DECEMBER 2000 WEATHER REVIEW
DECEMBER 2000 WEATHER REVIEW
The progressive, cool and wet weather of October which evolved first into a colder, then gradually milder/drier November, became quasi- stagnant for virtually the entire December resulting in one of the driest on record under moderate temps.. Total rain was a paltry 0.72", all of which fell during a 7 day showery period between the 9th and 16th as a series of once-potent storms slammed into our dry continental airmass and basically evaporated-on -contact..leaving paltry little rain in their wake. Actually, this lack of rain is just another manifestation of the same basic pattern we've had for months which has seen a mean flow of continental air flowing N-S or offshore into the sub tropical EPAC region. As the dry air flows south, it then turns gradually westward, where it amplifies the E-W trades and enhances surface cooling over the EPAC waters (La NIna), all of which reduces available moisture for storms to the north. Currently, SST's remain near normal, but the dry continental air that has been flowing for months is blocking tropical air from flowing north. While it is much too early in the year to project with high confidence the pattern for our second phase of Winter (Jan.-Mar.), the "D" word is being more than whispered about in matters of water control measures and power generation needs. And with the current energy crunch in California, below normal hydro-electric power generation in coming months/years could have a major impact on our economy. Once these powerful cause/effect systems get entrenched, only major changes elsewhere can dislodge the pattern or cause a change in the generic storm track. To illustrate how generic patterns can linger, keep in mind Cent. California has just experienced above average rains in 7 out the last 8 years, which immediately followed a 6 year period of much below normal rains. Many places like Fresno have just set all-time records for driest Nov./Dec.time periods... receiving only .08" for both months together. Here in Pacifica, 1.52" fell in Nov./Dec, less than 25% of our normal 7" for the same time period. After the very cold temps of early November, temps rebounded nicely with numerous days in the 60's, and no days of frost. The mean avg. temp of 53.6 was much more typical this time of year (typical mean is around 54)---yet was almost 2 degrees warmer than this November's mean of 51.9.
MONTHLY CLIMATOLOGICAL SUMMARY for DEC. 2000
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 50.7 57.4 5:00p 47.0 5:45a 12.8 0.0 0.00 1.5 13.0 1:15p ESE
2 52.5 60.3 4:30p 46.3 8:30a 11.7 0.0 0.01 2.7 18.0 2:00p NE
3 53.2 58.3 3:45p 48.8 9:15a 11.5 0.0 0.00 4.1 21.0 9:15a S
4 57.0 62.5 4:45p 51.9 2:45a 7.8 0.0 0.00 4.0 15.0 3:00p N
5 58.9 63.6 3:15p 56.1 8:45a 5.2 0.0 0.00 4.6 18.0 2:15p S
6 58.2 62.9 1:00p 54.3 9:00a 6.4 0.0 0.00 3.9 22.0 9:45a WNW
7 57.2 63.1 2:45p 54.3 12:00m 6.3 0.0 0.00 1.0 10.0 1:00p N
8 54.7 61.8 3:45p 49.4 11:45p 9.4 0.0 0.00 0.8 8.0 2:00p S
9 54.4 58.0 1:30p 49.6 12:15a 11.2 0.0 0.02 0.5 6.0 11:45a ESE
10 52.3 55.4 1:30p 45.2 12:00m 14.7 0.0 0.02 1.4 12.0 2:00p SSW
11 50.1 54.1 1:45p 45.5 12:15a 15.2 0.0 0.08 2.7 36.0 8:30p SSW
12 50.4 55.2 1:30p 47.1 9:15p 13.8 0.0 0.05 1.7 12.0 2:30a S
13 51.8 55.9 11:45a 48.3 1:15a 12.9 0.0 0.30 5.6 30.0 2:00p S
14 53.7 55.0 11:30p 50.0 7:00a 12.5 0.0 0.13 4.9 28.0 1:30a S
15 52.7 56.8 1:45p 48.1 10:30p 12.6 0.0 0.11 2.3 11.0 7:00a S
16 53.3 59.6 2:15p 49.0 7:00a 10.7 0.0 0.00 3.3 19.0 12:00p NNE
17 52.7 59.7 3:00p 46.4 6:45a 11.9 0.0 0.00 3.9 20.0 11:45a NNE
18 53.7 58.6 2:30p 50.1 8:00a 10.7 0.0 0.00 5.8 24.0 3:30a NNE
19 55.3 65.7 2:45p 48.5 7:00a 7.9 0.0 0.00 2.5 19.0 2:00a NE
20 54.6 61.9 3:00p 48.3 12:00m 9.9 0.0 0.00 3.5 25.0 1:15p WNW
21 52.6 57.3 10:00a 46.6 3:30a 13.1 0.0 0.00 4.6 28.0 12:45p S
22 52.8 58.6 3:00p 47.5 12:00m 12.0 0.0 0.00 0.9 12.0 1:30a N
23 50.2 56.2 2:00p 45.6 6:30a 14.1 0.0 0.00 0.6 8.0 1:15p N
24 50.6 56.6 2:00p 47.4 11:45p 13.0 0.0 0.00 1.8 16.0 11:30a NNE
25 52.6 57.5 2:45p 47.1 2:30a 12.7 0.0 0.00 3.9 19.0 11:15a NNE
26 54.3 61.3 2:45p 49.8 5:45a 9.5 0.0 0.00 3.6 19.0 11:30a N
27 54.6 62.5 2:45p 49.2 2:45a 9.2 0.0 0.00 3.3 19.0 8:45a WNW
28 56.6 64.4 2:30p 52.3 3:00a 6.7 0.0 0.00 3.4 16.0 6:00a S
29 54.7 61.5 2:15p 50.1 7:45a 9.2 0.0 0.00 2.5 12.0 6:15a ENE
30 53.4 60.5 1:30p 49.1 6:15p 10.2 0.0 0.00 2.6 13.0 7:45a S
31 52.5 61.1 2:45p 46.3 4:45a 11.3 0.0 0.00 2.4 18.0 7:45a N
-------------------------------------------------------------------------------------
53.6 65.7 19 45.2 10 335.8 0.0 0.72 2.9 36.0 11 S
Max >= 90.0: 0
Max <= 32.0: 0
Min <= 32.0: 0
Min <= 0.0: 0
Max Rain: 0.30 ON 12/13/00
Days of Rain: 7 (>.01 in) 3 (>.1 in) 0 (>1 in)
Heat Base: 65.0 Cool Base: 65.0 Method: (High + Low) / 2