2013 Hurricane Season: Very Active?

It has been a little over a month since the last of the 2013 hurricane season forecasts were made.  All of the forecasts call for an active season with the possibility of a very active season.  The third named storm of the season (Chantal) formed late on July 6, which is just over a month earlier than when the average “C” storm forms.  Is this a sign of a very active season?  Given conditions in the tropics I would say, yes.

Tropical Storm Chantal moves into the eastern Caribbean Sea.  Click on image for a larger view.  Credit: NOAA.

Two storms have already formed in the deep tropics (Barry, Chantal) and one is a Cape Verde storm which usually doesn’t get going until mid-August.  As Jeff Masters points out on his blog:

"Most years do not have named storm formations in June and July in the tropical Atlantic (south of 23.5°N); however, if tropical formations do occur, it indicates that a very active hurricane season is likely. For example, the seven years with the most named storm days in the deep tropics in June and July (since 1949) are 1966, 1969, 1995, 1996, 1998, 2005, and 2008. All seven of these seasons were very active. When storms form in the deep tropics in the early part of the hurricane season, it indicates that conditions are already very favorable for TC development. In general, the start of the hurricane season is restricted by thermodynamics (warm SSTs, unstable lapse rates), and therefore deep tropical activity early in the hurricane season implies that the thermodynamics are already quite favorable for tropical cyclone (TC) development."

This quote is attributed to Colorado State University researchers Phil Klotzbach and Bill Gray.

The Southeast Drought Continues

Droughts can be insidious.  Just when you think they’re gone, they’re back.  Actually it never went away in the Southeast, it just moved around.  The center of the drought began in northeast Florida in 2011 and moved to southern Georgia a year later.  Now the center of the drought is central Georgia and it is beginning to expand thanks to a dry January.

The Drought Monitor for the end of January 2011-13.  Click on the image for a larger view.  Image Credit: USDA.

The current drought began in the Southeast with the end of El Nino in 2010.  That was followed by two years of La Nina which brought drier than normal conditions particularly in the winter and spring.  The worst of the drought has been centered in central Georgia where extreme to exceptional drought conditions have persisted for two years.

However, drought conditions for southeast Georgia and northeast Florida actually disappeared this past summer thanks to two tropical weather systems (Beryl & Debby) which inundated the region with rain in late May and June.  Drought is creeping back into those areas.

Winter Outlook for 2012-13

The Climate Prediction Center released its early outlook for the upcoming winter this morning.  Much of the western U.S. will see warmer than normal temperatures while cooler than normal temperatures are expected for the Florida peninsula.  Equal chances of above or below normal temperatures are forecast for much of the East.

Much of the West will be dry particularly in the Pacific Northwest.  The Central Gulf region is expected to be wetter than normal.  This may help ease the drought in Georgia and South Carolina.

Click on either graphic for a larger version or go here for the temperature map and here for the precipitation map.  Image Credit: NOAA\CPC.

The Drought Eases In South Carolina

It takes time to move into a drought.  Likewise, it takes time to move out of a drought.  The recent rains have definitely eased the pain for South Carolina.  According to the latest drought monitor from the USDA only 22% of the state is in a severe drought or worse compared to 32% the previous week.  Much of the Pee Dee region is out of the drought completely.

Click on image for a larger view.  Image Credit: USDA.

The first four months of the year were a continuation of the drought that started in January 2010.  Only four months out of the past 28 months had been wet by the end of April.  The total rainfall by then for 2012 was 8.71 inches at the Columbia Metropolitan Airport or just over 2 inches per month.

The 2012 Hurricane Outlook

The Atlantic Basin has the most variable hurricane activity in the world and thus has become a challenge for meteorologists.  There seems to be a fascination with knowing what the season will be like, even if you can’t forecast where they may strike.

The Tropical Meteorology Project at Colorado State University has been making forecasts of the Atlantic hurricane seasons for the past 29 years.  It explains the need to forecast hurricane seasons this way:

“We issue these forecasts to satisfy the curiosity of the general public and to bring attention to the hurricane problem. There is a general interest in knowing what the odds are for an active or inactive season. One must remember that our forecasts are based on the premise that those global oceanic and atmospheric conditions which preceded comparatively active or inactive hurricane seasons in the past provide meaningful information about similar trends in future seasons. This is not always true for individual seasons. It is also important that the reader appreciate that these seasonal forecasts are based on statistical schemes which, owing to their intrinsically probabilistic nature, will fail in some years. Moreover, these forecasts do not specifically predict where within the Atlantic basin these storms will strike. The probability of landfall for any one location along the coast is very low and reflects the fact that, in any one season, most U.S. coastal areas will not feel the effects of a hurricane no matter how active the individual season is.”

Image Credit: SCMED Operations Center.

Every year South Carolina gears up for the expectation of hurricanes.  The state has a state-of-the-art facility to monitor hurricanes and emergency events.  Plans are reviewed and renewed.  Everyone is encouraged to become aware of their local situation and if need be know what routes are to be used for evacuations.  It is important to have hurricane kits and to update them each year.  This is also important for land-lovers since the effects of hurricanes can extend far inland.

Drought Worsens in South Carolina

Droughts are hard to define.  Meteorological droughts are prolonged periods with less than average precipitation, but the prolonged period is nebulous.  How many weeks or months must go by before a drought is declared?  Again this depends on how much precipitation has occurred.  Obviously if no precipitation occurs then it doesn't take long to enter a drought.  Defining when a drought started can also be difficult.  Thus, you often do not know that you are in a drought until it gets serious.

Remember December 2009?  The precipitation total for that month in Columbia was 9.31 inches, almost three times the normal value.  It was a record wet December.  In addition the four month of September through December totaled 25.96 inches which was a record for that four month period.  What happened?  A strong El Nino was in progress and most of the rain that year came in just that four months.

Click on image for the larger version.

In the 28 months since that time there have only been four months of above normal rainfall.  So in retrospect we have been in a period of drought since January 2010.  The rainfall deficit has been enormous during this time.  The deficit in Columbia has reached 25.57 inches in the past 28 months.  However, it is much worse along the Savannah River where Augusta has amassed a deficit of 38.71 inches in the same time period.  Thus the western part of South Carolina is in worse shape than the northeastern part of the state and this is reflected in the USDA Drought Monitor.

Is The Sky Falling?

The media got wind of a story released by NASA and the headline was irresistible.  It was a NASA-funded university study based on NASA satellite data.  Earth's clouds got a little lower, about one percent on average, during the first decade of this century.

Scientists at the University of Auckland in New Zealand analyzed the first 10 years of global cloud-top height measurements (from March 2000 to February 2010) from the Multi-angle Imaging SpectroRadiometer (MISR) instrument on NASA's Terra spacecraft. The study, published recently in the journal Geophysical Research Letters, revealed an overall trend of decreasing cloud height. Global average cloud height declined by around one percent over the decade, or by around 100 to 130 feet (30 to 40 meters). Most of the reduction was due to fewer clouds occurring at very high altitudes.

Data from NASA's MISR instrument on NASA's Terra spacecraft show that global average cloud height declined by about 1 percent over the decade from 2000 to 2010, or around 100 to 130 feet (30 to 40 meters). The graph here shows anomalies in global effective cloud-top height from the 10-year average, corrected to account for seasonal differences. The solid line represents the 12-month running average of 10-day anomalies, while the dotted line represents the trendline calculated by linear regression. Gray error bars indicate the sampling error (plus or minus 26 feet, or 8 meters) in the annual average. Image credit: University of Auckland/NASA JPL-Caltech.

La Nina is Peaking

NASA released today that La Nina appears to be peaking which increases "the odds that the Pacific Northwest will have more stormy weather this winter and spring, while the southwestern and southern United States will be dry."  NASA's satellites Jason-1 and -2 have been monitoring the progress of La Nina.  They recent detected an increase in La Nina conditions in the Pacific, but it is not expected to get any stronger.

The latest image of sea surface heights in the Pacific Ocean from NASA’s Jason-2 satellite shows that the current La Niña is peaking in intensity. Yellows and reds indicate areas where sea surface height is higher than normal (due to warm water), while blues and purples depict areas where sea surface height is lower than normal (due to cool water). Green indicates near-normal conditions. Image credit: NASA/JPL Ocean Surface Topography Team.

"Conditions are ripe for a stormy, wet winter in the Pacific Northwest and a dry, relatively rainless winter in Southern California, the Southwest and the southern tier of the United States," says climatologist Bill Patzert of JPL. "After more than a decade of mostly dry years on the Colorado River watershed and in the American Southwest, and only two normal rain years in the past six years in Southern California, low water supplies are lurking. This La Niña could deepen the drought in the already parched Southwest and could also worsen conditions that have fueled recent deadly wildfires."