Area Forecast Discussion
Issued by NWS Sacramento, CA
Issued by NWS Sacramento, CA
398 FXUS66 KSTO 152130 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 230 PM PDT Wed May 15 2024 .SYNOPSIS... Warmest temperatures of the year today, resulting in widespread moderate HeatRisk for the central and northern Sacramento Valley. Cooler, but still seasonably warm weather is expected through Friday, followed by cooler, closer to normal temperatures from the weekend into next week. && .DISCUSSION (Today through Saturday)... Dry weather is expected today, with the weak trough exiting eastward. This will end the potential for afternoon Sierra Crest thunderstorms, with dry weather expected there and across the area. Eastern Pacific ridging will build further into the region, bringing a day of peak heating for the week. Current temperatures at 1 pm were 2 to 7 degrees warmer than yesterday. High temperatures this afternoon look to make a run at the warmest the area has seen so far this year. Widespread 90s are expected throughout the Valley, with 40% to 70% probabilities of reaching triple digits for the western side of the northern and central Sacramento Valley. This is bringing widespread areas of moderate HeatRisk across the northern and central Sacramento Valley for today. Elsewhere at higher elevations, high temperatures are on track to reach the 70s to 80s. Along with the heat, there has been a breezy and dry northerly wind for the northern and central Sacramento Valley with gusts of 20 to 25 mph, though the stronger winds have already peaked. Diminishing northerlies are expected in that are through the afternoon, while onshore flow with the Delta Breeze will increasingly dominate the Delta, the southern Sacramento Valley and the northern San Joaquin Valley. This regime will help to cool temperatures slightly and lead to some modest moisture recovery as well. This cooling trend looks to be further reinforced by a series of troughs ejecting out of the Pacific Northwest toward the northern Plains from the end of the week into the weekend. This flow pattern will indirectly affect interior NorCal by flattening the ridge and lowering heights aloft. As a result, afternoon Valley high temperatures generally look to cool into the upper 80s to 90s to round out the work week, with locally breezy south to west winds. This slight cooling trend is expected to continue into the early weekend, with a passing trough to the northeast which should lead to a bit stronger of a south to west breeze on Saturday, with occasional gusts 20 to 25 mph and additional cooling into Delta Breeze influenced areas. && .EXTENDED DISCUSSION (Sunday THROUGH Wednesday)... As the aforementioned series of troughs continue to progress, a secondary closed low over the eastern Pacific looks to gradually translate eastward toward the West Coast through the weekend. The exact timing and resultant interaction with the troughing over the northern CONUS remains somewhat uncertain, but the majority of ensemble guidance remains in agreement that large scale troughing aloft, will become the primary upper level influence in the West through early to mid next week. The exact evolution of the interaction between the two troughs will dictate the eventual impacts for interior NorCal, but at the very least, temperatures are expected to hold in the near normal range next week. Current cluster analysis favors a continuation of mostly dry weather, but there is the potential for a slightly wetter pattern as well by the middle of next week. Current NBM projects some potential for mountain precipitation. && .AVIATION... VFR conditions next 24 hours. Southwesterly surface wind gusts 20-30 kts in the west Delta 00Z-12Z Thursday, otherwise winds generally less than 12 kts. && .STO WATCHES/WARNINGS/ADVISORIES... None. && $$