SLOweather

Sunday’s high in SLO was 74 degrees F. That’s exactly 40 degrees cooler than the high 2 days ago on Friday of 114! And right now Sunday night, it’s 30 degrees cooler (54) than it was Friday night. Good sleeping tonight!

PG&E DCPP Atmospheric UPDATE for Friday 06/20/08

ATMOSPHERIC CONDITION:

Record-breaking temperatures have developed on the ocean side of
the Cuesta Grade today.

Several factors have produced this record breaking condition:

1) A mesoscale high pressure system parked in place just east of
San Luis Obispo combined with a warm upper-atmosphere high
pressure ridge over California.

2) Persistent northeasterly (offshore) winds descending the
Cuesta Grade and producing compressive heating.

3) Very warm overnight lows which is not allowing the atmosphere
to cool, but to gradually warm over the last 72 hours.

4) The longest days of the year, with plenty of sunshine.

Temperatures in degrees F as of 1500 this afternoon.

Cal Poly…………………………… 108°
PG&E met tower at LOVR and foothill…… 114°
SLO Weather………………………….113°
Los Osos…………………………….110°
PG&E Community Center…………………113°
Diablo Canyon front gate at Avila Beach…115°
Diablo Canyon Power Plant met tower…….101°
San Luis Obispo Airport……………….111°
Arroyo Grande (ARGC1)…………………110°
Paso Robles Airport…………………..105°

Warm to hot temperatures will continue through tomorrow morning
on the ocean side of Cuesta Grade, but should begin to cool by
Saturday afternoon as the northwesterly (onshore) winds increase.
Our inland areas will remain hot on Saturday.

The low pressure system off northern California should move
northeastward with the associated upper-level trough moving inland
to the north late Saturday. The northwesterly (onshore) winds
will be increasing, especially on Sunday when temperatures will
drop way off. Coastal low clouds and fog will develop Sunday
night, with widespread fog expected by Monday morning. Brisk
onshore winds and a deep marine layer will bring cooler
temperatures to most of the interior on Monday through
Thursday.

PG&E San Francisco Met Office predicted temps:

Inland Temperatures, Paso Robles

Fri Sat Sun Mon Tue Wed Thu Fri
60 110 54 106 53 98 49 93 47 91 49 91 51 89 53 91

Inland Temperatures, San Luis Obispo

Fri Sat Sun Mon Tue Wed Thu Fri
67 108 54 90 53 78 50 73 49 73 51 74 53 75 52 77

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SLOweather hit 114 degrees F today.

The previous official temperature record for June 20th was 108° F in 1929.

The all-time temperature record is/was 112 on 14 Sept 1971 at Cal Poly (the official NWS SLO reporting station). I don’t yet know if they broke the all-time record but every other SLO site I’ve checked has.

(And thanks go out to Christina M for the inquiry that led to this post…)

At 2:53 PM, SLOweather hit 114 degrees F. A little later I checked one of my web pages, and it broke the thermometer:

When the outdoor temperature was hovering around 111 F, I took some surface temperature reading with an infrared thermometer. 2 redwood decks were 180 degrees! Wood doesn’t have much thermal mass, so they were almost tolerable to walk on barefoot.

The concrete driveway was 145 F (intolerable). And our little patch of grass out back was 107. Tolerable.

From the NWS…

…EXCESSIVE HEAT WARNING IN EFFECT FROM 11 AM TO 8 PM PDT THIS EVENING..
…EXCESSIVE HEAT WATCH IN EFFECT FROM SATURDAY 11 AM TO 8 PM PDT..

THE NATIONAL WEATHER SERVICE IN LOS ANGELES/OXNARD HAS ISSUED AN
EXCESSIVE HEAT WARNING…WHICH IS IN EFFECT FROM 11 AM TO 8 PM PDT
TODAY. AN EXCESSIVE HEAT WATCH HAS ALSO BEEN ISSUED. THE EXCESSIVE
HEAT WATCH IS IN EFFECT FROM 11 AM TO 8 PM PDT SATURDAY.

HIGH TEMPERATURES TODAY ARE EXPECTED TO TOP OUT BETWEEN 102 AND 108
DEGREES…WITH HEAT INDICES AROUND 105 DEGREES ACROSS THE INLAND
PORTIONS OF THE SAN LUIS OBISPO COUNTY COAST. WHILE SOME COOLING
NEAR THE IMMEDIATE COAST IS EXPECTED ON SATURDAY…HIGH TEMPERATURES
ABOVE 100 DEGREES ARE STILL POSSIBLE OVER INLAND AREAS.

AN EXCESSIVE HEAT WARNING MEANS THAT A PROLONGED PERIOD OF
DANGEROUSLY HOT TEMPERATURES WILL OCCUR. THE COMBINATION OF HOT
TEMPERATURES AND HIGH HUMIDITY WILL COMBINE TO CREATE A DANGEROUS
SITUATION IN WHICH HEAT ILLNESSES ARE LIKELY. DRINK PLENTY OF
FLUIDS…STAY IN AN AIR-CONDITIONED ROOM…STAY OUT OF THE SUN…AND
CHECK UP ON RELATIVES AND NEIGHBORS. NEVER LEAVE CHILDREN OR ANIMALS
IN PARKED VEHICLES EVEN WITH THE WINDOWS CRACKED…DEATH WILL LIKELY
RESULT.

Friday, 20 June 2008 marks the Summer Solstice, the first day of Summer in the Northern Hemisphere. And the local weather lately certainly feels like it. The Summer Solstice has the longest period of daylight, and the shortest night of the year. The solstice itself occurs as the sun passes over the equator to the north and occurs at 4:59 PM PDT.

This just in from John Lindsey…

PG&E DCPP Atmospheric UPDATE for Thursday 06/19/08

ATMOSPHERIC CONDITION:

A very unusual weather pattern continues today, as a mesoscale high
pressure (1018 mb) system remains in place just east of San Luis
Obispo, where temperatures exceed 100 degrees along the coast as
compared to the 70s in Santa Barbara and Monterey. This system has
broken many temperatures records throughout San Luis Obispo county
today and should continue to do so through Friday.

This area of high pressure has continued to produce northeasterly
(offshore) winds into the afternoon hours and a great deal of adiabatic
heating. At 12:56 the San Luis Obispo airport reached 102 degrees
while the Paso Robles airport was only at 98 degrees due to
compressive heating. The air mass coming off the Cuesta Grade
is also very dry with humidity levels below 10%.

The PG&E Community Center near Avila Beach reached 109 degrees
at 1300 while Arroyo Grande (ARGC1) hit 108 degrees at 12:54
this afternoon. Along our coastline, Diablo Canyon warmed
into the mid 90s and Avila Beach reached 102 degrees at 12:56
this afternoon.

Since that time, the northwesterly (onshore) winds have increased
somewhat along our coastline and through the Los Osos valley giving
some relief, but temperatures are expected to remain hot through
this evening.

This afternoon’s surface charts indicate another northeaster (offshore)
wind event developing on Friday morning, producing another day of hot
temperatures.

A cooling trend should begin on Saturday, except for our inland
areas which will remain hot, when the northwesterly (onshore) winds
increase. This cool marine air will surge through coastal gaps and passes
into the interior on Sunday, giving cooler inland  temperatures.
A cooling trend will continue through next week.

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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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SLO hit 99 yesterday around noon, breaking the record by one degree. Then the temp dropped a little and the dew point jumped quite a bit.

Last night’s LOW of 71.5 was about what our normal HIGH for the day is, 72.

From John Lindsey…

PG&E DCPP Atmospheric UPDATE for Wednesday 06/18/08

ATMOSPHERIC CONDITION:

The soundings from Vandenberg AFB indicates strong northeasterly
(offshore) winds and a very dry and warm airmass in the lower
atmosphere (below 6,000 feet) this morning.

This warm and dry airmass is being produced by high pressure
in the upper-levels of the atmosphere that will influence our
weather through Friday in the form of warm to hot temperatures
and mostly clear and dry conditions throughout San Luis Obispo
county.

The PG&E Community Center near Avila Beach has reached 96 degrees
by 10:30 a.m. this morning, while our coastline at Diablo Canyon
has already reached into the low 80s. As the northwesterly (onshore)
winds increase this afternoon, our coastline and coastal
valleys will cool, but our inland areas will remain hot.

Maximum temperatures across our inland areas could reach 105 degree
mark this afternoon while our coastal valleys are forecast to reach
the high 90s to the low 100s today. Our shoreline will reach the
mid to high 80s late this morning before cooling later this
afternoon and evening.

By Friday, Paso Robles could reach the 107 degree mark.

An upper-level trough of low pressure will approach the Pacific
Northwest coast this coming weekend and will displace the ridge
of high pressure further to the south. This condition will allow
for the marine layer to redevelop, and will produce increasing
northwesterly (onshore) winds, and cooler temperatures
across all locations as the weekend progresses.

At midnight last night, the temperature at SLOweather was a seasonal 55 degrees F. By 4 AM, however, it had risen to a balmy 73 degrees.

While at 6:30 it’s dropped back to 66, this presages the weather for the next few days. High temperatures are forecast to be well into the 90s until at least Saturday.