BASIC PATTERN:
Large Scale Pattern –
- There is the usual shift to a summer pattern occurring now. High pressure aloft, oriented E-W across the southern United States and Southern California is associated with moist easterly flow from the Caribbean and Gulf of Mexico, across southern Mexico, and into the Pacific south of Baja California.
- Tropical cyclones and easterly waves from the Caribbean produce rain upon crossing southern Mexico, then regenerate into tropical cyclones as they continue out over the tropical Pacific S of Baja. At this time there lacks support for NW-ward movement of tropical cyclones off the Baja coast which typically occurs later in the summer and early fall.
- Breezy and showery fronts focus into the Pacific Northwest in the near term. However, with the onset of the summer dry season, these will diminish as upper high pressure over Arizona migrates further N over Utah and Nevada to central and N California by early July.
- As the westerlies diminish in the Pacific Northwest, and high pressure becomes entrenched over California and Utah-Nevada, hot weather will become more persistent in California, and showers from land-falling fronts in the Pacific Northwest coast areas will diminish, followed by a return of hot weather in Washington and Oregon.
- Subsequent dry cold fronts will tend to raise the fire risk as hot daytime temperatures combine with gusty dry winds to start the fire season.
- A cold sea surface temperature anomaly persists along the coast of Central California south to northern Baja California. This will encourage recurrent fog and drizzle events in the coastal forests of N California, and usual night/morning fogs in coasts of central and S California.
- Bottom line for growers of avocado and other sensitive orchards and crops in the coastal hills-valleys of central and S California, watch for a higher than usual occurrence of hot days. This includes highs of mid to upper 90s during late June and the first part of July. The highest probability of 100-110 degree temperatures outside of the southern and eastern deserts is in the warmest intermediate valleys as warm upper high pressure rebuilds prior to start of monsoonal clouds and thunderstorms by mid-July.
- Precipitation trend: Approximate dates of showers in N California and Sierras are: Showers are suggested for 18-19 in Humboldt-Trinity-Del Norte-W Siskiyou Co’s, and N Sierras Lake Tahoe north. . . also, June 29, July 12-13.
- Tropical Cyclones: For June and July we expect a more active period developing for tropical cyclones, with help from easterly waves traversing southern Mexico from the Caribbean, then starting to turn west-northwestward at the coast of southern Baja California.
FORECASTS FOR CALIFORNIA
Forecast for Northern and Central California:
NORCAL Rains: Jun 17-18 (N areas), 29, and Jul 12-13.
CENTRAL CALIF Rains: Jun 18, 29 and Jul 13.
WARM SPELLS: Jun 26 Jul 1-3, Jul 6-10 and 15-18.
COOL SPELLS: Jun 17-19, 25, 29 and Jul 12-13.
FRONTS WITH RAINS: Jun 18-19, 25, 29 and Jul 12.
Forecast for S California:
SOCAL RAINS: Jul 5 (shwrs E), 10 (shwrs E) and 13.
SOCAL WARM SPELLS: Jun 21-22, Jul 10 and Jul 14-18.
SOCAL COOL OR COLD SPELLS: Jun 18-19 and Jul 5-7.
Forecast for Central Sierra Nevada:
Dates of mountain showers of rain are: Jun 18-19, 21-22,29,Jul 13.
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The listing of dates normally included for hot and cold spells, and precipitation are based on our CFSDaily and CFSDailyAI forecast products, and present expected trends in precipitation and temperature (CFSDailyAI) to 4km. Our system gives some consideration of terrain and coastal influence. We consider the CFSv2 as 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, 2022
Highlights: Summer begins with June as a very dry month expected across the state. High pressure will dominate the weather pattern. Some troughs will slide to the east into the Great Basin with brief cooling but dry across California. Monsoon considerations: Both short-term climate models (NMME and CFSv2) are suggesting a dry beginning to the summer monsoon season for SOCAL, western Arizona, and NW Mexico through June. The SE corner of California and S and E portions of Arizona have a better chance for monsoonal rains, beginning in early July.
Looking Ahead – Long Range Outlook
July 17-Aug 29, 2022... NORCAL and Central California: Becoming consistently warmer than normal in July, with some hot conditions (highs in the mid-90s to mid-100s during the hot spells. For the coastal hills, above-normal temperatures are expected for end of June, and most of July, with a well-established, although shallow marine layer. Some monsoonal showers should move into N and Central California mountains (Sierras and NE Plateau region and Cascades/Siskiyou’s by mid-July and reach a peak in the monsoon season mid to late July thru mid-August.
For SOCAL: Progressive trend towards above normal temperature. There is potential to turn hot and dry in early to mid-July just prior to monsoonal thunderstorm rains in the mountains. Foothill and coastal valley highs m90s (avocado areas), but intermediate valleys persistently into the m90s to m100s on occasion monsoonal moisture arrives in mid-July. Best chance for monsoonal showers and thunderstorms in mid-July through mid-August.
In summary, watch for some 100+ hot spells early in the summer season in end of June while cool fogs hang at the immediate coast/beach to midmornings, except those dates with strong upper high pressure and better support for offshore flow. The monsoon season will likely bring normal frequency of showers and thunderstorms late July thru most of August as the moist flow sets up from the Gulf of Mexico and Gulf of California.
(Terms and Definitions Used In This Weather Outlook)
Alan Fox & Zane Stephens...Fox Weather, LLC
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