30-Day Weather Outlook for May 31, 2020, to June 22, 2020

  • May 31, 2020

(May 31 – June 22)

Summary- The prevailing pattern is a high pressure ridge from N California westsouthwest or southwestward. Cold fronts coming S through California will tend to extend southwestward from southcentral-S California to the area SW – W of S California.

A long-lived pattern of troughing or low pressure will continue from southwest of Central California to about 25N then extend west toward Hawaii.

The MJO is showing a slow increase in activity over the next two weeks.

CFSDailyAI and CFSv2 suggest some rains primarily in northern California and the Sierras, and into Siskiyou Mountains and southern Oregon at times.

It is early for monsoonal showers and thunderstorms (TSTMS). However, the presence of upper lows may begin to bring tropical moisture northward into SOCAL and the Sierras, despite the lack of a usual summer monsoonal pattern.

Potential Dates of Precipitation (from Fox Weather's CFSDAILYAI system):

Salinas Valley-San Luis Obispo Co- S SierraNV:

Salinas Valley Showers: 6/2-3. Hot spells 6/4, 6/8-9, 6/11-12, 6/14-17, 6/22-27.

San Luis Ob/Edna: Hot spells 6/6, 6/9, 6/12, 6/15-17, 6/20-27th, 7/1.

Southern California Citrus/Avocado Area, San Luis Obispo Co to San Diego Co:

Southern California Citrus/Avocado Area: May 31-June 15.

Santa Barbara, Ventura to San Diego Co: No rainfall of consequence.

Hot spells:

Santa Barbara Co: 6/6, 6/12. 6/16-17th, 6/22-26th.  

Ventura Co: Hot 6/16-17th, 6/22-26th. 

San Diego/Orange: Hot 6/16-17, 6/22-26.

Summary – June 15 – July 15… In Northern and Central California, Hottest: 6/14-17, 6/22,27, 7/1-2.

San Luis Obispo Co... Hottest periods 6/15-17, 6/22-27.

Southern California… Shallow marine layer and hot inland. Hottest: 6/16-17, 6/22-26, 7/1-3.

Seasonal Outlook July 15 – August 31... Northern and Central California overall pattern…. Near normal rainfall (minimal). Above normal temperatures occur during all of July and all of August. Usual thunderstorms (TSTMS) in the central and N Sierra and Plateau. 

Southern California: San Luis Obispo Co, Santa Barbara Co, and Ventura to San Diego Counties east through Los Angeles to San Bernardino, Riverside and Imperial Counties…. Our latest guidance is suggesting a hot period in N and Northcentral California during mid-July, but near normal behavior of the marine layer at the SOCAL coast and valley areas. Although cloud amounts should be about normal, temperatures will drift above normal due to warmer sea surface off SOCAL and Baja. Weak troughs and upper lows will intermittently develop and deepen the marine layer as is normal for summer.

Looking further ahead into Sept – Nov, Dry and persistently warmer than normal conditions develop during the late Sept through Nov Santa Ana season.

Alan Fox...Fox Weather, LLC
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