Area Forecast Discussion
FXUS66 KSTO [Sacramento/WFO CA] 301739 AFDSTO ∨
FXUS66 KSTO 301739 AFDSTO [HEAD]
National Weather Service Sacramento California 9:39am PST Mon Nov 30 2015 ∨
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SACRAMENTO CA 939 AM PST MON NOV 30 2015 [HEAD]
Synopsis. Another cold morning today. A few showers are possible through Wednesday. The next storm system arrives Thursday with wet and windy weather. ∨
.SYNOPSIS... ANOTHER COLD MORNING TODAY. A FEW SHOWERS ARE POSSIBLE THROUGH WEDNESDAY. THE NEXT STORM SYSTEM ARRIVES THURSDAY WITH WET AND WINDY WEATHER. [DISC]
Discussion. Have updated forecast to add isolated/scattered showers for the entire area. Current radar trends showing better coverage with activity. There is still a dry layer 4000–8000 feet… but feel there is a better chance to saturate this layer given current radar trends and short term models. Precipitation amounts will be light and expect all amounts to be less than a tenth of an inch (0.10). Snow levels have dropped at times to 1500 over Lake County where a few flurries have been reported. ∨
.DISCUSSION... HAVE UPDATED FORECAST TO ADD ISOLATED/SCATTERED SHOWERS FOR THE ENTIRE AREA. CURRENT RADAR TRENDS SHOWING BETTER COVERAGE WITH ACTIVITY. THERE IS STILL A DRY LAYER 4000-8000 FEET...BUT FEEL THERE IS A BETTER CHANCE TO SATURATE THIS LAYER GIVEN CURRENT RADAR TRENDS AND SHORT TERM MODELS. PRECIP AMOUNTS WILL BE LIGHT AND EXPECT ALL AMOUNTS TO BE LESS THAN A TENTH OF AN INCH(0.10). SNOW LEVELS HAVE DROPPED AT TIMES TO 1500 OVER LAKE COUNTY WHERE A FEW FLURRIES HAVE BEEN REPORTED. [DISC]
Previous discussion. Clear skies earlier, but clouds ahead of a weakening system are beginning to move across Northern California and it's another cold early morning across the region. Current temperatures through the Central Valley range from the mid 20s to lower 30s. Redding and Red Bluff have already broken their record lows for the date, and most other valley sites are currently within a couple degrees of setting record lows. Widespread freeze over the weekend precludes issuance of Freeze Warnings until trees begin to Bud again by February, or unless there is a massive Arctic outbreak before that time. ∨
.PREVIOUS DISCUSSION... CLEAR SKIES EARLIER, BUT CLOUDS AHEAD OF A WEAKENING SYSTEM ARE BEGINNING TO MOVE ACROSS NORCAL AND IT`S ANOTHER COLD EARLY MORNING ACROSS THE REGION. CURRENT TEMPERATURES THROUGH THE CENTRAL VALLEY RANGE FROM THE MID 20S TO LOWER 30S. REDDING AND RED BLUFF HAVE ALREADY BROKEN THEIR RECORD LOWS FOR THE DATE, AND MOST OTHER VALLEY SITES ARE CURRENTLY WITHIN A COUPLE DEGREES OF SETTING RECORD LOWS. WIDESPREAD FREEZE OVER THE WEEKEND PRECLUDES ISSUANCE OF FREEZE WARNINGS UNTIL TREES BEGIN TO BUD AGAIN BY FEB, OR UNLESS THERE IS A MASSIVE ARCTIC OUTBREAK BEFORE THAT TIME. [DISC]
Offshore cold front will weaken today as it encounters the blocking ridge currently over the West Coast. A few showers will be possible, mainly across the Coast Range and northern portions of the area, but only light accumulations expected. Air mass is very dry and precipitation will be subjected to evaporation. Virga or some sprinkles are not out of the question further south. ∨
OFFSHORE COLD FRONT WILL WEAKEN TODAY AS IT ENCOUNTERS THE BLOCKING RIDGE CURRENTLY OVER THE WEST COAST. A FEW SHOWERS WILL BE POSSIBLE, MAINLY ACROSS THE COAST RANGE AND NORTHERN PORTIONS OF THE AREA, BUT ONLY LIGHT ACCUMULATIONS EXPECTED. AIR MASS IS VERY DRY AND PRECIP WILL BE SUBJECTED TO EVAPORATION. VIRGA OR SOME SPRINKLES ARE NOT OUT OF THE QUESTION FURTHER SOUTH. [DISC]
Dry weather will rule on Tuesday as ridging briefly rebuilds over the region. Temperatures will warm a few degrees from today, but areas of late night and early morning frost will once again be possible through the valley. ∨
DRY WEATHER WILL RULE ON TUESDAY AS RIDGING BRIEFLY REBUILDS OVER THE REGION. TEMPERATURES WILL WARM A FEW DEGREES FROM TODAY, BUT AREAS OF LATE NIGHT AND EARLY MORNING FROST WILL ONCE AGAIN BE POSSIBLE THROUGH THE VALLEY. [DISC]
Another weaker short-wave will move across the area Wednesday and may result in some light warm-advection precipitation across the far northern portion of the state. ∨
ANOTHER WEAKER SHORT-WAVE WILL MOVE ACROSS THE AREA WEDNESDAY AND MAY RESULT IN SOME LIGHT WARM-ADVECTION PRECIPITATION ACROSS THE FAR NORTHERN PORTION OF THE STATE. [DISC]
Stronger system still on the horizon for Thursday with potential for more significant precipitation and wind. Trend in the models is for a little deeper system which may slightly slow its onset across the area. ∨
STRONGER SYSTEM STILL ON THE HORIZON FOR THURSDAY WITH POTENTIAL FOR MORE SIGNIFICANT PRECIPITATION AND WIND. TREND IN THE MODELS IS FOR A LITTLE DEEPER SYSTEM WHICH MAY SLIGHTLY SLOW ITS ONSET ACROSS THE AREA. [DISC]
Extended discussion (Friday through Monday) ∨
.EXTENDED DISCUSSION (FRIDAY THROUGH MONDAY) [DISC]
Late week wet system is on track to bring widepread rain, significant mountain snow above 5000 feet and windy conditions. Main challenge with this system is the exact timing. The 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.] is slower than the now more progressive ECMWF [European Center for Medium-Range Weather Forecasts model] model to move this system inland. Overall, though, there is general agreement that this system will be across the area by early Thursday evening with precipitation peaking sometime in the late evening/early morning hours. Gusty winds are expected into the evening, and may cause additional issues with power outages and poor visibility with snow in the mountains. Snow continues over the Sierra into early Friday with snow levels dropping below 5000 feet as showers begin to taper off. By evening, this system should have exited the area. ∨
LATE WEEK WET SYSTEM IS ON TRACK TO BRING WIDEPREAD RAIN, SIGNIFICANT MOUNTAIN SNOW ABOVE 5000 FEET AND WINDY CONDITIONS. MAIN CHALLENGE WITH THIS SYSTEM IS THE EXACT TIMING. THE GFS IS SLOWER THAN THE NOW MORE PROGRESSIVE ECMWF MODEL TO MOVE THIS SYSTEM INLAND. OVERALL, THOUGH, THERE IS GENERAL AGREEMENT THAT THIS SYSTEM WILL BE ACROSS THE AREA BY EARLY THURSDAY EVENING WITH PRECIPITATION PEAKING SOMETIME IN THE LATE EVENING/EARLY MORNING HOURS. GUSTY WINDS ARE EXPECTED INTO THE EVENING, AND MAY CAUSE ADDITIONAL ISSUES WITH POWER OUTAGES AND POOR VISIBILITY WITH SNOW IN THE MOUNTAINS. SNOW CONTINUES OVER THE SIERRA INTO EARLY FRIDAY WITH SNOW LEVELS DROPPING BELOW 5000 FEET AS SHOWERS BEGIN TO TAPER OFF. BY EVENING, THIS SYSTEM SHOULD HAVE EXITED THE AREA. [DISC]
Dry weather is expected for Saturday. The next system moves through Sunday, but confidence is low in the details. At this point it looks like it will be a weaker system, with less precipitation and wind. (Ek) ∨
DRY WEATHER IS EXPECTED FOR SATURDAY. THE NEXT SYSTEM MOVES THROUGH SUNDAY, BUT CONFIDENCE IS LOW IN THE DETAILS. AT THIS POINT IT LOOKS LIKE IT WILL BE A WEAKER SYSTEM, WITH LESS PRECIPITATION AND WIND. EK [DISC]
Southwesterly flow aloft as weak Pacific frontal system moves through becoming northwesterly this afternoon with frontal passage. Isolated light precipitation possible… mainly over mountains. Generally VFR [Visual Flight Rules] conditions next 24 hours except isolated MVFR [Marginal Visual Flight Rules] possible over mountains in light showers til 06Z [10pm PST] Tuesday. ∨
SWLY FLOW ALF AS WEAK PAC FNTL SYS MOVS THRU BCMG NWLY THIS AFTN WITH FROPA. ISOLD LGT PCPN POSS...MNLY OMTNS. GENLY VFR CONDS NXT 24 HRS EXC ISOLD MVFR POSS OMTNS IN LGT SHWRS TIL 06Z TUE. [AVI2]
STO [Sacramento/WFO CA] Watches/Warnings/Advisories
.STO WATCHES/WARNINGS/ADVISORIES... NONE. [WARN]
30 Nov 12:02pm PST
This Afternoon Partly sunny, with a temperature falling to around 41 by 5pm. West wind 3 to 7 mph.
Tonight Partly cloudy, with a low around 31°. Calm wind becoming ESE 5 to 8 mph after midnight.
Tuesday Mostly sunny, with a high near 51°. ESE wind around 5 mph becoming light and variable.
Tuesday Night Partly cloudy, with a low around 33°. Calm wind becoming ENE 5 to 9 mph in the evening.
Wednesday A 10% chance of rain after 4pm. Partly sunny, with a high near 55°. ENE wind 5 to 7 mph becoming calm in the morning.
Wednesday Night A 20% chance of rain before 10pm. Mostly cloudy, with a low around 38°.
Thursday Rain likely. Mostly cloudy, with a high near 51°. Chance of precipitation is 60%.
Thursday Night Showers. Cloudy, with a low around 32°.
Friday A slight chance of rain and snow showers. Partly sunny, with a high near 43°.
Friday Night Partly cloudy, with a low around 32°.
Saturday Mostly sunny, with a high near 49°.
Saturday Night Mostly cloudy, with a low around 36°.
Sunday Partly sunny, with a high near 50°.
Partly sunny, with a temperature falling to around 41 by 5pm. West wind 3 to 7 mph.
Partly cloudy, with a low around 31. Calm wind becoming east southeast 5 to 8 mph after midnight.
Mostly sunny, with a high near 51. East southeast wind around 5 mph becoming light and variable.
Partly cloudy, with a low around 33. Calm wind becoming east northeast 5 to 9 mph in the evening.
A 10 percent chance of rain after 4pm. Partly sunny, with a high near 55. East northeast wind 5 to 7 mph becoming calm in the morning.
A 20 percent chance of rain before 10pm. Mostly cloudy, with a low around 38.
Rain likely. Mostly cloudy, with a high near 51. Chance of precipitation is 60%.
Showers. Cloudy, with a low around 32.
A slight chance of rain and snow showers. Partly sunny, with a high near 43.
Partly cloudy, with a low around 32.
Mostly sunny, with a high near 49.
Mostly cloudy, with a low around 36.
Partly sunny, with a high near 50.