A record quiet start to the 2010 Northern Hemisphere tropical cyclone season
The remnants of Tropical Depression Five have re-organized this morning, and the storm is pounding Southeast Louisiana with heavy rains. Radar imagery out of New Orleans shows that the remains of TD 5 have have formed some respectable low-level spiral bands that have brought heavy rains in excess of five inches in some areas. However, with the circulation center now moving over land, not much further development can occur.
Figure 1. Morning radar image of TD Five's remains.
Why so quiet in the Atlantic?
The Tropical Atlantic is quiet, and there are no threat areas to discuss today. The Invest 93 system we were tracking has been destroyed by dry air and wind shear. There are a couple of long-range threats suggested by some of the models--the GFS model predicts a tropical depression could form off the coast of Mississippi six days from now, and the NOGAPS model thinks something could get going in the Gulf of Mexico's Bay of Campeche seven days from now. Neither of these possibilities are worthy of concern at present. Overall, it's been a surprisingly quiet August, considering the pre-season predictions of a hyperactive season. According the National Hurricane Center, this hurricane season has been exactly average so far. There have been three named storms and one hurricane as of August 12. The average date of formation of the third named storm is August 13. One hurricane typically forms by August 10. One reason for this year's inactivity may be an unusual number of upper-level low pressure systems that have paraded across the tropical Atlantic. These lows, also called Tropical Upper Tropospheric Trough (TUTT) lows, tend to bring high wind shear that inhibits tropical cyclone formation. The other major factor appears to be that vertical instability has been unusually low in the Atlantic over the past month. Instability is measured as the difference in temperature between the surface and the top of the troposphere (the highest altitude that thunderstorm tops can penetrate to.) If the surface is very warm and the top of the troposphere is cold, an unstable atmosphere results, which helps to enhance thunderstorm updrafts and promote hurricane development. Since SSTs in the Atlantic are at record highs, enhancing instability, something else must be going on. Dry air can act to reduce instability, and it appears that an unusually dry atmosphere over the Atlantic this month is responsible for the lack of instability.
Figure 2. Vertical instability (in °C) over the Caribbean (left) and tropical Atlantic between the Lesser Antilles Islands and coast of Africa (right) in 2010. Normal instability is the black line, and this year's instability levels are in blue. The atmosphere became much more stable than normal in both regions at the end of July. This lack of instability also extends to the Gulf of Mexico and North Atlantic Ocean between Europe and North America, as well as the Western Pacific east of the Philippines, and the South Indian Ocean. Image credit: NOAA/CIRA.
A record quiet start to the 2010 tropical cyclone season in the Northern Hemisphere
What is really odd about this year, though, is the lack of tropical cyclone activity across the entire Northern Hemisphere. Usually, if one ocean basin is experiencing a quiet season, one of the other ocean basins is going bonkers. That is not the case this year. Over in the Eastern Pacific, there have been five named storms and two hurricanes. The average is seven named storms and four hurricanes for this point in the season. This year's quiet season is not too surprising, since there is a moderate La Niña event underway, and La Niña conditions usually supresses Eastern Pacific hurricane activity. But over in the Western Pacific, which usually generates more tropical cyclones than any ocean basin on Earth, it has been a near-record quiet season. Just four named storms have occurred in the West Pacific this year, and the average for this date is eleven. Only one typhoon season has had fewer named storms this late in the season--1998, with just three. The total number of named storms in the Northern Hemisphere thus far this year is fifteen, which is the fewest since reliable records began in 1948. Second place belongs to 1983 and 1957, with eighteen named storms. According to an email I received from NOAA hurricane researcher Gabe Vecchi, the lack of tropical cyclones so far this year in the Northern Hemisphere is between a 1-in-80 and 1-in-100 year event.
So, what is causing this quiet tropical cyclone season? One possibility is that since Northern Hemisphere land areas have heated up to record temperatures this summer, this has created strong rising motion over the continents. This rising motion must be compensated by strong sinking motion over the adjacent oceans in order to conserve mass. Sinking air causes drying and an increase in stability. Another possibility is that the unusual jet stream configuration that is responsible for the Russia heat wave and record flooding in Pakistan is also bringing dry, stable air to the Northern Hemisphere's tropical cyclone breeding grounds. It is also possible that climate change is causing the reduction in tropical cyclone activity, for a variety of complex reasons. Computer simulations of a future warmer climate generally show a reduction in global number of tropical cyclones (though the strongest storms get stronger), and it is possible we are seeing a preview of that future climate. Or, this year's quietness may simply be natural variability. It will be interesting to see when the Russian heat wave breaks if vertical instability over the Atlantic increases back to normal levels. Current forecasts from the GFS and ECMWF models project the Russian heat wave to break late next week.
Moscow's air remains clear; coolest temperatures in two weeks
Moscow's winds remained favorable for keeping smoke away from the city today, and temperatures "cooled" to at Moscow's Domodedovo airport to 33°C (91°F)--the lowest maximum temperature since a high of 32°C (90°F) was recorded on July 30. Moscow's airport has reached a maximum temperature of 30°C (86°F) or higher for 35 consecutive days now (at Moscow's official observing site, the Moscow Observatory, this string is 30 days.) Moscow's average high temperature for August 12 is 20°C (68°F). Moscow's high temperatures have averaged 15°C (27°F) above average so far this August--a truly extraordinary anomaly for a country so famous for its notorious cold weather. The latest forecast for Moscow calls for high temperatures of 30 - 33°C (86 - 91°F) Thursday through Monday. This is still 23°F above normal, but will be a welcome change from the extreme heat of the past two weeks. Long range forecasts from the ECMWF and GFS models continue to suggest that a series of troughs of low pressure will begin to attack the ridge of high pressure anchored over Russia beginning on Wednesday, bringing cooler temperatures just 5°C (8°F) above average to Russia late next week. By ten days from now, the ECMWF model shows a strong trough of low pressure over Moscow, and a end to the Great Russian Heat Wave of 2010.
Next update
I'll have an update Friday morning.
Jeff Masters
Reader Comments
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NATIONAL WEATHER SERVICE NEW ORLEANS LA
341 PM CDT THU AUG 12 2010
.SHORT TERM...
DISORGANIZED REMNANTS OF TD 5 ARE CONTINUING TO IMPACT PORTIONS OF
SOUTHEAST LOUISIANA AND SOUTHERN MISSISSIPPI. RADAR/SATELLITE
LOOPS INDICATE THAT THE EARLIER LOW PRESSURE CIRCULATION IS
LARGELY UNAPPARENT...ALTHOUGH IT APPEARS THAT SOME SORT OF
WEAK CIRCULATION HAS REFORMED SLIGHTLY TO THE EAST DIRECTLY SOUTH
OF COASTAL MISSISSIPPI. CONVECTION IS LARGELY CONFINED TO WEST
SIDE OF THE LOW...WHICH IS KEEPING PORTIONS OF FAR SOUTHEAST
LOUISIANA...INCLUDING THE NEW ORLEANS METRO AREA...IN THE
IMMEDIATE HEAVY RAIN THREAT. ACROSS THE REMAINDER OF THE
AREA...CONVECTION HAS BEEN SLOW TO DEVELOP AROUND THE BATON ROUGE
AND MCCOMB AREAS...BUT SCATTERED DIURNAL CONVECTION IS BEGINNING
TO SHOW ITSELF IN THESE AREAS.
THE LOW ITSELF SHOULD BEGIN TO MOVE SLOWLY TO THE NORTHWEST
THROUGH THE NIGHT AND INTO FRIDAY...WITH PERIODS OF HEAVY RAIN
CONTINUING. GREATEST HEAVY RAIN IMPACT STILL LOOKS TO BE ACROSS
FAR SOUTHEAST LOUISIANA...PARISHES ALONG THE GULF COAST...AND
COASTAL MISSISSIPPI. HOWEVER...MORE ISOLATED BOUTS OF MODERATE TO
HEAVY RAIN COULD OCCUR ACROSS THE REMAINDER OF THE FORECAST AREA.
WILL LEAVE THE ORIENTATION AND DURATION OF THE FLASH FLOOD WATCH
AS IS FOR NOW...WITH ENOUGH UNCERTAINTY REMAINING AS TO HOW LONG
THE LOW WILL REMAIN IN THE AREA.
FROM FRIDAY NIGHT ON...THE PRECIPITATION COVERAGE WILL LIKELY
BEGIN TO DECREASE...WITH THINGS RETURNING TO MORE OF A DIURNAL
THUNDERSTORM CYCLE. KAH
.LONG TERM...
UNCERTAINTY ABOUNDS IN THE EXTENDED...WITH THE GFS AND ECMWF BOTH
WANTING TO CURVE TD 5/S REMNANTS ACROSS THE SOUTHEASTERN CONUS AND
BACK OUT INTO THE GULF. A FRONTAL BOUNDARY WILL ALSO MOVE INTO THE
REGION LATE IN THE WEEKEND AND EARLY NEXT WEEK. STILL SOMEWHAT
SKEPTICAL ABOUT THE GFS AND ECMWF SOLUTIONS...BUT WILL CONTINUE TO
CARRY HIGHER DAYTIME POPS THROUGHOUT MUCH OF THE EXTENDED...WITH
THINGS DRYING OUT MARGINALLY TOWARD LATE NEXT WEEK. TEMPERATURES
WILL LARGELY BE NEAR TO ABOVE NORMAL THROUGHOUT THE EXTENDED. KAH
Back to top of the page up there ^
None since the Morning
you just got my vote for best avatar...lol
What about TX?
That's the Yugo 3000, right?
3:30PM EDT, THURSDAY, AUGUST 12, 2010
Remnant Tropical Depression Five continues to be a flood threat along the central Gulf Coast. Isolated areas of southeast Louisiana have received in upward of 10 inches of rainfall within the last 24 hours. A lot more rainfall is on the way. Surface observations, radar, and satellite data all indicate that the elongated 1008mb low center is still over the Chandeleur Sound. The low center hasn't gone completely inland just yet, and it may take at least several more hours to make landfall. Even once the low comes inland, the threat of heavy rainfall is likely to persist for the foreseeable future.
The 12Z runs of the GFS, CMC, UKMET, and ECMWF models all show the remnant low meandering around central Mississippi or Alabama before being shunted back into the northern Gulf of Mexico within the next 5 days. It is too early to say whether the low will fully re-emerge back into the Gulf after spending several days over land. However, the low will more likely maintain itself for an unusual amount of time over land due to a very favorable upper high located over the central Gulf Coast states. Frequent bands of heavy rainfall are likely to persist over the southern half of Louisiana, Mississippi, Alabama, and possibly even the Florida panhandle through the next 5 days. While breaks in rainfall will be occurring between these bands,isolated flooding in low lying areas is going to happen given the increasingly high totals from over an extended period. In addition to the flooding threat, we may very well have to watch for slight re-intensification down the road if the models happen to be correct. In short, Tropical Depression Five is far from finished.
Elsewhere in the tropical Atlantic, the pattern is beginning to change. First of all, a mid-level high pressure center over the southeast USA has induced troughing in the western Atlantic for most of the season thus far. Western Atlantic troughing enhances the number of upper lows traversing the Atlantic, Caribbean Sea, and Gulf of Mexico. As you may know, these upper lows can create a lot of unfavorable shear that disrupts tropical cyclones. Model forecasts show the pattern reversing. A trough will replace the southeast high pressure area over the next 7 days, and more mid-level ridging will take shape over the northwest Atlantic. This pattern should allow for a more favorable pattern for tropical cyclogenesis over the deep tropical Atlantic. Furthermore, the global Madden Julian Oscillation has been in an unfavorable state since mid to late July. A downward MJO supports a lack of vertical lift over the Atlantic, thus less tropical activity. Medium range models have shown the MJO becoming more favorable around August 20th for the past couple weeks. Given the change in both the pattern and the MJO, it looks as if the a real spike in activity will begin before the end of the month.
The potential start of the Atlantic increase in activity may occur in the eastern Atlantic near the African coast. While it is far too early to call for tropical development, the operational GFS has shown a tropical wave exiting Africa around Day 5-6. The model quickly strengthens the wave into a formidable tropical cyclone thereafter. The 12Z CMC run is also showing a similar scenario for the first time. In addition, while the 12Z ECMWF is not forecasting tropical development, it is starting to lower surface pressures over the central and eastern Atlantic around that time period.
Finally, the southwest Atlantic may also be an area to keep an eye on in the medium range. While no model is forecasting much in the way of disturbed weather, the ECMWF and GFS have been lowering surface pressures ever so slighly off the east coast of Florida. The southwest Atlantic and Bahamas does typically become an area to watch once mid-level ridging develops to the north near Atlantic Canada and New England.
I haven't seen any. Showers have been pretty light in NOLA for most of the day.
hmmmm. we will see I guess.
How'd you know that LOL!
its going under shear
Thanks for the picture.....I will believe when I see it though...
Are you sure you're east of St Lucia and not an island further north? I don't believe there is this much weather in the area you mentioned.
Tropical wave being influenced by the TUTT. Development unlikely.
yes, it will.
NATIONAL WEATHER SERVICE NEW ORLEANS LA
421 PM CDT THU AUG 12 2010
THE NATIONAL WEATHER SERVICE IN NEW ORLEANS HAS ISSUED A
* SEVERE THUNDERSTORM WARNING FOR...
EAST CENTRAL WASHINGTON PARISH IN SOUTHEAST LOUISIANA...
CENTRAL PEARL RIVER COUNTY IN SOUTHERN MISSISSIPPI...
THIS INCLUDES THE CITY OF POPLARVILLE...
* UNTIL 500 PM CDT
* AT 419 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A
SEVERE THUNDERSTORM CAPABLE OF PRODUCING DAMAGING WINDS IN EXCESS
OF 60 MPH. THIS STORM WAS LOCATED NEAR POPLARVILLE...AND MOVING
WEST AT 20 MPH.
* OTHER LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO
MCNEIL AND CROSSROADS
PRECAUTIONARY/PREPAREDNESS ACTIONS...
THIS IS A DANGEROUS STORM. IF YOU ARE IN ITS PATH...PREPARE
IMMEDIATELY FOR DAMAGING WINDS...DESTRUCTIVE HAIL...AND DEADLY CLOUD
TO GROUND LIGHTNING. PEOPLE OUTSIDE SHOULD MOVE TO A SHELTER...
PREFERABLY INSIDE A STRONG BUILDING BUT AWAY FROM WINDOWS.
&&
ok
I fear for you, my friend, if everything I say makes sense...I hear that medication helps!
Thanks, by the way, to you and all my supporters...now, on to November!
ok
lol
is that going to hit NJ???!!! looks awful close :(
if you guys could give me feedback on my 2010 hurricane season forecast it would be greatly appreciated
Nic try JFV you ar re ported
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