ECMWF appears to transition the system to fully warm-core right at the end of the forecast run at 240 hours just off the east coast of Florida.
Very interesting.
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Quoting Weather456:


Atmospheric pressures are also below climatological mean which is a great way of assessing cyclogenesis.


SLP Anomalies for May 19

Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting CybrTeddy:


Each season it gets more insane as more of the old crew leave.. we've now lost Press to boot.


WUMail me, Teddy...
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Quoting 2010hurricane:


I'll go with 85% of TS Alex forming

85%...do I hear 90%? 90%?
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Quoting Drakoen:


My bad, between north or northeast


seen
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting Levi32:
Surface pressures have been falling during the past 5 days in the western Caribbean and the Bahamas. This is a sign of the overall pattern starting to favor lower pressures over the entire SW Atlantic.

Caribbean buoy:



Bahamas Buoy:

IMG src="http://www.ndbc.noaa.gov/plot_met.php
station=41046&meas=pres&uom=E&time_diff=-4&time_label=EDT">


Atmospheric pressures are also below climatological mean which is a great way of assessing cyclogenesis.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting atmoaggie:

Dat's what I'm holding out for. Model consensus for a few cycles in a row leading up to the 96 hours out time frame (at a maximum).


I always said you were a smart man, atmo!
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Quoting Drakoen:


After looking at the 12z cyclone phase diagram, there is the possibility for subtropical development east of the Bahamas. The models don't agree on the track of the system so it's difficult to predict more accurately what will happen. The GFS takes it out the east, the ECMWF keeps it going west, the CMC has it going north.

One thing that is interesting on the ECMWF is its forecast for the core temperature to be warmer than the surrounding environment even though the system is largely embedded within the 500mb trough axis.


Figure1. ECMWF 850mb temperature forecast


The ECMWF appears to transition the system to fully warm-core right at the end of the forecast run at 240 hours just off the east coast of Florida.
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About

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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