• This week's San Luis Obispo Tribune's Weather Watch Column "Could rain - and big waves - be headed toward fire-ravaged California?" http://www.sanluisobispo.com/news/weather/weather-watch/ • You can catch live weather forecasts weekday mornings from 6-9 a.m. on KVEC 920 AM on First Look with Andy Morris • For weather updates, charts and photos, along with power outage information and other events you can follow me at: https://twitter.com/pge_john =========== PG&E DCPP Weather Forecast for Friday 10/20/17 ========== SEA/SWELL: The California NOAA Marine buoy, Station #59 about 375 miles west of San Francisco peaked at 24-feet with a 17-second period last night. Historically, the height of a northwesterly (310-degree, deep-water) swell from this direction with a 17-second period is attenuated by about half by the time it reaches the Diablo Canyon Waverider Buoy. Currently, a 5- to 7-foot northwesterly (310-degree, deep-water) swell (with 20- to 22-second period) is arriving along our coastline and will rapidly build through this morning, becoming an 11- to 13-foot northwesterly (315-degree, deep-water) sea and swell (with a 5- to 18-second period) this afternoon into tonight. Note: The offshore NOAA buoys will reach 16- to 18-feet in height today. This northwesterly sea and swell will decrease to 10 to 12 feet (with a 7- to 16-second period) on Saturday, further lowering to 8 to 10 feet (with an 8- to 13-second period) on Sunday. A 7- to 9-foot northwesterly (310-degree, deep-water) swell (with an 18- to 21-second period) is forecast along our coastline on Monday, increasing to 8 to 10 feet (with a 16- to 18-second period) on Tuesday. This swell will decrease to 4 to 6 feet (with an 11- to 13-second period) on Wednesday into Thursday. Typhoon Lan is forecast to travel northward along the east coast of Japan and then toward the Aleutian islands becoming extratropical. If the numerical models verify, a very long-period west-northwesterly swell could arrive along our coastline on Oct. 28 & 29. Arriving from the Southern Hemisphere: A 1- to 3-foot Southern Hemisphere (180-degree, deep- water) swell (with an 18- to 20-second period) is expected along our coastline on Saturday into Monday. ATMOSPHERIC CONDITION: A fast moving cold front is passing through the Central Coast this morning with rain. So far, many Central Coast locations have recorded between a tenth and a quarter of an inch of precipitation. This morning's cold front will be followed by moderate gale-force to fresh gale-force (32 to 46 mph) northwesterly winds with gust to 55 mph along the coastline and partly skies later this morning into tonight. Today's high temperatures will range between the mid to high 60s throughout the Central Coast. Increasing high pressure over the Great Basin will produce a major Santa Lucia wind event on Sunday into Wednesday. These winds will produce dry and warm to hot conditions throughout the Central Coast including the beaches. Fresh to strong (19 to 31 mph) Santa Lucia (northeasterly) winds are forecast Saturday, increasing to strong to gale- force (25 to 38 mph) levels with gust to 50 mph at Diablo Canyon on Sunday. These offshore winds could reach strong to gale-force levels with wind gust of 55 mph near the Estero Bay area, especially along Highway 41 from Morro Bay High School heading toward Atascadero about halfway up the grade. Also parts of eastern San Luis Obispo, including Cal Poly, San Luis Obispo High School and French Medical Center. These northeasterly winds will decrease to fresh to strong (19 to 31 mph) levels on Monday into Tuesday, further lowering by Wednesday. Air temperatures will continue to rise reaching the high 90s, if not the low 100s in the coastal valleys and along the beaches by Tuesday. Note: These Santa Lucia winds, warm to hot temperatures and low relative-humidity levels will produce extreme fire danger. Persistent northwesterly (onshore) winds will allow the marine layer to redevelop along the coastline by next Thursday producing cooler temperatures. The long-range charts are advertising a chance of rain on Oct. 31 into Nov. 2. These are long-range charts and will probably change. Weather graphics and power outage information are available at: twitter.com/pge_john. Yesterday's Today's Tomorrow's Min Max Min Max Min Max 53.1° 63.3° 55.5° 61.0° 52.0° 72.0° PG&E Weather Office in San Francisco predicted temperatures for San Luis Obispo County Inland Temperatures, Paso Robles Actual Predicted Thu Fri Sat Sun Mon Tue Wed Thu 38 83 53 68 35 76 38 85 42 91 43 96 45 95 43 91 Coastal Valleys Temperatures, San Luis Obispo Thu Fri Sat Sun Mon Tue Wed Thu 50 75 58 69 48 78 53 85 56 94 56 97 55 91 54 86 WINDS: Moderate gale-force to fresh gale-force (32 to 46 mph) with gust to 55 mph post-frontal northwesterly winds are forecast later this morning into this evening along the coastline. Fresh to strong (19 to 31 mph) Santa Lucia (northeasterly) winds are forecast Saturday, increasing to strong to gale- force (25 to 38 mph) levels with gust to 50 mph on Sunday. These northeasterly winds will decrease to fresh to strong (19 to 31 mph) levels on Monday into Tuesday. DIABLO CANYON METEOROLOGICAL TOWER WIND DATA: Today's Maximum Winds: Max peak winds: SE 8.3 mph @ 4:00 a.m. Max sustained wind: SE 6.5 mph @ 4:00 a.m. Yesterday's Maximum Winds: Max peak winds: NW 40.3 mph @ 2:45 p.m. Max sustained wind: NW 31.1 mph @ 3:00 p.m. SEAWATER TEMPERATURES: Seawater temperatures will range between 55 and 58 degrees through today, decreasing to 53 and 57 degrees on Saturday into Monday. Seawater temperatures will increase on Tuesday through next Friday. OCEAN CURRENTS: A southerly (offshore) flowing current is forecast to continue to flow southward into next Friday. SEAWATER VISIBILITY: Seawater visibility was 5 to 7 feet at the Diablo Canyon Intake. ========================================================================== 24-Hour Ocean Condition Outlook for Friday 10/20 to Saturday 10/21 SEA/SWELL: DIR. NW HT. 4-6 PER. 18-22 This morning Increasing to: DIR. NW HT. 8-10 PER. 5-20 Later this morning Increasing to: DIR. NW HT. 11-13 PER. 5-18 This afternoon Remaining at: DIR. NW HT. 11-13 PER. 6-17 Tonight WINDS: DIR. SE SPEED 5-10 This morning Increasing to: DIR. NW SPEED 30-35 + 45 later this morning Increasing to: DIR. NW SPEED 35-40 + 55 This afternoon Decreasing to: DIR. N SPEED 30-35 + 45 Tonight ========================================================================== 48-Hour Ocean Condition Outlook for Saturday 10/21 to Sunday 10/22 SEA/SWELL: DIR. NW HT. 10-12 PER. 7-17 Saturday morning Remaining at: DIR. NW HT. 10-12 PER. 8-17 Saturday afternoon Decreasing to: DIR. NW HT. 9-11 PER. 9-16 Saturday night (Combined with: DIR. S HT 1-3 PER 18-20 All day Saturday) WINDS: DIR. NE SPEED 15-20 + 20 Saturday morning Decreasing to: DIR. N SPEED 10-15 Saturday afternoon Increasing to: DIR. NE SPEED 20-25 + 30 Saturday night =========================================================================== Extended Ocean Condition Outlook: Fresh to strong (19 to 31 mph) Santa Lucia (northeasterly) winds are forecast Saturday, increasing to strong to gale- force (25 to 38 mph) levels with gust to 50 mph on Sunday. =========================================================================== The 24 - Hour Ocean Data From The Diablo Canyon Wave rider Buoy MONTH DAY TIME SIG.HEIGHT PERIOD SWELL DIRECTION SST 10 15 0800 5.4 10 286 58.8 10 16 0630 4.4 10 288 59.0 10 17 1700 4.3 18 206 61.5 10 18 0400 5.4 17 200 60.6 10 19 0600 5.3 11 272 59.9 10 20 0430 4.8 22 257 60.1 DCPP Ocean Lab Waverider Buoy Energy Spectral Analysis mo. day time sig.ht. sig.per. energy (cm.sq.) (cm) (sec) 22+ 20 17 15 13 11 9 7 ------------------------------------------------------------------------- 10 15 0800 164 11 0 2 8 28 143 453 429 265 10 16 0630 133 9 2 6 15 28 31 235 420 106 10 17 1700 132 4 13 224 136 122 76 84 84 250 10 18 0400 163 17 4 68 480 244 101 105 118 328 10 19 0600 161 4 1 5 60 109 88 395 203 414 10 20 0430 147 20 137 313 94 138 108 195 174 90 Daily Swell Inspection Program for today: NAME DAY TIME HEIGHT PERIOD SS (PST) (FEET) (SECONDS) (DEG. F) # 35 Central Bering Sea 20 0330 10 9 45.3 # 01 Ocean Station Papa n/a n/a n/a # 06 SE Papa 20 0345 n/a n/a 63.9 # 02 West Oregon 20 0325 21 16 n/a # 59 California 20 0310 23 17 63.7 # 44 Humboldt Bay Waverider 20 0330 19 18 50.4 # 29 Point Reyes Waverider 20 0315 18 17 53.1 # 42 San Francisco Sandbar 20 0325 11 18 54.7 # 15 Monterey Waverider Buoy 20 0349 18 17 55.2 # 28 Cape San Martin 20 0300 10 19 57.0 # 76 DCPP Waverider 20 0430 5 22 60.1 # 22 Santa Lucia Escarpment 20 0315 7 20 60.4 # 11 Point Arguello 20 0320 4 15 58.6 # 63 Harvest Buoy 20 0305 5 20 61.2 # 19 San Nicolas Island 20 0310 6 13 64.0 # 20 Scripps 20 0350 3 7 69.4 # 01 NW Hawaii 20 0330 11 9 80.2 # 04 SE Hawaii 20 0335 9 8 80.2 Precipitation at the Diablo Canyon Ocean Lab: Tuesday 1500 through Wednesday 1500 0.00 inches Wednesday 1500 through Thursday 1500 0.00 inches Thursday 1500 through Friday 0530 0.16 inches Precipitation this rain season (July 1 - June 30): 0.27 inches Average season rainfall at DCPP to date: 0.43 inches Ocean Lab Barometer: 29.98 in/Hg or 1015.4 mb +0.9 mb (Rising) Today's Sunrise 7:14 AM Sunset 6:21 PM Tomorrow's Sunrise 7:15 AM Sunset 6:20 PM Tides: Low Tide High Tide AM PM AM PM 20 Friday 4:35 1.4 5:25 0.2 10:43 5.5 11:43 4.4 21 Saturday 5:05 1.8 6:04 0.2 11:11 5.5 ----- --- 22 Sunday 5:36 2.2 6:45 0.3 11:40 5.3 (12:30 4.1) 23 Monday 6:08 2.6 7:31 0.4 1:22 3.9 12:11 5.1 24 Tuesday 6:46 2.9 8:23 0.6 2:25 3.7 12:46 4.8 ======================================================================== This day in weather history 1977 - Dutch Harbor in Alaska reported a barometric pressure reading of 27.31 inches (925 millibars) to establish an all-time record for the state. (The Weather Channel) 1987 - A storm system moving across the Saint Lawrence Valley produced 40 to 50 mph winds east of Lake Ontario. High winds downed some trees around Watertown NY, and produced waves seven feet high between Henderson Harbor and Alexandria Bay. Mason City IA and Waterloo IA tied for honors as cold spot in the nation with record lows for the date of 19 degrees. Severe thunderstorms in Oklahoma and northern Texas produced golf ball size hail and wind gusts to 65 mph. (Storm Data) ======================================================================== This weather forecast is a service provided by Pacific Gas and Electric Company (PG&E) to our energy customers. The forecast is valid only for the Diablo Canyon Power Plant coastline area (approximately a one-half mile radius surrounding the plant). Some of the information in this forecast is provided by Pacific Weather Analysis, with their permission. Replication of this email must be in its entirety. You may view and copy material from this forecast, provided you retain all copyright, trademark, and other proprietary notices displayed on the materials. Use of these materials in publications, radio, television, other media presentations, or other websites is prohibited without PG&E's express written consent. PG&E is a subsidiary of PG&E Corporation, one of the largest natural gas and electric utilities in the United States, delivering some of the nation's cleanest energy to 15 million people in northern and central California. If you would like to subscribe or unsubscribe to this daily forecast, please send an email to PGEweather@pge.com. Any questions about this forecast please E-mail John Lindsey at jcl5@pge.com