BASIC PATTERN:
Large Scale Pattern –
- We note that from the sea surface temperature anomalies and our IVTinit system, that there is support for occasional troughing near the coast of California…Central and North. The dominant pattern is for cool troughing to remain near coast or just west of California, resulting in normally sparse rain amounts in California with continuation of cool conditions coast and mild foothills and coastal valleys, on the mild to seasonably warm side for the San Joaquin and Sacramento Valley systems. Two week rain amounts in Sierras and Siskiyou’s for remainder of June are near or above normal for late June with below normal temperatures. 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 17-Jul 17, Precipitation Dates for N and Central California: Showers and thunderstorms (TSTMS) mainly mountain areas June 26-July 3. Breezy troughs occur 18-20 June, and 24-27 June. There still is some risk of coastal low clouds and drizzle, with a shower or two in the mountains. Warmups, as they occur, will either tend to be brief, or will wait until there is good solid high pressure aloft, with sunny conditions.
- Precipitation trends in S and W Mexico during 17 Jun thru mid July: Dry in June – 10 July, if we believe the CFSv2 model. Turning wet 15 July thru August Nayarit, Cabo Corrientes, Jalisco, Guerrero, and Michoacan as tropical cyclone season finally gets going. By contrast, the monsoonal rains for the Sea of Cortez coastal states (Sonora, Sinaloa, Baja California) appears to be delayed thru mid Jul, and possibly 20-25 Jul while extreme heatwave conditions prevail thru W Mexico states. Rains finally get going in Aug, and on into Sep with monsoonal moisture surging north into SE and S California, W Arizona.
- 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: Jun 19,26,30, Jul 3, 7-8, 11-13 and 16-17 (light N).
Norcal WARM/HOT SPELLS: Jun 22,24,26, Jul 5-6, 10, 15 and 19.
Norcal COOL SPELLS: Jun 30, Jul 3-4, 7-8, 11-14.
Norcal FROSTS: Unlikely.
Central Calif PRECIPITATION: Jun 15,18-19 few showers or drizzle coastal hills.
Central Calif WARM/HOT SPELLS: Jun 22,24,26, Jul 6-7, 9-10, 19.
Central Calif COOL SPELLS: Jun 30, Jul 4, 8, 12-13.
Central Calif DRY COLD WINDS: Jul 4, 8 and 13.
Forecast for Southern California:
SOCAL RAINS: Jul 18 drizzle.
SOCAL WARM/HOT SPELLS: Jul 6, 6-7 and 9-10.
SOCAL COOL SPELLS: Jun 30-Jul 1, 8, 13, 17-18.
Forecast for Central Sierra Nevada:
Central Sierra Nevada Precipitation - Main dates of rainshowers are...Jun 15,18, 26-Jul 2, 12 (few shwrs) 16-17.
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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 17 - July 17, 2023
Highlights: Generally near normal rainfall in most areas..but above normal rainfall (showers) through the Sierras. Warming to near normal during 25-30 June after a more gradual warm up during 17-24 June. There is continued transition to a warmer 25-30 Jun and seasonably mild to warm 1-10 Jul as “summer” sets in.
Looking Ahead – Long Range Outlook - July 17 - August 17, 2023
NORCAL and Central California: It turns intermittently much warmer in mid Jul to mid Aug as we head into midsummer while high pressure finally tries to build aloft. Seasonal curing of grasses for start of fire season still appears to lag behind schedule at the mid-July time, but should catch up closer to normal by Aug 1.
Long Range Outlook SOCAL: After the cool and drizzly conditions of June, we transition to warmer conditions about end of Jun, with a more rapid warmup after 2-3 Jul. From 23 June onward, the expected cold sea surface temperature anomaly should tend to keep the coast cool in SOCAL, while it turns warmer inland at times. This pattern is still notably inconsistent. We note that the September precipitation outlook map from CFSv2 is showing some support for above normal rainfall into SOCAL/L.A. basin. Such patterns can be significant for SOCAL in terms of TSTMS and rains. We’ll keep an eye on it in case something interesting starts to develop TSTM-wise.
Seasonal Curing of Fuels in the Forests of NORCAL and Sierras: When the subsequent seasonal dry-off of these understory fuels occurs in 16-30 June and on into July (depending on elevation in the Sierras), we could launch quickly into a robust fire season about July 20 and onward into August with thunderstorms and lightning strikes.
(Terms and Definitions Used In This Weather Outlook)
Alan Fox & Zane Stephens...Fox Weather, LLC
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