Forensic meteorological investigation of damaging wind and rainfall conditions in Long Beach, California between January 1 and January 31, 2017
Radar image of southern Los Angeles County at 2:35pm PST, 22 January 2017.
Prepared by: Dr. Ryan Truchelut Prepared for: Wilson Phillips Prepared on: September 21, 2017 Document reference number: WT20170905
WeatherTiger, LLC P.O. Box 894 Tallahassee, FL 32302 (850) 733-8431 http://www.weathertiger.com/
WT20170905: Page 1 Table of Contents
Background …...... …...... 3
Meteorological overview …...... 3
National Weather Service warning products …... 4
Observed meteorological data …...... 6
Storm damage reports …...... 9
Analysis …...... 10
Conclusions …...... 12
Appendix: Detailed data …...... 13
WT20170905: Page 2 I. Background
WeatherTiger, LLC has been contracted by Wilson Phillips of Long Beach, California to investigate the meteorological conditions during the month of January 2017 relevant to an ongoing insurance claim. The street address of the house is 2004 Ocean Avenue, Long Beach, California, which is located in coastal Los Angeles County at approximately 33.724 degrees north latitude, and 118.283 degrees west longitude. This coordinate is used to determine the distance between the claim site and the historical weather observations referenced in this report. In accordance with best practices in the feld of forensic meteorology, all historical data and forecast products used to prepare this report originate from the National Weather Service (NWS) and National Oceanic and Atmospheric Administration (NOAA), a division of the United States Department of Commerce.
This report was authored by Dr. Ryan Truchelut, in coordination with WeatherTiger research staf. My professional background in both operational forecasting and research meteorology is extensive. I am co-founder and President of WeatherTiger, a meteorological consulting frm ofering customized short- and long-range weather forecasts and full-spectrum decision support for commodity, risk, public safety, and retail markets. I have an undergraduate degree in Geosciences from Princeton University and master's and doctoral degrees in Meteorology from Florida State University, have authored papers for both peer-reviewed scientifc press and national media outlets, and served as the ofcial hurricane expert for the USA Today Network during the 2017 hurricane season. My academic credentials and professional experience qualify me to assess the weather conditions relevant to this case, and I will ofer my professional opinion on the probable meteorological causes of the damage to 2004 Ocean Avenue and an assessment of the use of weather data in the American Engineers engineering report in the Analysis section.
II. Meteorological overview
January of 2017 was a notably active period of weather in southern California, with multiple strong storms moving into the region from the southwest due to an active subtropical jet stream triggered by a La Nina event. This type of event is known as an “atmospheric river,” in which a steady fux of oceanic moisture moves into a single region repeatedly. After several years of much drier than normal conditions between 2013 and 2016, dry soil and repeated storm systems impacting the state led to widespread fooding issues and wind damage. These conditions were refected by the declaration of a State of Emergency by Governor of California Jerry Brown and the subsequent declaration of a Major Disaster area by the Federal Emergency Management Agency, both including all of Los Angeles County, as a result of the January storms.
To put the atmospheric river event of January 2017 into historical perspective, Figure 1 plots the percentage of normal rainfall received in the state of California, relative to the 30-year climate normal observed during 1981-2010. Los Angeles County, including Long Beach, received between 200 and 300% of average precipitation for January. More broadly, January 2017 ranked as the seventh-wettest January since 1895 for the entire state of California.
WT20170905: Page 3 Figure 1: Accumulated precipitation as a percentage of normal across California over January 2017. The claim site is marked with a red star on this fgure.
III. National Weather Service warning products
The NWS Local Forecast Ofce (LFO) responsible for issuing routine weather forecasts and severe weather warnings for Los Angeles County is NWS Oxnard. As with all 122 LFOs nationwide, NWS Oxnard is stafed continuously by trained meteorologists employed by the federal government to protect public safety. The Long Beach claim site is located in NWS forecast zone CAZ041, covering coastal Los Angeles County. All warnings referenced in this section cover CAZ041 and thus apply specifcally to Redondo Beach.
Refective of the active weather pattern occurring during January 2017, an unusual number of
WT20170905: Page 4 weather advisories and severe weather warnings were enacted during this time. Most relevant to this report are the three Wind Advisories and one Flash Flood Warning covering Redondo Beach. The NWS criteria for the issuance of a Wind Advisory are when sustained winds of 31 to 39 mph are expected to last for an hour or more, and/or wind gusts of 46 to 57 mph for any duration. Three Wind Advisories were issued during the study period for three separate storms: the frst for January 20th, the second for January 22nd extending into January 23rd, and the third for January 27th. The Wind Advisory for January 20th specifcally predicted, “gusts in excess of 55mph...possible across higher terrain such as the Palos Verdes peninsula,” located several miles south of Long Beach, as well as warned the public that “winds may down trees and power lines... with wet soils and strong gusty winds expected... there is a heightened potential for downed trees.” The full text of all the relevant NWS warnings and advisories may be found in the Appendix.
Figure 2: Flash Flood Warning polygon (green outline) covering Long Beach, CA, issued at 2:39PM PST, 22 January 2017, with doppler radar imagery. The claim site is marked with a red star.
The NWS' purpose for issuing a Flash Flood Warning Is to inform the public, emergency management, and other cooperating agencies that fash fooding is in progress, imminent, or highly likely. A Flash Flood Warning was issued at 2:39PM PST on January 22, 2017 by NWS Oxnard for a portion of southern Los Angeles County including Long Beach. This is shown graphically in Figure 2. The Warning was triggered by “widespread rainfall rates of around 0.75 inches per hour from Redondo Beach east through Long Beach and Lakewood,” and warned the public to take action due to the fact that “signifcant and serious urban fooding is expected on area roadways and freeways, especially on the 110 and 710 freeways.” It should be noted that Flash Flood Warnings cover only the area in which the fooding is occurring or expected, and are thus rare. Long Beach has only been placed under a Flash Flood Warning three times since 2005.
WT20170905: Page 5 The archived NWS advisory and warning products show that these events were widely predicted ahead of their occurrence to cause widespread wind and water damage across Los Angeles County generally and Long Beach specifcally. Based on these products, our study of the historical weather data will focus on January 20t h and January 22n d as the most likely timing for wind and wind-driven rain damage to the 2004 Ocean Avenue property.
IV. Observed meteorological data There are fve ofcial NOAA weather observation stations recording data each hour or more frequently within 12 miles of the claim site. Three of these observing stations are operated by the the National Weather Service and are located at Torrence Municipal (KTOA), Hawthorne Municipal (KHHR), and Los Angeles International (KLAX) Airports, respectively. The remaining two stations are marine weather stations operated by NOAA's National Ocean Service and located at the Port of Los Angeles Pier F (PFXC1) and Pier J (PRJC1), respectively.
There are two other sources of meteorological data used in this report. NOAA operates co-operative observation stations across the country, which report a more limited set of weather data on a less regular schedule. The NOAA co-operative station in Redondo Beach (RDOC1) reports daily rainfall totals and is located about 3.5 miles northwest of the claim site, Finally, the NWS releases local storm report data highlighting the strongest wind gusts or other extreme observations from all available credible weather sources via Public Information Statements. Local storm report products can give a better sense of the maximum possible gusts that may have occurred at a given location.
Figure 3: Daily and cumulative monthly rainfall totals for Redondo Beach (NOAA Co-op station RDOC1) for January 2017, with cumulative diference from January average conditions.
As shown in Section II, January 2017 was a notably wet month for Los Angeles County overall. In the Long Beach area, the historical observations show this to be particularly true at the local level. Figure 3 shows the daily rainfall totals over the month for the Redondo Beach reporting station, RDOC1. Of particular note are the precipitation totals associated with the January 20th storm of just over 1”, and
WT20170905: Page 6 especially the nearly 3” rainfall recorded from the fash food-producing system of January 22nd and 23rd. These observations are similar to the observed totals at KLAX and KHHR on these days, the next-nearest observation stations reporting daily rainfall totals. (KTOA only reports during daylight hours and marine stations such as PFXC1 and PRJC1 do not typically record rainfall data.) A table of daily rainfall data and the timing and direction of maximum sustained winds and wind gusts for all of these reporting stations, when available, are located in the Appendix.
Wind data over the investigation period was recorded at difering frequencies across the fve observing stations incorporated into this study. At KTOA, wind data was reported hourly, generally between 7AM and 9PM PDT. However, observations are missing from 10AM to 12PM on January 20th. At KLAX and KHHR, wind data were recorded every fve minutes, with observations as frequent as each minute during changing weather conditions in order to support airport operations. There are a number of missing wind observations during the period of heavy observed rainfall at KHHR and KLAX on January 20th, which is not particularly unusual. Wind data was more continuous with fewer missing observations at both KLAX and KHHR on January 22nd. Finally, the marine stations PFXC1 and PRJC1 record average winds each six minutes, as well as the highest fve-second gust occurring during the previous six minute period. Data records for both these stations are relatively uninterrupted during the days in question.
On January 20th, a line of heavy showers swept north towards southern Los Angeles County in the late morning hours. Heavy rainfall was frst recorded at KLAX at 10:10AM and Hawthorne at 10:25AM. As rainfall continued through noon, winds switched from being out of the southeast to being generally out of the south, then southwest, then out of the west by 2PM. Peak gusts of 41mph were observed out of the west at KHHR at 1:53PM and again at 2:05PM; at LAX, a maximum gust of 40mph was recorded at 2:00PM. Both sites reported an extended period of sustained winds out of the west between 25-32mph with multiple gusts into the upper 30s range between 6PM and 11PM, with only light additional precipitation, before subsiding. However, as mentioned previously, both of these records have a large number of missing observations, particularly earlier in the day.
The observations from PFXC1 and PRJC1, south and east of the claim site, are both continuous through the day on the 20th. Winds reached 25mph sustained out of the south-southeast around 10AM PDT, steadily increasing to around 35mph sustained out of the south by noon, with repeated gusts in excess of 40mph. The maximum sustained wind at PRJC1 of 38mph, with a gust to 46mph, was observed out of the south-southwest (202 degrees) at 12:24PM, just slightly higher and with similar timing to the peak gust at PFXC1. Winds then veered to due west by 2:00PM, with several additional gusts at PRJC1 above 40mph at that time. A time series of wind direction, strength and gusts for station PRJC1 on January 20th and January 22nd may be found in the Appendix.
On January 22nd, an approaching area of low pressure to the south of Los Angeles brought copious heavy rainfall to the Long Beach area, with rainfall rate data from KHHR and KLAX showing particularly heavy accumulations between 11AM and 4PM PST, in agreement with the timing of the issuance of the Flash Flood Warning. Winds remained gusty and generally out of the east or southeast through 4PM, with peak gusts of 30mph at 11:30AM and 12:25PM from due east at KLAX and sustained winds in the lower 20s. Similar but slightly higher wind speeds and directions were observed at PFXC1 and PRJC1, with east winds sustained at up to 27mph and gusting to 31mph (1:42PM, PRJC1) through 2PM, before switching to out of the south and increasing in intensity to a maximum sustained speed of 32mph (3:48PM, PRJC1) and highest gust of 38mph (3:54PM, PFXC1) by
WT20170905: Page 7 4PM. Winds eased after 5PM at all stations and veered to out of the west as the low pressure system moved north and inland. It should be noted that strong winds from the south, and to a lesser extent the east, are very rare in southern California. Figure 4 shows the climatological wind rose plot for KHHR (left) and KLAX (right), which in both cases shows that winds between SW and SE cumulatively occur less than 10% of the time, with vanishingly small proportions of that fraction being winds stronger than 10mph (yellows and reds). West winds are both the most common, and account for a dominant share of higher observed windspeeds.
Figure 4: Historical January wind direction and speed data for KHHR (left) and KLAX (right) over 1973- 2017 and 1970-2017, respectively. The length of the bars corresponds to how common a wind out of that compass point is, with the coloration indicative of the strength in mph.
While January 23rd was generally calmer across southern Los Angeles County, of note is a 42 mph sustained wind out of the west at 5:54PM on January 23rd, with a 54mph gust out of the west- northwest at 6:49PM reported at KTOA. Winds remained notably lower at other stations during this time. With no precipitation reported in the vicinity at the time, this is likely due to a strong pressure gradient interacting with local orographic factors as a west wind was squeezed around the Palos Verdes peninsula immediately to the south of the observation site. This is indicative of the strong infuence of localized and often idiosyncratic terrain factors on observed weather in southern California, which are capable of producing damaging weather conditions on small scales.
Figure 5: Peak wind gusts across Los Angeles County from NWS Storm Reports on January 20 and January 22, 2017.
WT20170905: Page 8 Finally, Figure 5 shows storm reports received received by the Oxnard NWS, with widespread wind gusts across Los Angeles County of between 55 and 75mph on both January 20th and January 22nd, justifying the issuance of the Wind Advisories. While some of these wind observations are infuenced by microscale efects such as funneling of winds in canyons and higher observation altitudes, they are nevertheless indicative of the potential for localized damaging gusts higher than what may have been observed at the nearest NWS observation station, including in Redondo Beach.
V. Storm damage reports
In addition to releasing forecasts and warnings, NWS ofces also receive storm damage reports from local law enforcement, emergency management, and media sources. These reports are not exhaustive and mostly refect damage to public infrastructure that is known in real-time, and are released in the form of Public Information Statements. NWS Oxnard received multiple reports of wind damage during each of the Wind Advisory events. At 1:45PM PST January 20 th, the NWS received a confrmed report from Santa Monica, CA, about 13 miles northwest of the claim site, that “gusty winds broke [the] top of [a] power pole, with lines down on Pacifc Coast Highway. Highway closed both directions.” In Avalon, CA, around 30 miles south of Long Beach, southwest wind gusts to 70mph were reported, causing a “roof shingle [to be] blown of building... portions of Catalina Island had power outages.”
During the January 22nd event, multiple reports of severe fooding were received by NWS Oxnard. These include a report at 1:55pm of Interstate 110 “completely fooded” on “both sides” three miles east of Torrance, a report at 2:21pm of Interstate 710 two miles west of Long Beach “completely fooded both directions with over 4 feet of water... too deep for tow trucks to reach vehicles,” and a report at 2:52pm of “4 feet of water on Sepulveda Boulevard near 110 Freeway,” four miles east of Torrance. These reports validate the intensity of the rain rate observed on the afternoon of January 22nd in the immediate vicinity of Long Beach.
VI. Analysis
Overall, the study of weather conditions associated with the January 20th and January 22nd - 23rd storms in southern Los Angeles County reveals a number of observations that are highly unusual for California weather. These include extended periods of strong winds out of the east and south, and numerous hours of wind-driven rainfall out of the east, in addition to the more commonly experienced strong winds out of the west. Per Wind Advisory products, observations, and storm reports, 2004 Ocean Avenue in Long Beach likely experienced wind gusts of 40-45mph out of the south on January 20th, with gusts of similar strength out of the west later in the afternoon. It is possible that these gusts may have reached 50mph, per the Wind Advisory forecast statement and NWS storm reports. On January 22nd, rain totals of approximately 3” in the early afternoon likely coincided with sustained winds from the east, southeast, and south of around 25-30mph, with top gusts of 35-40mph. This assessment is informed by the observations, nearby topographic features in the vicinity that could enhance peak gusts, as well as obstructions in the vicinity of the building. Per the pictures in the engineering reports, there is little to block wind coming from the south or east of 2004 Ocean Avenue, whereas a neighboring structure appeared to signifcantly impede winds from the west.
WT20170905: Page 9
In my opinion, these conditions subjected structures, including the property at 2004 Ocean Avenue, to weather stresses that had not been experienced in southern Los Angeles County for at least three to fve years, and perhaps longer. This is based on the rarity of Flash Flood Warnings in Long Beach, in which the January 22nd event was the only case since 2005 of rainfall meeting food criteria contemporaneously with winds out of the east. I have reviewed both the American Engineers and Building Consultants, LLC engineering reports of the damage and purported causation thereof to 2004 Ocean Avenue. As a meteorologist, I do not herein asses the initial condition of the structure prior to the January 2017 storms; however, I do fnd that the damage assessment as communicated in these reports is consistent with the forensic meteorological conditions as laid out above.
In particular, the Building Consultants, LLC report states that the observed damage to the clay tiles has occurred primarily over the damaged areas of the house, which are identifed in the American Engineers report as the bedrooms and bathrooms along the southern and eastern walls of the house. I concur with the assessment in the Building Consultants, LLC report that the damage to the clay tiles could have been caused by gusts out of the south and south-southwest of 40-45mph or more supported by the observational data early in the afternoon of January 20th. The force applied by windspeed scales with the square of velocity, meaning a 50mph gust applies over twice as much force to a structure as a 35mph gust. This means the roof damage was much more likely to be caused by the stronger gusts on January 20th than January 22nd. It should also be noted that the compass rose on the American Engineers blueprint is rotated approximately 15 degrees clockwise from reality; in other words, the front of the house does not face due south, but rather south- southwest. This is an important distinction, as it means the the roof eaves on the eastern side of the house also have exposure to edge uplift forces from winds out of the due south, increasing the potential for damage to the tiles.
The sustained winds and wind gusts observed in January 22nd storm system were notably weaker than those of January 20th, applying around half of the force of the January 20th gusts to the structure's roof, and would not have been able to account for observed damages. However, the sustained winds of 25mph out of the southeast with gusts to 35mph or so were coupled with extreme rainfall rates of 0.75-1” per hour over several hours, as refected in the Flash Flood Warning. This rainfall could have entered the house through the existing roof damage on the southern and eastern sides of the roof from the January 20th event, accounting for the damages along those walls. Additionally, this wind-driven heavy rain from the east and southeast would not have been blocked by structures and would have been oriented at such an angle as to directly impact the east-facing windows directly for a period of several hours between 12:00PM and 4:00PM PDT on January 22 nd. As stated in the observational data section, the co-incidence of heavy rainfall and strong winds from the east and southeast is extremely unusual in southern California climatology. No other Flash Flood Warning events in Long Beach accompanied by east or southeast winds have occurred since 2005. Therefore, the observed water damage to the east-facing windows likely took place on January 22 nd. While I am not a structural engineer, winds below thresholds typically considered structurally damaging can and do cause window leaks in my personal experience, especially during unusually heavy rainfall. Overall, in my judgement, the observed damages to 2004 Ocean Avenue can be explained by wind damage to southern and eastern sections of the roof on January 20th, followed by an extremely rare fooding rainfall event coupled with east winds that both led to water intrusions through the roof and east-facing windows on January 22nd.
WT20170905: Page 10 As a fnal note, I would like to note that the use of meteorological data in the American Engineers engineering report is misleading. In particular, the American Engineers report states:
“The wind speeds associated with those storms were relatively low, the highest average windspeed at 14 miles per hour. At this level, we would not expect wind-driven moisture to penetrate the building envelope of a residence in generally good condition.”
This is a misuse of time-averaged windspeed. I concur with the Building Consultants, LLC engineering report, in that wind damage is often a nearly instantaneous occurrence. For this reason, standard meteorological observations include fve-second wind gusts as a reported parameter, as this is the relevant time-averaging window for many types of structural damage. For the purpose of assessing roof damage, daily averaged windspeed is essentially meaningless and is not credible as a counter-argument for the possibility that the wind damage occurred during the January 2017 study period. Since force applied by wind to a structure scales with the square of (instantaneous) velocity, a day in which the wind averaged a steady 14mph is not comparable to a theoretical day in which winds were light for three-quarters of the day, and 60mph sustained winds were recorded for the other six hours. It is not a reasonable expectation that a building hit by a tornado would not sufer severe structural damage simply because the rest of the day was calm and the daily-averaged windspeed was low. While the American Engineers report includes a table citing the 42mph wind gust from the west in Hawthorne on January 20th, this information is not assessed in the body text, and there is no mention of the strong wind gusts from the south and east on either the 20th or 22nd. In my opinion, the American Engineers report's assessment of the meteorological data omits information that is relevant to the determination of the causes of observed damage at 2004 Ocean Avenue, and ofers only misleading averaged wind data.
VII. Conclusion
WeatherTiger, LLC performed an in-depth investigation into the weather conditions associated with the atmospheric river event impacting southern California in January 2017, specifcally the wind and rainfall conditions experienced in Long Beach. In general, we determined that the National Weather Service ofce issued multiple warnings for potentially damaging conditions, specifcally ahead of storms on January 20th and January 22nd-23rd, and that these warnings were justifed by the observational record and verifed storm damage reports received by the NWS ofce.
After a thorough assessment of the available reliable weather data in the vicinity of Long Beach, I can say with confdence that the observed weather in the study period was both highly unusual and potentially destructive in a way that is consistent with the damage to the structure. In my opinion, given the magnitude and direction of the wind gusts observed on January 20th , followed by the wind- driven severity of the rainfall rate on January 22nd, the meteorological conditions likely account for at least some of the observed roof and window damage and subsequent water intrusions at 2004 Ocean Avenue.
I attest that the information contained in this report is true to the best of my knowledge, and the opinions ofered herein represent my unbiased professional judgement.
WT20170905: Page 11 Hereby afrmed:
Ryan E. Truchelut, PhD Consulting meteorologist WeatherTiger, LLC
Electronically signed on this day: September 21, 2017.
VIII. Appendix: Detailed data
Item A: Text of Flash Flood Warning for issued by NWS Oxnard on January 22, 2017
BULLETIN - EAS ACTIVATION REQUESTED Flash Flood Warning National Weather Service OXNARD CA 239 PM PST SUN JAN 22 2017
The National Weather Service in OXNARD has issued a
* Flash Flood Warning for... Southern Los Angeles County in southwestern California...
* Until 430 PM PST
* At 234 PM PST, Doppler radar and rain gauges indicated that rain has increased in intensity across southern Los Angeles County, with widespread rainfall rates of around 0.75 inches per hour from Redondo Beach east through Long Beach and Lakewood. Significant and serious urban flooding is expected on area roadways and freeways, especially on the 110 and 710 freeways. The 110 freeway at Carson Street and the 710 freeway at Pacific Coast Highway are completely flooded.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Excessive runoff from heavy rainfall will cause flooding of small creeks and streams, urban areas, highways, streets and underpasses as well as other drainage areas and low lying spots.
A Flash Flood Warning means that flooding is imminent or occurring. If you are in the warned area move to higher ground immediately. Residents living along streams and creeks should take immediate precautions to protect life and property.
&&
WT20170905: Page 12 Item B: Text of Wind Advisory issued by NWS Oxnard on January 20, 2017
CAZ040-041-046-201830- /O.EXT.KLOX.WI.Y.0007.170120T1400Z-170121T1400Z/ VENTURA COUNTY COAST- LOS ANGELES COUNTY COAST INCLUDING DOWNTOWN LOS ANGELES- SANTA MONICA MOUNTAINS RECREATIONAL AREA- INCLUDING THE CITIES OF...VENTURA...OXNARD...CAMARILLO...MALIBU... SANTA MONICA...BEVERLY HILLS...HOLLYWOOD...LONG BEACH 226 AM PST FRI JAN 20 2017
...WIND ADVISORY NOW IN EFFECT FROM 6 AM THIS MORNING TO 6 AM PST SATURDAY...
* WINDS AND TIMING...AREAS OF SOUTHEAST TO SOUTH WINDS 15 TO 25 MPH WITH GUSTS TO 40 MPH WILL DEVELOP EARLY THIS MORNING...EXCEPT WIND SPEEDS WILL BE 20 TO 30 MPH WITH GUSTS TO 50 MPH IN THE SANTA MONICA MOUNTAINS. WINDS WILL SHIFT TO WEST AT SIMILAR SPEEDS THIS AFTERNOON...THEN CONTINUE THROUGH LATE TONIGHT BEFORE DIMINISHING.
* IMPACTS...GUSTY WINDS WILL MAKE DRIVING DIFFICULT...ESPECIALLY FOR DRIVERS OF HIGH PROFILE VEHICLES. SINCE THE SOILS ARE WET...THERE IS A HEIGHTENED POTENTIAL FOR DOWNED TREES.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
WHEN DRIVING...USE EXTRA CAUTION. BE PREPARED FOR SUDDEN GUSTY CROSS WINDS. 828 PM PST THU JAN 19 2017
...WIND ADVISORY REMAINS IN EFFECT FROM 10 AM FRIDAY TO 6 AM PST SATURDAY...
* WINDS...SOUTH WINDS WILL INCREASE TO 15 TO 30 MPH WITH GUSTS UP TO 45 MPH ACROSS THE LOS ANGELES AND VENTURA COUNTY COAST AND SANTA MONICA MOUNTAINS AHEAD OF A COLD FRONT. ISOLATED GUSTS IN EXCESS OF 55 MPH ARE POSSIBLE ACROSS THE HIGHER TERRAIN SUCH AS THE PALOS VERDES PENINSULA AND THE HILLS ABOVE MALIBU. WINDS WILL SHIFT TO THE WEST LATE THURSDAY AFTERNOON AND CONTINUE THROUGH MUCH OF FRIDAY NIGHT.
* IMPACTS...GUSTY WINDS WILL MAKE DRIVING DIFFICULT... ESPECIALLY FOR DRIVERS OF HIGH PROFILE VEHICLES. WINDS MAY DOWN TREES AND POWER LINES. WITH WET SOILS AND STRONG GUSTY WINDS EXPECTED...THERE IS A HEIGHTENED POTENTIAL FOR DOWNED TREES. 226 AM PST FRI JAN 20 2017
...WIND ADVISORY NOW IN EFFECT FROM 6 AM THIS MORNING TO 6 AM PST SATURDAY...
* WINDS AND TIMING...AREAS OF SOUTHEAST TO SOUTH WINDS 15 TO 25 MPH WITH GUSTS TO 40 MPH WILL DEVELOP EARLY THIS MORNING...EXCEPT WIND SPEEDS WILL BE 20 TO 30 MPH WITH GUSTS TO 50 MPH IN THE SANTA MONICA MOUNTAINS. WINDS WILL SHIFT TO WEST AT SIMILAR SPEEDS THIS AFTERNOON...THEN CONTINUE THROUGH LATE TONIGHT
WT20170905: Page 13 BEFORE DIMINISHING.
* IMPACTS...GUSTY WINDS WILL MAKE DRIVING DIFFICULT...ESPECIALLY FOR DRIVERS OF HIGH PROFILE VEHICLES. SINCE THE SOILS ARE WET...THERE IS A HEIGHTENED POTENTIAL FOR DOWNED TREES.
1012 AM PST FRI JAN 20 2017
...WIND ADVISORY REMAINS IN EFFECT UNTIL 6 AM PST SATURDAY...
* WINDS AND TIMING...AREAS OF SOUTHEAST TO SOUTH WINDS 15 TO 25 MPH WITH GUSTS TO 40 MPH WILL DEVELOP HIS MORNING... EXCEPT WIND SPEEDS WILL BE 20 TO 30 MPH WITH GUSTS TO 50 MPH IN THE SANTA MONICA MOUNTAINS. WINDS WILL SHIFT TO WEST AT SIMILAR SPEEDS THIS AFTERNOON...THEN CONTINUE THROUGH LATE TONIGHT BEFORE DIMINISHING.
* IMPACTS...GUSTY WINDS WILL MAKE DRIVING DIFFICULT...ESPECIALLY FOR DRIVERS OF HIGH PROFILE VEHICLES. SINCE THE SOILS ARE WET...THERE IS A HEIGHTENED POTENTIAL FOR DOWNED TREES.
301 PM PST FRI JAN 20 2017
...WIND ADVISORY REMAINS IN EFFECT UNTIL 6 AM PST SATURDAY...
* WINDS AND TIMING...WEST WINDS 20 TO 30 MPH WITH GUSTS BETWEEN 40 AND 50 MPH WILL CONTINUE THROUGH LATE TONIGHT BEFORE DIMINISHING.
* IMPACTS...GUSTY WINDS WILL MAKE DRIVING DIFFICULT...ESPECIALLY FOR DRIVERS OF HIGH PROFILE VEHICLES. SINCE THE SOILS ARE WET...THERE IS A HEIGHTENED POTENTIAL FOR DOWNED TREES.
904 PM PST FRI JAN 20 2017
...WIND ADVISORY REMAINS IN EFFECT UNTIL 6 AM PST SATURDAY...
* WINDS AND TIMING...WEST WINDS 20 TO 30 MPH WITH GUSTS BETWEEN 40 AND 50 MPH WILL CONTINUE THROUGH LATE TONIGHT.
* IMPACTS...GUSTY WINDS WILL MAKE DRIVING DIFFICULT...ESPECIALLY FOR DRIVERS OF HIGH PROFILE VEHICLES. SINCE THE SOILS ARE WET...THERE IS A HEIGHTENED POTENTIAL FOR DOWNED TREES.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
WHEN DRIVING...USE EXTRA CAUTION. BE PREPARED FOR SUDDEN GUSTY CROSS WINDS. &&
Item C: Text of Wind Advisory issued by NWS Oxnard on January 22, 2017
CAZ040-041-087-222015- /O.EXB.KLOX.WI.Y.0008.000000T0000Z-170122T2300Z/ VENTURA COUNTY COAST-
WT20170905: Page 14 LOS ANGELES COUNTY COAST INCLUDING DOWNTOWN LOS ANGELES- CATALINA AND SANTA BARBARA ISLANDS- INCLUDING THE CITIES OF...VENTURA...OXNARD...CAMARILLO...MALIBU... SANTA MONICA...BEVERLY HILLS...HOLLYWOOD...LONG BEACH...AVALON 339 AM PST SUN JAN 22 2017
...WIND ADVISORY IN EFFECT UNTIL 3 PM PST THIS AFTERNOON...
THE NATIONAL WEATHER SERVICE IN LOS ANGELES/OXNARD HAS ISSUED A WIND ADVISORY...WHICH IS IN EFFECT UNTIL 3 PM PST THIS AFTERNOON.
* WINDS AND TIMING...SOUTHEAST TO SOUTH WINDS 20 TO 30 MPH WITH GUSTS TO 40 MPH WILL DEVELOP THIS MORNING...THEN SHIFT TO SOUTHWEST AND DIMINISH SOME DURING THE MID AFTERNOON HOURS.
* IMPACTS...GUSTY WINDS WILL MAKE DRIVING DIFFICULT...ESPECIALLY FOR DRIVERS OF HIGH PROFILE VEHICLES. SINCE THE SOILS ARE WET...THERE IS A HEIGHTENED POTENTIAL FOR DOWNED TREES AND POWER LINES.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
WHEN DRIVING...USE EXTRA CAUTION. BE PREPARED FOR SUDDEN GUSTY CROSS WINDS.
Item D: Quality-controlled wind data from station PRJC1 (Los Angeles Pier J) between Noon and 4pm PST on January 20, 2017
(Note: All times are given in GMT, which can be converted to PST local at GMT-8. Wind speeds are given in meters per second, which can be converted to miles per hour by multiplying by 2.23. Wind directions are given in the compass origination point in degrees, where north is 0 degrees, east is 90 degrees, south is 180 degrees, and west is 270 degrees. Highest wind gust at 2024GMT from the south-southwest is bolded for convenience.)
#YY MM DD hh mm WDIR WSPD GST #yr mo dy hr mn degT m/s m/s 2017 01 20 18 00 155 10.3 12.4 2017 01 20 18 06 160 11.2 13.0 2017 01 20 18 12 164 13.1 14.5 2017 01 20 18 18 166 13.8 16.0 2017 01 20 18 24 165 12.8 14.9 2017 01 20 18 30 162 11.6 14.2 2017 01 20 18 36 179 7.6 11.2 2017 01 20 18 42 189 13.5 16.1 2017 01 20 18 48 187 13.6 16.5 2017 01 20 18 54 187 12.5 14.0 2017 01 20 19 00 189 11.2 12.6 2017 01 20 19 06 180 9.7 10.8 2017 01 20 19 12 169 11.1 13.8 2017 01 20 19 18 162 12.2 14.9 2017 01 20 19 24 161 10.4 12.5 2017 01 20 19 30 160 8.3 10.0 2017 01 20 19 36 164 10.5 15.8 2017 01 20 19 42 174 14.3 17.3 2017 01 20 19 48 175 15.5 18.8 2017 01 20 19 54 176 15.0 18.2 2017 01 20 20 00 178 15.3 18.3 2017 01 20 20 06 195 14.7 17.7
WT20170905: Page 15 2017 01 20 20 12 195 16.0 18.9 2017 01 20 20 18 197 15.8 19.1 2017 01 20 20 24 202 17.0 20.6 2017 01 20 20 30 219 14.2 17.9 2017 01 20 20 36 225 11.4 14.4 2017 01 20 20 42 219 13.2 17.3 2017 01 20 20 48 215 12.7 15.0 2017 01 20 20 54 214 11.9 13.8 2017 01 20 21 00 214 9.6 11.6 2017 01 20 21 06 229 10.9 13.9 2017 01 20 21 12 244 11.4 13.4 2017 01 20 21 18 246 12.7 14.9 2017 01 20 21 24 249 13.3 15.3 2017 01 20 21 30 250 12.6 14.4 2017 01 20 21 36 252 12.6 15.5 2017 01 20 21 42 252 13.4 16.0 2017 01 20 21 48 247 12.9 14.9 2017 01 20 21 54 247 12.4 14.7 2017 01 20 22 00 252 14.2 16.9 2017 01 20 22 06 257 15.0 18.2 2017 01 20 22 12 259 14.3 18.8 2017 01 20 22 18 263 12.8 18.2 2017 01 20 22 24 265 9.6 12.7 2017 01 20 22 30 261 10.6 12.4 2017 01 20 22 36 267 10.0 12.4 2017 01 20 22 42 267 11.3 13.7 2017 01 20 22 48 265 12.8 15.1 2017 01 20 22 54 261 12.5 15.1 2017 01 20 23 00 262 11.6 14.5 2017 01 20 23 06 261 13.2 15.5 2017 01 20 23 12 263 12.4 15.7 2017 01 20 23 18 266 11.0 13.2 2017 01 20 23 24 270 11.4 13.3 2017 01 20 23 30 273 10.1 12.8 2017 01 20 23 36 272 11.3 14.0 2017 01 20 23 42 267 12.1 14.1 2017 01 20 23 48 267 11.4 13.6 2017 01 20 23 54 268 11.8 14.2 2017 01 21 00 00 268 12.9 15.6
Item E: Quality-controlled wind data from station PRJC1 (Los Angeles Pier J) between 10am and 4:30pm PST on January 22, 2017 #YY MM DD hh mm WDIR WSPD GST #yr mo dy hr mn degT m/s m/s 2017 01 22 18 00 81 9.4 11.7 2017 01 22 18 06 82 9.2 11.4 2017 01 22 18 12 82 9.2 11.4 2017 01 22 18 18 80 8.8 10.2 2017 01 22 18 24 76 8.3 10.4 2017 01 22 18 30 73 7.3 8.9 2017 01 22 18 36 83 8.0 9.6 2017 01 22 18 42 84 7.8 9.6 2017 01 22 18 48 86 7.6 9.6 2017 01 22 18 54 83 9.3 10.5 2017 01 22 19 00 83 9.9 11.5 2017 01 22 19 06 83 8.7 10.7 2017 01 22 19 12 88 9.0 10.3 2017 01 22 19 18 83 9.0 10.4 2017 01 22 19 24 80 9.3 11.0 2017 01 22 19 30 77 9.3 10.7 2017 01 22 19 36 76 8.3 10.2 2017 01 22 19 42 80 8.5 10.0 2017 01 22 19 48 88 8.6 11.5 2017 01 22 19 54 94 10.2 11.2 2017 01 22 20 00 93 10.1 11.9 2017 01 22 20 06 92 8.6 10.1 2017 01 22 20 12 89 9.3 10.7
WT20170905: Page 16 2017 01 22 20 18 84 9.2 10.4 2017 01 22 20 24 85 9.0 10.6 2017 01 22 20 30 82 8.7 10.3 2017 01 22 20 36 88 9.2 11.3 2017 01 22 20 42 99 9.9 12.6 2017 01 22 20 48 99 8.8 10.7 2017 01 22 20 54 101 10.0 11.5 2017 01 22 21 00 101 11.3 13.1 2017 01 22 21 06 98 10.1 12.2 2017 01 22 21 12 93 9.0 11.3 2017 01 22 21 18 93 9.5 11.0 2017 01 22 21 24 98 9.7 12.0 2017 01 22 21 30 102 10.1 12.3 2017 01 22 21 36 103 10.7 13.1 2017 01 22 21 42 110 12.0 14.0 2017 01 22 21 48 108 11.2 13.3 2017 01 22 21 54 115 10.4 12.2 2017 01 22 22 00 123 10.2 12.3 2017 01 22 22 06 130 9.9 11.5 2017 01 22 22 12 130 9.6 11.1 2017 01 22 22 18 129 9.8 11.2 2017 01 22 22 24 127 9.3 10.5 2017 01 22 22 30 131 8.1 9.7 2017 01 22 22 36 140 8.1 10.1 2017 01 22 22 42 156 8.3 10.9 2017 01 22 22 48 164 9.1 10.8 2017 01 22 22 54 172 9.0 11.5 2017 01 22 23 00 175 10.7 12.9 2017 01 22 23 06 175 10.9 12.9 2017 01 22 23 12 180 11.1 12.8 2017 01 22 23 18 180 10.8 13.5 2017 01 22 23 24 180 10.9 13.2 2017 01 22 23 30 180 12.5 14.8 2017 01 22 23 36 180 13.1 15.8 2017 01 22 23 42 184 12.7 14.7 2017 01 22 23 48 183 14.2 16.1 2017 01 22 23 54 182 13.1 15.1 2017 01 23 00 00 182 13.6 16.2 2017 01 23 00 06 182 13.0 15.1 2017 01 23 00 12 183 13.2 15.3 2017 01 23 00 18 183 12.9 14.5 2017 01 23 00 24 185 13.0 14.9 2017 01 23 00 30 185 12.5 14.1
Item F: Table of maximum wind gust observations at NOAA weather data observation stations, January 20 & 22, 2017
KTOA KHHR KLAX PRJC1 PFXC1 January 32mph, W, 42mph, WNW, 41mph, W, 46mph, SSW, 42mph, SSW 20th 1:55pm 1:51pm 2:00pm 12:24pm 12:24pm January 30mph, WSW, 30mph, WSW, 30mph, WSW, 36mph, S, 38mph, S, 22nd 3:50pm 11:00pm 11:23pm 4:00pm 3:54pm
WT20170905: Page 17 Item G: Table of maximum rainfall accumulations at NOAA weather data observation stations, January 20 & 22, 2017
KTOA KHHR KLAX PRJC1 PFXC1 January N/a 1.25” 1.35” N/a N/a 20th January N/a 2.72” 2.94” N/a N/a 22nd
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