Area Forecast Discussion
FXUS66 KSTO [Sacramento/WFO CA] 101129 AFDSTO ∨
FXUS66 KSTO 101129 AFDSTO [HEAD]
National Weather Service Sacramento California 4:29am PDT Sat Oct 10 2015 ∨
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SACRAMENTO CA 429 AM PDT SAT OCT 10 2015 [HEAD]
Synopsis. Mostly clear with above normal temperatures through midweek. High clouds and locally breezy conditions over the higher elevations of the Sierra this weekend. End of next week could see more clouds and mountain showers as a weather system moves up from Southern California. ∨
.SYNOPSIS... MOSTLY CLEAR WITH ABOVE NORMAL TEMPERATURES THROUGH MIDWEEK. HIGH CLOUDS AND LOCALLY BREEZY CONDITIONS OVER THE HIGHER ELEVATIONS OF THE SIERRA THIS WEEKEND. END OF NEXT WEEK COULD SEE MORE CLOUDS AND MOUNTAIN SHOWERS AS A WEATHER SYSTEM MOVES UP FROM SOUTHERN CALIFORNIA. [DISC]
Discussion (tonight through Tuesday) the state of California has high pressure ridging across central California while two low pressure systems flank that ridge to the northwest (Gulf of Alaska) and to the south (off the coast of Baja California). However, weather will stay dry for our CWA [County Warning Area; see the LWP home page (link at bottom of page) for a CWA map] through middle of next week. The ridge will weaken slightly this weekend as a pulse of energy associated with the Gulf of Alaska low moves into the Pacific Northwest. This will help the Delta breeze make a subtle return and will cause some breezy conditions over the Sierra later this afternoon into evening. This will make daytime highs over the weekend slightly cooler than Friday, but values will remain slightly above normal. The Fort Ord profiler [instrument designed to measure horizontal winds directly above its location, and thus measure the vertical wind profile. Profilers operate on the same principles as Doppler radar.] is showing a hint of a marine layer early this morning, but it's pretty shallow (around 500 ft thick). The onshore gradient is forecast to be a moderate onshore flow around 2–3 mb for the SFO [San Francisco CA]-SAC [Sacramento CA] gradient by early evening. Daytime highs today will be in the mid to upper 80s for the valley, mid 70s to mid 80s through the Delta, and mid 60s to low 80s for higher terrain which is approximately 5–10° above average. ∨
.DISCUSSION (TONIGHT THROUGH TUESDAY) THE STATE OF CA HAS HIGH PRESSURE RIDGING ACROSS CENTRAL CA WHILE TWO LOW PRESSURE SYSTEMS FLANK THAT RIDGE TO THE NORTHWEST (GULF OF ALASKA) AND TO THE SOUTH (OFF THE COAST OF BAJA CALIFORNIA). HOWEVER, WEATHER WILL STAY DRY FOR OUR CWA THROUGH MIDDLE OF NEXT WEEK. THE RIDGE WILL WEAKEN SLIGHTLY THIS WEEKEND AS A PULSE OF ENERGY ASSOCIATED WITH THE GULF OF ALASKA LOW MOVES INTO THE PAC NW. THIS WILL HELP THE DELTA BREEZE MAKE A SUBTLE RETURN AND WILL CAUSE SOME BREEZY CONDITIONS OVER THE SIERRA LATER THIS AFTERNOON INTO EVENING. THIS WILL MAKE DAYTIME HIGHS OVER THE WEEKEND SLIGHTLY COOLER THAN FRIDAY, BUT VALUES WILL REMAIN SLIGHTLY ABOVE NORMAL. THE FORT ORD PROFILER IS SHOWING A HINT OF A MARINE LAYER EARLY THIS MORNING, BUT IT`S PRETTY SHALLOW (AROUND 500 FT THICK). THE ONSHORE GRADIENT IS FORECAST TO BE A MODERATE ONSHORE FLOW AROUND 2-3 MB FOR THE SFO-SAC GRADIENT BY EARLY EVENING. DAYTIME HIGHS TODAY WILL BE IN THE MID TO UPPER 80S FOR THE VALLEY, MID 70S TO MID 80S THROUGH THE DELTA, AND MID 60S TO LOW 80S FOR HIGHER TERRAIN WHICH IS APPROXIMATELY 5-10 DEGREES ABOVE AVERAGE. [DISC]
For Monday and Tuesday of next week, the high pressure ridging across the state will re-strengthen. This warming trend will push daytime highs up to 15° above normal. Valley highs will peak in the low 90s by Tuesday as dry conditions continue. (JBB) ∨
FOR MONDAY AND TUESDAY OF NEXT WEEK, THE HIGH PRESSURE RIDGING ACROSS THE STATE WILL RE-STRENGTHEN. THIS WARMING TREND WILL PUSH DAYTIME HIGHS UP TO 15 DEGREES ABOVE NORMAL. VALLEY HIGHS WILL PEAK IN THE LOW 90S BY TUESDAY AS DRY CONDITIONS CONTINUE. JBB [DISC]
Extended discussion (Wednesday through Saturday) ∨
.EXTENDED DISCUSSION (WEDNESDAY THROUGH SATURDAY) [DISC]
Middle of next week looks dry under an upper level high pressure ridge over the Western US a closed upper low pressure system off the Southern California coast is forecast to continue drifting northward on Wednesday and may begin to impact Northern California towards the end of the week. 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.] remains the wetter model painting scattered precipitation over Northern California on Thursday while the ECMWF [European Center for Medium-Range Weather Forecasts model] which remains a bit farther south indicates somewhat drier conditions. With this weak low pushing into a strong ridge… believe ECMWF [European Center for Medium-Range Weather Forecasts model] probably has a better handle on this scenario and have weighed more heavily on this model. For now… have kept any precipitation threat confined to the Sierra Cascade Range Thursday and Friday with just a small drop in daytime temperatures. Longer range models are hinting at a break down of the dominant Western US ridge beginning next weekend. At this time… any significant change remains beyond the 7 day timeframe so first part of next weekend looks dry. ∨
MIDDLE OF NEXT WEEK LOOKS DRY UNDER AN UPPER LEVEL HIGH PRESSURE RIDGE OVER THE WESTERN U.S. A CLOSED UPPER LOW PRESSURE SYSTEM OFF THE SOCAL COAST IS FORECAST TO CONTINUE DRIFTING NORTHWARD ON WEDNESDAY AND MAY BEGIN TO IMPACT NORTHERN CALIFORNIA TOWARDS THE END OF THE WEEK. GFS REMAINS THE WETTER MODEL PAINTING SCATTERED PRECIPITATION OVER NORCAL ON THURSDAY WHILE THE ECMWF WHICH REMAINS A BIT FARTHER SOUTH INDICATES SOMEWHAT DRIER CONDITIONS. WITH THIS WEAK LOW PUSHING INTO A STRONG RIDGE...BELIEVE ECMWF PROBABLY HAS A BETTER HANDLE ON THIS SCENARIO AND HAVE WEIGHED MORE HEAVILY ON THIS MODEL. FOR NOW...HAVE KEPT ANY PRECIP THREAT CONFINED TO THE SIERRA CASCADE RANGE THURSDAY AND FRIDAY WITH JUST A SMALL DROP IN DAYTIME TEMPERATURES. LONGER RANGE MODELS ARE HINTING AT A BREAK DOWN OF THE DOMINANT WESTERN U.S RIDGE BEGINNING NEXT WEEKEND. AT THIS TIME...ANY SIGNIFICANT CHANGE REMAINS BEYOND THE 7 DAY TIMEFRAME SO FIRST PART OF NEXT WEEKEND LOOKS DRY. [DISC]
VFR [Visual Flight Rules] conditions all TAF [Terminal Aerodrome Forecast] sites next 24 hours. Increasing southwest winds after 18Z [11am PDT]. Gusts up to 15 knots [17 mph] over valley but up to 40 knots [46 mph] over Sierra Nevada. Winds decreasing after about 06Z [11pm PDT] Sunday. ∨
VFR CONDITIONS ALL TAF SITES NEXT 24 HOURS. INCREASING SOUTHWEST WINDS AFTER 18Z. GUSTS UP TO 15 KNOTS OVER VALLEY BUT UP TO 40 KNOTS OVER SIERRA NEVADA. WINDS DECREASING AFTER ABOUT 06Z SUNDAY. [AVI2]
STO [Sacramento/WFO CA] Watches/Warnings/Advisories
.STO WATCHES/WARNINGS/ADVISORIES... NONE. [WARN]
10 Oct 5:02am PDT
Today Sunny, with a high near 87°. East wind 6 to 11 mph becoming SSW 13 to 18 mph in the afternoon. Winds could gust as high as 28 mph.
Tonight Mostly clear, with a low around 58°. SSW wind 6 to 11 mph becoming light and variable.
Sunday Sunny, with a high near 80°. East wind 7 to 9 mph becoming WSW in the afternoon.
Sunday Night Mostly clear, with a low around 56°. SSW wind 6 to 8 mph becoming ENE in the evening.
Columbus Day Sunny, with a high near 82°. ENE wind around 8 mph becoming WSW in the morning.
Monday Night Mostly clear, with a low around 57°.
Tuesday Sunny, with a high near 83°.
Tuesday Night Partly cloudy, with a low around 58°.
Wednesday Mostly sunny, with a high near 83°.
Wednesday Night Partly cloudy, with a low around 58°.
Thursday Mostly sunny, with a high near 78°.
Thursday Night Partly cloudy, with a low around 58°.
Friday Mostly sunny, with a high near 77°.
Sunny, with a high near 87. East wind 6 to 11 mph becoming south southwest 13 to 18 mph in the afternoon. Winds could gust as high as 28 mph.
Mostly clear, with a low around 58. South southwest wind 6 to 11 mph becoming light and variable.
Sunny, with a high near 80. East wind 7 to 9 mph becoming west southwest in the afternoon.
Mostly clear, with a low around 56. South southwest wind 6 to 8 mph becoming east northeast in the evening.
Sunny, with a high near 82. East northeast wind around 8 mph becoming west southwest in the morning.
Mostly clear, with a low around 57.
Sunny, with a high near 83.
Partly cloudy, with a low around 58.
Mostly sunny, with a high near 83.
Partly cloudy, with a low around 58.
Mostly sunny, with a high near 78.
Partly cloudy, with a low around 58.
Mostly sunny, with a high near 77.