Area Forecast Discussion
FXUS66 KSTO [Sacramento/WFO CA] 220558 AFDSTO ∨
FXUS66 KSTO 220558 AFDSTO [HEAD]
National Weather Service Sacramento California 9:58pm PST Sun Dec 21 2014 ∨
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SACRAMENTO CA 958 PM PST SUN DEC 21 2014 [HEAD]
Synopsis. Dry through Tuesday under high pressure ridge with patchy fog. There is a chance another system may affect the region Wednesday into early Christmas Day. ∨
.SYNOPSIS... DRY THROUGH TUESDAY UNDER HIGH PRESSURE RIDGE WITH PATCHY FOG. THERE IS A CHANCE ANOTHER SYSTEM MAY AFFECT THE REGION WEDNESDAY INTO EARLY CHRISTMAS DAY. [DISC]
Discussion. Patchy fog beginning to form over the area this evening. Although… just enough winds have continued along with a few patches of clouds to keep the fog from becoming widespread. Fog will be densest overnight where winds diminish and skies clear. North winds will increase after 10am Monday. This will likely mix out the fog by noon with sunny skies possible during the afternoon. Current forecast handles this well and no evening update will be needed. ∨
.DISCUSSION... PATCHY FOG BEGINNING TO FORM OVER THE AREA THIS EVENING. ALTHOUGH...JUST ENOUGH WINDS HAVE CONTINUED ALONG WITH A FEW PATCHES OF CLOUDS TO KEEP THE FOG FROM BECOMING WIDESPREAD. FOG WILL BE DENSEST OVERNIGHT WHERE WINDS DIMINISH AND SKIES CLEAR. NORTH WINDS WILL INCREASE AFTER 10 AM MONDAY. THIS WILL LIKELY MIX OUT THE FOG BY NOON WITH SUNNY SKIES POSSIBLE DURING THE AFTERNOON. CURRENT FORECAST HANDLES THIS WELL AND NO EVENING UPDATE WILL BE NEEDED. [DISC]
Previous discussion. Moisture will continue to stream into the region this evening but generally any lingering showers will be in the mountains through tonight. Overcast skies overnight might limit the amount of valley fog around Sacramento but skies may start to clear enough by morning where fog may start forming. Some fog is still being reported in the foothills and mountains and will likely continue to have some overnight. ∨
.PREVIOUS DISCUSSION... MOISTURE WILL CONTINUE TO STREAM INTO THE REGION THIS EVENING BUT GENERALLY ANY LINGERING SHOWERS WILL BE IN THE MOUNTAINS THROUGH TONIGHT. OVERCAST SKIES OVERNIGHT MIGHT LIMIT THE AMOUNT OF VALLEY FOG AROUND SACRAMENTO BUT SKIES MAY START TO CLEAR ENOUGH BY MORNING WHERE FOG MAY START FORMING. SOME FOG IS STILL BEING REPORTED IN THE FOOTHILLS AND MOUNTAINS AND WILL LIKELY CONTINUE TO HAVE SOME OVERNIGHT. [DISC]
A strong ridge of high pressure builds over the interior to keep the interior dry for Monday and Tuesday. Fog continues to look like it may become an issue each night and morning starting Monday morning. The thicker fog for Monday may be limited to the San Joaquin Valley. Tuesday the fog should expand further north into the Sacramento region. ∨
A STRONG RIDGE OF HIGH PRESSURE BUILDS OVER THE INTERIOR TO KEEP THE INTERIOR DRY FOR MONDAY AND TUESDAY. FOG CONTINUES TO LOOK LIKE IT MAY BECOME AN ISSUE EACH NIGHT AND MORNING STARTING MONDAY MORNING. THE THICKER FOG FOR MONDAY MAY BE LIMITED TO THE SAN JOAQUIN VALLEY. TUESDAY THE FOG SHOULD EXPAND FURTHER NORTH INTO THE SACRAMENTO REGION. [DISC]
As the ridge builds expect most temperatures to warm well above normal… 10–15° above normal. Redding could be flirting with reaching 70° on Tuesday. Further south in the valley moist air and morning fog and a temperature inversion may limit the amount of warm up. I expect adjacent foothills to end up being warmer. ∨
AS THE RIDGE BUILDS EXPECT MOST TEMPERATURES TO WARM WELL ABOVE NORMAL...10 TO 15 DEGREES ABOVE NORMAL. REDDING COULD BE FLIRTING WITH REACHING 70 DEGREES ON TUESDAY. FURTHER SOUTH IN THE VALLEY MOIST AIR AND MORNING FOG AND A TEMPERATURE INVERSION MAY LIMIT THE AMOUNT OF WARM UP. I EXPECT ADJACENT FOOTHILLS TO END UP BEING WARMER. [DISC]
On Wednesday a system will approach the region but most models keep the interior dry except for the far northwest part of the state. Wednesday night as the system passes through continues to look like the best chance of any precipitation. ∨
ON WEDNESDAY A SYSTEM WILL APPROACH THE REGION BUT MOST MODELS KEEP THE INTERIOR DRY EXCEPT FOR THE FAR NORTHWEST PART OF THE STATE. WEDNESDAY NIGHT AS THE SYSTEM PASSES THROUGH CONTINUES TO LOOK LIKE THE BEST CHANCE OF ANY PRECIPITATION. [DISC]
Extended discussion (Thursday through Sunday) ∨
.EXTENDED DISCUSSION (THURSDAY THROUGH SUNDAY) [DISC]
Drier northwesterly flow will move over the area in the wake of the Christmas Eve system heading into next weekend. This could bring a period of breezy north winds to the forecast area, along with colder overnight temperatures. The ECMWF [European Center for Medium-Range Weather Forecasts model] and GEM [Global Environmental Multiscale model] are hinting at another inside slider system early next week, whereas 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 dry. With low confidence in the forecast, our forecast closely resembles climatology for early next week. ∨
DRIER NORTHWESTERLY FLOW WILL MOVE OVER THE AREA IN THE WAKE OF THE CHRISTMAS EVE SYSTEM HEADING INTO NEXT WEEKEND. THIS COULD BRING A PERIOD OF BREEZY NORTH WINDS TO THE FORECAST AREA, ALONG WITH COLDER OVERNIGHT TEMPERATURES. THE ECMWF AND GEM ARE HINTING AT ANOTHER INSIDE SLIDER SYSTEM EARLY NEXT WEEK, WHEREAS THE GFS IS DRY. WITH LOW CONFIDENCE IN THE FORECAST, OUR FORECAST CLOSELY RESEMBLES CLIMATOLOGY FOR EARLY NEXT WEEK. [DISC]
Expect most locations to again deteriorate to IFR [Instrument Flight Rules]/MVFR [Marginal Visual Flight Rules] with local LIFR [Low Instrument Flight Rules] this evening and tonight as fog develops. Expect most locations to improve to VFR [Visual Flight Rules]/MVFR [Marginal Visual Flight Rules] by 18–20Z [10am–12pm PST] Monday. ∨
EXPECT MOST LOCATIONS TO AGAIN DETERIORATE TO IFR/MVFR WITH LOCAL LIFR THIS EVENING AND TONIGHT AS FOG DEVELOPS. EXPECT MOST LOCATIONS TO IMPROVE TO VFR/MVFR BY 18-20Z MONDAY. [AVI2]
STO [Sacramento/WFO CA] Watches/Warnings/Advisories
.STO WATCHES/WARNINGS/ADVISORIES... NONE. [WARN]
17 Miles Nw Yosemite Valley CA
1:40pm PST Dec 21 2014
Overnight. Mostly clear, with a low around 38°. ENE wind around 13 mph.
Monday. Sunny, with a high near 59°. NE wind 8 to 14 mph, with gusts as high as 18 mph.
Monday Night. Mostly clear, with a low around 39°. ENE wind 14 to 16 mph, with gusts as high as 23 mph.
Tuesday. Sunny, with a high near 60°. NE wind 8 to 16 mph, with gusts as high as 22 mph.
Tuesday Night. Mostly clear, with a low around 37°. ENE wind 7 to 9 mph.
Wednesday. Mostly sunny, with a high near 56°.
Wednesday Night. A 20% chance of rain. Mostly cloudy, with a low around 35°.
Christmas Day. Partly sunny, with a high near 49°.
Thursday Night. Partly cloudy, with a low around 34°.
Friday. Sunny, with a high near 50°.
Friday Night. Mostly clear, with a low around 35°.
Saturday. Mostly sunny, with a high near 52°.
Saturday Night. Partly cloudy, with a low around 36°.
Sunday. Mostly sunny, with a high near 50°.