Can anyone help explain these reading from GLA & PIK airport weather
stations.

look at the sharp drop then rise at 4am GMT in Glasgow:

Glasgow Airport, United Kingdom
(EGPF) 55-52N 004-26W 0M

Pressure (altimeter) 29.18 in. Hg (0988 hPa)
ob EGPF 011020Z 12011KT 9999 VCSH FEW015 BKN020 09/06 Q0988

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24 Hour Summary
Time
EST (UTC) Temperature
F (C) Dew Point
F (C) Pressure
Inches (hPa) Wind
MPH Weather

1 AM (6) Dec 01 48 (9) 44 (7) 29.23 (0990) ESE 12 light rain showers
Midnight (5) Dec 01 48 (9) 44 (7) 29.26 (0991) ESE 8 drizzle
11 PM (4) Nov 29 33 (1) 32 (0) 29.65 (1004) ENE 6 light rain
10 PM (3) Nov 30 42 (6) 41 (5) 29.32 (0993) E 6 light drizzle
9 PM (2) Nov 30 44 (7) 41 (5) 29.32 (0993) E 7 light drizzle

I'd have thought this was just an error, but the same event happens in
PIK:

Prestwick Airport, United Kingdom
(EGPK) 55-30N 004-35W 0M


Time
EST (UTC) Temperature
F (C) Dew Point
F (C) Pressure
Inches (hPa) Wind
MPH Weather


2 AM (7) Dec 01 48 (9) 44 (7) 29.21 (0989) SSE 16 light rain
1 AM (6) Dec 01 48 (9) 44 (7) 29.23 (0990) SSE 15 light rain
Midnight (5) Dec 01 50 (10) 44 (7) 29.23 (0990) SSE 13 light rain
11 PM (4) Nov 30 50 (10) 44 (7) 29.26 (0991) SSE 10 light rain,
drizzle
10 PM (3) Nov 30 50 (10) 44 (7) 29.32 (0993) SSE 9 light rain
9 PM (2) Nov 29 37 (3) 35 (2) 29.71 (1006) SE 6 light rain
8 PM (1) Nov 30 48 (9) 44 (7) 29.35 (0994) SSE 7
7 PM (0) Nov 30 46 (8) 42 (6) 29.35 (0994) SSE 6


Can anyone enlighten me?

thanks

Douglas