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
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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
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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