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