December 2001 Wx Review - Record Monthly Rains!
For December, 12.84" fell at my location, obliterating our old monthly record of 9.32" set in 1996, and was the tiurd highest monthly total ever (max = 13.77" in Jan.'93). A Whopping 2.67" fell on 12/01. San Francisco reported 10.55" of rain, highest since 1955, and only the second time 10+" fell in December since the 1800's. 20 days of rain, with 3 days over 1" and 14 days >0.10". The mean temp was a chilly 51.3F, about 2F below normal. Severe Thunderstorms broke out on the 20th, especially over the South Bay, with two Emergency Alerts issued for separate cells...the first of which produced a brief F0 tornado near Watsonville, and the second producing hail almost 1" in diameter and over 3"+ in normally dry Morgan Hill. The general storm track shifted from a progressive one at the beginning of the month as storms slid down the coast NW-SE, producing high winds, squally rains and low snow levels. By months end, the Wintertime west coast bridge was finally developing as parent lows began getting shunted north, retrograding back into the GOA. However the coast remained under a strong SW-NE flow along the northern edge of the ridge, often tapping sub-tropical moisture (Pineapple connections) with the moisture streams riding in on a jet that once reached 150+kts. High surf from the strong offshore systems have created some minor beach errosion and the Pacifica Pier was closed for several days due to unsafe conditions.
MONTHLY CLIMATOLOGICAL SUMMARY for DEC. 2001
NAME: HOME CITY: Pacifica STATE: Ca ELEV: 540' LAT: 37.36'N LONG: 122.27'W
TEMPERATURE (°F), RAIN (in), WIND SPEED (mph)
HEAT COOL AVG
MEAN DEG DEG WIND DOM
DAY TEMP HIGH TIME LOW TIME DAYS DAYS RAIN SPEED HIGH TIME DIR
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1 52.9 54.3 12:00m 50.8 12:30a 12.5 0.0 2.67 12.2 49.0 11:30a S
2 53.4 56.3 5:30a 47.0 12:00m 13.3 0.0 2.42 13.1 53.0 4:30a S
3 49.4 53.9 1:30p 45.7 12:00m 15.2 0.0 0.03 2.7 16.0 3:45p SSW
4 48.4 55.6 1:30p 42.8 4:00a 15.8 0.0 0.00 3.1 23.0 5:30a N
5 52.5 54.6 4:30p 48.2 12:30a 13.6 0.0 0.56 6.9 29.0 1:30p S
6 55.7 60.1 1:30p 52.1 10:00p 8.9 0.0 0.06 1.5 15.0 11:30p N
7 55.2 60.0 2:30p 49.9 7:00a 10.0 0.0 0.00 4.4 26.0 1:00p NNE
8 54.4 60.3 2:00p 48.7 12:00m 10.5 0.0 0.00 2.6 30.0 10:30p NW
9 49.6 54.8 2:30p 45.8 11:30p 14.7 0.0 0.16 4.4 36.0 6:00a N
10 49.2 55.0 1:30p 42.9 5:00a 16.0 0.0 0.00 5.7 34.0 4:30p N
11 50.3 54.7 1:00p 46.4 8:30a 14.4 0.0 0.00 4.2 23.0 12:30a N
12 50.4 55.5 2:00p 45.9 7:30a 14.3 0.0 0.00 2.1 17.0 2:00a WNW
13 49.7 54.3 12:30p 44.0 6:00a 15.8 0.0 0.53 4.4 38.0 12:00m ESE
14 48.0 52.2 2:00a 42.9 12:00m 17.4 0.0 0.45 7.4 44.0 1:30a N
15 47.1 55.0 2:00p 40.7 4:30a 17.2 0.0 0.00 1.2 12.0 1:00a WNW
16 51.6 57.0 4:00p 45.5 12:30a 13.8 0.0 0.04 3.2 27.0 9:30p S
17 51.1 55.4 1:00p 44.0 11:30p 15.3 0.0 0.75 4.6 30.0 5:00a S
18 47.0 55.0 2:00p 41.8 5:30a 16.6 0.0 0.01 0.9 8.0 1:00p NNE
19 49.0 54.1 2:00p 45.2 5:00a 15.3 0.0 0.43 5.0 38.0 8:00p S
20 49.3 51.3 2:00p 46.9 12:30a 15.9 0.0 0.81 11.2 40.0 3:30p S
21 48.5 52.5 2:30p 45.3 7:30a 16.1 0.0 0.02 2.5 19.0 1:30a N
22 51.1 52.3 1:00p 49.6 12:30a 14.1 0.0 0.59 5.7 46.0 9:00a S
23 50.8 54.5 1:30p 48.6 10:30p 13.5 0.0 0.04 2.6 16.0 2:00p NNE
24 49.7 53.9 2:30p 45.0 8:00a 15.5 0.0 0.00 4.2 17.0 12:30p N
25 52.4 57.1 2:00p 48.1 5:00a 12.4 0.0 0.01 2.3 15.0 11:30a N
26 51.8 54.6 4:00p 49.3 7:30a 13.1 0.0 0.01 4.4 18.0 7:00p WSW
27 56.1 63.4 12:00p 51.2 6:00a 7.7 0.0 0.11 5.2 29.0 4:30p S
28 52.4 56.5 12:30a 49.6 11:30p 12.0 0.0 1.71 4.9 26.0 4:00p N
29 52.6 57.0 1:30p 49.3 4:30a 11.8 0.0 0.61 3.0 18.0 10:30a N
30 54.6 56.4 1:00p 53.4 6:30p 10.1 0.0 0.80 6.6 44.0 8:00p S
31 55.5 59.1 12:00p 53.7 7:30a 8.6 0.0 0.02 3.1 20.0 12:30a S
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51.3 63.4 27 40.7 15 421.5 0.0 12.84 4.7 53.0 2 S
Max >= 90.0: 0
Max <= 32.0: 0
Min <= 32.0: 0
Min <= 0.0: 0
Max Rain: 2.67 ON 12/01/01
Days of Rain: 20 (>.01 in) 14 (>.1 in) 3 (>1 in)
Heat Base: 65.0 Cool Base: 65.0 Method: (High + Low) / 2