Latest Weather Forecast
Weather Forecast 10/20/17
John Lindsey
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.
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about this forecast please E-mail John Lindsey at jcl5@pge.com
San Luis Obispo, California 93407