Area Forecast Discussion
Issued by NWS Sacramento, CA
Issued by NWS Sacramento, CA
134 FXUS66 KSTO 262128 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 228 PM PDT Sun May 26 2024 .SYNOPSIS... A warming trend continues this week, with generally above normal temperatures. Minor HeatRisk is expected early in the week, with the moderate through the week ahead. Weak onshore flow also persists through Tuesday, before dry, northerly flow arrives from Wednesday through the end of the week. Elevated fire weather concerns for the northern and central Sacramento Valley Thursday. && .DISCUSSION... Upper level ridging with mostly clear skies has brought warmer temperatures for today, with 2 pm temperatures 5 to 15 degrees higher than the same time on Saturday. Valley highs in the mid to upper 80s are on track. Broad troughing aloft will continue to influence interior NorCal as another trough from the Gulf of Alaska moves eastward toward the Pacific Northwest early this week. A few isolated, late day showers will be possible along the Sierra crest on Monday, generally south of the Highway 50 corridor. Generally this pattern will lead to warming temperatures into week, with afternoon high temperatures rising into in the mid 80s to low 90s. This pattern will also allow south to west winds to continue, bringing Delta breezes with some cooling in the evening and at night for influenced areas. Ensemble guidance continues to show the trough exiting eastward from the Pacific Northwest mid to late week. This track will increase northerly winds, especially over the northern and central Sacramento Valley. There is a 45-55% probability of wind gusts greater than 40 mph in those areas. The gusty winds with low humidity will bring elevated fire weather concerns there and for the adjacent foothills. Fine fuels are not completely cured, though, which is a mitigating factor. Onshore, westerly flow persists further southward, generally from I-80 to the south, with higher humidity recovery at night. Temperatures overall still look to remain slightly above normal, with Valley high temperatures in the mid 80s to low 90s, and 70s to 80s at higher elevations, today through Thursday. Minor HeatRisk is expected to accompany these temperatures through Wednesday, with areas of Moderate HeatRisk for the central and southern Sacramento Valley on Thursday as temperatures rise a little higher. && .EXTENDED DISCUSSION (Thursday THROUGH Sunday)... While upper level troughing will have kept the area from getting to far above normal temperatures early in the week, by Thursday the dominant pattern becomes transient ridging. The transition from troughing to ridging will bring breezy winds on Thursday, along with the potential for strong gusts. NBM currently has the potential for 30 mph gusts or stronger in the northern Sacramento Valley sitting around 35 to 80% probability, with highest chances along the I-5 corridor in the northern Sacramento Valley. Probabilities for 40 mph gusts or stronger are more localized between Red Bluff and Dunnigan along the I-5 corridor, but are still around 30 to 55% in that area. These winds will also likely bring low relative humidities to the Valley, as low as the low to mid teens, though primarily this will be in the northern Sacramento Valley. The entrance of the ridging pattern will also increase temperatures to above normal in the late week and into the early weekend, with highs in the 90s in the Valley, 80s in the foothills, and 70s in the mountains. The ridging will be interrupted by shortwave troughing late in the weekend however, bringing temperatures back closer to normal. //SP && .AVIATION... VFR conditions next 24 hours, except for local southwest wind gusts to 20 kts near the Delta. && .STO WATCHES/WARNINGS/ADVISORIES... None. && $$