Special Weather Statement
Dept Atmospheric and Oceanic Sciences UCLA
2:15 PM PDT Monday, 07 May 2012

This April was wetter than normal(big contrast to the rainless April last year).
The total for the month was 1.82 inches(normal is 0.97). It was the wettest
April since 2006(3.26 inches that year). Rank-wise, it rated a 20th wettest
April on record. Five measurable rain days accounted for the month's total.
That's two days more than normal. The first event actually occurred on the
evening of 31 March(local calendar time). However, in Greewich Mean Time(time
zone used in recording UCLA data), that fell on the 1st. Light rain amounted
to 0.07 inch that day. Rain began late evening on the 10th. Intense rain
fell briefly between 11:25-11:32 PM. During the last minute of that period,
a maximum rainfall rate of 1.2 inches per hour was recorded. Rain continued
into the pre-dawn period on the 11th. Intense rain was recorded from 3:33-3:45
AM and 3:43-3:45 AM(1.2 inches per hour rate in the last minute of the former
period). A final brief, light shower may have occurred mid-morning. The storm
total(rainfall recorded for 11th) was 0.81 inch. Light rain showers started in
the pre-dawn hours of the 13th. Rain was steady from mid-morning till mid- 
afternoon. A few showers fell between 3 PM and 4:15 PM. Occasional intense rain
fell between 10:44 AM and 11:34 AM. A maximum rainfall rate of 1.8 inches per
hour was recorded 11:24-11:25 AM. This was also during the time of a thunderstorm
(11:00-11:50 AM...thunder loudest around 11:30 AM). Rainfall for the day was 0.48
inch. Light drizzle/rain fell in the wee early hours of the 23rd(some lingering
mist up to about 7 AM). Rainfall that day was just 0.02 inch. The final storm of
the month started in mid-afternoon on the 25th. It began as occasional sprinkles,
but measurable rain didn't occur till 7:14 PM. Rain was steady by 9 PM, and it
continued till about 1:20 AM on the 25th. Occasional light showers fell thereafter
till about 7:30 AM. Intense rain fell briefly between 10:31-10:33 PM and 10:36-
10:41 PM(both on the 25th). Rain recorded for the 26th was 0.44 inch. No rainfall
records were set or tied this month.

This month was slightly cooler than normal. The average temperature was 60.5 degrees
(0.8 degree below normal). While last year averaged much higher(63.3 degrees), two
years ago averaged much lower(58.7 degrees). Rank-wise, it was only the 27th coolest
April on record. The average maximum temperature was 68.6 degrees(0.9 degree below
normal). It ranked 26th coolest in that category. The average minimum temperature was
52.4 degrees(0.6 degree below normal). It ranked tied for 28th coolest in this category
(first in 1946). Only two days reached at least 80 degrees this month(four days are
normal). The highest temperature of the month was 82 degrees(7th and 25th). Like last
year there were two days where the maximum temperature failed to reach 60 degrees(11th
and 13th this year). Normal is one day. One day this month recorded a minimum temperature
below 46 degrees(normal number of such days). The 43 degree minimum on the 14th was
the lowest temperature this month. It tied for the record low temperature for that date
(first time in 1956). This was likely the final day of the season with a minimum temperature
no higher than 45 degrees(period centered around the winter months). 24 March is the long
term average date for a minimum of 45 degrees or lower.

On a side note, the temperature dropped five degree in five minutes during a thunderstorm
on the 13th. At 11:22 AM, the campus temperature was 55 degrees, but it fell to 50 degrees
just five minutes later. It was quite windy with intense rain during the latter minutes.

Visibility this month fell to one mile or less on one date this month. It occurred on the
20th. Early morning low clouds/fog reduced the visibility to 0.75 mile around 6 AM.

Like last year, this April was unusually windy. There were nine days this month with 
significant wind(at least 25 mph gusts). Windy weather started out the beginning of the 
month. Northwest to north-northwest winds blew strongly from mid-afternoon into the
evening hours. The peak sustained wind was northwest at 30 mph at 3:26 PM. The peak gust
of the day (and month) was 47 mph(North-northwest at 7:06 PM...sustained wind was 25 mph).
The breezy weather continued into the morning hours of the 2nd (diminished greatly by
sunrise though).The maximum sustained wind of the day was north-northwest at 28 mph(1:08 AM).
The peak gust of the day was 41 mph(North-northwest at 1:19 AM). Brisk north-northwest winds
began mid-evening on the 5th. The peak wind of the day was 32 mph(10:33 PM). Brisk winds
continued into the 6th,but it became intermittent by 5:35 AM. Significant wind gusts ended
after 7:07 AM that day. The peak gust on the 6th was 39 mph (3:59 AM). Occasionally brisk
north-northwest wind blew between 7:26-8:20 AM on the 7th. A 25 mph gust at 7:50 AM was the
highest wind gust that day. Occasionally brisk southwest winds occurred mid-morning till
early evening on the 11th. The maximum gust that day was 29 mph(2:36 PM). Another round of
brisk southwest wind occurred on the 12th(mid-morning to early evening). The maximum gust for
for this day was 26 mph(3:41 PM). Occasionally brisk southeast to south-southeast wind started
on the 13th at 8:49 AM. The wind veered to west-southwest by 11:24 AM. Occasionally breezy 
weather continued through the early evening. The peak wind that day occurred during a thunderstorm.
A maximum sustained west-southwest wind of 25 mph occurred at 11:24 AM(gusted to 36 mph).
A peak gust to 38 mph occurred a minute later. The final wind event of the month occurred
on the 25th. Brisk south to mostly southwest wind occurred between 2:53-3:43 PM. A peak southwest
wind gust to 35mph occurred at 3:07 and 3:12 PM.

J. Murakami

Rainfall in inches
24 hour rainfall measured from Midnight to Midnight, Greenwich Mean Time
Normals are defined using a 30 year mean from 1981-2010
UCLA records date back to 1932
All times given in Pacific Standard Time