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Alastair Thompson

Follow @althecat

27 Apr, 5 tweets, 3 min read

@Arab_Storms

Presumably this is this storm that is just getting underway on the Yemen/Saudi Border. @Arab_Storms

https://twitter.com/Arab_Storms/status/1386947552335917058

@NOAA

Forecast weather parameters as at 7am [From @NOAA GFS computer model latest run] :
- High levels of précipitable airborn water, needed for storm
- High levels of CAPE (energy per kg of water) = unstable air = thunderstorm potential

The other factor is the rapidly rising temperature (animation here runs from midnight Monday to midnight Tuesday. The temperature peaks in the early - which is when we tend to see thunderstorm development rapidly accelerate.

The other factor in play is the arrival of cold air coming in from the arctic, having traversed Europe. The collision of this cold dry ai (black/brown in this 48 hour animation) and the warm wet air helps produce the forecast high levels of rainfall/hail.

And finally this animation shows the 2 m temperature anomaly (blue and green shows colder than normal) through to midnight on Friday. Very high levels of rainfall forecast in Yemen is the reason for particularly high anomaly there.

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More from @althecat

Alastair Thompson

@althecat

28 Apr

A high resolution taken today by the NASA Modis satellite of the #NileBasin and the #MiddleEast is below.

The day started with storms in the East of the #HornOfAfrica #Yemen and the #KSA and got very busy over the day.

28 April Rain forecasts follow:

This first animation shows the beginning of a plume of water coming across the Sahara from the Atlantic. Forecasts indicate water from this plume will arrive in the #MiddleEast and #HoA in 10 days time.

This animation shows the West African Monsoon and the plume of précipitable water making its away across over the Sahara over the coming week.

Read 14 tweets

Alastair Thompson

@althecat

28 Apr

Dawn breaks on the Middle East and Horn of Africa on 28 April with numerous active storms in play.

#ArabianStorms #Ethiopia

Afternoon update 2.45pm: Both #KSA storms have expanded and we now have significant #ArabianStorms in Oman and the #UAE.

Meanwhile in the #Horn of Africa #Ethiopia rainfall to feed the Nile is getting underway, and storms are sparking up along the #Somaliland coast.

Read 5 tweets

Alastair Thompson

@althecat

28 Apr

Good Morning....

Earlier....

Read 4 tweets

Alastair Thompson

@althecat

27 Apr

https://twitter.com/althecat/status/1382719761210036225

A major West African Monsoon (WMA) Sahara water transit event has just started. [See animation below).

This thread contains 10 day ECMWF, CMC & ACCESS-G model forecasts of its trajectory & impact on Europe.

The quoted thread addresses #ClimateChange implications.

https://twitter.com/althecat/status/1382719761210036225

Here you see the beginning of this event. It is much larger than earlier iterations of the same phenomena. These streams of air-born water are roughly 4000 kms long.

This tweet and the next three contain 10-day forecasts of the trajectory of this hydrological atmospheric phenomena. They forecast precipitable water, the quantity of water which is held in the atmosphere measured in inches.

The first one is from the Euro ECMWF model.

Read 19 tweets

Alastair Thompson

@althecat

27 Apr

https://twitter.com/althecat/status/1387035399504097281

An image of thunderstorm activity in the Ethiopian #Abbay #BlueNile basin this afternoon, also showing significant rains South #Yemen and over most of #Somalia.

Todays, 27th April, accumulated rain forecasts for the #MiddleEast & #HornOfAfrica follow in the thread below.

https://twitter.com/althecat/status/1387035399504097281

#ArabianStorms activity was boosted today by moisture flowing from the #Ethiopian monsoon rains in the Ethiopian Highlands, the watershed of the #Abbay #BlueNile catchment.

Below you see a 10-day GFS forecast of accumulated rain over North Africa.

This animation shows the flows of moisture from this morning across the Red Sea. A process which is called the "Southern Gate" by Saudi weather entusiasts. #ArabianStorms #Abbay #BlueNile #GERD