Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA
Issued by NWS San Joaquin Valley, CA
804 FXUS66 KHNX 302017 AFDHNX Area Forecast Discussion National Weather Service Hanford CA 117 PM PDT Sun Jun 30 2024 && .KEY MESSAGES... 1. Warming continues this weekend, before a dangerous, long- duration heat wave hits the central valley of California through the holiday week and into next weekend. 2. An Excessive Heat Warning has been issued for Tuesday July 2nd through Monday July 8th, and may need to be extended through next weekend as the event nears. 3. The risk of grass fires will continue to increase with herbaceous fuel loading at or near 120% of normal. A long period of excessive heat, minimum relative humidities near 15% and poor overnight relative humidity recoveries will add to the grass fire risk. && .DISCUSSION... As the high pressure system in the Pacific approaches California, temperatures will continue to rise as it gets nearer. Tomorrow, temperatures in the San Joaquin Valley will be in the low 100s before rising steeply by Tuesday, where theyll be in the high 100s. On Wednesday, July 3rd, there is more than a 50 percent chance of many places within the San Joaquin Valley hitting 110 degrees as a high temperature. Here are probabilities that select cities will see 110 degrees or more as a high temperature on Wednesday: Merced: 57% Madera: 58% Fresno: 56% Lemoore: 79% Hanford: 64% Visalia: 48% Porterville: 50% Bakersfield: 52% These probabilities for 110 degrees go down by about 10 percent on Thursday (Independence Day) and Friday, but jump back up to around the same values for Saturday. Because of this extended heatwave, an Excessive Heat Warning has been issued from Tuesday, July 2nd at 11am through Monday, July 8th, at 8am. Low temperatures will also be high, with the same cities mentioned above having a 40% or more chance of seeing low temperatures at 70 degrees or above Wednesday through Sunday. With low temperatures this high, temperature recovery will be very poor through next weekend. As a result, much of the San Joaquin Valley and West Side Hills will be under an Extreme HeatRisk level Thursday through Saturday. With an Extreme HeatRisk level, the entire population is at risk for heat- related illnesses if they dont have access to adequate cooling and hydration. Ensemble model guidance shows that the high pressure system will sit stationary over California for a bit, and high temperatures will continue to be above 100 degrees through the middle of next week as well, but stay tuned as the forecast becomes clearer. Alongside this heat, relative humidity values will be very low throughout the valley, with minimum relative humidity percentages being in the teens. This alongside very low fuel moisture and herbaceous fuel loading at or near 120 percent of normal will result in an increased risk of grass fires through the holiday week and weekend. && .AVIATION... Continued areas of MVFR and local IFR visibility due to smoke at and around the Fresno County fires will continue in the Sierra Nevada and adjacent foothills. Otherwise, VFR conditions will prevail across the central California interior for the next 24 hours. && .FIRE WEATHER... Fuel moistures are typically at their lowest and Energy Release Component is typically the highest from now through July. Near record low 100 hour and 1000 hour fuel moisture are forecast to occur during the peak of the heatwave next week, especially in the Central Valley. Additionally, ERC is forecast to approach record highs. This will create an increased risk for grass fires, especially on the 4th of July. && .AIR QUALITY ISSUES... Air Quality Alert due to smoke impacts from wildfires. && .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... Excessive Heat Warning from 11 AM Tuesday to 8 AM PDT Monday for CAZ300>322-324-332-334-336>339. && $$ public/aviation/fire weather...AS PIO/IDSS.......................DCH weather.gov/hanford