Theory #1

[Alice Purjorick]

Prevailing wind May in Luz NNW 337°
https://www.windfinder.com/windstatistics/praia_da_luz

Screenshot of weather conditions recorded from nearest weather station below.

Taking into consideration
 a) the front door is on the easterly of the north-facing side of the block & set in a recess at the end of a potential wind tunnel
b) the patio door is on the south-facing side, protected in a recess on the patio by an adjacent wall & a balcony overhead
c) the bedroom window beside the front door was open (for the purpose of this theory)

are any of my learned friends/adversaries able to state the probability of the front door slamming shut behind Madeleine?
b) the patio door is on the south

Our grannies knew the answer to that question, near enough [seriously!].
Is the patio door open or closed?

[Alice Purjorick]

Agreed. That is likely showing a through draft at the instant in time the photograph is taken, when the patio doors are visibly, and therefore provably, open.

Cross ventilation effects are not universally straight through, they can double back on themselves.

Wind shadow effects in urban areas could also impact the situation at a micro level.

On a breezy night, with sources of ventilation, I do not see how the front door slamming can be definitively ruled out as a possibility.

Agreed.

[Alice Purjorick]

The apartment block is in an elevated position above the sea, and night time breeze blowing down towards the sea would in my opinion be capable of causing the effect witnessed and described by Kate at the bedroom window.

Like the blowing door curtain in the crime scene photograph it may have been momentary either due to a sudden gust or as you detailed earlier due to a particular circumstance or set of circumstances within.

The bedroom door slammed shut in the breeze but I don't think the front door would as it is hung to close in the opposite direction from that indicated by the action of the curtains.

In my opinion to slam the front door would require a gust coming from the sea with the effect on the curtains being ... billowing out of the window ... and billowing into the room from the patio door.

Why?

[misty]

Our grannies knew the answer to that question, near enough [seriously!].
Is the patio door open or closed?

Patio door was ajar but had been opened on 2 occasions when Matt & Kate entered to check on the children.

[Robittybob1]

Patio door was ajar but had been opened on 2 occasions when Matt & Kate entered to check on the children.

And Kate went back to see that she hadn't left the door open after the  bedroom door slammed.  So she is aware of the causes and solutions.

[misty]

And Kate went back to see that she hadn't left the door open after the  bedroom door slammed.  So she is aware of the causes and solutions.

Kate would not have anticipated the bedroom window could have been wide open behind the curtains.

[Robittybob1]

Kate would not have anticipated the bedroom window could have been wide open behind the curtains.

At what stage are you talking about?  When she first entered the apartment, or immediately when the bedroom door slammed?  She started going through a type of checklist.  Step 1. check the door she had just gone through, then Step 2. check the room.

Once she entered the room looking for the source of the air current she might have a differential diagnoses list.
a. Open window
b. Air from the air conditioner.
c. Poltergeist even.
(It was surprising how often on You Tube when doors slam shut that people put that down to some sort of haunting.)

[Alice Purjorick]

Patio door was ajar but had been opened on 2 occasions when Matt & Kate entered to check on the children.

So are we considering a problem within these limits ?:[including but not limited to]
1) Meteoroligical conditions as recorded at some unspecified airfield [ possibly up to 30 klicks away. Some keen type paid 80 euros for that print out....gosh].
2) The front door is shut.
3) An adjacent window and associated shutter, in the same building elevation as the front door, is open but the dimensions of the aperture are unknown.
4) The patio door is open but but the dimensions of the aperture are unknown.
5) The dimensions of the front door are unknown.
6) The mass of the front door is unknown.
7) The door hinge materials of construction are unknown therefore mu is unknown.

We ain't gonna become fat on that lot but we could have a bit of fun chucking typical numbers about to arrive at a sense check. The skellington in the cupboard* is the pesky patio door and its unknown attitude.
Going on "nod in" my opinion is that one would be hard pressed to come up with a conclusive argument one way or another i.e there is no single right answer.

*  https://www.youtube.com/watch?v=BxwoqPY834c     

[ShiningInLuz]

At what stage are you talking about?  When she first entered the apartment, or immediately when the bedroom door slammed?  She started going through a type of checklist.  Step 1. check the door she had just gone through, then Step 2. check the room.

Once she entered the room looking for the source of the air current she might have a differential diagnoses list.
a. Open window
b. Air from the air conditioner.
c. Poltergeist even.
(It was surprising how often on You Tube when doors slam shut that people put that down to some sort of haunting.)

What air conditioner?

[Robittybob1]

What air conditioner?

That is a question Kate would have to go through  (there is some sort of vent in the kids room).

[ShiningInLuz]

That is a question Kate would have to go through  (there is some sort of vent in the kids room).

Is there an air conditioning unit visible in any of the incident photos?  Is there an extraction unit visible anywhere on the exterior of 5A?

[misty]

So are we considering a problem within these limits ?:[including but not limited to]
1) Meteoroligical conditions as recorded at some unspecified airfield [ possibly up to 30 klicks away. Some keen type paid 80 euros for that print out....gosh].
2) The front door is shut.
3) An adjacent window and associated shutter, in the same building elevation as the front door, is open but the dimensions of the aperture are unknown.
4) The patio door is open but but the dimensions of the aperture are unknown.
5) The dimensions of the front door are unknown.
6) The mass of the front door is unknown.
7) The door hinge materials of construction are unknown therefore mu is unknown.

We ain't gonna become fat on that lot but we could have a bit of fun chucking typical numbers about to arrive at a sense check. The skellington in the cupboard* is the pesky patio door and its unknown attitude.
Going on "nod in" my opinion is that one would be hard pressed to come up with a conclusive argument one way or another i.e there is no single right answer.

*  https://www.youtube.com/watch?v=BxwoqPY834c     

Correction.
2. The front door is open to an unknown angle.

Not to worry, Alice. If the skeleton had been found in the cupboard we could argue over how it got there & the contents of the autopsy report.
It's just trying to piece together a sequence of questionable events to reach the conclusion defined in the OP theory. At least this gives you the opportunity to link to backing music of your choice.

[misty]

At what stage are you talking about?  When she first entered the apartment, or immediately when the bedroom door slammed?  She started going through a type of checklist.  Step 1. check the door she had just gone through, then Step 2. check the room.

Once she entered the room looking for the source of the air current she might have a differential diagnoses list.
a. Open window
b. Air from the air conditioner.
c. Poltergeist even.
(It was surprising how often on You Tube when doors slam shut that people put that down to some sort of haunting.)

I was referring to the moment after the bedroom door slammed. The position she first noticed it in(around 45-50°) shows that there was insufficient wind force to close it at that angle. Only when she drew the door towards her did the momentum kick in.
If the reduced airflow from the patio door could escape through the open window or partly open front door, why would the front door slam shut?
If the front door had slammed shut when Kate or Matt entered through the patio door, why wouldn't they have heard it?

[sadie]

I think you have your facts wrong here "The route of the trail ending at the Tapas Bar is consistent with a route MBM may have taken if she wished to find her parents. I believe there is a door between the passageway and the pool area, which is locked at night." 
 Please explain.

I dont think that tere is ANY door between the passageway and the ;pool area, Rob.

The whole complex is built into a hill side with a moderately steep walk up from the Tapas area to the apartments.   The whole Tapas area is flat and horizontal.   The Passageway /pathway is pretty horizontal and a fair deal higher than the flat Tapas area .

Í have memories of a fairly high vertical wall between the two.  I dont think that there is any entrance from that passageway into the Tapas gardens.

I feel sure that there are photos and videos illustrating from the Tapas area this difference in levels.


I haven't the energy to look for these photos/ videos and am totally willing to be proven
wrong.   It is a long time since I was there.

[Robittybob1]

I don't think that there is ANY door between the passageway and the pool area, Rob.

The whole complex is built into a hill side with a moderately steep walk up from the Tapas area to the apartments.   The whole Tapas area is flat and horizontal.   The Passageway /pathway is pretty horizontal and a fair deal higher than the flat Tapas area .

Í have memories of a fairly high vertical wall between the two.  I dont think that there is any entrance from that passageway into the Tapas gardens.

I feel sure that there are photos and videos illustrating from the Tapas area this difference in levels.


I haven't the energy to look for these photos/ videos and am totally willing to be proven
wrong.   It is a long time since I was there.

I didn't see a door either.  I'll put it on the list of things to check.