It is a well-known phenomenon that the Tropical North Atlantic (TNA) warms in boreal spring and early summer (April – June) following El Nino peaks in boreal winter (Enfield and Mayer, 1997). This involves formation of the so-called extratropical atmospheric stationary Rossby wave trains from the tropical Pacific (e.g., Lee et al., 2008). A new paper published... Continue Reading →
Increasing frequency of North American winter extremes caused by the eastward shift of the North Pacific Oscillation
The North Pacific Oscillation (NPO) is a dipole oscillation of the sea level pressure (or the atmospheric mass) between the subpolar low and subtropical high over the North Pacific Ocean. A study published in Nature Climate Change showed that the center of the NPO shifted eastward during the recent decades (1995-2014), and thus increased the frequency of... Continue Reading →
2019 US severe weather season kicked off with deadly tornado outbreak in Alabama and Georgia
2019 US severe weather season started with 39 reported tornadoes throughout southeastern Alabama, Georgia, Florida Panhandle and South Carolina in March 3. At least 20 people have been confirmed dead in Lee County, Alabama alone. On March 2 at 10:51am, NOAA/SPC forecasted an enhanced risk of severe thunderstorms for Sunday, March 3, from southern Alabama... Continue Reading →
Pantropical inter-ocean interactions & the rising influence of tropical Atlantic Ocean
Conventional view so far has been that El Nino - Southern Oscillation (ENSO) is largely responsible for energizing the dominant modes of SST variability in the tropical Atlantic and Indian Oceans through changes in the Walker circulation and extratropical atmospheric waves. However, recent studies have shown that SST variability in the tropical Atlantic and Indian... Continue Reading →
Ocean precursors to the extreme Atlantic 2017 hurricane season
A recent study published in nature communications investigated three ocean precursors, namely surface latent heat flux and wind stress curl over the main development region (MDR, 10–20°N, 20–80°W) and the Atlantic Meridional Overturning Circulation (AMOC) at 26.5°N, to the active hurricane seasons in 2005, 2010 and 2017. The study showed that in 2005 and 2010, a weakened... Continue Reading →
Recent warming of the Indian Ocean suppresses the Indian summer monsoon circulation
A recent article published in Science Advances analyzed an atmospheric reanalysis dataset (MERRA2) covering the 1980–2016 period to show that a significant warming occurred in the Indian Ocean over the study period, and thus reduced the temperature difference between the Indian subcontinent and Indian Ocean in boreal summer. The reduced land-ocean temperature difference in turn produced anomalous... Continue Reading →
Arctic sea-ice decrease may suppress U.S. tornado activity in summer
The observed losses in Arctic sea ice during the past decades have been linked to the relaxation of poleward thickness gradients (thus weakened zonal winds) and a slower eastward progression of Rossby waves in the upper-level, which help promote prolonged extreme weather conditions, such as heat waves, within the mid-latitudes (e.g., Francis & Vavrus, 2012). However, the background... Continue Reading →
June 14, 2018 – ENSO Update: El Niño Watch
NOAA CPC's current ENSO alert system status is El Nino Watch: ENSO-neutral is favored through Northern Hemisphere summer 2018, with the chance for El Niño increasing to 50% during fall, and ~65% during winter 2018-19. http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.shtml https://www.climate.gov/news-features/blogs/enso/june-2018-enso-update-el-ni%C3%B1o-watch
June 2, 2018 – Preliminary data from NOAA’s Storm Prediction Center indicate that the U.S. had a record low number of tornadoes
The spring severe weather season for the U.S. (March - May) is finally over. We had 449 EF0 - EF5 tornadoes from Jan 1 to June 2, which is a record low number for the period and certainly well below the historical average during 2005 - 2015 (792). Recent studies have suggested that U.S. tornado... Continue Reading →
May 24, 2018 – NOAA’s Climate Prediction Center predict a near- or above-normal 2018 Atlantic hurricane season
NOAA’s forecasters predict a 70-percent likelihood of 10 to 16 named storms (winds of 39 mph or higher), of which 5 to 9 could become hurricanes (winds of 74 mph or higher), including 1 to 4 major hurricanes (category 3, 4 or 5; with winds of 111 mph or higher). An average hurricane season produces 12 named storms,... Continue Reading →
Ocean to Climate 