UKMO North Atlantic and Tropical Storm forecast , 1 June 2017, predicts slightly enhanced activity when compared to long term averages. The first storm of the year, Arlene, happened in April.
2017 forecast is:
Tropical Storms (> 39mph wind): 13
Hurricanes (> 74 mph wind): 8
ACE index : 145
The Accumulated Cyclone Energy (ACE) index. A measure of the collective intensity and duration of all named tropical storms and hurricanes during the season.
The first storm of the year, Arlene, happened in April.
Anticyclone centered Western Europe gives light and variable winds and clear overnight skies in that part of the world. EOSDIS Worldview captures snowy Alps and radiation fog and low stratus in the Po Valley delineating the mountainous geography of Italy.
The Atlantic Hurricane seasons starts this week on Wednesday the first of June.
Tropical storm naming is well under way already. ‘Bonnie’ (featured image) has just been downgraded from ‘Tropical Storm’ to ‘Tropical Depression’ and is the first system to make landfall on the USA this year.
D: Tropical Depression – wind speed less than 39 MPH S: Tropical Storm – wind speed between 39 MPH and 73 MPH H: Hurricane – wind speed between 74 MPH and 110 MPH M: Major Hurricane – wind speed greater than 110 MPH
The question arises as to the expected intensity of the 2016 season. Theories link the El Nino (ENSO) to the intensity of the hurricane season. It is thought that higher than average sea surface temperatures in the tropical Atlantic follow an El Nino and sea surface temperatures feed energy into tropical storm systems. This has been an El Nino year. Other observations report unusually cold regions of the Atlantic Ocean further north which may mitigate any warming later in the season.
Reports are a little mixed:
Reuters reports that US meteorologists at NOAA predict greater than average numbers this year. NOAA’s website itself is sticking to a ‘near normal’ pattern of tropical storms. Other reports abound.
Always thought that weather forecasting was a tricky business; it makes weather watching interesting though….
News reports communicate that heavy rain, flooding and landslides have taken lives and destroyed infrastructure in East Africa over the last month or so. Some point the finger at El Nino as being the culprit.
The Africa Rainfall Climatology (NOAA NCEP), which estimates rainfall based on satellite derived cloud top temperature fused with station observations and other measurements, shows considerable areas of above average rainfall (see featured image).
Enhanced tropical rainfall in this region is associated with El Nino with its greater than average sea surface temperatures in the Pacific and Indian Oceans. A chart of current sea surface temperature anomalies follows.
SST Anomaly Apr-May 2016
Latest guidance from NOAA NCEP is that El Nino is present and is weakening.
MODIS imagery from NASA Worldview gave us a clear view of the Fort McMurray forest fires on 6 May 16 with and extensive smoke plume extending towards the south east of the area.
Surface winds appear to be light-ish. The smoke plume is streaming down the flow in the middle atmospheric layers at 5000 ft.
The Worldview system also allows us to analyse the concentration of the combustion product, CO. The following split image, covering exactly the same area, shows the more intense area of carbon monoxide in the white and red arc.
An unusually strong El Nino pattern this year is reportedly linked to a ‘deadly red tide’ in Chile. The implication is that sea temperature anomalies are causing an algal bloom which renders fish and shell fish poisonous to eat. Fishermen in Los Lagos are protesting that their government is not doing enough to mitigate the event.
MODIS Aqua imagery presented by NASA can be analysed for Chlorophyll concentration, see featured image above (chlorophyll by MODIS Aqua 26 Apr 16). The oranges and reds indicate high chlorophyll level with blues lower. Such analysis is only possible in cloud free skies. Unfortunately the great southern ocean makes a ready supply of the white puffy stuff and I had to go back a couple of days to get a break in the canopy to get this image.
El Nino is one of the three stages in the El Nino-Southern Oscillation (ENSO). El Nino is a warm anomaly, La Nina is a cold anomaly and the third stage is neutral.
The National Weather Service sea surface temperature is included below for information. Cold up welling along the coast of Chile is a usual part of the ocean circulation and brings nutrients which feed marine life. A warm anomaly suppresses this effect and is bad news for communities reliant on the sea for food. The warm anomaly along the coast of South America shows up in yellows and oranges.
India has been suffering from a heat wave lately: see Heat Wave in India 22 Apr 16, on this blog.
There are now (2 May 16) news reports of many forest fires in Northern India and Nepal. These must have arisen, in part, as a consequence of the prevailing hot and dry conditions of the heat wave.
Evidence of these fires is available from space.
The featured image shows a MODIS analysis of the location of surface fires, these are marked with red dots. The milky white region in the lower right hand quadrant of the picture is, I think, the resulting smoke plume which now covers the region to the south of the Himalaya.
The 5000 ft (850mb) streamlines, taken from the Earth website, back this analysis up by indicating an eastwards movement of air in the middle to lower layers of the atmosphere in this region.
Earth, 850 mb wind 2 May 16
Further analysis of combustion products is also available on MODIS. The white pixels below, coincident with the original white plume, represent relatively high levels of carbon monoxide in the air column.
