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Here's the current METAR from CYYZ:

CYYZ 140700Z 26011KT 15SM FEW025 BKN045 BKN080 M05/M08 A2984 RMK SC1SC5AC1 AC TR SLP116

Does anyone know what each section of text of the remarks section means?

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So the posted parts means the following:

  RMK    = REMARKS   
  SC     = Stratocumulus Clouds
  1      = 1/8 (0/8 = no clouds / 8/8 = overcast clouds)`
  SC     = Again Stratocumulus Clouds
  5      = 5/8
  AC     = Altocumulus Clouds
  1      = 1/8
  AC TR  = Traces of Altocumulus
  SLP116 = Sea Level Pressure of 1011.6 mBar (just add a 10 before the given number and divide by 10)

Cloud Types:

  • Ac-Altocumulus
  • As-Altostratus
  • Cb-Cumulonimbus
  • Cc-Cirrocumulus
  • Ci-Cirrus
  • Cs-Cirrostratus
  • Cu-Cumulus
  • Fc-Fractocumulus
  • Fs-Fractostratus
  • Ns-Nimbostratus
  • Sc-Stratocumulus
  • St-Stratus

(Source: Wikipedia)

Octas:

enter image description here

(Source: Navcanada)

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  • $\begingroup$ What's the difference between "completely overcast" and "sky completely obscured... by a phenomenon with a base not at the surface"? $\endgroup$ – Michael Seifert Feb 15 '19 at 18:32
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    $\begingroup$ @MichaelSeifert, I am not sure, but I suppose things like smoke (blowing across at some height) or volcanic ash would qualify. Basically something that looks like clouds, but is formed by something else than water condensation. $\endgroup$ – Jan Hudec Feb 15 '19 at 19:28
  • $\begingroup$ Isn't there a typo in the pressure? I believe SLP116 should mean 1011.6 hPa, not 1016 (which would be way too much for the 29.84 inHg; but then, 29.84 inHg is just 1010.5 hPa, not 1011.6) $\endgroup$ – Jan Hudec Feb 15 '19 at 19:47
  • $\begingroup$ @JanHudec of course! You're right, I fixed the number and added the explanation how it works. It's adding 10 in front and dividing by 10 to get the pressure in mBars. $\endgroup$ – Pascal Ackermann Feb 15 '19 at 20:14
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    $\begingroup$ Nice observation @JanHudec - The small difference between 1010.5 and 1011.6 is because SLP is corrected for the 12-hour mean temperature. It's used by meteorologists; it's not a metric conversion of inHg for use by the pilots as a QNH. $\endgroup$ – ymb1 Feb 15 '19 at 21:14
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The digit after the cloud layer type is the amount in oktas. See chapter "16.3.13.1 Layer type and amount (oktas)" in the canadian MANOBS Manual of Surface Weather Observations.

Amended 2019-02-16 to add:
Above manual also notes that the layer types and amounts in the RMK section correspond to the cloud layers aloft reported in the main section, and that the amount for layers aloft is reported as summation amount (as seen from the ground) while in the RMK section the amount is only for this layer, i.e. for your example:

  1. FEW025: few clouds (1-2/8) ⇔ SC1: 1/8 stratocumulus
  2. BKN045: broken layer (5-7/8) ⇔ SC5: 5/8 stratocumulus
  3. BKN080: broken layer (5-7/8) ⇔ AC1: 1/8 altocumulus

To just decode the remarks you could also use metaf2xml with this link:

Remarks:
========
SC1SC5AC1  phenomenon w. opacity:
           1/8 (1/10) or less, but not 0/8 (0/10) stratocumulus
           5/8 (6/10) stratocumulus
           1/8 (1/10) or less, but not 0/8 (0/10) altocumulus
AC TR      traces of: altocumulus
SLP116     sea level pressure: 1011.6 hPa = 29.87 in. Hg = 759 mmHg
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