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SEPTEMBER 2001 WX REVIEW

09/24/01-Major T'storm Outbreak in Bay Area!
After a very boring, mild-to-cool and featureless early September, a Pacific (not tropical) upper low pushed to the coast with THREE major squall bands in front of the parent low and almost 0.2" of rain during a brilliant Tstorm, with thunder and lightning lasting a couple of hours, bringing our monthly rain total to 0.21", and total rain to date (since July 1) to .35". NWS reported an estimated 1,600 lightning strikes in Cent. California moved through the area late in the afternoon through 2100 hrs. Other unconfirmed reports had over 4,000 hits over all of northern California, which puts this storm relatively on par with the record Sept. '99 event. However, I was out chasing the lightning, as I was in '99, and this event was much tammer than the '99 event. I won't quibble the numbers, but I can't agree that the lightning was equal to '99. Interesting though, that two major summer events such as this year's and '99 produced the most lightning in local weather records within 2 years of each other (different mechanisms, though). This year's event was notable in another regard....I watched the entire day's cloud development, and I never saw a Thunderhead! In fact, not even a cumulus cloud. As sometimes happens, upper level moisture can produce extreme turbulence within a fairly narrow zone in the atmosphere. Hence, clouds seen from the ground take on a rather benign alto stratus look, with cells on top of the stratus. I monitored clouds tops via the internet, and never saw a top > 25,000', with cloud base generally around 8,000'. From my vantage point on the west side of The Bay, I could see over 30 miles in any direction...and lightning was occuring randomly over the entire area. Note that in '99, the summer storms preceeded a drier than normal winter overall. Will have to wait and see if history repeats. Tropical showers/Tstorms in Sept. are certainly not unheard of, occurring on average every 2-3 years, and are most prone in mid Sept thru early Oct. ---almost always coming from tropical surges usually from dying hurricanes. This time, the low was North Pacific in origin, moving N-S to off Pt Concepcion before drifting back up to the NE, picking up both moisture from a dying tropical storm and cold air support as it pushed north. The upper low was pushed East by yet another digging trough coming down from the GOA, which at one point was progged to give more rain, but basically fizzled out and scooted into the PacNW. September is also our typical "Summer" period, and frequently has the highest mean temp of the year (59-61 typical). This year, Indian Summer (misnomer) didn't arrive in earnest to San Francisco until the last week of the month, (as well as our Golden Crown sparrows which arrived exactly on schedule on Friday the 28th). A few daily records were set regionally, hitting 91F in Pacifica (new daily record) on the 30th. Some other interesting side notes for the month:
At the end of the month, offshore SST's developed a steep temperature gradient about 25 miles offshore of Marin County/Bodega Bay.. According to a local outdoor writer, as well as my own fishing information, near-shore temps were at 53F (as of 09/27) which is 6-8 degrees cooler than typical this time of year. These temps continued out to only 20 miles offshore, where an abrupt change in SST occurred, with 62-64F noted. The dividing line between warm and cold water was extremely sharp, only 100-200 yards wide in some places (estimated), with major upwelling taking place on the cool side where huge schools of krill accumulated, and as a result the largest groups of whales seen in memory gorged on the feed. However, the water temp was so cold anchovy and sardines were pushed north, and Oregon commercial fisherman actually outfished their California cousins. California Kings were caught in record numbers in Oregon, while Oregon Silvers (coho), which feed on krill, were caught down here. In the warm water, tropical fish were showing with sailfish, dorado and baracuda in the mix and huge numbers of albacore tuna being caught by party boats.
09/25/01 -2 Major Solar Flares - The Solar max continued to provide turbulent space weather as two more X-class flares errupted, sending a large and intense proton event screaming to Earth. Despite Solar Max based on sunspot number happening in 2000, the current activity has rivaled the peak. Effects on planetary weather will need to be monitored, especially the onset of the rainy season should the activity continue at it's current pace.

                   MONTHLY CLIMATOLOGICAL SUMMARY for SEP. 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  59.7  69.8  12:00p  53.3  11:30p   3.4   0.0  0.00   1.5  11.0   1:30p   WNW
 2  59.5  70.3  12:00p  50.7   3:30a   4.5   0.0  0.00   1.9  11.0   2:30p     S
 3  60.9  70.9   2:00p  52.9   5:00a   3.1   0.0  0.00   1.9   9.0  10:30a   SSW
 4  60.2  71.3  11:30a  55.0   7:00a   1.8   0.0  0.00   3.0  14.0   3:00p     S
 5  58.6  65.9   1:00p  53.1  11:30p   5.5   0.0  0.00   4.4  20.0   2:30p     S
 6  59.4  73.3   2:00p  49.2   6:30a   3.8   0.0  0.00   1.1   9.0  12:30a   SSW
 7  62.8  82.7   2:00p  49.7   5:00a   0.0   1.2  0.00   1.3  10.0   2:30p     W
 8  58.8  69.9   1:30p  50.5   4:30a   4.8   0.0  0.00   4.8  23.0   2:00p     S
 9  59.7  68.8   3:00p  55.2   1:00a   3.0   0.0  0.00   5.6  22.0  10:30a     S
10  64.5  73.6   2:00p  57.9  12:00m   0.0   0.8  0.00   3.0  17.0  11:30a   SSW
11  62.1  72.6  11:30a  55.7   9:30p   0.8   0.0  0.00   1.9  11.0  10:30a   SSW
12  58.6  62.5  12:30p  56.7   5:00a   5.4   0.0  0.00   4.2  14.0   1:30p     S
13  57.4  64.9   1:00p  54.6  10:30p   5.3   0.0  0.00   2.2  12.0  12:30a   SSW
14  57.7  68.0   1:00p  50.8   7:00a   5.6   0.0  0.00   1.9  11.0   6:30p   SSE
15  56.0  58.5   2:00p  54.2   4:30a   8.7   0.0  0.00   2.8  12.0  12:00p   SSW
16  55.4  56.8  12:30p  54.2  12:00m   9.5   0.0  0.04   4.1  17.0   7:30p   SSW
17  56.6  65.8   2:00p  53.2   6:30a   5.5   0.0  0.01   2.2  11.0   2:00a   WNW
18  56.5  65.2  11:30a  53.4   5:30a   5.7   0.0  0.00   1.8  10.0   4:30p     W
19  58.9  70.6   1:30p  51.3   5:00a   4.1   0.0  0.00   0.8  10.0   3:30p   WNW
20  58.2  68.2   1:30p  52.5  12:30a   4.7   0.0  0.00   1.4  10.0   1:30p     W
21  58.0  67.1  12:00p  52.7  12:00m   5.1   0.0  0.00   1.8  10.0  12:30p   SSW
22  57.6  69.7   3:00p  47.8   7:00a   6.3   0.0  0.00   1.4   9.0   1:00p   SSE
23  57.9  66.5   1:00p  51.6   4:30a   6.0   0.0  0.00   1.7   9.0   1:30p   ESE
24  58.8  66.0   1:30p  54.6   6:00a   4.7   0.0  0.19   1.4   9.0   1:30p     N
25  61.2  69.3  12:30p  56.7   2:30a   2.0   0.0  0.02   1.9  11.0   3:00a   WNW
26  62.2  72.1   2:30p  55.3   6:30a   1.3   0.0  0.00   2.3  12.0   2:00p     S
27  58.9  65.9   2:00p  55.2  12:00m   4.4   0.0  0.00   4.6  18.0  12:00p     S
28  59.0  67.0   2:30p  53.8   6:00a   4.6   0.0  0.00   3.3  17.0   3:30p     S
29  60.7  73.0  12:00p  51.7   6:30a   2.7   0.0  0.00   1.6   9.0  10:30a     S
30  73.1  90.6   2:30p  58.3  12:30a   0.0   9.4  0.00   2.5  19.0  12:00p   SSW
-------------------------------------------------------------------------------------
    59.6  90.6    30    47.8    22   122.1  11.4  0.26   2.5  23.0     8     SSW


Max >= 90.0:  1
Max <= 32.0:  0
Min <= 32.0:  0
Min <=  0.0:  0
Max Rain: 0.19 ON  9/24/01
Days of Rain: 3 (>.01 in) 1 (>.1 in) 0 (>1 in)
Heat Base:  65.0  Cool Base:  65.0  Method: (High + Low) / 2