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FXUS66 KMTR [Monterey CA] 220059 AFDMTR 

FXUS66 KMTR 220059
AFDMTR [HEAD]

National Weather Service San Francisco Bay Area 5:59pm PDT Tue Aug 21 2018 

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
559 PM PDT TUE AUG 21 2018 [HEAD]

Synopsis. After a period of cooling, a slight warming trend will begin tomorrow as the upper trough influencing our current weather exits to the northeast. This will allow temperatures to rebound to near seasonal averages by late this week. Coastal clouds are still expected to persist and penetrate inland each night. 

.SYNOPSIS...AFTER A PERIOD OF COOLING, A SLIGHT WARMING TREND WILL
BEGIN TOMORROW AS THE UPPER TROUGH INFLUENCING OUR CURRENT WEATHER
EXITS TO THE NORTHEAST. THIS WILL ALLOW TEMPERATURES TO REBOUND TO
NEAR SEASONAL AVERAGES BY LATE THIS WEEK. COASTAL CLOUDS ARE
STILL EXPECTED TO PERSIST AND PENETRATE INLAND EACH NIGHT. [DISC]

Discussion. As of 02:11pm PDT Tuesday… stratus has mainly dissipated across the region with some lingering clouds around the San Francisco Bay and northward. Satellite imagery also shows smoke drifting across the North Bay from various wildfires. Thanks to persistent cloud cover and an upper trough stretching across Northern California, temperatures this afternoon are around 5–10° cooler than this time yesterday. Expect another round of overnight and morning low clouds as the marine layer is forecast to remain above 1500 ft. 

.DISCUSSION...AS OF 02:11 PM PDT TUESDAY...STRATUS HAS MAINLY
DISSIPATED ACROSS THE REGION WITH SOME LINGERING CLOUDS AROUND THE
SAN FRANCISCO BAY AND NORTHWARD. SATELLITE IMAGERY ALSO SHOWS
SMOKE DRIFTING ACROSS THE NORTH BAY FROM VARIOUS WILDFIRES. THANKS
TO PERSISTENT CLOUD COVER AND AN UPPER TROUGH STRETCHING ACROSS
NORTHERN CALIFORNIA, TEMPERATURES THIS AFTERNOON ARE AROUND 5 TO
10 DEGREES COOLER THAN THIS TIME YESTERDAY. EXPECT ANOTHER ROUND
OF OVERNIGHT AND MORNING LOW CLOUDS AS THE MARINE LAYER IS
FORECAST TO REMAIN ABOVE 1500 FT. [DISC]

The upper low over Idaho and associated trough that brought us cooler weather will move to the northeast tomorrow, allowing the ridge of high pressure over the desert southwest to strengthen. This will kick off a warming trend through the rest of the week and into the coming weekend. A broad upper trough over British Columbia and an upper low well to the west of California will prevent the aforementioned ridge from strengthening enough to cause any significant warming. Most locations will remain near seasonal normals through the week. This translates to afternoon high temperatures in the 60s to low 70s along the coast and 80s to 90s inland. Overnight and morning low clouds are expected to continue as well. 

THE UPPER LOW OVER IDAHO AND ASSOCIATED TROUGH THAT BROUGHT US
COOLER WEATHER WILL MOVE TO THE NORTHEAST TOMORROW, ALLOWING THE
RIDGE OF HIGH PRESSURE OVER THE DESERT SOUTHWEST TO STRENGTHEN.
THIS WILL KICK OFF A WARMING TREND THROUGH THE REST OF THE WEEK
AND INTO THE COMING WEEKEND. A BROAD UPPER TROUGH OVER BRITISH
COLUMBIA AND AN UPPER LOW WELL TO THE WEST OF CALIFORNIA WILL
PREVENT THE AFOREMENTIONED RIDGE FROM STRENGTHENING ENOUGH TO
CAUSE ANY SIGNIFICANT WARMING. MOST LOCATIONS WILL REMAIN NEAR
SEASONAL NORMALS THROUGH THE WEEK. THIS TRANSLATES TO AFTERNOON
HIGH TEMPERATURES IN THE 60S TO LOW 70S ALONG THE COAST AND 80S TO
90S INLAND. OVERNIGHT AND MORNING LOW CLOUDS ARE EXPECTED TO
CONTINUE AS WELL. [DISC]

Looking into the medium range, CPC [Climate Prediction Center] outlooks continue to show near normal temperatures over California. This morning's 8–14 day outlook even shows below normal temperatures for much of the West Coast. 

LOOKING INTO THE MEDIUM RANGE, CPC OUTLOOKS CONTINUE TO SHOW NEAR
NORMAL TEMPERATURES OVER CALIFORNIA. THIS MORNING`S 8-14 DAY
OUTLOOK EVEN SHOWS BELOW NORMAL TEMPERATURES FOR MUCH OF THE WEST
COAST. [DISC]

Aviation. As of 5:57pm PDT Tuesday… a moderately deep marine layer up to 2400 and 2800 feet will likely compress tonight into Wednesday as lower level thermal ridging strengthens; 925 mb temps warm 6°C-12°C from midday earlier today through Wednesday afternoon. Bodega Bay, Fort Ord, Point Sur [Big Sur CA] profilers starting to show some warming and compression of the marine layer on recent check. 

.AVIATION...AS OF 5:57 PM PDT TUESDAY...A MODERATELY DEEP MARINE
LAYER UP TO 2400 AND 2800 FEET WILL LIKELY COMPRESS TONIGHT INTO
WEDNESDAY AS LOWER LEVEL THERMAL RIDGING STRENGTHENS; 925 MB TEMPS
WARM 6C-12C FROM MIDDAY EARLIER TODAY THROUGH WED AFTERNOON. BODEGA
BAY, FORT ORD, POINT SUR PROFILERS STARTING TO SHOW SOME WARMING AND
COMPRESSION OF THE MARINE LAYER ON RECENT CHECK. [AVIA]

The 18Z [11am PDT] NAM [North American Meso (formerly Eta) model] shows increasing surface dewpoint temperatures sweeping SE-E across the coastal waters and a weak low pressure circulation setting up just west of Mendocino/Sonoma Counties tonight through Thursday morning. This supports ongoing widespread ocean based stratus feed along with at least patchy fog (4:20pm visibility 1/2–1 mile in fog at the Farallon Islands). Based on recent high-res model output wildfire smoke both aloft and probability some smoke extending to the surface will advance inland and add to presently smoky conditions over the Bay Area through this evening into Wednesday; clearing Wednesday could be a very slow process, many locations may have stratus and a mix of fog/smoky/hazy conditions all day. 

THE 18Z NAM SHOWS INCREASING SURFACE DEWPOINT TEMPERATURES SWEEPING
SE-E ACROSS THE COASTAL WATERS AND A WEAK LOW PRESSURE CIRCULATION
SETTING UP JUST WEST OF MENDOCINO/SONOMA COUNTIES TONIGHT THRU THU
MORNING. THIS SUPPORTS ONGOING WIDESPREAD OCEAN BASED STRATUS FEED
ALONG WITH AT LEAST PATCHY FOG (4:20 PM VISIBILITY 1/2-1 MILE IN FOG
AT THE FARALLON ISLANDS). BASED ON RECENT HIGH-RES MODEL OUTPUT
WILDFIRE SMOKE BOTH ALOFT AND PROB SOME SMOKE EXTENDING TO THE
SURFACE WILL ADVANCE INLAND AND ADD TO PRESENTLY SMOKY CONDITIONS
OVER THE BAY AREA THROUGH THIS EVENING INTO WEDNESDAY; CLEARING
WEDNESDAY COULD BE A VERY SLOW PROCESS, MANY LOCATIONS MAY HAVE
STRATUS AND A MIX OF FOG/SMOKY/HAZY CONDITIONS ALL DAY. [AVI2]

Expect moderate to poor slant range visibility through mid-late week, and surface visibilities reduced to MVFR [Marginal Visual Flight Rules]-IFR [Instrument Flight Rules] due to combo fog and smoke, along with lowering stratus ceilings to IFR [Instrument Flight Rules]-VLIFR [Very Low Instrument Flight Rules]

EXPECT MODERATE TO POOR SLANT RANGE VISIBILITY THROUGH MID-LATE
WEEK, AND SURFACE VISIBILITIES REDUCED TO MVFR-IFR DUE TO COMBO
FOG AND SMOKE, ALONG WITH LOWERING STRATUS CEILINGS TO IFR-VLIFR. [AVI2]

Vicinity of KSFO [San Francisco CA]… stratus coverage is more extensive late this afternoon, plenty of stratus feed off the ocean, and the marine layer is moderately deep. Stratus ceilings are likely to lower as lower level warming steps up through the evening into Wednesday morning. Scattering of stratus may hold off until Wednesday afternoon. Horizontal visibilities are good at the moment, but should generally decrease through the evening; KHAF visibility and ceiling (IFR [Instrument Flight Rules]) have been steadily lowering. 

VICINITY OF KSFO...STRATUS COVERAGE IS MORE EXTENSIVE LATE THIS
AFTERNOON, PLENTY OF STRATUS FEED OFF THE OCEAN, AND THE MARINE
LAYER IS MODERATELY DEEP. STRATUS CEILINGS ARE LIKELY TO LOWER AS
LOWER LEVEL WARMING STEPS UP THROUGH THE EVENING INTO WEDNESDAY
MORNING. SCATTERING OF STRATUS MAY HOLD OFF UNTIL WEDNESDAY
AFTERNOON. HORIZONTAL VISIBILITIES ARE GOOD AT THE MOMENT, BUT
SHOULD GENERALLY DECREASE THROUGH THE EVENING; KHAF VSBY AND CIG
(IFR) HAVE BEEN STEADILY LOWERING. [AVI2]

SFO [San Francisco CA] bridge approach… moderate to poor slant range visibility for the period. Otherwise similar to KSFO [San Francisco CA]

SFO BRIDGE APPROACH...MODERATE TO POOR SLANT RANGE VISIBILITY FOR
THE PERIOD. OTHERWISE SIMILAR TO KSFO. [AVI2]

Monterey Bay terminals… MVFR [Marginal Visual Flight Rules] gradually lowering to IFR [Instrument Flight Rules] tonight, patchy LIFR [Low Instrument Flight Rules]-VLIFR [Very Low Instrument Flight Rules] is possible depending how quickly the marine layer compresses; may need to adjust visibilities/ceilings lower by 06Z [11pm PDT] TAF [Terminal Aerodrome Forecast] issuance. Slow mixing process on Wednesday, clearing probability delayed at least til late morning if not afternoon with brief window of clearing in the afternoon. Stratus/fog likely rolling back inland early Wednesday evening and night. 

MONTEREY BAY TERMINALS...MVFR GRADUALLY LOWERING TO IFR TONIGHT,
PATCHY LIFR-VLIFR IS POSSIBLE DEPENDING HOW QUICKLY THE MARINE
LAYER COMPRESSES; MAY NEED TO ADJUST VSBYS/CIGS LOWER BY 06Z TAF
ISSUANCE. SLOW MIXING PROCESS ON WEDNESDAY, CLEARING PROB DELAYED
AT LEAST TIL LATE MORNING IF NOT AFTERNOON WITH BRIEF WINDOW OF
CLEARING IN THE AFTERNOON. STRATUS/FOG LIKELY ROLLING BACK INLAND
EARLY WEDNESDAY EVENING AND NIGHT. [AVI2]

Marine. As of 4:52pm PDT Tuesday… light onshore winds over the coastal waters through the coming days. Breezy onshore winds will develop near coastal gaps through the afternoon and evenings. Winds will increase over the northern waters Friday into the weekend. Light mixed swell overall. 

.MARINE...AS OF 4:52 PM PDT TUESDAY...LIGHT ONSHORE WINDS OVER
THE COASTAL WATERS THROUGH THE COMING DAYS. BREEZY ONSHORE WINDS
WILL DEVELOP NEAR COASTAL GAPS THROUGH THE AFTERNOON AND EVENINGS.
WINDS WILL INCREASE OVER THE NORTHERN WATERS FRIDAY INTO THE
WEEKEND. LIGHT MIXED SWELL OVERALL. [AVIA]

MTR Watches/Warnings/Advisories

  • Tonight: none. 
.MTR WATCHES/WARNINGS/ADVISORIES...
.TNGT...NONE. [WARN]

Public Forecast: AS; Aviation: Canepa; Marine: DRP 

PUBLIC FORECAST: AS
AVIATION: CANEPA
MARINE: DRP [CRED]
VISIT US AT WWW.WEATHER.GOV/SANFRANCISCO [LINK]

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WWW.YOUTUBE.COM/NWSBAYAREA [DISC]

Point Forecast

Montara CA

21 Aug 7:55pm PDT

Tonight Patchy fog after 11pm. Otherwise, mostly cloudy, with a low around 56°. South wind around 9 mph.
Wednesday Patchy fog before 11am. Otherwise, cloudy, then gradually becoming mostly sunny, with a high near 61°. SSW wind 8 to 11 mph.
Wednesday Night Patchy fog after 11pm. Otherwise, increasing clouds, with a low around 56°. South wind 7 to 9 mph.
Thursday Patchy fog before 11am. Otherwise, mostly cloudy, with a high near 61°. South wind around 9 mph.
Thursday Night Patchy fog after 11pm. Otherwise, mostly cloudy, with a low around 55°. South wind around 9 mph.
Friday Patchy fog before 11am. Otherwise, mostly cloudy, with a high near 60°.
Friday Night Patchy fog after 11pm. Otherwise, mostly cloudy, with a low around 54°.
Saturday Patchy fog before 11am. Otherwise, mostly cloudy, with a high near 60°.
Saturday Night Patchy fog after 11pm. Otherwise, mostly cloudy, with a low around 54°.
Sunday Patchy fog before 11am. Otherwise, partly sunny, with a high near 60°.
Sunday Night Mostly cloudy, with a low around 54°.
Monday Partly sunny, with a high near 60°.
Monday Night Mostly cloudy, with a low around 54°.
Tuesday Partly sunny, with a high near 60°.
Tonight
Patchy fog after 11pm. Otherwise, mostly cloudy, with a low around 56. South wind around 9 mph.
Wednesday
Patchy fog before 11am. Otherwise, cloudy, then gradually becoming mostly sunny, with a high near 61. South southwest wind 8 to 11 mph.
Wednesday Night
Patchy fog after 11pm. Otherwise, increasing clouds, with a low around 56. South wind 7 to 9 mph.
Thursday
Patchy fog before 11am. Otherwise, mostly cloudy, with a high near 61. South wind around 9 mph.
Thursday Night
Patchy fog after 11pm. Otherwise, mostly cloudy, with a low around 55. South wind around 9 mph.
Friday
Patchy fog before 11am. Otherwise, mostly cloudy, with a high near 60.
Friday Night
Patchy fog after 11pm. Otherwise, mostly cloudy, with a low around 54.
Saturday
Patchy fog before 11am. Otherwise, mostly cloudy, with a high near 60.
Saturday Night
Patchy fog after 11pm. Otherwise, mostly cloudy, with a low around 54.
Sunday
Patchy fog before 11am. Otherwise, partly sunny, with a high near 60.
Sunday Night
Mostly cloudy, with a low around 54.
Monday
Partly sunny, with a high near 60.
Monday Night
Mostly cloudy, with a low around 54.
Tuesday
Partly sunny, with a high near 60.

This page is generated dynamically from the National Weather Service's NWS point forecast and Area Forecast Discussion, reformatted for readability. NWS glossary; about point forecasts. For more information, visit the Lobitos Weather Project home page. Comments and corrections are welcome: