Weathernotes Archive

Dec. 25 - Storm Misses Los Angeles. Trough Producing Some Rain & Snow. A Pacific storm system -- which at one point was expected to be the wettest of the rain season thus far -- took a more westward track and skirted the coast of Southern California on Christmas Eve, generally producing only modest rainfall across the area.
Dec. 23 - Potent Pacific Storm Takes Aim at California. A potent appearing Pacific storm system is developing off the coast of Oregon and Northern California and headed our way. Significant rain, with snow at the higher elevations, is expected over much of the state.
Dec. 18 - Rain, Snow, and Blustery Winds in Southern California. High Impact Weather for Christmas? A cold upper level low produced widespread rain and snow in Southern California, closing highways, fouling traffic, and chilling Southlanders. As much as a foot of snow was reported in the Antelope Valley and the snow level dropped to near 2000 ft in the foothills and mountains of Ventura and Los Angeles counties.
Dec. 16 - Back to Back Upper Level Lows. An intense upper level low, fed in part by moisture that originated in the subtropical mid-Pacific, produced widespread rain in Southern California, with snow at the higher elevations. Precipitation totals generally ranged from about 1 to 3 inches, and new rainfall records for December 15 were set at LAX, UCLA, Long Beach, San Gabriel and Santa Barbara.
Dec. 12 - Wintry Weather Expected in Southland. Downtown Los Angeles (USC) rainfall has dropped to about six-tenths of an inch below normal. If a storm later this weekend works out as expected, we could be back above normal by Monday night.

Feb. 25 - Pacific Storm Soaks California -- Dumps More Snow in Sierra. Weather conditions were tough for the Amgen Tour of California cyclists cranking over Mill Creek Summit yesterday. The Mill Creek RAWS recorded an average temperature of 35°F, with winds of 25 mph, gusting to 40 mph, at about the time the peloton cleared the summit. Since mid-week last week some Sierra snow sensors have recorded as much as 8 or 9 inches snow water equivalent of precipitation -- the rough equivalent of 6 or 7 feet of snow. Today's Statewide Summary of Snow Water Equivalents, provided by the California Cooperative Snow Surveys, reports the Sierra snowpack at 119% of normal for the date and 101% of the average April 1 seasonal total.
Feb. 22 - Intense Pacific Storm Approaching West Coast. Rapidly intensifying Pacific low pressure system approaching the west coast looks very impressive on satellite images this afternoon, with strong upper and low level jet dynamics, a good moisture feed, and a classic baroclinic leaf.
Feb. 21 - Extended Pacific Jet Sends Us Some Rain! Precipitation totals from the first of a series of shortwaves associated with a extended Pacific jetstream produced rainfall amounts ranging from about 0.1 to 0.25 inch in the Los Angeles area yesterday, with up to about 0.5 inch recorded in some mountain locations.
Feb. 14 - Trough Wetter Than Expected. Pattern Change Next Week? A more westward position of the upper low than forecast by yesterday's 18z GFS and NAM, has resulted in a more vigorous system that has produced rain in several areas of the Southland and snow in the mountains.The last few runs of the GFS have been indicating a transition back to a wetter pattern around mid-week of next week, when a strong Pacific jet and a series of shortwave troughs are forecast to target the west coast.
Feb. 5 - Western Drought Severity Lessens. More Rain For Los Angeles, More Snow For The Sierra. Sunday's storm added more rain to Southern California's unexpectedly wet water year totals, and more snow to the Sierra snowpack. This rain season western storms have reduced drought classifications by as much as three steps in some areas of California and four in Arizona. Sierra snow course measurements for February 1 are coming in and manual measurements are confirming what automatic snow sensors have already reported -- that the Sierra snowpack is well above normal for the date.

Jan. 28 - Eight Days of Los Angeles Rain One of Longest Wet Periods on Record. According to NWS Preliminary Climatology Data (CF6), Downtown Los Angeles has recorded measurable rain on each of eight days from January 21 to January 28, 2008. This puts it in the top six of the station's wettest periods from 1921-2007.
Jan. 25 - Heavy Rain Expected Overnight Saturday. The extensive circulation around an upper level low is forecast to interact with the southern branch of the jet stream and an associated plume of sub-tropical moisture, and draw the jet and moisture into Southern California overnight on Saturday.
Jan. 24 - New Upper Level Low May Tap Tropical Moisture. You can see why the weather models had such a tough time with yesterday's forecast for Los Angeles. Much of the day the main rain band associated with the upper level low spinning off the coast was stalled and producing moderate to heavy rain in areas of Ventura, Santa Barbara and San Luis Obispo counties. New daily rainfall records were set at Santa Barbara, Santa Maria, and Paso Robles airports.
Jan. 22 - Upper Level Low Spinning Showers into Southern California -- Heavier Rain May Be On Tap. In a rain season characterized by upper level lows, yet another one has set up shop off the coast and has been sending some showers our way. As of 8:00 a.m. this morning rainfall totals around the Los Angeles area have generally ranged from a few hundredths of an inch to as much as about 0.25 inch in a few locations.
Jan 7. - Series of Storms Soaks West. Precipitation totals in the Los Angeles area from Friday morning to this morning generally ranged from 2-5 inches in the basin and valleys, and from 5 to 10 inches or more in the local foothills and mountains. San Marcos Pass, near Santa Barbara recorded nearly 11 inches of rain, and OPIDS Camp, near Mt. Wilson, recorded nearly 13 inches of precipitation.

Aug. 31 - Heat Wave Expected to Continue. Los Angeles Pierce College in Woodland Hills recorded a high temperature of 109°F on Wednesday and Thursday, and so far today has reached a temperature of about 108°F. The hot weather is expected to continue through Labor Day, along with periods of higher than normal humidity.
Aug. 27 - Hurricane Dean Moisture Produces Some Showers. Remnant moisture from Hurricane Dean produced a few showers around the area over the weekend.
Aug. 24 - Cool July! Southern California Winter Precipitation Outlook. Have you noticed it's been cooler this summer? Last year Pierce College in Woodland Hills recorded a high temperature of at least 100°F on 25 of 31 days in July, culminating in a sweltering record high of 119°F. This year only 10 days in July reached the 100° mark at the school. Virtually all international dynamic coupled climate models are forecasting cooler equatorial Pacific SSTs this Fall, trending towards neutral conditions this Spring. As a result, most longer range outlooks are similar to the Nov-Dec-Jan Precipitation Outlook from the CPC, and somewhat typical of a La Niña, with an increased chance of higher than normal precipitation in the Pacific northwest and a increased chance of lower than normal precipitation in the southwest.

Jul. 4 - Driest Water Year On Record. There was no measurable rain recorded this May or June at Downtown Los Angeles (USC). The most recent measurable rain was on April 22 when 0.04 inch of rain was recorded. From July 1, 2006 to June 30, 2007, Los Angeles recorded only 3.21 inches of rain, breaking the record set in 2001-2002 as the driest year since recordkeeping began in 1877.
Jul. 24 - A Little Rain is Better Than None! Although only a trace of rain was observed at Downtown Los Angeles (USC) yesterday, several stations in Los Angeles County recorded some precipitation. Rainfall amounts ranged from 0.01 inch or so, to as much as 0.15 inch at Opids Camp in the San Gabriel Mountains.

Apr. 23 - Wettest Day in Driest Year? Friday's vigorous system produced 0.50 inch of rain at Downtown Los Angeles (USC). According to the NWS, this is the latest date in the water year that Los Angeles has recorded it's first day of 0.5 inch, or more, of rain.
Apr. 16 - Scattered Showers in Southern California. Downtown Los Angeles (USC) was one of just a few places in Southern California that received measurable rain yesterday as a result of moisture wrapping around a late season upper low.

Feb. 1 - July-January 5th Driest on Record. Warm Superbowl Sunday. Pattern Change Ahead? While some locations in the Los Angeles area were pounded by heavy showers on Tuesday, with rain rates on the order of a 0.25 inch/hour, Downtown Los Angeles (USC) recorded only 0.02 inch of rain. This increased the water year total (since July 1) to 1.50 inches, which is 5.62 below normal, and the 5th driest water year on record.
Feb. 9 - Will Los Angeles Be Short-Changed Again? A strong Pacific storm system with a very moist sub-tropical connection is forecast to produce more than an inch of precipitation over much of California the next 72 hours, with as much as 5 inches (liquid equivalent) forecast in some areas of the central Sierra Nevada. Given our meager amount of rainfall this rain season, it is unfortunate that the projected amount of precipitation falls off dramatically south of Santa Barbara.
Feb. 19 - Rainy Monday with More on the Way? Upper low and trough has produced widely varying rainfall intensities and amounts across the area, with CNRFC reporting as little as 0.01 inch at Malibu, and as much as 0.71 inch at Browns Canyon for the 24 hr. period ending at 8:00 a.m. So far Downtown Los Angeles (USC) as recorded 0.03 inch since midnight and 0.09 inch the last 24 hours.
Feb. 28 - Two Fronts — Not Enough Rain. Only the first of two cold fronts held together well enough to produce measurable rain throughout the Los Angeles area. Rainfall amounts from Monday's frontal passage generally ranged from few hundredths to a few tenths in the basin and valleys, with up to an inch or so in the mountains. Downtown Los Angeles (USC) recorded 0.04 inch of rain on Monday, no rain on Tuesday, and a trace of precipitation today, bringing the water year total to 2.42 inches, which is 8.38 inches below normal. This is less rainfall for the date than in the record dry water year of 2001-2002.

Jan. 6 - Wind Instead of Rain. Frigid End of the Week? El Niño May Have Peaked. So far this rain season passing cold fronts have stirred up more wind than rain. This was the case again overnight Thursday. A weakening cold front produced little precipitation, but its passage generated winds in excess of 80 mph at the Cheeseboro RAWS near Agoura, and Whitaker Peak RAWS along the I-5 corridor south of Gorman. Dr. Klaus Wolter's Multivariate ENSO Index (MEI) for November/December decreased from 1.293 to 0.985. This resulted in the biggest one-month drop in MEI rank on record for this time of year.
Jan. 15 - Record Low Temperatures. Drought Continues. Usual El Niño Impacts Still On Hold. Chance of Showers? Many new record low temperatures for the date were set across the area early Sunday morning, including Downtown Los Angeles at 36°F, Burbank at 26°F, Long Beach at 31°F, Palmdale 10°F, and Lancaster at a frigid 3°F. Woodland Hills tied the record for the date at 20°F, as did the Santa Monica Pier at 39°F. According to the NWS Climate Report for January 14, 2007, Los Angeles (USC) has recorded only 1.31 inches of rain since the water year began on July 1.
Jan. 26 - Chance of Weekend Showers. January One of the Driest on Record? So far this January Downtown Los Angeles (USC) has recorded only 0.01 inch of rain. This makes it a contender for one of the driest Januarys on record. Where it will rank depends on the amount of rain a cut-off upper low currently spinning off the California coast generates in the Los Angeles area over the next few days.
Jan. 29 - Continuing Chance of Showers. July-January One of the Driest on Record. According to the NWS Climate Reports, Los Angeles (USC) recorded only 0.16 inch of rain on Saturday, and none on Sunday. This brings the preliminary January rainfall total to 0.17 inch – tied with January 1984 as the 10th driest on record – and the water year total (since July 1) to 1.48 inches. A water year total less than 1.72 inches on February 1 would rank this season's July-January rainfall as the 5th driest on record.

Dec. 8 - Change to More Seasonable Pattern? MEI Exceeds Strong El Niño Threshold. If the computer weather models have their way, it looks like some cooler, wetter weather will be moving into Southern California this weekend. It's already raining up in the Bay area, and Intellicast composite radar shows the rain band down to about Pt. Conception. Dr. Klaus Wolter's Multivariate ENSO Index (MEI) for October/November increased from 1.03 to 1.29. This moves the MEI above the strong El Niño threshold, as defined by the index. It is the 5th highest MEI for all October-November values (since 1950). and is the highest ranked value since April-May 1998.
Dec. 15 - Difficult Forecast for the Weekend. The computer weather models have been having a tough time getting a handle on the system forecast to move through Southern California this weekend. While there's a pretty good chance it will be damp, blustery, and cool much of this weekend, the difficult question is just how damp will it get?
Dec. 26 - Another Difficult Forecast. Yet again this rain season, computer weather models have been having a tough time with the forecast, and seem to be understating precipitation amounts for the storm expected to affect the area over the next 24 hours or so.

Nov. 9 - November Temperatures Soar. El Niño Continues to Strengthen. Slight Chance of a Shower? Woodland Hills' (Pierce College) high temperature of 101°F on Tuesday was the highest November temperature ever recorded there. Downtown Los Angeles' 97°F set a new record for the date, and it was the highest temperature ever recorded by the station so late in the season. Many other stations around the area also set new record highs.
Nov. 24 - NOAA Releases Updated Winter Outlook. Chance of Showers Monday. Warm November. El Niño Continues to Strengthen. NOAA released its final Winter Outlook for the 2006-2007 U.S. Winter season on November 16. The revised outlook indicates a somewhat better chance of a wetter than normal Winter in Southern California, than the outlook issued October 19. It's been warm this November. Downtown Los Angeles (USC) set new high temperature records for the date on November 6, November 7 and November 20. The average high temperature the first 22 days of November was 81.4°F, which is about 7°F above normal.

Oct. 2 - First Autumn Showers. NOAA Issues Unscheduled El Niño Advisory. TAO/TRITON Moorings Vandalized. The first widespread measurable rain of the 2006-2007 rain season moved into Southern California yesterday, and continued overnight. In an unscheduled advisory, issued September 13, 2006, NOAA announced that El Niño conditions had developed in the tropical Pacific and could strengthen into a moderate event by winter.
Oct. 13 - Chance of Showers. MEI Above Moderate El Niño Threshold. Initial NOAA Winter Outlook Released. An upper level low that produced several inches of snow at South Lake Tahoe and Mammoth Mountain earlier this week is now located off the coast of Southern California and spinning bands of showers into the area. Dr. Klaus Wolter's Multivariate ENSO Index (MEI) for August/September increased to 0.892. This moves the MEI to just above the moderate El Niño threshold.
Oct. 30 - NOAA Releases Updated Winter Outlook. El Niño Continues to Strengthen. Over the past three weeks the Southern Oscillation Index (SOI) has dropped from about -8 to about -16 and another westerly windburst has occurred in the western equatorial Pacific. TAO/TRITON 5-Day Depth Averaged Temperature data shows two large areas of anomalies of 1.7 °C or more. No El Niño impacts here yet, just great Autumn weather.

Sep. 14 - A Few Sprinkles Around Southland. MEI Exceeds El Niño Threshold. A shortwave wrinkle in a broad upper trough over the West, associated vorticity, and an 80 kt. jet max nosing into Southern California combined to produce a few showers in the area this morning. Dr. Klaus Wolter's Multivariate ENSO Index (MEI) for July/August increased to 0.75, and moves the MEI well above the weak El Niño threshold.

Aug. 3 - Record July Heat. New El Niño Developing? This July you didn't have to run an ultramarathon in Death Valley to experience extreme heat. According to the NWS, Pierce College in Woodland Hills recorded a new all time high temperature for that station of 119°F. This was the highest temperature ever recorded at an NWS observation site in Los Angeles County. Triple digit highs were recorded at Pierce College a record 24 days of July.
Aug. 18 - Westerly Windbursts May Signal El Niño Onset. TAO/TRITON zonal wind data and Climate Data Assimilation System (CDAS) 850-hPa Wind Anomalies indicate a westerly windburst is occurring in the western equatorial Pacific. Dr. Klaus Wolter's Multivariate ENSO Index (MEI) for June/July increased to 0.64, and as Dr. Wolter points out, this is a an increase of more than 1.2 standard deviations in three months, and moves the MEI above the weak El Nino threshold.

Jun. 9 - Marine Layer Produces Some Drizzle. Passage of a weak upper trough has deepened the marine layer and produced some drizzle overnight, and this morning, in the Los Angeles basin and valleys. As of 8:00 this morning, LAX has recorded 0.01 inch of precipitation, and several other stations have recorded amounts ranging from a trace to 0.01 inches.

May 18 - Summer Monsoon, to be Followed by Winter Rain? So far this year we've had eighty degree temps in February, foothill snow in March, and record rain in April; so why not a Summer monsoon pattern in May, followed by an unseasonably strong Winter-like Pacific storm system?
May 22 - Rainfall Record Set in 1921 Broken. According to a NWS preliminary Record Event Report, released at 12:50 this afternoon, Downtown Los Angeles (USC) has recorded 0.67 inches of rain so far today, surpassing a record of 0.33 inches set in 1921. As of 11:00 A.M., the NWS reports that the total rainfall recorded at Los Angeles (USC) for the storm has been 0.84 inches.

Apr. 5 - Record Rain in Los Angeles -- Record Snow at Mammoth Mountain! The strong Pacific low pressure system that has been spinning off the West coast since Sunday is finally moving onshore this morning. The late season low has been pumping copious amounts of sub-tropical moisture into the state, resulting in moderate to heavy rain in many areas, swollen rivers and creeks, and heavy snow at the higher elevations of the Sierra. According to preliminary NWS data, Downtown Los Angeles (USC) set a new rainfall record of 1.44 inches yesterday, breaking the record for the date set in 1921.
Apr. 10 - Chance of a Shower Over Next 24 Hours. Chance of Rain Friday? Intellicast.com composite radar from 6:30 this morning shows a precipitation band associated with an embedded shortwave and persistent upper level trough along the coast of California. As the current trough moves onshore, it is replaced by yet another upper level trough and its associated surface low. The system is forecast to cut-off, and like most cut-off upper lows, creates a great deal of uncertainty in the forecast -- like when, where and how much precipitation?
Apr. 12 - Rain Forecast for Friday. GOES-10 water vapor image show huge upper level low over the eastern Pacific with quasi-stationary frontal zone impacting the Monterey and San Francisco areas, northward. RAMDIS shows the center of circulation more or less stationary, with the low continuing to extend southward, and some eastward movement of the frontal boundary.
Apr. 14 - More Seasonable Weather Forecast for Southern California. Remember the weather just before Valentine's Day? On February 13th Los Angeles (USC) recorded a high temperature of 86 degrees. Just a week later it snowed in the foothills, and it seems like it's been cool with showers or rain every few days ever since.
Apr. 26 - Neverending Cool Pattern Continues. Chance of Showers and Thunderstorms in Southern California. La Niña Wanes. Another upper level low, the latest in our series of upper level lows, is spinning off the coast of Southern California this morning, and producing showers and thunderstorms to the north of Pt, Conception and in the San Joaquin Valley.

Mar. 3 - Series of Systems Forecast for California. Chance of Showers Monday. Weak La Niña Rebounds. Frontal zone associated with Pacific low pressure system is working its way through Southern California this morning. Intellicast.com composite radar from 6:15 shows a mix of light, moderate, and some heavier showers around the area.
Mar. 9 - Chance of Low Elevation Snow in Southern California. The third in a week-long series of northern stream Pacific low pressure troughs is digging into the West today and is expected to produce rain and snow throughout much of California over the next 48 hours or so. A combination of low freezing levels and convection could result in snow flurries down into the 1500-2000 ft. range in the Los Angeles area overnight Friday.
Mar. 11 - Low Elevation Snow in Southern California! This morning, at about 2000 ft. in the Simi Hills, periodic snow showers added a white accent to the black, brown, and greens of a landscape in the process of recovering from the Topanga Fire. The snow was wet, and not much was accumulating, but it was SNOW in March within a mile or two of the Simi and San Fernando Valleys.
Mar. 16 - Déjà Vu All Over Again? In a virtual rerun of last week's cold, wet, and snowy weather, another cold upper level trough is forecast to move through Southern California Friday and Saturday, and bring with it cool temperatures, a pretty good chance of rain, and perhaps snow back down around the 2500 ft. level. At the moment, it looks like 500 mb thickness and 850 mb temperatures won't drop quite as low as last week's storm, and that the coldest temperatures won't occur until later in the storm.
Mar. 20 - Spring Begins with Below Normal Temperatures and Chance of Showers. Friday and Saturday's showery system wasn't quite as cold, and wasn't quite as wet, as the storm a week ago Saturday, but did produce several inches of snow in the local mountains, and from 0.01 to about 0.5 inch of rain at the lower elevations. Yet another in our continuing series of March storms is forecast to produce some more showers this evening into tomorrow morning.
Mar. 27 - Active March Weather Pattern Forecast to End with a Bang! Of one thing we can be sure... Beyond this week, there will be no more storms this March! Cool temperatures and periodic showers have been the hallmarks of this month, and it looks like the approaching system could be one of the strongest in the series.
Mar. 29 - Jet Energized Front Breaks Rainfall Record Set in 1895! Yesterday's 1.62 inches of rain at Los Angeles (USC) set a new record for the date, breaking a record set in 1895. Sub-tropical moisture and favorable placement of a 100 kt. jet max enhanced the dynamics and precipitation within the frontal zone associated with a Pacific low pressure system as the front moved through Southern California.
Mar. 31 - March Madness to Continue into April? Intellicast.com composite radar shows band of showers working its way through Southern California this morning, but so far only a small amount of precipitation is making it to the ground. CNRFC's Observed Precipitation shows rainfall amounts of around 0.04 inch associated with the band. March's wet pattern does look like it will continue into April. A strong Pacific low pressure system is forecast to affect the area early Monday into Tuesday.

Nov. 8 - Upper Low Threatens Rain. ENSO Neutral... For Now. MJO Won't Start. 12z NAM and GFS forecast chance of rain. In absence of El Niño and La Nina Madden-Julian Oscillation (MJO) can become an important factor in our weather. Multivariate ENSO Index (MEI) for Sep/Oct dropped below -0.2 for the first time since Oct/Nov 2001. Drop into true La Niña conditions appears possible.
Nov. 10 - Cut-off upper low continues to spin WSW of Pt. Conception and has produced precipitation ranging from light rain in the Los Angeles basin to heavier rainfall in orographically favored slopes of the Ventura and Santa Barbara mountains.

Feb. 11 - Moderate to heavy rain in areas of Los Angeles and Ventura counties.
Feb. 14 - California may be impacted by an extended period of wet weather.
Feb. 18 - Strong embedded cells result in heavy rain. 12z NAM forecasts more than 5 inches of rain at Los Angeles.
Feb. 19 - Rainfall total for the water year at Los Angeles exceeds 27 inches, ranking it the 9th wettest on record. 4.5 inches of additional rain forecast by the 12z NAM.
Feb. 21 - Rainfall total for water year at Los Angeles now 31.36 inches, ranking it the 5th wettest on record, surpassing the big El Niño winters of 1982-83 and 1997-98.
Feb. 22 - Los Angeles receives 7.61 inches of rain, increasing the seasonal total to 32.87 inches -- the fourth wettest rainy season on record. 12z NAM forecasts low to move slowly down the coast bringing with it the potential for severe weather.
Feb. 23 - Rainfall total for the water year at Los Angeles (USC) 33.87 inches, ranking the season the 3rd wettest on record, surpassing 1977-78. OPIDS Camp has recorded a cumulative seasonal precipitation total of 107 inches.
Feb. 25 - Scattered showers and thunderstorms in moist unstable air associated with a broad area anti-cyclonic circulation centered over the Four Corners area. NWS Public Information Statements with rainfall totals and additional information related to February 17-23 heavy rainfall event.

2004

Nov. 21 - Upper low over Southern California results in wind, rain and some lower elevation snow. Portions of Highway 138 and Interstate 10 were closed, and snow was reported down to as low as 1000 ft.
Nov. 20 - CPC Long-lead Precipitation Outlook forecasts a slightly better chance of above normal precipitation in Southern California.

2003

2002

Nov. 7 - Angeles National Forest is closed due to extremely dry conditions and the resultant fire danger. Large areas of the western U.S. are experiencing drought conditions. heavy rain and snow is forecast over the northern two-thirds of the state.
Nov. 9 - More precipitation in one storm than the total recorded for the previous 10 months

July 2002

April 2002

March 2002

February 2002

January 2002

2001

December 2001

November 2001

October 2001

July 2001

April 2001

March 2001

February 2001

January 2001

2000

December 2000

November 2000

October 2000