<Back to Archives>

<Back to Main Menu>

MARCH 1999 WEATHER SUMMARY

March started out rather blustery (but not like a lion as in years past), then maintained a seemingly constant barrage of unsettled weather for the remainder of the month. The main feature was the temperature, which turned out as one of the coldest on record, with a mean temperature of only 49.9F, about 5 degrees below normal (54.6F). In most parts of the Bay Area, it was between the 4th and 6th coldest March on record, and some stations have archives dating back to the middle 1800's. The dominant pattern which created the cold temps was a near-constant polar jet that maintained a strong N-S orientation resulting from winds circulating around a high anchored in the southern Aleutions and offshore about 1500 miles. The eastern edge of the High kept pushing lows up and over into Alaska, then southward along the West Coast, pulling cold, arctic with them. These cold core lows for the most part cut off as they passed the US/Can border, then would meander down the coast. While the frequency of rains (13 days of rain) was actually a bit above normal , only one storm produced over 1" ( on the 8th) due to constant lack of moisture. The moisture supply (or lack of) was quite consistent with the continuing impact of our now waning La Nina . A total of 4.03" was recorded here in Pacifica, which is near normal (4.13"). Snow fell frequently down to the 3K' level, and occasionally as low as 2K'. in the immediate Bay Area, and even lower snow levels were reported in the far northern counties (Napa and Lake counties mostly). An interesting note is the reduced precip in the Sierras, as the cut off lows kept off the coast for the most part, and only brief snows made it inland. By month's end, the cut off lows had started to move closer to the coast, and the last two actually move inland to our north, producing the month's best Sierra snow. Rain for the climatological year now stands at 24.24", which is above the yearly norm of 23" (at my house). Another Pacifica station in the north part of town, also reports rain (21.64") exceeding the yearly norm (19.76"). However, continuing the yearlong trend of having San Francisco/Pacifica be the cutoff line between above and below average rains, Half Moon Bay, only 15 miles to our south, is still over 4" away from their yearly average of 26.8".  Santa Cruz and localized zones in the southern Coastal range remains an anomaly, as a couple of potent lows and troughs that skirted the Bay Area but went inland near Monterey has produced rains about 115% of normal. For the most part, points south are below normal for rain, with dryness increasing the farther south you go. An interesting comparison is  this year's rain to date and last year's, while both above normal, in 1998 (El Nino) we had 43" as compared to 24" this year (La Nina). The number of rain days also reflected significant differences, as '97-'98 had 92 days of rain by this time and this year has had 68. It will be very interesting to note how the last three months of this year's rainy season evolves. In '97-'98, we had 32 days of rain between April and the end of June. This year, I suspect that number will be significantly lower.

                   MONTHLY CLIMATOLOGICAL SUMMARY for MAR. 1999


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  52.1  59.2   1:30p  45.2  12:00m  12.8   0.0  0.00   1.9  13.0   2:00p   WSW
 2  53.3  63.9   1:30p  45.4  12:30a  10.3   0.0  0.10   5.2  32.0  11:30p     S
 3  50.0  55.7  12:30p  46.1  12:00m  14.1   0.0  0.19   3.9  27.0  12:30a   WNW
 4  48.2  54.2  12:00p  43.0  12:00m  16.4   0.0  0.00   4.2  22.0   4:30a     N
 5  47.5  56.6   2:30p  41.0   3:00a  16.2   0.0  0.00   1.5  15.0  12:30p   SSE
 6  46.7  54.6   1:30p  42.1   4:30a  16.7   0.0  0.00   2.3  16.0   2:30p     S
 7  47.6  54.6   1:30p  41.6   2:00a  16.9   0.0  0.00   2.8  20.0   2:30p    SE
 8  48.4  50.9  11:00a  45.7  12:00m  16.7   0.0  1.13   9.1  39.0   3:30p     S
 9  46.6  52.4   1:30p  41.8  12:00m  17.9   0.0  0.03   3.5  24.0   1:30a     S
10  46.7  54.0   2:30p  40.4   4:30a  17.8   0.0  0.00   1.9  12.0   1:30p   WNW
11  49.1  56.7   1:30p  42.5   4:30a  15.4   0.0  0.00   2.8  13.0   6:30a     W
12  49.6  57.9   1:30p  43.1   5:30a  14.5   0.0  0.01   2.0  13.0   4:30p   SSE
13  50.2  58.4   2:00p  43.6   2:00a  14.0   0.0  0.00   2.8  18.0   4:30p   WSW
14  47.7  52.0   9:00a  44.0   9:00p  17.0   0.0  0.73   2.8  24.0  10:00a   SSW
15  48.6  55.3   1:30p  43.6   2:30a  15.6   0.0  0.06   2.9  20.0  10:00p   SSW
16  50.4  54.9   2:30p  47.4   5:30a  13.8   0.0  0.00   2.6  16.0   1:30a   SSW
17  50.6  57.2  12:30p  46.6  10:00p  13.1   0.0  0.00   2.4  13.0  12:00m   SSW
18  52.0  56.7   1:00p  47.4   2:00a  12.9   0.0  0.00   5.2  29.0   1:30p     S
19  50.7  54.1   4:30p  47.3  10:00p  14.3   0.0  0.09   4.0  34.0   9:00a   NNE
20  51.3  58.1   2:30p  45.1   6:30a  13.4   0.0  0.01   4.0  19.0   3:00p   NNE
21  52.8  59.1   3:00p  48.8  11:30p  11.1   0.0  0.05   5.1  24.0  12:30p     S
22  50.2  57.4   1:00p  44.3   6:00a  14.2   0.0  0.11   4.1  24.0  10:00p     S
23  50.8  57.1   2:00p  46.0   6:30a  13.5   0.0  0.24   3.2  20.0   1:30a     S
24  53.0  56.9  12:00p  49.7  12:00m  11.7   0.0  0.88   5.5  32.0   4:30p     S
25  53.1  60.1   2:00p  48.9  12:00m  10.5   0.0  0.22   2.3  18.0   8:30p   SSW
26  50.6  55.8  12:00p  47.4  12:00m  13.4   0.0  0.00   5.3  28.0   8:30p    NW
27  49.7  56.8   1:00p  45.8   6:00a  13.7   0.0  0.00   5.8  26.0   3:30a     N
28  50.2  59.1   1:30p  43.7   5:00a  13.6   0.0  0.00   3.0  14.0   4:30p     N
29  51.1  58.9   3:00p  45.4   2:30a  12.8   0.0  0.00   2.9  16.0   2:30p    NW
30  49.0  55.8   1:30p  42.3   6:00a  16.0   0.0  0.18   6.4  36.0   7:30p     S
31  47.9  54.6  12:30p  43.1   4:30a  16.2   0.0  0.00   4.1  22.0   6:30p   WNW
-------------------------------------------------------------------------------------
    49.9  63.9     2    40.4    10   446.4   0.0  4.03   3.7  39.0     8       S


Max >= 90.0:  0
Max <= 32.0:  0
Min <= 32.0:  0
Min <=  0.0:  0
Max Rain: 1.13 ON  3/08/99
Days of Rain: 13 (>.01 in) 8 (>.1 in) 1 (>1 in)
Heat Base:  65.0  Cool Base:  65.0  Method: (High + Low) / 2