Weather forecast for Monday May 2

May 2, 2011

By JOHN LINDSEY from PG&E

A 1,030 millibar Eastern Pacific High is centered about 700 miles northwest of San Luis Obispo while a thermal low remains over Southern California.

Gentle to moderate northeasterly (offshore) winds are producing clear skies and warmer temperatures. Temperatures along the coastline will range between to mid 70s along the beaches and low 80s in the coastal valleys. Farther inland, temperatures will be similar or slightly warmer than on Sunday.

A dry cold front will move down the California Coastline today and will likely produce marine low clouds tonight into Tuesday morning. This cold front will be followed by increasing northwesterly (onshore) winds and cooler weather along the beaches and coastal valleys, except for areas across the interior where little change is forecast.

High pressure builds into the region on Wednesday and Thursday for another couple of warm days. Temperatures on Wednesday should go up by about 5 and 10 degrees with the North County reaching the the low 90s on Wednesday and Thursday.

Increasing northwesterly (onshore) winds Friday and Saturday will bring the marine layer off the Pacific and produce cooler temperatures. However, a persistent ridge of high pressure in the upper-atmosphere will keep an omega-shaped storm track far to the north. There is still no hint of any rain in the long-term forecast.

Yesterday’s         Today’s          Tomorrow’s
Min    Max        Min    Max         Min     Max
51.8°   71.6°     52.9°   65.0°      51.0°    59.0°

PG&E San Francisco Met Office predicted temps:

Inland Temperatures, Paso Robles

Actual                    Predicted

Sun              Mon          Tue           Wed           Thu          Fri          Sat          Sun           Mon
34 81        40 85       41 86       44 89         45 88      46 85     46 80    47 78      42 75

Coastal Valleys Temperatures, San Luis Obispo

Sun               Mon           Tue          Wed         Thu          Fri          Sat            Sun          Mon
43 78        42 81         43 77      48 81      48 74       49 74    49 70     48 69       47 69

SEA/SWELL:

This morning’s 2- to 3-foot northwesterly (290-degree deep-water) swell (with an 8- to 11-second period) will continue at this height and period through this morning.

A 2- to 4-foot northwesterly (310-degree deep-water) sea and swell (with a 5- to 9-second period) will develop along our coastline this afternoon through tonight as the northwesterly winds pick up along the coastline later this afternoon.

This northwesterly sea and swell will further build to 4 to 6 feet (with a 7- to 12-second period) Tuesday.

A 5- to 7-foot northwesterly (290-degree deep-water) swell (with an 8- to 11-second period) is forecast along our coast Wednesday, decreasing to 4 to 6 feet Thursday.

Increasing northwesterly winds along the California coastline and a late-season 881-millibar Gulf of Alaska storm will produce a 5- to 7-foot northwesterly (290-degree deep-water)
sea and swell (with a 7- to 13-second period) on Friday through Saturday.

This northwesterly (310-degree deep-water) sea and swell will decrease on 4- to 6-feet (with a 6- to 12-second period) on Sunday through next Monday.

WINDS:

This morning’s gentle (8- to 12-mph) northeasterly (offshore) winds will shift and increase out of the northwest to moderate to fresh (13- to 24-mph) levels this afternoon.

Strong to gale force (25- to 38-mph) northwesterly winds are forecast on Tuesday.

A pattern of gentle northwesterly (8- to 12-mph) winds developing during the night and morning hours, increasing to moderate to fresh (13- to 24-mph) levels by the afternoon hours are forecast on Wednesday and Thursday.

Strong to gale force (25- to 38-mph) northwesterly winds are forecast on Friday through next Monday.

DIABLO CANYON METEOROLOGICAL TOWER WIND DATA:

Today’s winds:

Max peak winds:      NE        3.1 mph at    9:00 a.m.
Max sustained wind:  NE        1.9 mph at    9:00 a.m.

Yesterday’s Maximum Winds:

Max peak winds:      NW       30.0 mph at    4:45 p.m.
Max sustained wind:  NW       22.4 mph at    4:45 p.m.

SEAWATER TEMPERATURES:

The Diablo Canyon waverider buoy is reporting a sea surface temperature of 54.5 degrees while the Nortek AWAC current meter is reporting 52.2 degrees.

Intake seawater temperatures will range between 51- and 53-degrees through Tuesday morning, decreasing to 49- and 51 degrees on Tuesday afternoon and night.

Intake seawater temperatures are forecast to range between 50- and 52 degrees on Wednesday through Thursday, decreasing on Friday, Saturday and Sunday.

OCEAN CURRENTS:

A southerly (offshore) current will continue to flow southward through Sunday.

SEAWATER VISIBILITY:

Seawater visibility was 26- to 28-feet at the Diablo Canyon Intake.

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24-Hour Ocean Condition Outlook for Monday 05/02 to Tuesday 05/03

Sea/Swell       DIR. NW      HT.   2-3   PER.   8-11  This morning
Increasing to:  DIR. NW      HT.   2-4   PER.   5-11  This afternoon
Remaining  at:  DIR. NW      HT.   2-4   PER.   5-11  Tonight

(Combine with:   DIR. SW      HT.    1    PER.  12-14  All day)

WINDS:          DIR. NE      SPEED  5-10              This morning
Increasing to:  DIR. NW      SPEED 15-20 + 25         This afternoon
Remaining  at:  DIR. NW      SPEED 15-20 + 25         Tonight
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48-Hour Ocean Condition Outlook for Tuesday 05/03 to Wednesday 05/04

Sea/Swell       DIR. NW      HT.   3-5   PER.   5-11  Tuesday morning
Increasing to:  DIR. NW      HT.   4-6   PER.   5-12  Tuesday afternoon
Remaining  at:  DIR. NW      HT.   4-6   PER.   5-12  Tuesday night

WINDS:          DIR. NW      SPEED 10-15 + 20         Tuesday morning
Increasing to:  DIR. NW      SPEED 25-30 + 40         Tuesday afternoon
Decreasing to:  DIR. NW      SPEED 20-25 + 25         Tuesday night
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Extended Ocean Condition Outlook:

Decreasing northwesterly winds are forecast on Wednesday and Thursday.

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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
04    29    0612     6.8       10            281          49.6
04    30    1042     6.9       11            286          57.2
05    01    0512     5.5       11            286          52.2
05    02    0742     2.2       14            213          54.5

(cm) (sec)  22+   20    17    15    13     11    9    7
———————————————————————
04 29  0612  206    9     1     2     3    26    70   407   924  440
04 30  1042  209   11     1     3     4    18   113  1027   735  337
05 01  0512  169    9     1     5     5    18    24   450   663  274
05 02  0742   68    4     4     9    14    20    23    18    43  109

Daily Swell Inspection Program

NAME                      DAY   TIME    HEIGHT   PERIOD     SST
(PST)   (FEET)  (SECONDS) (DEG. F)

# 166  Ocean Station Papa       2    0402      10        6       42.6
# 06   SE Papa                  2 0750 7 8 53.2
# 59   California Buoy          2    0750       5       13       55.8
# 01   Point Reyes Waverider    2    0746       4       14       52.7
# 15   Monterey Waverider Buoy  2    0750       2       13       52.7
# 28   Cape San Martin, Ca      2 0750 4 9 52.2
# 50   DCPP Waverider Buoy, Ca  2    0742       2       14       55.6
# 63   Harvest Buoy             2    0720       3       14       50.7
# 01   NW Hawaii                2 0750 5 6 76.6

* 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.

Saturday  1500 through Sunday      1500   0.00 inches
Sunday    1500 through Monday      1500   0.00 inches

Precipitation this rain season (July 1 – June 30): 25.98 inches
Average season rainfall at DIP to date:            24.00 inches

Ocean Lab Barometer:  30.26 in/Hg or 1024.6 mb  +1.4 mb (Rising)
Sunrise and Sunset

Today’s         Sunrise 6:11 AM      Sunset 7:49  PM
Tomorrow’s      Sunrise 6:10 AM      Sunset 7:50  PM

Tides:
Low Tide                 High Tide
AM          PM           AM          PM
2 Monday      4:34 -0.2    3:49  1.8   10:56 3.6   10:00  5.4
3 Tuesday     5:08 -0.4    4:17  2.0   11:38 3.5   10:28  5.4
4 Wednesday   5:45 -0.6    4:47  2.2   12:23 3.4   10:59  5.4
5 Thursday    6:25 -0.6    5:20  2.4    1:12 3.3   11:33  5.3
6 Friday      7:08 -0.6    5:59  2.6    —- —    2:08  3.3
7 Saturday    7:56 -0.5    6:51  2.8   12:13 5.2    3:10  3.3
8 Sunday      8:49 -0.4    8:06  2.8    1:00 4.9    4:12  3.4
9 Monday      9:43 -0.3    9:42  2.7    1:59 4.6    5:05  3.7
10 Tuesday    10:38 -0.1   11:15  2.3    3:13 4.3    5:48  4.0
11 Wednesday  11:31  0.1   —–  —    4:38 4.0    6:26  4.5
12 Thursday   12:30  1.6   12:20  0.4    6:03 3.8    7:02  5.0
13 Friday      1:31  0.8    1:07  0.7    7:20 3.8    7:39  5.5
14 Saturday    2:25 -0.1    1:52  1.0    8:29 3.8    8:17  6.0
15 Sunday      3:15 -0.8    2:36  1.3    9:31 3.9    8:56  6.3
16 Monday      4:04 -1.3    3:21  1.6   10:30 3.9    9:37  6.5
17 Tuesday     4:52 -1.6    4:07  1.9   11:27 3.9   10:20  6.5
18 Wednesday   5:40 -1.7    4:54  2.1  (12:22 3.8)  11:04  6.3
19 Thursday    6:29 -1.5    5:44  2.3   (1:19 3.8)  11:51  5.9
20 Friday      7:19 -1.2    6:41  2.5    —- —    2:17  3.8
21 Saturday    8:10 -0.8    7:48  2.6   12:40 5.4    3:17  3.8
22 Sunday      9:02 -0.4    9:09  2.6    1:33 4.8    4:16  3.9
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This day in weather history

1899 – A storm buried Havre, MT, under 24.8 inches of snow, an all-time record for that location. The water equivalent of 2.48 inches was a record 24 hour total for the month
of May.

1990 – Thunderstorms produced severe weather from northeastern Texas to western Arkansas during the evening and early nighttime hours. Thunderstorms spawned a tornado which injured thirteen persons at Paris TX, and produced baseball size hail at Rio Vista TX. Thunderstorm rains of four to seven inches caused flash flooding in west central Arkansas, southern and eastern Oklahoma, and northern Texas. (The National Weather Summary) (Storm Data)

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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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