Preliminary Summer 2010 forecast

Summer will soon be upon us here in the Northern Hemisphere and with that comes the summer forecast. Since the only maps I have been able to get are ones that are not explicitly representive of California but rather for the nation, I have opted to issue my first summer forecast as a text based forecast for now until a better map graphic becomes available. Since California's climate is so diverse in Summer it becomes a daunting task to issue a graphical forecast so I've resorted to text for that reason as well. So, given that this past winter was an El Nino winter there can be mixed signals as to whether temps will be above/below or near average over the summer. One particular indication about El Nino and La Nina is valid for winter temps but not as much for summer temps. In addition the influence of the PNA on the pattern is less clear in the summer, therefore, the forecast becomes even more difficult. Let me start region by region:

Northern California coast from the Oregon border to the city of Monterrey:

This region should see temps at or slightly above normal given the sea surface temperatures are warmer than average, the prevalence of the fog is partly due to SST's thus, we could expect some days to have above average temps this summer because of a shallow marine layer. Offshore flow will increasingly become more frequent as well as we head into the latter months of the summer given that if we do get into a La Nina we would see more inside slider type systems producing strong offshore flow, hence the forecast of slightly above normal temps as well. Some select cities for highest possible temp over the summer season:

San Francisco(SFO): 98-100F
Monterey( Airport): 90-93F
San Jose(SJC): 101-103F

Northern and Central California inland areas from Redding down to Fresno/Bakersfield:

This area should have above normal temps this Summer with the signal pointing towards a neutral to possible La Nina ENSO we could easily see temps average above normal in this area. Expecting to see 100's and 110's in most areas in this region as is typical with above normal summers. I'm expecting to see about 45-55 100F+ days for Redding with the rest of the major cities in the region averaging near 30 days of 100F+ for the season. Some expected peak temps for the region in these selected cities:

Redding(Airport): 114-116F
Red Bluff(Airport): 112-114F
Sacramento(Downtown): 108-110F
Stockton(Airport): 107-109F
Fresno(FAT): 110-113F
Bakersfield(Meadows Field): 111-115F

Central and Southern California Coastal Areas from San Luis Obispo to San Diego:

In this region temps should also average above normal with a lack of substantial marine layer for the months of July and August as the El Nino begins to wane and neutral ENSO conditions to possible La Nina forming begin to factor in. The largest departure from average temps should be over the LA and San Diego areas rather than the central coast. Because there are large variations in temps because of micro climates in the area I'll simplify the area to two distinct regions, SoCal coastal areas will be cities that have actual coastline property entrained into their municipalities and inland areas which lie from 20miles from the seashore all the way to 80miles from the seashore. Beyond that will be considered desert areas. This area will see some 100F temps occasionally this season with the onslaught of Santa Ana winds as the season progresses with strong high pressures overhead. This area will also see some occasional monsoonal moisture creating higher humidity but no rainfall above slim amounts is expected along the coast. Some selected cities peak temp forecast, all locations unless specified temps will be for the airport in that city:

San Luis Obispo: 97-100F
Santa Barbara: 92-95F
Los Angeles(LAX): 88-92F
Newport Beach(SNA): 90-94F
Oceanside: 92-95F
San Diego(SAN): 90-93F

Southern California Inland areas and Desert regions:

In this region expect temps to be near to slightly above normal as offshore winds will cause temps to be warm in inland areas but have a negative effect on desert areas. The desert regions should see the usual heat with near or above 120F temps possible in those areas but inland areas should not exceed 110F in SoCal urban areas, with 100F temps possible but not too frequent. As for monsoonal moisture, I'm expecting the usual monsoon events to occur with perhaps a slight increase in activity compared to normal because of warm SST's off the coast due to El Nino. This should also create some humid conditions in these areas when it occurs. Select cities/regions peak temp forecast, again unless indicated the temps shown will be for the airport or nearest reporting station:

Riverside: 105-108F
Ontario: 104-107F
Palm Springs: 115-118F
Death Valley Nat'l Park(Furnace Creek): 122-125F

That sums up the urban areas for both NorCal and SoCal. The basic idea here about this summer is that it's going to be for most areas at or above normal for the overall three month period. Unlike last year where some areas had a very cool summer season along the coast, this year should feature warmer weather overall. This is a preliminary forecast and I'll have an update sometime before the Memorial Day holiday weekend when meteorological summer begins.