BASIC PATTERN:
Large Scale Pattern –
- We note that from the sea surface temperature anomalies and IVTinit, there is support for a tendency for occasional troughing near the coast of California…Central and North. The dominant pattern is for troughing to remain just west of California, resulting in near normal rain amounts in California per latest update. Sea surface temperature anomaly support for troughing near Oregon and NW California has diminished. Above normal rainfall will continue in the Central Sierra Nevada from Yosemite NP north to the NE California Plateau and Lassen Co.
- Precipitation Trend Jun 2-30, Precipitation Dates for N and Central California: Rain and showers mostly the first two weeks of June. Above normal rainfall in most of the Sierras. Prospect for onset of summer in June… the first half of June is shown by CFSv2 as showery at times. There are some good N or NNW wind events, and these are often showery, with late-spring-type conditions. Cool weather normally accompanies the rains, while the warm-ups tend to wait until there is good high pressure aloft, with sunny conditions.
- Precipitation trends in S and W Mexico during June and July, and through late summer …drier than normal during the early summer. Then Aug and Sept turn wetter than normal in southern Mexico. Arizona has already seen monsoon-like showers and TSTMS at the end of May. Upper lows developing around 5-10 June and again in mid June, will tend to kick Arizona and W Mexico into some monsoonal TSTM activity. We should start to see a warm sea surface temperature anomaly reappear SW Mexico coast and southern Mexico with above normal rainfall about July to midsummer. In the fall as we transition from autumn to early winter 2023, we expect a strengthening El Nino pattern to develop. A significant El Nino is expected.
FORECASTS FOR CALIFORNIA
Forecast for Northern and Central California:
Norcal PRECIPITATION Trend: 5-8 and 8-14 Jun, 20-22 Jun.
Norcal WARM/HOT SPELLS: 2-3 Jun briefly.
Norcal COOL SPELLS: 6-9 and 9-15 Jun, 20-22 Jun.
Norcal FROSTS: 7-8 Jun in Potter Valley, Mendocino Co cold spots.
Central Calif PRECIPITATION: 6 Sierras, 7-14 Sierras and coastal mtns Monterey-San Luis Obispo.
Central Calif WARM/HOT SPELLS: 2-4 Jun.
Central Calif COOL SPELLS: June 6, and 8-14.
Central Calif DRY COLD WINDS: 7th psbl frost central coastal vlys.
Forecast for Southern California:
SOCAL RAINS: TSTMS 5-6th Ventura-San Bdno Co’s mtns, 7-14 mstly Ventura Co W-NW.
SOCAL WARM/HOT SPELLS: Jun 2-4, 16-24.
SOCAL COOL SPELLS: Cool about Jun 6-7 and 13.
Forecast for Central Sierra Nevada:
Central Sierra Nevada Precipitation - Main dates of rainshowers are….. 5-8 and 8-11, 13, Jun, 20-23 Jun.
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The listings of dates normally included for hot and cold spells, and precipitation are approximate. They are based on our CFSDaily and CFSDailyAI products; and present expected trends in precipitation and temperature (FoxCFSDailyAI) to 5km. Our system gives some consideration to terrain and coastal influence. We consider the CFSv2 one of the better ways to represent basic weather down in the sub-monthly time scale beyond the 15–day GFS or monthly maps from CFSv2 or NMME.
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Southern California Deserts Outlook for June 2 - June 30, 2023
Highlights: Generally near normal rainfall in most areas..but above normal rainfall (showers) into the Sierras south portion. Cooler than normal in end-of-May-mid June followed by transition to warmer than normal mid to late June.
Looking Ahead – Long Range Outlook - July 1 - July 31, 2023
NORCAL and Central California: In general, during this period, tendency for troughing at California coast supports cool and showery conditions in the N and Central Sierras, Siskiyou’s. In first few days of June (per CFSv2), we may emerge to a brief stretch of hot days for interior N and Central California, and warmer in the Sierras on 17-19. More showers occur 20-22. Possibly turning much warmer late June as high pressure finally starts to build aloft.
Long Range Outlook SOCAL: We have continued cool and showery conditions 5-16 June. There appears to be a more rapid warmup after 22 June. From 23 June onward, the expected cold sea surface temperature anomaly would tend to keep the coast cool in SOCAL.
Seasonal Curing of Fuels in the Forest of N California/Sierras: Robust 1-15 June growth of fuels, i.e. brush understory in the forests. When the subsequent seasonal dry-off of these understory fuels occurs in 23-30 June and on into July (depending on elevation in the Sierras), we could launch quickly into a robust fire season about July 15-20 and onward into August.
(Terms and Definitions Used In This Weather Outlook)
Alan Fox & Zane Stephens...Fox Weather, LLC
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