Weather forecast for Thursday April 28

April 28, 2011

By JOHN LINDSEY from PG&E

A 1,036 millibar Easter Pacific High will move towards the Oregon Coastline, while a 1,006 millibar low pressure system takes a position over The Mojave Desert.

This condition will produce moderate gale to fresh gale force (32- to 46-mph) northwesterly winds along our coastline this afternoon through Friday. These onshore winds will produce cooler temperatures throughout San Luis Obispo County. At the moment the time of the strongest winds will occur Friday afternoon with gust reaching nearly 50 mph along the coastline.

A spectacular weekend is in store across the Central Coast as another high pressure ridge moves over California. This condition will produce northeasterly (offshore) winds during
the morning hours on Saturday, Sunday and Monday.  This offshore flow will give clear and warmer weather with temperatures reaching into the 80s across the interior and coastal valleys and 70s closer to the coast.

Temperatures will continue to warm next week, reaching the high 80s in the coastal valleys to the low 90s in the North County on Monday through Wednesday.

Yesterday’s         Today’s          Tomorrow’s
Min    Max        Min    Max         Min     Max
51.4°   57.8°     50.2°   57.0°      51.0°    56.0°

PG&E San Francisco Met Office predicted temps:

Inland Temperatures, Paso Robles

Actual                    Predicted

Wed             Thu         Fri           Sat          Sun           Mon         Tue          Wed          Thu
39 80       42 77      44 69    41 73     45 82       39 86       41 92       44 91        47 81

Coastal Valleys Temperatures, San Luis Obispo

Wed              Thu          Fri          Sat          Sun          Mon          Tue          Wed         Thu
49 69        47 71      45 66     44 69      47 80     43 86      43 86      45 87       49 69

SEA/SWELL:

This morning’s 4- to 6-foot northwesterly (310-degree deep-water)sea and swell (with a 5- to 11-second period) will continue at this height and period through this morning.

Moderate gale- to fresh-gale (32- to 46-mph) northwesterly winds will develop along the Central Coast later this afternoon through Friday and will generate 7- to 9-foot northwesterly (310-degree deep-water) sea and swell (with a 5- to 11-second period) on this afternoon through Friday morning.

This northwesterly sea and swell will further increase to 8- to 10-feet with the same period on Friday afternoon and night.

The northwesterly sea and swell will decrease to 6- to 8-feet on Saturday, further lowering to 4- to 6-feet (with a 7- to 11-second period) on Sunday.

A 3- to 5-foot northwesterly (290-degree deep-water) swell (with an 8- to 11-second period) is forecast along our coastline on Monday through Tuesday morning.

This northwesterly swell will increase to 4- to 6-feet (with an 8- to 11-second period) on Tuesday afternoon and will remain at this height period through next Friday.

WINDS:

This morning’s moderate to fresh (13- to 24-mph) northwesterly winds will increase to moderate gale to fresh gale (32- to 46-mph) levels along our coastline this afternoon through Friday.

Gentle to moderate (8- to 18-mph) northeasterly (offshore) winds will develop on Saturday, Sunday and Monday morning, followed by fresh to strong (19- to 31-mph) northwesterly winds on Saturday afternoon and moderate to fresh (13- to 24-mph) northwesterly winds on Sunday and Monday afternoon.

Fresh to strong (19- to 31-mph) northwesterly winds are forecast on Tuesday, decreasing on Wednesday and Thursday.

DIABLO CANYON METEOROLOGICAL TOWER WIND DATA:

Today’s winds:

Max peak winds:      NW       23.1 mph at    6:30 a.m.
Max sustained wind:  NW       16.6 mph at    7:15 a.m.

Yesterday’s Maximum Winds:

Max peak winds:      NW       37.8 mph at    4:00 p.m.
Max sustained wind:  NW       27.1 mph at    4:00 p.m.

SEAWATER TEMPERATURES:

The Diablo Canyon waverider buoy is reporting a sea surface
temperature of 55.2 degrees while the Nortek AWAC current
meter is reporting 48.8 degrees.

Intake seawater temperatures will range between 48- and 51
-degrees through this morning , decreasing to 47- and
50-degrees this afternoon and remaining at this level
through Tuesday.

OCEAN CURRENTS:

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

SEAWATER VISIBILITY:

Seawater visibility was 17- to 19-feet at the Diablo Canyon Intake.

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24-Hour Ocean Condition Outlook for Thursday 04/28 to Friday 04/29

Sea/Swell       DIR. NW      HT.   5-7   PER.   5-11  This morning
Increasing to:  DIR. NW      HT.   7-9   PER.   5-11  This afternoon
Remaining  at:  DIR. NW      HT.   7-9   PER.   5-11  Tonight

WINDS:          DIR. NW      SPEED 15-20 + 25         This morning
Increasing to:  DIR. NW      SPEED 30-35 + 45         This afternoon
Remaining  at:  DIR. NW      SPEED 30-35 + 45         Tonight
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48-Hour Ocean Condition Outlook for Friday 04/29 to Saturday 04/30

Sea/Swell       DIR. NW      HT.   7-9   PER.   5-11  Friday morning
Increasing to:  DIR. NW      HT.   8-10  PER.   5-11  Friday afternoon
Remaining  at:  DIR. NW      HT.   8-10  PER.   5-11  Friday night

WINDS:          DIR. NW      SPEED 30-35 + 40         Friday morning
Increasing to:  DIR. NW      SPEED 40-45 + 50         Friday afternoon
Decreasing to:  DIR. NW      SPEED 30-40 + 45         Friday night
===========================================================================

Extended Ocean Condition Outlook: Decreasing northwesterly winds will develop over the weekend.

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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    24    2312     6.7        8            275          51.4
04    25    0442     5.2        7            278          55.2
04    26    2142     7.4        8            288          52.7
04    27    0212     5.4        9            278          55.6
04    28    0442     4.9       11            284          55.2

(cm) (sec)  22+   20    17    15    13     11    9    7
———————————————————————
04 24  2312  204    7     2     8    78   144    80    37   557  721
04 25  0442  159    7     1     7    77   103    78    55   190  364
04 26  2142  224    9     2     3     6    24    84   570  1019  686
04 27  0212  164    9     1     5     6    25    72   222   487  438
04 28  0442  150   11     1     2    15    39    81   412   301  282

Daily Swell Inspection Program

NAME                      DAY   TIME    HEIGHT   PERIOD     SST
(PST)   (FEET)  (SECONDS) (DEG. F)
# 166  Ocean Station Papa      28    0402       7       11       42.6
# 06   SE Papa                 28    0450       9       11       52.7
# 59   California Buoy         28    0450       6       11       55.8
# 01   Point Reyes Waverider   28    0446       6       11       52.0
# 15   Monterey Waverider Buoy 28    0450       5       11       52.3
# 28   Cape San Martin, Ca     28    0450       7       11       54.1
# 50   DCPP Waverider Buoy, Ca 28    0442       5       11       55.2
# 63   Harvest Buoy            28    0420       8       11       51.6
# 01   NW Hawaii               28    0450       7       10       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.

Tuesday   1500 through Wednesday   1500   0.00 inches
Wednesday 1500 through Thursday    1500   0.00 inches

Precipitation this rain season (July 1 – June 30): 25.98 inches
Average season rainfall at DIP to date:            23.93 inches

Ocean Lab Barometer:  30.14 in/Hg or 1020.5 mb  +0.3 mb (Rising)
Sunrise and Sunset

Today’s         Sunrise 6:15 AM      Sunset 7:46  PM
Tomorrow’s      Sunrise 6:14 AM      Sunset 7:47  PM

Tides:
Low Tide                 High Tide
AM          PM           AM          PM
28 Thursday    2:13  1.2    1:57  0.9    8:00 3.7    8:23  4.7
29 Friday      2:52  0.8    2:27  1.1    8:49 3.7    8:47  4.9
30 Saturday    3:27  0.4    2:55  1.4    9:33 3.7    9:10  5.1
1 Sunday      4:00  0.0    3:22  1.6   10:15 3.7    9:34  5.2
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
=========================================================================

This day in weather history

1921 – A severe hailstorm in Anson County, NC, produced hail the size of baseballs. Gardens, grain fields and trees were destroyed. Pine trees in the storm’s path had to be cut for lumber because of the hail damage.

1928 – A coastal storm produced tremendous late season snows in the Central Appalachians, including 35 inches at Bayard WV, 31 inches at Somerset PA, and 30 inches at Grantsville MD. High winds accompanying the heavy wet snow uprooted trees and unroofed a number of homes. The storm caused great damage to fruit trees and wild life. (David Ludlum)

2004 – Yesterday’s high temperature reached 92.4 degrees at Diablo Canyon. This afternoon’s high temperature was only 55.4 degrees, 37 degrees cooler then it was yesterday afternoon!

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