Major TRW in Saudi Desert - Mecca

[JBG]

Yesterday's tragic train collapse in Mecca, Saudi Arabia (over 100 killed) was sparked by a severe thunderstorm and heavy rain in Mecca (link to story) and (link) to Weather Underground. I am not a weather expert. What could have caused such an extreme event in an unlikely place. Excerpts from news story and weather observation:

 

 

 

Storm hits Mecca with devastating consequences

 

Thunderstorms are a potent and potentially deadly force of nature. Lightning, flash flooding and powerful wind gusts all have the capacity to kill.

 

But rarely can one individual storm have had such deadly consequences as the one which hit Mecca around 14:30 GMT on Friday.

 

The number of dead and injured continues to rise, following the collapse of a giant crane onto the Grand Mosque.

Mobile phone images appear to show a crane adjacent to the mosque being struck by lightning and authorities have said that winds in the area were gusting to 83 km/h.

 

The autumn season is the period when thunderstorms are most likely in Mecca.

Of the 20 days on which thunderstorms occur each year, half of those will be during the months of September, October and November.

 

This particular storm was one of several which occured during Friday afternoon, developing over the Asir Mountains, south of the city, before drifting northwards.

 

These storms developed because of a combination of favourable atmospheric conditions.

 

Firstly, the area of low pressure, which had spawned dust storms across the Levant in previous days, drifted southwards into northern Saudi Arabia.

 

 

 

Hourly Weather History & Observations Time (AST) Temp. Heat Index Dew Point Humidity Pressure Visibility Wind Dir Wind Speed Gust Speed Precip Events Conditions                                                                                                                                 5:19 PM 104.0 °F 112.2 °F 69.8 °F 33% 29.80 in 2.5 mi South 13.8 mph - N/A Thunderstorm Thunderstorm 5:31 PM 96.8 °F 103.1 °F 69.8 °F 41% 29.86 in 1.6 mi South 13.8 mph - N/A Rain , Thunderstorm Thunderstorms and Rain 6:00 PM 78 °F - 70 °F 69% 29.88 in 4 mi South 2.3 mph - - Rain , Thunderstorm Thunderstorms and Rain 6:54 PM 77.0 °F - 69.8 °F 78% 29.95 in 3.7 mi South 3.5 mph - N/A Rain , Thunderstorm Thunderstorms and Rain 9:00 PM 85 °F - 68 °F 47% 29.78 in 6 mi South 2.3 mph - - Rain Light Rain

 

If anyone knows how to correctly post the Wunderground chart, please do so.

[nrgjeff]

Dewpoints are impressive over the desert. The surrounding Gulfs and Indian Ocean are at the warmest of the year, which probably promotes that kind of humidity in the desert. Enter a closed low drifting south into SA and the upper levels are just a bit unstable. Set-up looks a lot like a Southwest US Monsoon storm event, except the disturbance came from the north instead of on easterly flow.

 

Regardless of the cause it is a sad story that so many people died outside - esp at worship. It is also a wake-up call to American (and all) event organizers - if Indiana last year was not enough.

[JBG]

Dewpoints are impressive over the desert. The surrounding Gulfs and Indian Ocean are at the warmest of the year, which probably promotes that kind of humidity in the desert. Enter a closed low drifting south into SA and the upper levels are just a bit unstable. Set-up looks a lot like a Southwest US Monsoon storm event, except the disturbance came from the north instead of on easterly flow.

 

Regardless of the cause it is a sad story that so many people died outside - esp at worship. It is also a wake-up call to American (and all) event organizers - if Indiana last year was not enough.

If that setup exists why is virtually any rain so rare in SA?