274 FXUS66 KHNX 210930 AFDHNXArea Forecast Discussion National Weather Service Hanford CA 230 AM PDT Sun Sep 21 2025
.KEY MESSAGES... 1. Temperatures warm back up early this week.
2. A slight chance of showers and thunderstorms continues this weekend in the higher elevations of the Sierra Nevada.
3. More widespread precipitation is in store for the mountains and desert by Tuesday. There is also a chance of rain returning to the San Joaquin Valley on Tuesday into Wednesday with a 20 to 40 percent chance of a tenth of an inch of rain.
4. There is at least a 5% chance of excessive rainfall across Central California on Wednesday and Thursday.
&&
.DISCUSSION... Lingering moisture and weak instability should be enough for afternoon showers with a 15%-25% chance of thunderstorms across the Sierra Nevada. Otherwise, will expect the warming trend in temperature to continue through the early part of this week. At this point, a ridge pattern over the area will dominate Central Californias weather, as we heat up. Yet, an upper low off the California Coast will support another surge of moisture and precipitation returns to area around the mid-week period. Probability of Measurable Precipitation increases toward mid- week as widespread precipitation will be observed. The pattern toward Sierra Nevada showers returns toward the end of the week.
Latest ensemble precipitation analysis has the onset of widespread precipitation starting on Tuesday. A majority of the probabilistic analysis confines measurable precipitation to the south-end around Kern County. By Wednesday, 24 hour rain probabilities show amounts reaching 0.50 (half an inch) with some extreme values reaching up to 0.75. Therefore, with probabilities reaching high values, there is at least a 5% chance of experiencing excessive rainfall on Wednesday. The northward surge of moisture will present similar conditions on Thursday as the probability of excessive rainfall continues.
By Friday, the passage of the upper low through Southern California will change the flow pattern toward a drier one with a change toward cooler conditions. Probability of Exceedance of reaching 95 degree by Friday remains at less than 30%. These percentages increases confidence in high temperatures that are near normal for this time of year. At the same time, lingering moisture from the second push of moisture will allow for the continuation of convection across the Sierra into next weekend.
&&
.AVIATION... 12Z Update:
Across the Sierra Nevada, there is a 10 to 20 percent chance of thunderstorms from 20Z today through 03Z Monday. MVFR conditions are possible until 17Z today due to haze, especially in the eastern San Joaquin Valley. Otherwise, VFR prevails for the next 24 hours.
&&
.AIR QUALITY ISSUES... None.
&&
.CERTAINTY...
The level of certainty for days 1 and 2 is high. The level of certainty for days 3 through 7 is medium.
Certainty levels include low...medium...and high. Please visit www.weather.gov/hnx/certainty.html for additional information and/or to provide feedback.
&&
.HNX WATCHES/WARNINGS/ADVISORIES... None.
&&
$$
public...Molina aviation....Molina
weather.gov/hanford
NWS HNX Office Area Forecast Discussion