Weather forecast for Friday February 25

February 25, 2011

By JOHN LINDSEY from PG&E

SEA SWELL:

Strong to gale force (25 to 38 mph) southwesterly winds will generate 5- to 7-foot southwesterly (220-degree shallow-water) seas later this morning through this afternoon.

A 7- to 9-foot northwesterly (300-degree deep-water) sea and swell (with a 7- to 13-second period) is forecast along our coastline tonight and will remain at this height and
period through Sunday morning, decreasing to 4- to 6-feet (with an 8- to 11-second period) by Sunday night.

A 3- to 5-foot northwesterly (300-degree deep-water) swell (with a 9- to 15-second period is forecast along our coastline on Monday and Tuesday.

Increasing southerly winds will generate 8- to 10-foot southerly (195-degree shallow-water) seas on Wednesday, followed by a 5- to 7-foot (270-degree deep-water) swell
(with a 10- to 12-second period) on Thursday.

Inland Temperatures, Paso Robles

Actual                    Predicted

Thu         Fri          Sat         Sun         Mon         Tue         Wed          Thu          Fri
32-56   46-52    33-45     26-52    26-58      29-61    40-56       43-60    37-61

Coastal Valleys Temperatures, San Luis Obispo

Thu         Fri           Sat          Sun           Mon         Tue        Wed          Thu        Fri
40-58   47-54    35-48     31 -46       32-60       36-64   43-59      45-62    41-64

ATMOSPHERIC CONDITION:

A very cold upper-level low pressure system currently off San Francisco will continue to move southward along the California coastline. This morning’s rain showers will turn
to study rain as the associated cold front passes the Central Coast between 1 and 4 p.m. this afternoon.

During frontal passage, southwesterly winds will reach strong to gale force (25 to 38 mph) levels.

Warmer air at low elevations have mixed in with this cold weather system and has kept snow levels above 3,000 feet in the vicinity of the coast.  However, interior locations will see somewhat low snow levels near 2,500 feet along the front. Snow levels will lower sharply behind the cold front, and will be near 1,000 feet. Little accumulation is expected at these elevations, with most snowfall occurring along the cold front at 2,500 feet or higher.

Rain will turn to scattered showers tonight and should continue through Saturday morning as an upper-level trough passes over our area.  Total rain fall amounts should range between 0.50 and 1.00 inches.

If showers continue into Saturday morning, there could be snow down to 1,000 feet, including the possibility of measureable snow on the Cuesta Grade. Snow flurries cloud develop at lower altitudes, but it’s not expected to stick to the ground.

Heavy snow is a good bet across the Sierra today and into Saturday with up to 3 feet or so is expected in the higher terrain of the Sierra and many inches in the Sierra foothills.

Temperatures on Saturday will be way below normal for the end of February. Saturday’s highs will only reach the mid 40s in many Central Coast locations. Overnight lows will be quite
cold with Paso Robles reaching the mid 20s by Sunday morning and San Luis Obispo dropping to the low 30s.

Warmer and mostly clear weather will develop on Monday into Tuesday with temperatures reaching the 60s.

For next week, it continues to look like a turn towards very mild and wet weather on Wednesday as a somewhat subtropical weather system crosses the Central Coast. Rain fall amounts with this warm system could range between 1.25 and 2 inches.

After a break in the weather Thursday through next Friday, another wet weather system looks likely next weekend.

DIABLO CANYON AIR TEMPERATURES:

Diablo Canyon Meteorological Tower Air Temperature Data

Yesterday’s         Today’s          Tomorrow’s
Min    Max        Min    Max         Min     Max
47.1°   52.5°     48.5°   53.0°      40.0     47.0

PG&E San Francisco Met Office predicted temps:

WINDS:

This morning’s moderate to fresh (13 and 18 mph) southwesterly winds will increase to strong to gale force (25 to 38 mph) levels this afternoon.

These strong to gale force (25 to 38 mph) southwesterly winds will shift out of the northwest by tonight.

Fresh to strong (19 to 31 mph) northwesterly winds are forecast on Saturday, decreasing to moderate to fresh (13 and 24 mph) levels on Sunday.

Gentle variable winds are forecast on Monday.

Increasing southerly winds will develop on Tuesday, reaching strong to gale force (25 to 38 mph) levels on Wednesday.

DIABLO CANYON METEOROLOGICAL TOWER WIND DATA:

Today’s winds:

Max peak winds:      SW       26.8 mph at   8:45 p.m.
Max sustained wind:  SW       20.5 mph at   8:45 p.m.

Yesterday’s Maximum Winds:

Max peak winds:      NW       17.9 mph at   5:45 p.m.
Max sustained wind:  NW       14.5 mph at   5:45 p.m.

SEAWATER TEMPERATURES:

The Diablo Canyon waverider buoy is reporting a sea surface
temperature of 56.5 degrees while the Nortek AWAC current
meter is reporting 53.6 degrees.

Intake seawater temperatures will range between 54- and 56
-degrees through Wednesday.

OCEAN CURRENTS:

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

A southerly (offshore) flowing current will develop on Saturday and will continue to flow southward through Monday, becoming a northerly (onshore) current on Tuesday through Wednesday.

SEAWATER VISIBILITY:

Seawater visibility was 25 to 27 feet at the Diablo Canyon Intake.

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24-Hour Ocean Condition Outlook for Friday 02/25 to Saturday 02/26

Sea/Swell       DIR. NW      HT.   4-6   PER.  10-12  This morning
Increasing to:  DIR. NW      HT.   5-7   PER.  10-12  This afternoon
Increasing to:  DIR. NW      HT.   7-9   PER.  10-12  Tonight

(Combined with:  DIR. WSW     HT.   3-5   PER.   4-6   This morning)
(Increasing to:  DIR. WSW     HT.   5-7   PER.   4-6   This afternoon)
(Decreasing to:  DIR. W       HT.   2-4   PER.   5-7   Tonight)

WINDS:          DIR. SW      SPEED 15-20 + 30         This morning
Increasing to:  DIR. SW      SPEED 25-30 + 40         This afternoon
Decreasing to:  DIR. NW      SPEED 20-25 + 35         Tonight
===========================================================================
48-Hour Ocean Condition Outlook for Saturday 02/26 to Sunday 02/27

Sea/Swell       DIR. NW      HT.   7-9   PER.   7-13  Saturday morning
Remaining  at:  DIR. NW      HT.   7-9   PER.   7-13  Saturday afternoon
Remaining  at:  DIR. NW      HT.   7-9   PER.   7-13  Saturday night

WINDS:          DIR. NW      SPEED 15-20 + 25         Saturday morning
Increasing to:  DIR. NW      SPEED 20-25 + 35         Saturday afternoon
Decreasing to:  DIR. NW      SPEED 15-20 + 30         Saturday night
===========================================================================

Extended Ocean Condition Outlook:

Today’s longer range models are not indicating any high-energy swell events over the next two weeks.

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The 24 – Hour Ocean Data From The Diablo Canyon Wave rider Buoy
MONTH  DAY  TIME  SIG.HEIGHT   PERIOD   SWELL DIRECTION     SST
02    20    1113     9.0       12            270          59.0
02    21    2113     3.3       11            278          57.2
02    22    0513     2.2       15            272          54.0
02    22    1413     3.7       11            263          56.1
02    23    0643     5.6       11            286          56.1
02    24    1643     3.7        8            292          57.0
02    25    0713     4.7       12            272          56.5

(cm) (sec)  22+   20    17    15    13     11    9    7
———————————————————————–
02 20  1113  275   13     4     9    17   347  1334  1195   779  408
02 21  2113  101    9     1     2     6    34    36   140   160  120
02 22  0513   68    4     1     5     5    49    33    26    46   71
02 22  1413  114    7     1     6     7    40    62    93   163  210
02 23  0643  172    7     1     6     8    51   183   338   290  445
02 24  1643  114    4     1     6    19    15    43    67   162  266
02 25  0713  143    4     1     3    18    45    75   133   122  746

Daily Swell Inspection Program

NAME                      DAY   TIME    HEIGHT   PERIOD     SST
(PST)   (FEET)  (SECONDS) (DEG. F)
# 166  Ocean Station Papa      25    0402      10       10       42.1
# 06   SE Papa                 25    0750      15       11       53.1
# 59   California Buoy         25    0750      11       12       54.3
# 01   Point Reyes Waverider   25    0746       8       12       51.1
# 15   Monterey Waverider Buoy 25    0750       7        6       53.8
# 28   Cape San Martin, Ca     25    0750       7       12       53.6
# 50   DCPP Waverider Buoy, Ca 25    0713       5       12       56.5
# 63   Harvest Buoy            25    0720       6       13       54.5
# 01   NW Hawaii               25    0750       6        9       73.4

* 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.

Monday     1500 through Tuesday    1500   0.00 inches
Tuesday    1500 through Wednesday  1500   0.00 inches
Wednesday  1500 through Thursday   0700   0.04 inches

Precipitation this rain season (July 1 – June 30): 19.45 inches
Average season rainfall at DIP to date:            17.45 inches

Ocean Lab Barometer:   29.98 in/Hg or 1015.1 mb  -1.5 mb (Falling)

Sunrise and Sunset

Today’s         Sunrise 6:38 AM      Sunset 5:55  PM
Tomorrow’s      Sunrise 6:38 AM      Sunset 5:56  PM

Tides:
Low Tide                 High Tide
AM          PM           AM          PM
25 Friday     11:15  0.1   10:15  2.7    3:24 5.3    6:18  3.3
26 Saturday  (12:21 -0.2)  11:41  2.6    4:40 5.2    7:19  3.6
27 Sunday     —–  —    1:14 -0.3    5:48 5.3    8:01  3.9
28 Monday     12:46  2.4    1:56 -0.4    6:45 5.3    8:33  4.0
1 Tuesday     1:35  2.1    2:32 -0.3    7:33 5.3    9:01  4.2
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This day in weather history

1922 – The temperature at Los Angeles, CA, soared to 92 degrees to establish a record for the month of February. (David Ludlum)

1977 – Dust reduced visibilities from eastern Virginia through the southeastern states to Florida between the 24th and the 28th. The dust originated in the western Great Plains on the 22nd and 23rd, with wind gusts above 100 mph reported at Guadalupe Pass TX, at White Sands NM, in Sherman County KS, and in eastern Colorado.

1989 – Unseasonably warm weather prevailed in the central U.S. Dodge City KS reported record high of 80 degrees. (Storm Data)

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The National Weather Service will conduct Weather Spotter Training at the PG&E Energy Education Center this Monday February 28, 2011 at 6:30 p.m.

The National Weather Service Storm Spotter Program is a volunteer organization of people with an interest in the weather.

This training session is free and open to the public. Anyone interested in volunteering to become a storm spotter for the National Weather Service is welcome to attend.

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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