July 30, 2021 - The National Weather Service Hanford Office reports scattered thunderstorms will develop over the mountains this afternoon and linger into the evening hours.
In addition to dangerous cloud to ground lightning, a few thunderstorms will bring small hail, wind gusts to about 40 mph and heavy rainfall with the potential for flash flooding.
Hikers should be prepared to seek a safe place when skies turn ominous and thunder is heard.
Area Forecast Discussion National Weather Service Hanford CA 229 AM PDT Fri Jul 30 2021 .SYNOPSIS... Slightly warmer than average high temperatures look likely into the foreseeable future over the forecast area. Monsoonal moisture will provide the Sierra Nevada with a chance of afternoon and evening thunderstorms each day until Sunday. && .DISCUSSION...Latest radar images show a few remnant showers over the Sierra Nevada. Otherwise, expect a warm and muggy morning with mid-level cloud cover throughout Central California with yet another warmer than average afternoon today. Additional showers and thunderstorms are expected to develop by this afternoon in the mountains and desert, so these areas may not be quite as warm as on Thursday. There is even a slight chance for showers with afternoon and evening thunderstorms along the east side of the San Joaquin Valley from today until Saturday. The upper-level ridge over the Plains and much of the Western U.S. combined with the offshore trough will continue to bring a south to southeast flow carrying additional subtropical moisture along with embedded impulses. We will keep the Flash Flood Watch in effect until Saturday evening for the mountain areas from Yosemite to the Tehachapi Mountains as these areas will be most favorable for storms that produce heavy rainfall. Also, the precipitable water will be sufficient for scattered thunderstorms to produce heavy rainfall in these areas during today and Saturday. By Sunday, expect a decrease in storm coverage, or mainly over the Sierra Nevada. The monsoonal moisture will begin to shift northeastward, as the flow aloft turns more southwesterly while the upper-level trough approaches the coast of Northern CA. Afterward, a drying trend is likely for much of next week. However, we will likely see little relief over the next several days from triple digit temperatures in the warmest areas, including in the San Joaquin Valley and Kern County desert areas. The only exception is some locations in the Central Valley and Kern County desert may not quite reach 100 degrees on Saturday, but that will depend on the amount of cloud cover. A gradual warming trend is expected for Sunday until the middle of the week as high pressure redevelops over much of Southern California and the Desert Southwest and builds northward, per latest deterministic and ensemble guidance. The position of the ridge will likely keep any monsoonal moisture over Arizona and eastward from Monday until at least Thursday. Also for later next week, the desert region of eastern Kern County might heat back up a bit, as there is a probability of about 40 percent that high temperatures will reach near 110 degrees by Thursday in portions of the Kern County desert, such as in the Indian Wells Valley. Otherwise, many Kern County desert locations will top 105 degrees by the middle of the week. Probabilities of triple digits remain at least 50 percent in much of the San Joaquin Valley over the next several days. In addition, blended guidance shows around 20-25 percent chance of highs returning to 105 degrees in the Central Valley by next Friday. && .AVIATION... Mountain obscurations in showers and scattered thunderstorms possible over the Sierra Nevada for mainly this afternoon and evening, or 19Z Friday until 03Z Saturday. Also expect isolated to scattered thunderstorms with local MVFR ceilings and visibility possible at times over the Kern County mountains and desert during this afternoon and evening. Otherwise, VFR conditions will prevail through the next 24 hours. && .AIR QUALITY ISSUES... On Friday July 30 2021... Unhealthy for sensitive groups in Fresno... Kern... Madera... Merced and Tulare Counties and Sequoia National Park and Forest. Further information is available at Valleyair.orgSource: NWS