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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
------------------------------------------------------------------------------------
 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
-------------------------------------------------------------------------------------
    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