keeping watch on the weather and weather related events
Towering cumulus over the London Array, outer Thames Estuary. Complex low pressure lies over the North Sea countries. Watnall balloon suggest unstable to sea surface temperatures with drying up at about 15,ooo ft. AVHRR image, 1420Z, picks out this development at the end of a cumulus boundary running through the south east.
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.
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.
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.
UKMO monthly climate summaries report that March 2016 was a little cold in the UK based past history.
The temperature extremes in Scotland make good reading: maximum overall UK temperature of 
The climate comparisons are different according to which region and data you look at. Residents of Kent will note that the North coast was colder than average by 
Whistable and Herne Bay residents will recognise this picture but will also look forward to the high temperatures we expect in the Thames Estuary during the summer, when the region wins the sunshine race hands down.
UKMO climate information for April give average temperatures for Kent at 
Current, April 2016, temperatures are several degrees lower.
We should be used to variability in this part of the world and unseasonable weather is the norm in the UK. What would we talk about otherwise?
The physical processes of the atmosphere mix cold air at the pole with hot air at the equator with the overall aim of evening out the temperature everywhere. Atmospheric thickness between standard pressure levels is the way the average heat content of the atmosphere is represented by meteorologists. Current situation is indicated in the featured image above.
Blue is thin, dense and cold. Orange is thick, rarefied and warm. One rule of thumb says that anywhere on the blue side of the white 528 line is subject to greater than 50% probability of snow/sleet in any precipitation.
Current UK weather is currently subjected to a cut off area of cold air being mixed down from the pole: meteorologists call this a cold pool.
Weather is a zero sum game: if there are losers then there are also winners. Note that Russia has relatively warm air being mixed north. Anyone to the north of Norway (North Cape to Murmansk) is enjoying unseasonably warm weather.
