PG&E weather forecast for Friday January 21

January 21, 2011

By JOHN LINDSEY from PG&E

SWELL:

This morning’s 5- to 7-foot west-northwesterly (290-degree deep-water) swell (with a 20- to 22-second period) will increase to 7- to 9-feet (with an 18- to 20-second period) this afternoon. This long-period swell will further build  to 8- to 10-feet by tonight.

This swell will continue to increase to 9- to 11-feet (with a 15- to 18-second period) on Saturday.

Note: Swell heights will be higher at the offshore buoys.

This west-northwesterly (285-degree deep-water) swell will decrease to 8- to 10-feet (with a 14- to 17-second period) on Sunday, further lowering to 6- to 8-feet by Monday through Tuesday.

A 6- to 8-foot west-northwesterly (285-degree deep-water) swell (with a 14- to 18-second period) is forecast along our coastline on Wednesday, increasing to 7- to 9-feet (with a 13- to 15-second period) on Thursday.

Preliminary analysis:

Another long-period, west-northwesterly (285-degree deep-water)  swell will arrive along our coastline on Jan 30.

ATMOSPHERIC CONDITION:

The 1,030 millibar Eastern Pacific High parked about 500 miles to  west-northwest of San Luis Obispo combined with a ridge of high  pressure over California will continue to produce dry and clear weather through next week.

The exception will be the San Joaquin Valley where tule fog will persist through next week.

High temperatures will range between the high 60s to low-70s in the North County (Paso Robles) and along the northwesterly (Morro Bay and Los Osos) facing beaches.

High temperatures in the coastal valleys (San Luis Obispo) and along the southwesterly (Avila Beach and Cayucos) facing beaches will reach the mid to high-70s.

Overall, January is shaping up to be a very dry month after a very wet December, the second wettest since 1996.

DIABLO CANYON AIR TEMPERATURES:

Diablo Canyon Meteorological Tower Air Temperature Data

Yesterday’s           Today’s            Tomorrow’s
Min    Max         Min    Max          Min     Max
52.7°   62.6°      51.8°   64.0°       52.0     64.0

PG&E San Francisco Met Office predicted temps:

Inland Temperatures, Paso Robles

Actual                    Predicted

Thu       Fri      Sat      Sun      Mon     Tue      Wed     Thu     Fri
33-71   33-67  40-68  40-68  40-68    40-69   41-69   41-68  35-68

Coastal Valleys Temperatures, San Luis Obispo

Thu       Fri     Sat      Sun     Mon      Tue      Wed      Thu      Fri
41-74   38-72 38-73  44-74  44-77    41-76   37-75    41-75   40-69

WINDS:

A pattern of gentle to moderate (8 and 18 mph) and at times gusty northeasterly (offshore) winds developing during the night and morning hours, increasing out of northwest to moderate to fresh (13 and 24 mph) levels during the afternoon hours will continue through Monday.

Gentle northeasterly (offshore) winds are forecast on Tuesday through next Friday.

DIABLO CANYON METEOROLOGICAL TOWER WIND DATA:

Today’s winds:

Max peak winds:      SE        7.8 mph at   8:30 a.m.
Max sustained wind:  SE        6.0 mph at   8:30 a.m.

Yesterday’s Maximum Winds:

Max peak winds:      NW       27.7 mph at   4:45 p.m.
Max sustained wind:  NW       20.4 mph at   4:45 p.m.

SEAWATER TEMPERATURES:

The Diablo Canyon waverider buoy is reporting a sea surface temperature of 53.2 degrees while the Nortek AWAC current meter is reporting 53.0 degrees.

Intake seawater temperatures will range between 53 and 55-degrees through Monday, increasing to 54 and 56-degrees on Tuesday and remaining at this range through next Friday.

OCEAN CURRENTS:

Both the DCPP Cal Poly CODAR stations and the DCPP Nortek AWAC meter are indicating a northerly (onshore) flowing current.

This northerly (onshore) flowing current will continue to flow northward through most of next week.

SEAWATER VISIBILITY:

Seawater visibility was 5 to 7 feet at the Diablo Canyon Intake.

==========================================================================
24-Hour Ocean Condition Outlook for Friday 01/21 to Saturday 01/22

Swell           DIR. WNW     HT.   5-7    PER. 20-22  This morning
Increasing to:  DIR. WNW     HT.   7-9    PER. 18-20  This afternoon
Increasing to:  DIR. WNW     HT.   8-10   PER. 18-20  Tonight

WINDS:          DIR. SE      SPEED  5-10              This morning
Increasing to:  DIR. NW      SPEED 15-20 + 25         This afternoon
Decreasing to:  DIR. NE      SPEED 10-10              Tonight

48-Hour Ocean Condition Outlook for Saturday 01/22 to Sunday 01/23

Swell           DIR. WNW     HT.   9-11   PER. 17-19  Saturday morning
Remaining  at:  DIR. WNW     HT.   9-11   PER. 16-18  Saturday afternoon
Remaining  at:  DIR. WNW     HT.   9-11   PER. 16-18  Saturday night

WINDS:          DIR. NE      SPEED 10-15              Saturday morning
Increasing to:  DIR. NW      SPEED 10-15 + 20         Saturday afternoon
Decreasing to:  DIR. NE      SPEED 10-15              Saturday night
===========================================================================

Extended Ocean Condition Outlook:

There are no signs of any rain events for the rest of January and it appears that this month will end up below normal for rainfall after a very wet December.

===========================================================================

The 24 – Hour Ocean Data From The Diablo Canyon Wave rider Buoy
MONTH  DAY  TIME  SIG.HEIGHT   PERIOD   SWELL DIRECTION     SST
01    17    0613     6.4       13            258          53.6
01    18    0313     7.6       22+           250          57.2
01    18    0943     9.4       20            261          53.2
01    19    0943    10.7       10            285          55.0
01    20    1043     6.2       10            292          53.4
01    21    0413     6.0       22+           263          53.2
01    21    0713     5.6       20            265          53.2

(cm) (sec)  22+   20    17    15    13     11    9    7
———————————————————————–
01 17  0613  195    7     2     5     7   115   484   491   385  324
01 18  0313  233    9   310   387    24    73   376   688   781  333
01 18  0943  286   20   212  2073   204   275   392   393   661  334
01 19  0413  279   17    19   225   889   753   728   549   616  533
01 19  0943  327    9    11   135   406   799   609   894  2103  862
01 20  1043  190    9     3    11    45   291   405   338   535  343
01 12  0413  184   20   241   505    35   262   244   179   213  235
01 21  0713  170   20   122   623    45   198   173   139   158  178

Daily Swell Inspection Program

NAME                      DAY   TIME    HEIGHT   PERIOD     SST
(PST)   (FEET)  (SECONDS) (DEG. F)
# 166  Ocean Station Papa      21    0402      15       14       42.8
# 06   SE Papa                 21    0750      11       17       52.7
# 59   California Buoy         21    0750      12       18       55.8
# 01   Point Reyes Waverider   21    0746      12       20       52.0
# 15   Monterey Waverider Buoy 21    0750       6       18       53.4
# 28   Cape San Martin, Ca     21    0750      10       21       53.1
# 50   DCPP Waverider Buoy, Ca 21    0713       6       20       53.2
# 63   Harvest Buoy            21    0720       7       21       54.7
# 01   NW Hawaii               21    0750      12       16       75.0

* Note: Height (significant swell height) is the average height of the waves in the top third of the wave record. Maximum wave height may be up to TWICE the height in the data shown in the above table.

Precipitation at the Diablo Canyon Ocean Lab.

Wednesday  1500 through Thursday   1500   0.00 inches
Thursday   1500 through Friday     1500   0.00 inches

Precipitation this rain season (July 1 – June 30): 17.61 inches
Average season rainfall at DIP to date:            10.74 inches

Ocean Lab Barometer:   30.07 in or 1018.2 mb  +1.2 mb (Steady)

Sunrise and Sunset

Today’s         Sunrise 7:09 AM      Sunset 5:20  PM
Tomorrow’s      Sunrise 7:08 AM      Sunset 5:21  PM

Tides:
Low Tide                 High Tide
AM          PM           AM
21 Friday      4:17  1.8    5:16 -0.9   10:18 6.1   11:49  4.8
22 Saturday    5:14  1.6    5:54 -0.5   11:09 5.6   —–  —
23 Sunday      6:17  1.5    6:33  0.1   12:29 5.0   12:05  4.9
24 Monday      7:30  1.3    7:15  0.8    1:13 5.3    1:11  4.1
25 Tuesday     8:52  1.1    8:02  1.5    2:02 5.4    2:37  3.4
26 Wednesday  10:20  0.7    9:00  2.1    2:57 5.6    4:27  3.1
27 Thursday   11:39  0.2   10:14  2.5    3:58 5.7    6:17  3.2
28 Friday    (12:44 -0.2)  11:32  2.6    5:01 5.8    7:33  3.4
29 Saturday   —–  —-   1:36 -0.5    6:00 5.9    8:24  3.7
30 Sunday     12:39  2.6    2:20 -0.7    6:54 5.9    9:04  3.9
31 Monday      1:33  2.5    2:59 -0.8    7:41 6.0    9:37  4.0
1 Tuesday     2:19  2.3    3:32 -0.7    8:22 5.9   10:06  4.1
=========================================================================

This day in weather history

1863 – A severe coastal storm dropped heavy rain on the Fredericksburg area of Virginia. It disrupted a Union Army offensive in an ill famed “mud march”. (David Ludlum)

1985 – Three days of snow squalls at Buffalo NY finally came to an end. The squalls, induced by relatively warm water in Lake Erie, produced 34 inches of snow at the International Airport, with up to 47 inches reported in the suburbs of Buffalo. President Reagan was sworn in for a second term in the coldest Inauguration Ceremony of record. Cold and wind resulted in wind chill readings as much as 30 degrees below zero. (Sandra and TI Richard Sanders – 1987)

1988 – High pressure over northern Nevada and low pressure off the coast of Southern California combined to produce high winds in the southwestern U.S. Wind gusts in the San Francisco area reached 70 mph at Fremont. (Storm Data)

2009 – After nine straight days of temperatures reaching above 80° at the San Luis Obispo County Airport (which is a record for the month of January) we will see cooler but mild temperatures under partly to mostly cloudy skies.

2010 – This morning’s 14 to 16 foot northwesterly (290-degree deep-water) swell (with a 13-16 second period) will decrease to 12 to 14 feet by this afternoon.

Emergency tip:

If you see downed power lines, leave the area immediately and then call 911 and PG&E at 1-800-743-5000.

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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