Area Forecast Discussion FXUS66 KSTO [Sacramento/WFO CA] 121028 AFDSTO ∨ FXUS66 KSTO 121028 AFDSTO [HEAD] National Weather Service Sacramento California 2:28am PST Wed Feb 12 2025 ∨ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SACRAMENTO CA 228 AM PST WED FEB 12 2025 [HEAD] Synopsis. Another cool and dry morning ahead a weather system bringing moderate to heavy rain and snow and gusty winds Wednesday night to Friday. ∨ .SYNOPSIS... ANOTHER COOL AND DRY MORNING AHEAD A WEATHER SYSTEM BRINGING MODERATE TO HEAVY RAIN AND SNOW AND GUSTY WINDS WEDNESDAY NIGHT TO FRIDAY. [DISC] Discussion. Radar imagery this evening is beginning to show the first line of radar returns as moisture makes it way towards Northern California. Things will remain relatively quiet throughout the morning with most precipitation falling as virga and just across the far southwestern corner of the CWA [County Warning Area; see the LWP home page (link at bottom of page) for a CWA map]. Precipitation moves into interior Northern California this evening over the western side of the valley and track westward throughout the Thursday early morning. Thursday morning will be the wettest period, first in the valley then by late morning over the Sierra. Snow and rain rates begin to taper down Thursday night into Friday morning with most precipitation over by very early Saturday morning. Here is look into impacts during this stretch of weather. ∨ .DISCUSSION... RADAR IMAGERY THIS EVENING IS BEGINNING TO SHOW THE FIRST LINE OF RADAR RETURNS AS MOISTURE MAKES IT WAY TOWARDS NORTHERN CA. THINGS WILL REMAIN RELATIVELY QUIET THROUGHOUT THE MORNING WITH MOST PRECIPITATION FALLING AS VIRGA AND JUST ACROSS THE FAR SOUTHWESTERN CORNER OF THE CWA. PRECIPITATION MOVES INTO INTERIOR NORTHERN CA THIS EVENING OVER THE WESTERN SIDE OF THE VALLEY AND TRACK WESTWARD THROUGHOUT THE THURSDAY EARLY MORNING. THURSDAY MORNING WILL BE THE WETTEST PERIOD, FIRST IN THE VALLEY THEN BY LATE MORNING OVER THE SIERRA. SNOW AND RAIN RATES BEGIN TO TAPER DOWN THURSDAY NIGHT INTO FRIDAY MORNING WITH MOST PRECIPITATION OVER BY VERY EARLY SATURDAY MORNING. HERE IS LOOK INTO IMPACTS DURING THIS STRETCH OF WEATHER.... [DISC] Beginning with snow, snow level Wednesday night will be 1500–2500 feet over Shasta County/Coast Range areas with 3000–4500 feet over the Sierra Mountains. Increasing snow levels move in from the south and by Thursday morning be 3500–5000 feet over northern Shasta and 5000–7000 feet across the Sierra. By the evening much of Northern California will see 4500–5500 feet before lowering to around 4000–5000 feet Friday morning. This will bring periods of moderate to heavy snowfall with feet of snow expected for the Sierra above 4500 feet and up to a foot for the northern Shasta County areas above 2000 feet. Additionally, there continues to a chance of snow across the lower elevations of the northern SAC [Sacramento CA]. Valley with EC [European Center for Meteorology (or East Central)] and GFS [Global Forecast System: global spectral model used primarily for aviation weather forecasts; provides guidance out to 384 hours at 00, 06, 12 and 18UTC.] ensembles showing snow accumulations as low as Redding although is a high level of uncertainty, combined by the potential mitigating affect of snow falling on rain and/or there being a mix of rain and snow. Local effects could really come into play and in areas where cold air can be trapped may see snow but locally warmer areas see rain or mixed precipitation. No matter what, plan for slippery road conditions and travel delays as the weather system moves through. ∨ BEGINNING WITH SNOW, SNOW LEVEL WEDNESDAY NIGHT WILL BE 1500-2500 FEET OVER SHASTA COUNTY/COAST RANGE AREAS WITH 3000-4500 FEET OVER THE SIERRA MOUNTAINS. INCREASING SNOW LEVELS MOVE IN FROM THE SOUTH AND BY THURSDAY MORNING BE 3500-5000 FEET OVER NORTHERN SHASTA AND 5000-7000 FEET ACROSS THE SIERRA. BY THE EVENING MUCH OF NORTHERN CA WILL SEE 4500-5500 FEET BEFORE LOWERING TO AROUND 4000-5000 FEET FRIDAY MORNING. THIS WILL BRING PERIODS OF MODERATE TO HEAVY SNOWFALL WITH FEET OF SNOW EXPECTED FOR THE SIERRA ABOVE 4500 FEET AND UP TO A FOOT FOR THE NORTHERN SHASTA COUNTY AREAS ABOVE 2000 FEET. ADDITIONALLY, THERE CONTINUES TO A CHANCE OF SNOW ACROSS THE LOWER ELEVATIONS OF THE NORTHERN SAC. VALLEY WITH EC AND GFS ENSEMBLES SHOWING SNOW ACCUMULATIONS AS LOW AS REDDING ALTHOUGH IS A HIGH LEVEL OF UNCERTAINTY, COMBINED BY THE POTENTIAL MITIGATING AFFECT OF SNOW FALLING ON RAIN AND/OR THERE BEING A MIX OF RAIN AND SNOW. LOCAL EFFECTS COULD REALLY COME INTO PLAY AND IN AREAS WHERE COLD AIR CAN BE TRAPPED MAY SEE SNOW BUT LOCALLY WARMER AREAS SEE RAIN OR MIXED PRECIPITATION. NO MATTER WHAT, PLAN FOR SLIPPERY ROAD CONDITIONS AND TRAVEL DELAYS AS THE WEATHER SYSTEM MOVES THROUGH. [DISC] With all that being said, Winter Storm Warnings remain in effect for northern Shasta County/Coast Range above 2000 feet from 10pm Wednesday to 4am Friday for 3–8 inches with 1–2 feet above 3500 feet and winds up to 45 mph. For the Sierra and southern Cascades, our warning will be from 10pm Wednesday to 10pm Friday for 2–5 feet possible above 6000 feet and 5–15 inches between 4500–6000 feet and winds as high as 60 mph. Very difficult travel conditions with chain controls and road closures are expected and heaviest snowfall is expected on Thursday with rates of 1–2 inches per hours at times. ∨ WITH ALL THAT BEING SAID, WINTER STORM WARNINGS REMAIN IN EFFECT FOR NORTHERN SHASTA COUNTY/COAST RANGE ABOVE 2000 FEET FROM 10 PM WEDNESDAY TO 4 AM FRIDAY FOR 3-8 INCHES WITH 1-2 FEET ABOVE 3500 FEET AND WINDS UP TO 45 MPH. FOR THE SIERRA AND SOUTHERN CASCADES, OUR WARNING WILL BE FROM 10 PM WEDNESDAY TO 10 PM FRIDAY FOR 2-5 FEET POSSIBLE ABOVE 6000 FEET AND 5-15 INCHES BETWEEN 4500-6000 FEET AND WINDS AS HIGH AS 60 MPH. VERY DIFFICULT TRAVEL CONDITIONS WITH CHAIN CONTROLS AND ROAD CLOSURES ARE EXPECTED AND HEAVIEST SNOWFALL IS EXPECTED ON THURSDAY WITH RATES OF 1-2 INCHES PER HOURS AT TIMES. [DISC] Widespread rain will impact interior Northern California over the same timeframe. The NBM shows a 60–90% probability of 1 inch of rain or more in the valley with a 60–90% probability of 2 inches or more in the foothills . Rain may be moderate to heavy at times, creating slick roads, mud/rock slides in the foothills, high flows on area waterways and minor flooding issues. There is also a 10–20% probability of isolated thunderstorms Thursday afternoon through Friday that could lead to locally heavier rain amounts. A Flood Watch has been issued for elevations below the primary snow line to address these conditions. ∨ WIDESPREAD RAIN WILL IMPACT INTERIOR NORCAL OVER THE SAME TIMEFRAME. THE NBM SHOWS A 60-90% PROBABILITY OF 1 INCH OF RAIN OR MORE IN THE VALLEY WITH A 60-90% PROBABILITY OF 2 INCHES OR MORE IN THE FOOTHILLS . RAIN MAY BE MODERATE TO HEAVY AT TIMES, CREATING SLICK ROADS, MUD/ROCK SLIDES IN THE FOOTHILLS, HIGH FLOWS ON AREA WATERWAYS AND MINOR FLOODING ISSUES. THERE IS ALSO A 10 TO 20 PERCENT PROBABILITY OF ISOLATED THUNDERSTORMS THURSDAY AFTERNOON THROUGH FRIDAY THAT COULD LEAD TO LOCALLY HEAVIER RAIN AMOUNTS. A FLOOD WATCH HAS BEEN ISSUED FOR ELEVATIONS BELOW THE PRIMARY SNOW LINE TO ADDRESS THESE CONDITIONS. [DISC] Gusty southerly winds are forecast with this system, generally around 30–50 mph gusts in the lower elevations Wednesday night through early Friday, strongest on Thursday. A Wind Advisory has been issued for portions of the valley to address impacts such as difficult driving conditions for high profile vehicles, potential power outages, downed trees or tree branches, and loose objects blowing around. ∨ GUSTY SOUTHERLY WINDS ARE FORECAST WITH THIS SYSTEM, GENERALLY AROUND 30 TO 50 MPH GUSTS IN THE LOWER ELEVATIONS WEDNESDAY NIGHT THROUGH EARLY FRIDAY, STRONGEST ON THURSDAY. A WIND ADVISORY HAS BEEN ISSUED FOR PORTIONS OF THE VALLEY TO ADDRESS IMPACTS SUCH AS DIFFICULT DRIVING CONDITIONS FOR HIGH PROFILE VEHICLES, POTENTIAL POWER OUTAGES, DOWNED TREES OR TREE BRANCHES, AND LOOSE OBJECTS BLOWING AROUND. [DISC] Saturday looks to be mostly a transition day after the mid week storm tapers off and we see a brief break in precipitation. Saturday evening will see light showers move ocer the northern SAC [Sacramento CA]. Valley and southern Cascades are with 25–55% of seeing precipitation. ∨ SATURDAY LOOKS TO BE MOSTLY A TRANSITION DAY AFTER THE MID WEEK STORM TAPERS OFF AND WE SEE A BRIEF BREAK IN PRECIPITATION. SATURDAY EVENING WILL SEE LIGHT SHOWERS MOVE OCER THE NORTHERN SAC. VALLEY AND SOUTHERN CASCADES ARE WITH 25-55% OF SEEING PRECIPITATION. [DISC] Extended discussion (Sunday through Wednesday). ∨ .EXTENDED DISCUSSION (SUNDAY THROUGH WEDNESDAY)... [DISC] Ensemble guidance then indicates by Sunday morning another weather system has pushed its wave into the Northern California, mainly over the mountains and N. SAC [Sacramento CA]. Valley. This system looks much weaker than the upcoming mid-week storm, and appears to be more progressive as well. Little to no impacts are expected from this weekend storm, with just some dusting of snow, light showers, and locally breezy winds. On Monday, as any lingering precipitation tapers off, it appears we can expect a return to drier and slightly warmer weather that continues into Tuesday. ∨ ENSEMBLE GUIDANCE THEN INDICATES BY SUNDAY MORNING ANOTHER WEATHER SYSTEM HAS PUSHED ITS WAVE INTO THE NORTHERN CA, MAINLY OVER THE MOUNTAINS AND N. SAC. VALLEY. THIS SYSTEM LOOKS MUCH WEAKER THAN THE UPCOMING MID- WEEK STORM, AND APPEARS TO BE MORE PROGRESSIVE AS WELL. LITTLE TO NO IMPACTS ARE EXPECTED FROM THIS WEEKEND STORM, WITH JUST SOME DUSTING OF SNOW, LIGHT SHOWERS, AND LOCALLY BREEZY WINDS. ON MONDAY, AS ANY LINGERING PRECIPITATION TAPERS OFF, IT APPEARS WE CAN EXPECT A RETURN TO DRIER AND SLIGHTLY WARMER WEATHER THAT CONTINUES INTO TUESDAY. [DISC] Aviation. ∨ .AVIATION... [AVIA] VFR [Visual Flight Rules] conditions expected to prevail through 00Z [4pm PST] Thursday, when a storm system brings widespread MVFR [Marginal Visual Flight Rules] conditions and periods of IFR [Instrument Flight Rules]/LIFR [Low Instrument Flight Rules] due to moderate to heavy precipitation. Heavier precipitation rates expected to start after 06Z [10pm PST] Thursday. Snow levels start around 1000' to 2000' with start of precipitation in Shasta County and southern Cascades before rising to 3500' to 4500' over Thursday (2500' to 4500' in the Sierra, rising to 4500' to 6000'). Southerly surface winds across the valley, around 10–20 kts [12–23 mph], with gusts 30–45 kts [35–52 mph] at times, starting after 06Z [10pm PST] Thursday. South to southwesterly gusts in the Sierra 60–70 kts [69–81 mph] after 06Z [10pm PST] Thursday. ∨ VFR CONDITIONS EXPECTED TO PREVAIL THROUGH 00Z THURSDAY, WHEN A STORM SYSTEM BRINGS WIDESPREAD MVFR CONDITIONS AND PERIODS OF IFR/LIFR DUE TO MODERATE TO HEAVY PRECIPITATION. HEAVIER PRECIP RATES EXPECTED TO START AFTER 06Z THURSDAY. SNOW LEVELS START AROUND 1000` TO 2000` WITH START OF PRECIP IN SHASTA COUNTY AND SOUTHERN CASCADES BEFORE RISING TO 3500` TO 4500` OVER THURSDAY (2500` TO 4500` IN THE SIERRA, RISING TO 4500` TO 6000`). SOUTHERLY SURFACE WINDS ACROSS THE VALLEY, AROUND 10 TO 20 KTS, WITH GUSTS 30 TO 45 KTS AT TIMES, STARTING AFTER 06Z THURSDAY. SOUTH TO SOUTHWESTERLY GUSTS IN THE SIERRA 60 TO 70 KTS AFTER 06Z THURSDAY. [AVI2] STO [Sacramento/WFO CA] Watches/Warnings/Advisories
.STO WATCHES/WARNINGS/ADVISORIES... FLOOD WATCH FROM THIS EVENING THROUGH FRIDAY EVENING FOR CARQUINEZ STRAIT AND DELTA-CENTRAL SACRAMENTO VALLEY-MOTHERLODE- MOUNTAINS SOUTHWESTERN SHASTA COUNTY TO WESTERN COLUSA COUNTY- NORTHEAST FOOTHILLS/SACRAMENTO VALLEY-NORTHERN SACRAMENTO VALLEY- SHASTA LAKE AREA / NORTHERN SHASTA COUNTY-SOUTHERN SACRAMENTO VALLEY-WEST SLOPE NORTHERN SIERRA NEVADA-WESTERN PLUMAS COUNTY/LASSEN PARK. [WARN]
WINTER STORM WARNING FROM 10 PM THIS EVENING TO 4 AM PST FRIDAY FOR MOUNTAINS SOUTHWESTERN SHASTA COUNTY TO WESTERN COLUSA COUNTY-SHASTA LAKE AREA / NORTHERN SHASTA COUNTY-WEST SLOPE NORTHERN SIERRA NEVADA-WESTERN PLUMAS COUNTY/LASSEN PARK. [WRN2]
WIND ADVISORY FROM 10 PM THIS EVENING TO 10 AM PST FRIDAY FOR CARQUINEZ STRAIT AND DELTA-CENTRAL SACRAMENTO VALLEY-NORTHERN SACRAMENTO VALLEY-NORTHERN SAN JOAQUIN VALLEY-SOUTHERN SACRAMENTO VALLEY. [WRN2] |
Point Forecast Auburn CA 12 Feb 08:35am PST Today Mostly sunny, with a high near 51°. Calm wind becoming west around 5 mph in the afternoon. Tonight Showers, mainly after 9pm. The rain could be heavy at times. Low around 41°. Calm wind becoming ESE 5 to 9 mph in the evening. Winds could gust as high as 39 mph. Chance of precipitation is 100%. New precipitation amounts between a half and three quarters of an inch possible. Thursday Showers, with thunderstorms also possible after 4pm. Some of the storms could produce heavy rainfall. High near 52°. South wind around 16 mph, with gusts as high as 38 mph. Chance of precipitation is 100%. New rainfall amounts between 1 and 2 inches possible. Thursday Night Showers and possibly a thunderstorm. Low around 44°. South wind 13 to 15 mph, with gusts as high as 31 mph. Chance of precipitation is 100%. New precipitation amounts between a half and three quarters of an inch possible. Friday Showers. High near 51°. South wind 7 to 11 mph, with gusts as high as 21 mph. Chance of precipitation is 80%. Friday Night Patchy frost after 5am. Otherwise, partly cloudy, with a low around 36°. Saturday Patchy frost before 7am. Otherwise, partly sunny, with a high near 55°. Saturday Night Mostly cloudy, with a low around 41°. Sunday A chance of showers. Mostly cloudy, with a high near 55°. Sunday Night A chance of showers, mainly before 10pm. Mostly cloudy, with a low around 43°. Washington's Birthday A chance of showers. Partly sunny, with a high near 56°. Monday Night Partly cloudy, with a low around 37°. Tuesday Mostly sunny, with a high near 57°. Today Mostly sunny, with a high near 51. Calm wind becoming west around 5 mph in the afternoon. Tonight Showers, mainly after 9pm. The rain could be heavy at times. Low around 41. Calm wind becoming east southeast 5 to 9 mph in the evening. Winds could gust as high as 39 mph. Chance of precipitation is 100%. New precipitation amounts between a half and three quarters of an inch possible. Thursday Showers, with thunderstorms also possible after 4pm. Some of the storms could produce heavy rainfall. High near 52. South wind around 16 mph, with gusts as high as 38 mph. Chance of precipitation is 100%. New rainfall amounts between 1 and 2 inches possible. Thursday Night Showers and possibly a thunderstorm. Low around 44. South wind 13 to 15 mph, with gusts as high as 31 mph. Chance of precipitation is 100%. New precipitation amounts between a half and three quarters of an inch possible. Friday Showers. High near 51. South wind 7 to 11 mph, with gusts as high as 21 mph. Chance of precipitation is 80%. Friday Night Patchy frost after 5am. Otherwise, partly cloudy, with a low around 36. Saturday Patchy frost before 7am. Otherwise, partly sunny, with a high near 55. Saturday Night Mostly cloudy, with a low around 41. Sunday A chance of showers. Mostly cloudy, with a high near 55. Sunday Night A chance of showers, mainly before 10pm. Mostly cloudy, with a low around 43. Washington's Birthday A chance of showers. Partly sunny, with a high near 56. Monday Night Partly cloudy, with a low around 37. Tuesday Mostly sunny, with a high near 57. |
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