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Area Forecast Discussion
Issued by NWS Sacramento, CA
Issued by NWS Sacramento, CA
005 FXUS66 KSTO 150831 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 131 AM PDT Thu Aug 15 2024 .SYNOPSIS... Near to slightly below normal temperatures persist alongside periodically breezy diurnal winds heading into the weekend. && .Discussion... Temperatures will be maintained around near normal to slightly below normal today and Friday by a weak shortwave trough moving through the area. NBM is projecting temperatures around the low to mid 90s in the Valley through Friday, after which, over the weekend a larger and stronger trough will build just offshore of California and Oregon. This will bring increased onshore winds on Saturday and Sunday, with NBM predicting a 55 to 80% probability of southerly to southwesterly winds that are at least 25 mph in the northern Sacramento Valley (30-50% elsewhere in the Valley). Relative humidities will rise at the same time on Saturday, generally reaching the 40 to 60% range, before decreasing again on Sunday to the 20 to 30% range. So while we`ll need to keep a close eye on conditions through the weekend for any active wildfires, humidities should temper some concerns for winds on Saturday. Saturday also sees the highest (though still relatively slight) chances for thunderstorms, primarily in northeastern Shasta and far eastern Tehama counties, with NBM showing a 10 to 20% probability of storms developing in that area (highest in northeastern Shasta County). && .EXTENDED DISCUSSION (Monday THROUGH Thursday)... Clusters and ensembles are generally in good agreement that the trough that develops along our coastline will remain mostly stationary through Tuesday as a ridge builds over the Four Corners area and tries to push the trough further away and weaken it. These two upper level features look to duke it out further on Wednesday and Thursday, with most solutions showing fluctuations in the strength of the trough before it builds back up as the ridge moves eastward. All that to say, the evolution of these features means temperatures should remain near normal to slightly below normal through the extended period, with Valley highs generally ranging in the 90s, and high temperatures at higher elevations between the high 60s and high 80s. Ultimately, exact temperatures will be dependent on how far offshore the low places itself initially, but currently NBM is showing at least a 20-55% probability of temperatures below 90 degrees in the Valley throughout the extended forecast period (highest chances on Monday). && .AVIATION... VFR conditions next 24 hours. Surface winds generally below 12 knots except local southwest to west surface wind gusts 15-25 kts after 22Z (strongest near the west Delta). && .STO WATCHES/WARNINGS/ADVISORIES... None. && $$