Some random notes and thoughts on our little heat wave this past week—-
A 590dm – 592dm upper high was over SoCal Wed/Thu. Offshore flow from the N and NE peaked on Wed and Wed night, with LAX-DAG grads at around -4 and LAX-BFL grads at about -6 mb. Upper support for strong surface winds was absent, so Santa Ana winds were not widespread.
Some peak winds in the region—
Camp 9 RAWS above San Fernando (4000′) —- N 44 on Tue evening and N 36 mph on Wed evening
Chilao —- N 37 Tue morning
Simi Valley RAWS —- N 30 on Wed afternoon
Saugus RAWS —- N 39 on Tue afternoon
VNY AP —- N 31 mph late Tue evening
BUR AP —- strongest hourly wind ob — SE 6 knots!
Fremont Cyn RAWS in Orange County —- ENE 30 mph on Tue morning
Generally, peak wind gusts were only into the 20s except at the typically wind-prone spots, where it gusted into the 30s. North winds did not even surface at Ontario AP for this event. It was a perfect setup for hot temps in many coastal and valley locales where winds were very light during the early and mid afternoon and the marine influence was totally absent.
Max temps in the SF valley were generally 99F to 102F on Wed/Oct 12 and 99F to 103F on Thu/Oct 13. On the 12th (Wed), when offshore gradients were quite strong during the afternoon, San Gabriel hit 104F. On Thu, gradients relaxed significantly, the highly modified sea breeze blew during the afternoon, and San Gabriel’s high was only 99F.
At L.A./USC, max on Wed was 99F and on Thu was 98F. Given the 105F max temps on Wed at FUL, Anaheim, Santa Ana FS, and Yorba Linda, I was a little surprised that L.A./USC hit only 99F. Wind was calm or very light and dew point was in the 40s here at USC midday and early afternoon. Very similar wind and dew points existed at FUL (Fullerton AP) during the day Tue. Apparently there was just a little more mixing and subsidence in those coastal Orange County communities (due to closer proximity to mountain slopes to the northeast?) compared to L.A. which permitted them to be about 5-6 degrees hotter….any thoughts?
An APRS station in Fullerton (ne of FUL AP) hit 107F on Wed, but I don’t know if the exposure there is adequate. LGB had 102F on Wed, and SLI (Los Alamitos Air Field) had 100F on Wed. The L.A. “CARB” station on N Main St. hit 105F on both Wed and Thu, but those values seem a little inflated probably due to poor exposure.
In any case, the readings of 105F in Orange County are impressive for so late in the warm season. Santa Ana Fire Station has been hotter in October on only one other day, when it was 106F on October 16, 1958 (data since 1906, according to the Western Region Climate Center). I figure that if we had not had our significant rain event on Oct. 5th, our max temps this week would have been a degree or two higher.
On Wednesday evening N to NE winds blew in many coastal and valley areas, and the temperature was in the upper 80s towards midnight in many places. Chatsworth and Northridge were 87F-88F at 11 p.m. Wed., and at the Simi RAWS station it was 88F at 1 a.m. and 2 a.m. on Thu morning. Overnight lows for Thursday include 82F at Simi Valley and Getty Center, 78F at UCLA, and 79F at 3092′ at the Santa Ana radar site.
Forecast-wise, the upper high lingers nearby this weekend, and then builds back over SoCal Mon/Tue with weak surface gradients, so max temps may be back up around 100F in the valleys at least. The models continue the relatively high heights and warm weather (though gradually cooler compared to Mon/Tue) here through the weekend of Oct 22/23, and the GFS shows a Fantasyland tropical system near/over Baja from the 24th to 26th with plenty of moisture spreading north into extreme SoCal and much of AZ.
I’ll paste some NWS record temp statements below —
Bill R.
RECORD EVENT REPORT
NATIONAL WEATHER SERVICE SAN DIEGO CA
540 PM PDT THU OCT 13 2011
…HIGHEST MAXIMUM TEMPERATURE RECORDS BROKEN OR TIED ON OCTOBER 13…
LOCATION NEW RECORD OLD RECORD PERIOD OF RECORD
EL CAJON 99 98 IN 1999 SINCE 1979
ESCONDIDO 99 96 IN 1999 SINCE 1979
FULLERTON AIRPORT 99 97 IN 2005 SINCE 1998
JOHN WAYNE AIRPORT 93 87 IN 2005 SINCE 1999
…HIGHEST MINIMUM TEMPERATURE RECORDS BROKEN OR TIED ON OCTOBER 13…
LOCATION NEW RECORD OLD RECORD PERIOD OF RECORD
CHULA VISTA 66 64 IN 1970 SINCE 1918
ESCONDIDO 62 61 IN 1938 SINCE 1900
$$
EVMI
000
SXUS76 KSGX 130048
RERSGX
RECORD EVENT REPORT
NATIONAL WEATHER SERVICE SAN DIEGO CA
540 PM PDT WED OCT 12 2011
…HIGHEST MAXIMUM TEMPERATURE RECORDS BROKEN OR TIED ON OCTOBER 12…
LOCATION NEW RECORD OLD RECORD PERIOD OF RECORD
ALPINE 97 95 IN 1999 SINCE 1952
CHULA VISTA 95 92 IN 1991 SINCE 1918
EL CAJON 104 97 IN 1999 SINCE 1979
SANTA ANA 105 104 IN 1950 SINCE 1906
VISTA 99 95 IN 1983 SINCE 1957
FULLERTON AIRPORT 105 95 IN 1999 SINCE 1998
JOHN WAYNE AIRPORT 99 88 IN 1999 SINCE 1999
RAMONA 101 96 IN 1999 SINCE 1974
$$
EVMI
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000
SXUS76 KLOX 130039
RERLOX
RECORD EVENT REPORT
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
545 PM PDT WED OCT 12 2011
…RECORD HIGH TEMPERATURES SET IN SOUTHERN CALIFORNIA…
A RECORD HIGH TEMPERATURE OF 99 DEGREES WAS SET AT DOWNTOWN LOS
ANGELES (USC) CA TODAY. THIS TIES THE OLD RECORD OF 99 SET IN 1950.
A RECORD HIGH TEMPERATURE OF 102 DEGREES WAS SET AT LONG BEACH CA
TODAY. THIS BREAKS THE OLD RECORD OF 96 SET IN 1963.
A RECORD HIGH TEMPERATURE OF 90 DEGREES WAS SET AT SANTA BARBARA
AIRPORT CA TODAY. THIS BREAKS THE OLD RECORD OF 83 SET IN 1950.
$$
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