Area Forecast Discussion
Issued by NWS Sacramento, CA
Issued by NWS Sacramento, CA
722 FXUS66 KSTO 202011 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 111 PM PDT Mon May 20 2024 .SYNOPSIS... Warm and dry weather with periodically breezy to gusty northerly winds continues through midweek. A cooling trend is then expected from Friday into the upcoming holiday weekend as onshore flow returns. && .DISCUSSION... As of early this afternoon, aside from some cumulus beginning to bubble along the Sierra, mostly clear skies are evident over the remainder of interior NorCal on latest GOES-West satellite imagery. Breezy to gusty northerly winds also continue, with strongest gusts of 30 to 35 mph being observed through the northern and central Sacramento Valley. Winds are expected to gradually lessen through the afternoon, with strongest gusts generally subsiding by the late evening hours. Otherwise, a few isolated showers will be possible (15% to 25% chance) along the Sierra crest, generally south of the I-80 corridor, through the early evening. Moving into Tuesday, northerly winds will remain breezy, but lesser than today. Heights aloft are expected to rise for a brief period ahead of the next passing shortwave trough traveling through the Pacific Northwest, which will result in temperatures warming back to slightly above normal by Tuesday afternoon. Wednesday looks to see similarly breezy and seasonably warm conditions, with the aforementioned trough then beginning to dig toward the Intermountain West late Wednesday into Thursday. As this trough moves within the vicinity of interior NorCal, another period of gusty northerly winds is expected on Thursday, with forecast gusts to 30 mph across the northern and central Sacramento Valley. Additionally, there is a 40% to 60% probability of gusts reaching 40 mph in this corridor as well. && .EXTENDED DISCUSSION (Friday THROUGH Monday)... Following the shortwave passage on Thursday, broad, large scale troughing aloft looks to overtake the region from Friday into the weekend. Despite the fairly active upper level pattern, impacts at the surface generally look to remain limited. The primary shift will be from northerly surface winds to breezy south to west winds as onshore flow returns to interior NorCal. High temperatures by Friday look to cool to near normal under this regime. Within this broad troughing, an embedded shortwave trough then looks to dig across the Pacific Northwest and into the northern Great Basin, resulting in, more or less, another glancing blow for interior NorCal. Given the proximity of the trough, a few isolated showers cannot be completely ruled out over the northern Sacramento Valley and across the higher terrain on Saturday, but current probabilities of exceeding 0.10" of rainfall reside below 5% at this time. The primary impact will be temperatures cooling to below normal on Saturday, with Valley high temperatures in the 70s and 50s to 60s at higher elevations. The shortwave responsible for this cool down is then expected to allow the broad troughing to eject eastward, with heights aloft then rising again and upper level ridging beginning to build in across the western CONUS from Sunday into early next week. Onshore flow is then expected to persist alongside temperatures gradually warming back up above normal for Memorial Day. && .AVIATION... VFR conditions next 24 hours. Areas of northerly surface wind gusts 15-25 kts across the Northern Sacramento Valley and I-5 corridor north of Sacramento until 21z Tuesday. Winds elsewhere will begin to slowly trend down after 21z Monday lowering under 12 kts in the Valley after 03z Tuesday. && .STO WATCHES/WARNINGS/ADVISORIES... None. && $$