Area Forecast Discussion
Issued by NWS Sacramento, CA
Issued by NWS Sacramento, CA
993 FXUS66 KSTO 302120 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 220 PM PDT Tue Apr 30 2024 .Synopsis... Gusty north winds expected through the Valley tonight through Wednesday afternoon. Quiet and dry weather prevail through Friday. Precipitation chances return this weekend. && Abundant sunshine across Northern California this afternoon as high pressure ridging keeps our weather dry, quiet, warm, and sunny through Friday. Several short-wave troughs pass over the Pacific Northwest with broad ridging over the eastern Pacific and Northern California. As those troughs pass through, the surface pressure gradient is expected to tighten resulting in gusty northerly winds throughout the Valley. Winds pick up tonight and are expected to last through late morning on Wednesday with gusts of 35-40 mph. The strongest winds are forecast over the western half of the Sacramento Valley along the I-5 corridor and through the Delta. The National Blend of Models (NBM) has a 50 to 70% chance of gusts greater than 40 mph over the area and A Wind Advisory is in effect from now until 5PM Wednesday. Difficult driving conditions are anticipated and unsecured, loose objects may blow around. Winds weaken by Wednesday afternoon, but northerly gusts of 15 to 20 mph return to the Valley on Thursday before returning to a breezy diurnal flow pattern on Friday. Valley high temperatures will be in the upper 70s to mid 80s through Friday, as we follow a gradual warming trend. Looking ahead to this weekend, a weather system will bring returning precipitation chances to interior NorCal along with cooler temperatures. && .EXTENDED DISCUSSION (Saturday THROUGH Tuesday)... Confidence in increasing in a cooler, wetter pattern for the weekend as a cold core low from the Gulf of Alaska drops southward into the region. Ensembles and clusters do have some uncertainty in the exact track of this low, though, which will determine exactly how wet this system will be. A surface cold front is expected to move through on Saturday. This will bring widespread moderate showers to the area. National Blend of Models has trended quite a bit higher with current forecast rainfall amounts, with ensembles leaning more towards the low passing near/over the area. WPC liquid storm total QPF is now forecasting around a third of an inch to two thirds of an inch of rain in the Valley. An inch to around 2 inches of liquid precipitation is now projected in the foothills and mountains. Snow levels start high, over 8,000 feet, then are projected to drop down to 4000-5000 feet by early Sunday, as the system is winding down. Current forecast shows a few inches of snow impacting the Sierra passes. There is currently a 40-50% probability of 4" for the higher Sierra over the weekend. This could bring minor travel impacts at the passes, with the best potential for accumulating snow Saturday night into early Sunday. The pattern suggests some potential for convection, though the current Thunderstorm Probability is below 15%. If the core of the low tracks more over land, this would increase the potential for thunderstorms, so this will be watched closely. Temperatures cool down quite a bit for the weekend, with Saturday highs about 20 degrees lower than on Friday. Sunday could see a little warming as the clouds begin to break up, but will still remain well below normal for this time of year. Model uncertainty continues into early next week, with an unsettled pattern, though a general shift to northwest flow should limit the potential for most precipitation to the northern mountains and foothills. There is a wide spread in National Blend of Models high temperatures, so we will have to wait and see how things trend temperature-wise as we get closer to that period. && .AVIATION... Clear skies and VFR conditions expected across interior NorCal over the next 24 hrs. Gusty northerly surface winds are expected through the Sacramento Valley after 06Z Wednesday, with sustained winds 15 to 25 kts and gusts 35 to 40 kts. Gusts up to 25 kts elsewhere in the Valley. Over the mountains, northeasterly gusts 20 to 30 kts are expected 06Z to 18Z Wednesday. && .STO WATCHES/WARNINGS/ADVISORIES... Wind Advisory from 11 PM this evening to 5 PM PDT Wednesday for Carquinez Strait and Delta-Central Sacramento Valley-Northern Sacramento Valley-Southern Sacramento Valley. && $$