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Area Forecast Discussion

FXUS66 KMTR [Monterey CA] 230528 AFDMTR 

FXUS66 KMTR 230528
AFDMTR [HEAD]

National Weather Service San Francisco Bay Area 10:28pm PDT Mon May 22 2017 

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
1028 PM PDT MON MAY 22 2017 [HEAD]

Synopsis. Look for cooler conditions through most of the week as a onshore flow combines with the marine layer. Minor warming is then expected during the upcoming weekend especially for inland locations. 

.SYNOPSIS...LOOK FOR COOLER CONDITIONS THROUGH MOST OF THE WEEK AS
A ONSHORE FLOW COMBINES WITH THE MARINE LAYER. MINOR WARMING IS
THEN EXPECTED DURING THE UPCOMING WEEKEND ESPECIALLY FOR INLAND
LOCATIONS. [DISC]

Discussion. As of 9:00pm PDT Monday… no forecast updates planned for this evening with about a 1500 foot marine layer in place along the immediate coast. Low clouds making their way through the Golden Gate and into the Berkeley hill as well as spreading inland around the Monterey Bay region. Inland areas that reached the 90s today will see more significant cooling for Tuesday as onshore flow continues to increase with a deepening marine layer in response to upper troughing aloft. 

.DISCUSSION...AS OF 9:00 PM PDT MONDAY...NO FORECAST UPDATES
PLANNED FOR THIS EVENING WITH ABOUT A 1500 FOOT MARINE LAYER IN
PLACE ALONG THE IMMEDIATE COAST. LOW CLOUDS MAKING THEIR WAY
THROUGH THE GOLDEN GATE AND INTO THE BERKELEY HILL AS WELL AS
SPREADING INLAND AROUND THE MONTEREY BAY REGION. INLAND AREAS THAT
REACHED THE 90S TODAY WILL SEE MORE SIGNIFICANT COOLING FOR
TUESDAY AS ONSHORE FLOW CONTINUES TO INCREASE WITH A DEEPENING
MARINE LAYER IN RESPONSE TO UPPER TROUGHING ALOFT. [DISC]

All available MOS [Model Output Statistics] data suggests continued cooling trend through midweek for inland areas with robust onshore winds in place and likely persistent stratus around the coast and bays. The trend will be for near or below normal temperatures for much of the rest of the work week. 

ALL AVAILABLE MOS DATA SUGGESTS CONTINUED COOLING TREND THROUGH
MIDWEEK FOR INLAND AREAS WITH ROBUST ONSHORE WINDS IN PLACE AND
LIKELY PERSISTENT STRATUS AROUND THE COAST AND BAYS. THE TREND
WILL BE FOR NEAR OR BELOW NORMAL TEMPERATURES FOR MUCH OF THE REST
OF THE WORK WEEK. [DISC]

Looking ahead to the long holiday weekend, long range models suggest a seasonable weather pattern with dry and near normal temps. 

LOOKING AHEAD TO THE LONG HOLIDAY WEEKEND, LONG RANGE MODELS
SUGGEST A SEASONABLE WEATHER PATTERN WITH DRY AND NEAR NORMAL
TEMPS. [DISC]

Previous discussion… as of 1:15pm PDT Monday. As expected temperatures are running cooler for all locations away from the coast today with many spots 5–12° less than values from Sunday. Current readings show a wide range from 50s and 60s to parts of the coast with 70s and 80s inland. Still a few hours of heating, so would expect the warmest inland spots to again get into the 90s, however the number of locations should be less than yesterday. Satellite shows widespread clouds along the water and with the minor onshore flow expected to continue, likely that many of the local beaches will see little to no sunshine today. Tonight will be a near repeat of last night with patchy fog along the coast and to some inland spots. Lows will mostly be in the 50s with 60s above 1500 feet. 

.PREV DISCUSSION...AS OF 1:15 PM PDT MONDAY...AS EXPECTED TEMPERATURES
ARE RUNNING COOLER FOR ALL LOCATIONS AWAY FROM THE COAST TODAY
WITH MANY SPOTS 5 TO 12 DEGREES LESS THAN VALUES FROM SUNDAY.
CURRENT READINGS SHOW A WIDE RANGE FROM 50S AND 60S TO PARTS OF
THE COAST WITH 70S AND 80S INLAND. STILL A FEW HOURS OF HEATING,
SO WOULD EXPECT THE WARMEST INLAND SPOTS TO AGAIN GET INTO THE
90S, HOWEVER THE NUMBER OF LOCATIONS SHOULD BE LESS THAN
YESTERDAY. SATELLITE SHOWS WIDESPREAD CLOUDS ALONG THE WATER AND
WITH THE MINOR ONSHORE FLOW EXPECTED TO CONTINUE, LIKELY THAT MANY
OF THE LOCAL BEACHES WILL SEE LITTLE TO NO SUNSHINE TODAY.
TONIGHT WILL BE A NEAR REPEAT OF LAST NIGHT WITH PATCHY FOG ALONG
THE COAST AND TO SOME INLAND SPOTS. LOWS WILL MOSTLY BE IN THE 50S
WITH 60S ABOVE 1500 FEET. [DISC]

Synoptically the ridge of high pressure in charge will begin to flatten out through the week as a system dives down from Canada and works into the northern Rockies. 500 mb heights will drop from 587 dm [decameters] today to 573 dm [decameters] by Thursday. Inland locations that have been in the 90s the past few days will drop back into the upper 60s to the lower 70s. Closer to the coast widespread mid 50s to mid 60s can be expected. With the onshore flow in place, much of the week could by quite grey at the coast. 

SYNOPTICALLY THE RIDGE OF HIGH PRESSURE IN CHARGE WILL BEGIN TO
FLATTEN OUT THROUGH THE WEEK AS A SYSTEM DIVES DOWN FROM CANADA
AND WORKS INTO THE NORTHERN ROCKIES. 500 MB HEIGHTS WILL DROP FROM
587 DM TODAY TO 573 DM BY THURSDAY. INLAND LOCATIONS THAT HAVE
BEEN IN THE 90S THE PAST FEW DAYS WILL DROP BACK INTO THE UPPER
60S TO THE LOWER 70S. CLOSER TO THE COAST WIDESPREAD MID 50S TO
MID 60S CAN BE EXPECTED. WITH THE ONSHORE FLOW IN PLACE, MUCH OF
THE WEEK COULD BY QUITE GREY AT THE COAST. [DISC]

Longer range guidance shows the ridge trying to rebuild by the weekend although heights will be less than the past few days. By Sunday inland spots will be back in the mid 70s to mid 80s away from the coast with 60s to mid 70s near the water. 

LONGER RANGE GUIDANCE SHOWS THE RIDGE TRYING TO REBUILD BY THE
WEEKEND ALTHOUGH HEIGHTS WILL BE LESS THAN THE PAST FEW DAYS. BY
SUNDAY INLAND SPOTS WILL BE BACK IN THE MID 70S TO MID 80S AWAY
FROM THE COAST WITH 60S TO MID 70S NEAR THE WATER. [DISC]

Aviation. As of 10:27pm PDT Monday… stratus and fog are heavily blanketing the immediate coast with some stratus and fog reaching through the Golden Gate this evening; IFR [Instrument Flight Rules] ceilings and visibilities are forecast to continue in these areas tonight and Tuesday morning. 

.AVIATION...AS OF 10:27 PM PDT MONDAY...STRATUS AND FOG ARE
HEAVILY BLANKETING THE IMMEDIATE COAST WITH SOME STRATUS AND FOG
REACHING THROUGH THE GOLDEN GATE THIS EVENING; IFR CIGS AND VSBYS
ARE FORECAST TO CONTINUE IN THESE AREAS TONIGHT AND TUESDAY MORNING. [AVIA]

The marine layer depth ranges from approx 1,000 feet Bay Area to 1,500 North Central Coast. 925 mb temperatures remain nearly unchanged over the Bay Area and cool less than 1°C over the Central Coast tonight thus the marine layer depth should remain nearly unchanged overnight, possibly including Tuesday as well. 

THE MARINE LAYER DEPTH RANGES FROM APPROX 1,000 FEET BAY AREA TO
1,500 NORTH CENTRAL COAST. 925 MB TEMPERATURES REMAIN NEARLY
UNCHANGED OVER THE BAY AREA AND COOL LESS THAN 1C OVER THE CENTRAL
COAST TONIGHT THUS THE MARINE LAYER DEPTH SHOULD REMAIN NEARLY
UNCHANGED OVERNIGHT, POSSIBLY INCLUDING TUESDAY AS WELL. [AVI2]

Gusty onshore winds are likely over the San Francisco Bays Tuesday afternoon and evening, similarly gusty winds are expected again Wednesday. Lower level cooling will become more robust by this time Tuesday evening through Wednesday thus the marine layer depth should increase and stratus and fog intrusion should then really get underway. 

GUSTY ONSHORE WINDS ARE LIKELY OVER THE SAN FRANCISCO BAYS TUESDAY
AFTERNOON AND EVENING, SIMILARLY GUSTY WINDS ARE EXPECTED AGAIN
WEDNESDAY. LOWER LEVEL COOLING WILL BECOME MORE ROBUST BY THIS
TIME TUESDAY EVENING THROUGH WEDNESDAY THUS THE MARINE LAYER DEPTH
SHOULD INCREASE AND STRATUS AND FOG INTRUSION SHOULD THEN REALLY
GET UNDERWAY. [AVI2]

A little more than moderate confidence VFR [Visual Flight Rules] persists for most of the Bay Area terminals tonight with exception of southerly flow bringing LIFR [Low Instrument Flight Rules]/VLIFR [Very Low Instrument Flight Rules] ceilings and visibilities to KSTS [Santa Rosa CA] late tonight and Tuesday morning. For Monterey Bay Area IFR [Instrument Flight Rules]/LIFR [Low Instrument Flight Rules] will continue into Tuesday morning. 

A LITTLE MORE THAN MODERATE CONFIDENCE VFR PERSISTS FOR MOST OF THE
BAY AREA TERMINALS TONIGHT WITH EXCEPTION OF SOUTHERLY FLOW BRINGING
LIFR/VLIFR CIGS AND VSBYS TO KSTS LATE TONIGHT AND TUESDAY MORNING.
FOR MONTEREY BAY AREA IFR/LIFR WILL CONTINUE INTO TUESDAY MORNING. [AVI2]

Vicinity of KSFO [San Francisco CA]VFR [Visual Flight Rules]. W-NW winds 5–10 knots [6–12 mph] tonight, becoming gusty from the W-NW Tuesday afternoon and evening. 

VICINITY OF KSFO...VFR. W-NW WINDS 5-10 KNOTS TONIGHT, BECOMING GUSTY
FROM THE W-NW TUESDAY AFTERNOON AND EVENING. [AVI2]

SFO [San Francisco CA] bridge approach… similar to KSFO [San Francisco CA]

SFO BRIDGE APPROACH...SIMILAR TO KSFO. [AVI2]

Monterey Bay terminals… IFR [Instrument Flight Rules]/LIFR [Low Instrument Flight Rules] prevails tonight into late Tuesday morning. VFR [Visual Flight Rules] returns late Tuesday morning and afternoon, onshore winds will likely bring stratus and fog back in Tuesday evening. 

MONTEREY BAY TERMINALS...IFR/LIFR PREVAILS TONIGHT INTO LATE TUESDAY
MORNING. VFR RETURNS LATE TUESDAY MORNING AND AFTERNOON, ONSHORE WINDS
WILL LIKELY BRING STRATUS AND FOG BACK IN TUESDAY EVENING. [AVI2]

Marine. As of 9:45pm PDT Monday… surface high pressure over the eastern Pacific will strengthen from tonight into Wednesday morning keeping northwesterly winds going over the outer waters. A surface ridge of high pressure over the Central Coast will cause winds over the inner coastal waters to be primarily light southwesterly through Tuesday. Except for the Monterey Bay onshore winds will be gusty over the bays each afternoon and evening at least through mid-week. 

.MARINE...AS OF 9:45 PM PDT MONDAY...SURFACE HIGH PRESSURE OVER
THE EASTERN PACIFIC WILL STRENGTHEN FROM TONIGHT INTO WEDNESDAY
MORNING KEEPING NORTHWESTERLY WINDS GOING OVER THE OUTER WATERS. A
SURFACE RIDGE OF HIGH PRESSURE OVER THE CENTRAL COAST WILL CAUSE
WINDS OVER THE INNER COASTAL WATERS TO BE PRIMARILY LIGHT
SOUTHWESTERLY THROUGH TUESDAY. EXCEPT FOR THE MONTEREY BAY ONSHORE
WINDS WILL BE GUSTY OVER THE BAYS EACH AFTERNOON AND EVENING AT
LEAST THROUGH MID-WEEK. [AVIA]

MTR Watches/Warnings/Advisories

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

Public Forecast: RWW; Aviation/Marine: Canepa 

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

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WWW.YOUTUBE.COM/NWSBAYAREA [DISC]

Point Forecast

Half Moon Bay Airport

22 May 11:35pm PDT

Overnight Patchy fog. Otherwise, mostly cloudy, with a low around 50°. South wind 3 to 5 mph.
Tuesday Patchy fog before 11am. Otherwise, partly sunny, with a high near 57°. South wind 5 to 7 mph.
Tuesday Night Patchy fog after 11pm. Otherwise, mostly cloudy, with a low around 50°. Calm wind becoming SSE around 6 mph after midnight.
Wednesday Patchy fog before 11am. Otherwise, cloudy, then gradually becoming mostly sunny, with a high near 59°. South wind 9 to 11 mph.
Wednesday Night Patchy fog after 11pm. Otherwise, mostly cloudy, with a low around 50°. South wind 14 to 17 mph, with gusts as high as 22 mph.
Thursday Patchy fog before 11am. Otherwise, partly sunny, with a high near 60°.
Thursday Night Patchy fog after 11pm. Otherwise, mostly cloudy, with a low around 50°.
Friday Patchy fog before 11am. Otherwise, partly sunny, with a high near 60°.
Friday Night Patchy fog after 11pm. Otherwise, mostly cloudy, with a low around 50°.
Saturday Patchy fog before 11am. Otherwise, partly sunny, with a high near 60°.
Saturday Night Patchy fog. Otherwise, mostly cloudy, with a low around 50°.
Sunday Patchy fog. Otherwise, partly sunny, with a high near 60°.
Sunday Night Patchy fog. Otherwise, mostly cloudy, with a low around 49°.
Memorial Day Patchy fog. Otherwise, partly sunny, with a high near 60°.
Overnight
Patchy fog. Otherwise, mostly cloudy, with a low around 50. South wind 3 to 5 mph.
Tuesday
Patchy fog before 11am. Otherwise, partly sunny, with a high near 57. South wind 5 to 7 mph.
Tuesday Night
Patchy fog after 11pm. Otherwise, mostly cloudy, with a low around 50. Calm wind becoming south southeast around 6 mph after midnight.
Wednesday
Patchy fog before 11am. Otherwise, cloudy, then gradually becoming mostly sunny, with a high near 59. South wind 9 to 11 mph.
Wednesday Night
Patchy fog after 11pm. Otherwise, mostly cloudy, with a low around 50. South wind 14 to 17 mph, with gusts as high as 22 mph.
Thursday
Patchy fog before 11am. Otherwise, partly sunny, with a high near 60.
Thursday Night
Patchy fog after 11pm. Otherwise, mostly cloudy, with a low around 50.
Friday
Patchy fog before 11am. Otherwise, partly sunny, with a high near 60.
Friday Night
Patchy fog after 11pm. Otherwise, mostly cloudy, with a low around 50.
Saturday
Patchy fog before 11am. Otherwise, partly sunny, with a high near 60.
Saturday Night
Patchy fog. Otherwise, mostly cloudy, with a low around 50.
Sunday
Patchy fog. Otherwise, partly sunny, with a high near 60.
Sunday Night
Patchy fog. Otherwise, mostly cloudy, with a low around 49.
Memorial Day
Patchy fog. Otherwise, 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: