Weather forecast for Wednesday February 16

February 16, 2011

By JOHN LINDSEY from PG&E

SEA SWELL:

This morning’s 8- to 10 foot northwesterly (300-degree deep-water) swell (with an 11- to 16-second period) will increase to 11- to 13-feet (with 13- to 15-second period) tonight and will remain at this height and period through Thursday morning.

Combined with this northwesterly swell will be 5- to 7-foot southerly (190-degree shallow-water) seas this morning and again on Thursday afternoon into Friday.

Note: High tides of 6.2 feet will occur during the morning hours today and tomorrow.

This northwesterly (300-degree deep-water) swell will decrease to 10- to 12-feet by Thursday afternoon, further lowering to 8- to 10-feet (with a 12- to 14-second period) by Thursday
night.

A 7- to 9-foot west-northwesterly (295-degree deep-water) swell (with an 11- to 13-second period) is forecast along our coastline on Friday and will remain at this height and period
through Sunday.

Increasing southerly (190-degree shallow-water) seas will develop on Monday and will be followed by another 11- to 13-foot west-northwesterly (290-degree deep-water) swell
(with an 11- to 14-second period) on Tuesday through next Wednesday.

PG&E San Francisco Met Office predicted temps:

Inland Temperatures, Paso Robles

Actual                    Predicted

Tue          Wed         Thu         Fri         Sat         Sun         Mon         Tue         Wed
51-61     51-53     39-52     41-52   35-52   33-55    33-52     34-49     36-53

Coastal Valleys Temperatures, San Luis Obispo

Tue          Wed         Thu         Fri         Sat         Sun         Mon          Tue         Wed
49-61     52-56    39-54     43-55   37-56   36-59   36-56        37-52   37-56

ATMOSPHERIC CONDITION:

A cold front passed Diablo Canyon at 6:45 a.m. with moderate to heavy rain. The winds shifted out of the southwest in less than 15 minutes and the temperature dropped from 53.4 degrees to 51.3 degrees.

The winds at Condor Lookout Station, located at an elevation of 3,190 feet on Hi Mountain in the Los Padres National Forest or about 15 miles east of San Luis Obispo as the crow flies,
reached 45 mph sustained with gust to 57 mph.

Scattered rain showers will continue through this afternoon, ending by tonight. Snow levels initially at 5,500 feet this morning will drop to 3,500 feet by tonight.

Due to the ongoing rain showers, I will update total rainfall amounts from this system on tomorrow’s report. Many locations in San Luis Obispo County have recorded between 0.33 and 1.25 inches.

Today’s high temperatures will reach the low to mid 50s with overnight lows ranging between the mid 30s to low 40s throughout the county.

A 1,003 millibar low pressure system will quickly drop out of the Gulf of Alaska behind this morning’s cold front.

This vigorous weather system is forecast to move over our area on Thursday afternoon with strong to gale force (25 and 38 mph) southerly winds and periods of heavy rain. The associated cold front is forecast to stall over San Luis Obispo County and tap into a plume of subtropical moisture Thursday night into Friday evening. Rain will turn to showers by Friday night, ending by Saturday morning.

Rainfall totals from this system should range between 1 and 1.5 inches in the North County, 1.0 and 2.5 inches in the coastal valleys and 2.5 and 4.5 inches along the coastal mountains due to oragraphic enhancement.

A break in the weather is forecast on Satruday afternoon through Monday afternoon. Then another cold Gulf of Alaska weather system will drop southward across the Central Coast Monday night into Tuesday with another round of gale force southerly winds, moderate to heavy rain and low snow levels. The wet weather should continue on and off into early March.

DIABLO CANYON AIR TEMPERATURES:

Diablo Canyon Meteorological Tower Air Temperature Data

Yesterday’s         Today’s          Tomorrow’s
Min    Max        Min    Max         Min     Max
53.6°   58.1°     50.8°   54.0°      51.0     55.0

WINDS:

Moderate to fresh (13 to 24 mph) west-northwesterly winds are forecast this afternoon and tonight, shifting out of the south on Thursday.

These southerly winds will reach strong to gale (25 to 38 mph) level by Thursday afternoon into Friday morning, then will shift and decrease out of the northwest on Friday afternoon through Sunday.

Fresh to strong (19 to 31 mph) northwesterly winds will develop on Monday morning, further increasing to strong to gale (25 to 38-mph) levels by Monday night into Tuesday morning.

DIABLO CANYON METEOROLOGICAL TOWER WIND DATA:

Today’s winds:

Max peak winds:      SE       36.5 mph at   5:45 a.m.
Max sustained wind:  SE       24.4 mph at   5:45 a.m.

Yesterday’s Maximum Winds:

Max peak winds:      SE       26.8 mph at  10:45 p.m.
Max sustained wind:  SE       20.6 mph at   9:30 p.m.

SEAWATER TEMPERATURES:

The Diablo Canyon waverider buoy is reporting a sea surface temperature of 54.0 degrees while the Nortek AWAC current meter is reporting 54.1 degrees.

Intake seawater temperatures will range between 53- and 55
-degrees through Friday.

OCEAN CURRENTS:

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

A northerly (onshore) flowing current will continue to flow northward through Friday.

SEAWATER VISIBILITY:

Seawater visibility was 2 to 3 feet at the Diablo Canyon Intake.

==========================================================================
24-Hour Ocean Condition Outlook for Wednesday 02/16 to Thursday 02/17

Sea/Swell       DIR. NW      HT.   8-10  PER.  12-16  This morning
Increasing to:  DIR. NW      HT.   9-11  PER.  13-15  This afternoon
Increasing to:  DIR. NW      HT.  11-13  PER.  13-15  Tonight

(Combined with:  DIR. S       HT.   5-7   PER.   4-6   This morning)

WINDS:          DIR. SE      SPEED 30-35 + 40         This morning
Decreasing to:  DIR. WNW     SPEED 20-25              This afternoon
Decreasing to:  DIR. WNW     SPEED 15-20              Tonight
===========================================================================
48-Hour Ocean Condition Outlook for Thursday 02/17 to Friday 02/18

Sea/Swell       DIR. NW      HT.  11-13  PER.  13-15  Thursday morning
Decreasing to:  DIR. NW      HT.  10-12  PER.  13-15  Thursday afternoon
Decreasing to:  DIR. NW      HT.   8-10  PER.  12-14  Thursday night

(Combined with:  DIR. S       HT.   5-7   PER.   4-6   Late Thursday)

WINDS:          DIR. SE      SPEED 10-15              Thursday morning
Increasing to:  DIR. SE      SPEED 20-25 + 30         Thursday afternoon
Increasing to:  DIR. SE      SPEED 30-35 + 40         Thursday night
===========================================================================

Extended Ocean Condition Outlook:

Increasing southerly (190-degree shallow-water) seas will develop on Monday and will be followed by another 11- to 13-foot west-northwesterly (290-degree deep-water) swell (with an 11- to 14-second period) on Tuesday through next Wednesday.

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

The 24 – Hour Ocean Data From The Diablo Canyon Wave rider Buoy
MONTH  DAY  TIME  SIG.HEIGHT   PERIOD   SWELL DIRECTION     SST
02    10    0413     4.4       17            261          53.2
02    11    1443     4.2       13            268          60.8
02    12    1243     3.0       12            261          60.1
02    13    1943     5.2       14            258          55.8
02    14    0813     3.9       13            263          54.5
02    15    0413     8.2       12            268          53.8
02    16    0513     9.1       11            279          54.0

(cm) (sec)  22+   20    17    15    13     11    9    7
———————————————————————–
02 10  0413  133   17     5    46   258    87    70   254   126  135
02 11  1443  128   13     2    16    98   188   432   127    31   54
02 12  1143  100   11     1     6    47   154   102   193    67   42
02 13  1943  159   13     2     4    19   392   515   454   119   52
02 14  0813  120   13     2     5    17    98   295   203   100  139
02 15  0413  251   11     3     7    11   210  1042  1076   885  284
02 16  0513  278    4     4    18    25   253   794  1129   828 1237

Daily Swell Inspection Program

NAME                      DAY   TIME    HEIGHT   PERIOD     SST
(PST)   (FEET)  (SECONDS) (DEG. F)
# 166  Ocean Station Papa      16    0402      13       11       42.4
# 06   SE Papa                 16    0550      18       14       53.6
# 59   California Buoy         16    0550      16       13       55.9
# 01   Point Reyes Waverider   16    0546      14       13       52.5
# 15   Monterey Waverider Buoy 16    0550      11       12       53.8
# 28   Cape San Martin, Ca     16    0550      10       12       54.5
# 50   DCPP Waverider Buoy, Ca 16    0513       9       12       54.0
# 63   Harvest Buoy            16    0520      10       13       55.4
# 01   NW Hawaii               16    0550       7        8       73.9

* 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.

Sunday     1500 through Monday     1500   0.02 inches
Monday     1500 through Tuesday    1500   0.02 inches
Tuesday    1500 through Wednesday  0900   0.36 inches

Precipitation this rain season (July 1 – June 30): 18.07 inches
Average season rainfall at DIP to date:            15.74 inches

Ocean Lab Barometer:   29.85 in/Hg or 1010.8 mb  +0.5 mb (Rising)

Sunrise and Sunset

Today’s         Sunrise 6:48 AM      Sunset 5:46  PM
Tomorrow’s      Sunrise 6:47 AM      Sunset 5:47  PM

Tides:
Low Tide                 High Tide
AM          PM           AM          PM
16 Wednesday   1:39  2.0    2:55 -1.0    7:49 6.2    9:22  4.3
17 Thursday    2:30  1.6    3:31 -1.0    8:37 6.2    9:53  4.7
18 Friday      3:20  1.2    4:06 -0.8    9:25 6.1   10:27  5.1
19 Saturday    4:12  0.8    4:42 -0.4   10:15 5.7   11:03  5.4
20 Sunday      5:07  0.5    5:19  0.2   11:08 5.1   11:43  5.6
21 Monday      6:06  0.4    5:58  0.8   —– —   12:07  4.5
22 Tuesday     7:13  0.4    6:40  1.5   12:26 5.7    1:17  3.8
=========================================================================

This day in weather history

1899 –  Washington D.C. received 1.26 inches of rain in six hours atop a snow cover more than 30 inches deep making it the soggiest day of record. (Sandra and TI Richard Sanders – 1987)

1903 –  The temperature at Pokegama Dam MN plunged to 59 degrees below zero to establish a state record. (David Ludlum)

1988 –  Santa Ana winds in southern California gusted to 50 mph in the Rancho Cucamonga area. Quiet weather prevailed across the rest of the nation. (Storm Data)

1989 –  A surge of arctic air produced all-time record high barometric pressure readings of 31.08 inches at Duluth MN, 30.97 inches at Chicago IL and 30.94 inches at South Bend
IN. Readings of 31.00 inches at Milwaukee WI and 30.98 inches at Rockford IL tied their all-time records.

Unseasonably warm weather prevailed across the southeastern U.S. Highs of 81 degrees at Athens GA, 87 degrees at Charleston SC, 85 degrees at Macon GA, and 86 degrees at
Savannah GA were records for February.

2009 –  An intense upper-level trough passed over Diablo Canyon at 6:15 a.m. and produced very heavy rain. The rain fall rate at one point reached 2.2 inches per hour. Along with the
rain, sustained southeasterly winds reached 40 mph with gusts to 52 mph at 2 a.m.

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