An African wave worth watching; 2nd warmest June on record
There's finally a African tropical wave worth mentioning, in what has been a very inactive June/July period for African waves with a potential to develop. A tropical wave near 12N 36W, about 1200 miles west of the coast of Africa, is triggering some modest heavy thunderstorm activity over the open ocean as the storm moves west at 10 - 15 mph. NHC designated this wave 97 L at noon today. Wind shear is a modest 15 knots over the disturbance, which is low enough to allow some slow development over the next few days. As long as the disturbance stays south of Puerto Rico's latitude (18°N), wind shear should remain low enough to allow development. However, there is a substantial amount of African dust and dry air surrounding the system on its west and north sides. This dry air will retard development, and may be able to completely disrupt the disturbance at some point over the next 3 - 4 days. None of the computer models develop the disturbance. The National Hurricane Center is giving this system a low (less than 30% chance) of developing into a tropical depression in the next 48 hours.
Figure 1. The first African wave of 2009 worth watching.
Second warmest June on record
The globe recorded its second warmest June on record, 0.02°C short of the record set in 2005, according to the National Climatic Data Center. The period January - June was the fifth warmest such period on record. Global temperature records go back to 1880. The most notable warmer-than-average temperatures were recorded across parts of Africa and most of Eurasia, where temperatures were 3°C (5°F) or more above average. The global ocean Sea Surface Temperature (SST) for June 2009 was the warmest on record, 0.59°C (1.06°F) above the 20th century average. This broke the previous June record set in 2005. The record June SSTs were due in part to the development of El Niño conditions in the Eastern Pacific. If El Niño conditions continue to strengthen during the coming months, we will probably set one or more global warmest-month-on-record marks later this year. The last time Earth experienced a second warmest month on record was in October 2008.
Figure 1. Departure of temperature from average for June 2009. Image credit: National Climatic Data Center.
June sea ice extent in the Arctic 4th lowest on record
June 2009 Northern Hemisphere sea ice extent was the 4th lowest since 1979, according to the National Snow and Ice Data Center. The record June low was set in 2006. This summer's melt is lagging behind the melting in the summer of 2007, which set the record for the lowest amount of summer sea ice in the Arctic. Forecasts of summer Arctic sea ice melt made in early June by two teams of German scientists put the odds of a new record sea ice minimum this year between 7% and 28%. With the amount of sunlight in the Arctic now on the wane, it appears unlikely that we will set a new record sea ice minimum in 2009. This year will probably have the 2nd or 3rd least sea ice extent on record come September, when the melting season ends. The ice-free seas that nearly surround Greenland now have contributed to temperatures of 2 - 3°C above average over the island over the past ten days. With clear skies and above-average temperatures likely over most of the island for at least the next week, we can expect near-record July melting over portions of the Greenland Ice Sheet this month.
Northwest Passage likely to open for the third consecutive year
The fabled Northwest Passage is more than half clear now, and has a good chance of melting free for the third consecutive year--and third time in recorded history. The first recorded attempt to find and sail the Northwest Passage was in 1497, and ended in failure. The thick ice choking the waterways thwarted all attempts at passage for the next four centuries. Finally, in 1905, Roald Amundsen completed the first successful navigation of the Northwest Passage. It took his ship two-and-a-half years to navigate through narrow passages of open water, and his ship spent two cold, dark winters locked in the ice during the feat.
We can be sure the Northwest Passage was never open from 1900 on, as we have detailed ice edge records from ships (Walsh and Chapman, 2001). It is very unlikely the Passage was open between 1497 and 1900, since this spanned a cold period in the northern latitudes known as "The Little Ice Age". Ships periodically attempted the Passage and were foiled during this time. The Northwest passage may have been open at some period during the Medieval Warm Period, between 1000 and 1300 AD.
Figure 3. Ice extent as measured by an AMSR-E microwave satellite sensor on July 15, 2009. Most of the famed Northwest Passage (red lines) has melted out. Image credit: University of Bremen.
References
Walsh, J.E and W.L.Chapman, 2001, "Twentieth-century sea ice variations from observational data", Annals of Glaciology, 33, Number 1, January 2001 , pp. 444-448.
I'll have an update on the African tropical wave at least once this weekend if the system doesn't fall apart.
Jeff Masters
Reader Comments
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Yes good explaination however I dont totally agree with it. I am not sold there is a low at the surface. Also that SFC chart is old, the front over southern CONUS has already moved much farther east which is going to shift the long wave pattern and I think it could impact the ridge building in leaving shear levels too high.
Latest IR Atlantic Image
Beell is one of the steering gurus here. I liked his take on it.
Add in my gut feeling to the cyclogenesis probabilities. Otherwise well written. lol
RIP 2009??? That reminds me of my uncle. People were calling him for dead three years before he actually went. Besides, El Nino is not the grim reaper for all storms.
You need to go back and read the post - I didn't say "sfc" - I said "low pressure." The sfc map is from NOAA - it ain't that dayumed old. But, that's cool, we don't all have to agree here - it's weather, folks have different opinions. Plz, just don't mis-quote what I post. Thanks.
Walter Cronkite reflects on what it was like to be on the air while watching the first man reach the moon. (CBSNews.com)
Link
No worries...wasnt starting anything but usually when we say low pressure it is assumed at the surface. Low pressure results in a low. My bad for assuming.
As for the chart there are a lot of charts done on 3 hour intervals or you can just get the raw data and check it out. 6 hours is a long time and with a nice front like we are seeing in CONUS, it is moving pretty quick and will shift the long wave pattern which steers these trop waves.
How did the models verif this afternoon?
FLASH******
Walter Cronkite has passed away.
RIP
Get off your dayum high horse MLC, it is just a weather blog!
Excellent point - ********pooooof**********, another one joins the ignore list early. Thanks. Glad I didn't have to weed through more of that crap!
RB, hat's not the only thing that looks like...well, nevermind.
Looks like most everyone is in agreement on steering, for the most part. I like MLC's explanation.
Uhm, there's a place called HAMWeather, they might have some plots, probably the same ones from earlier, tho, if anyone's interested in grabbing them.
They are Long enough to see significant synoptic changes.
Atlantic Ocean View (Updated ~3 hours)
it might not be the cat 4 that China is used to but they better watch out this is a serious rain maker
No No how did the verify? Like high low placement, intensity, wind direction, wind speed, frontal placement etc.
strong winds
So did anyone ever find out why we went from 95L to 97L? lol.
evening here! never did hear an answer on that one, maybe someone forgot to count...
Typo? haha just kidding but it is interesting. Must have missed on or they felt 96L is bad luck just like high rises dont have a 13th floor?
yep
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