Area Forecast Discussion
Issued by NWS San Francisco Bay Area, CA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS66 KMTR 271207
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
507 AM PDT WED MAY 27 2015

.SYNOPSIS...A MODEST WARMING TREND IS EXPECTED TO BEGIN TODAY
PERSISTING THROUGH SATURDAY...MOST APPARENT INLAND AS HIGH PRESSURE
BUILDS ALONG THE COAST. ANOTHER COOLING TREND WILL START ON SUNDAY
AND CONTINUE INTO EARLY NEXT WEEK AS A WEAK PACIFIC LOW APPROACHES
THE COAST. MOSTLY DRY CONDITIONS WILL CONTINUE INTO EARLY NEXT
WEEK.

&&

.DISCUSSION...AS OF 3:00 AM PDT WEDNESDAY...AFTER MULTIPLE DAYS OF
WIDESPREAD CLOUDS AND COOLER THAN NORMAL TEMPERATURES ACROSS THE
BOARD TODAY WILL BE THE START OF A TRANSITION TO MORE TYPICAL LATE
MAY WEATHER. CURRENT SATELLITE PRODUCT SHOWS CLOUDS ACROSS A GOOD
PORTION OF OUR AREA...HOWEVER WORTH NOTING THAT IN SOME AREAS IT
HAS NOT FILED IN AS MUCH AS PREVIOUS NIGHTS. IN ADDITION...THE
SURFACE FLOW WHICH HAS BEEN MODERATE TO ROBUST FROM THE WEST HAS
SWITCHED TO NOW BEING MORE FROM THE NORTHWEST AS THE NORTH TO
SOUTH PIECE HAS INCREASED BY MORE THAN 2.5 MB OVER THE PAST 24
HOURS. RH VALUES ARE ALMOST ALL DRIER COMPARED TO YESTERDAY AS
WELL. THEREFORE...EXPECTATIONS ARE FOR A QUICKER BURN-OFF TODAY
WITH A BETTER CHANCE FOR COASTAL SPOTS TO SEE MORE SUNSHINE. TEMPS
WILL ALSO INCREASE A MODEST AMOUNT TODAY PARTICULARLY FOR INLAND
SPOTS. HIGHS WILL RANGE FROM 60S AT THE COAST TO 70S AND LOWER 80S
INLAND.

SYNOPTICALLY A RIDGE OF HIGH PRESSURE WILL BUILD OVERHEAD WITH THE
RIDGE AXIS EXPECTED TO BE NEAR OUR AREA FRIDAY AND SATURDAY. THIS
WILL COINCIDE WITH 850 MB TEMPS HITTING THEIR WARMEST READINGS FOR
THE WEEK...19 TO 20C. INLAND TEMPS WILL RETURN BACK TO ABOVE
NORMAL LEVELS WITH EVENT A FEW LOWER 90S POSSIBLE. HIGHS WILL ONLY
SEE MINOR INCREASES AT MOST COASTAL SPOTS AS THE COOL SEA SURFACE
TEMPS COMBINE WITH AFTERNOON SEA BREEZES. OVERALL TEMPERATURE
GRADIENTS WILL BE NORMAL FOR OUR AREA GOING INTO SUMMER -- UPPER
50S AT THE COOLEST OCEAN SPOTS WITH LOWER 90S IN SOUTHERN MONTEREY
COUNTY.

TEMPERATURES WILL START TO COOL ON SUNDAY AS AN UPPER LEVEL LOW
MOVES INTO THE PACNW/NORCAL REGION. MODELS BRING THE SOUTHERN
EXTENT OF MOISTURE INTO THE NORTH BAY SO ADDED A SLIGHT CHANCE OF
RAIN FOR SUNDAY. THE LOW IS EXPECTED TO QUICKLY EJECT TO THE
NORTHEAST WITH ANOTHER RIDGE FORECAST TO BUILD IN BEHIND IT.
WARMER THAN NORMAL TEMPERATURES ARE EXPECTED FOR THE SECOND HALF
OF NEXT WEEK ALONG WITH MOSTLY DRY CONDITIONS.
&&

.AVIATION...AS OF 5:15 AM PDT WEDNESDAY... MEDIUM CONFIDENCE
FORECAST THIS MORNING. LEANING TOWARDS WRF AND RUC GUIDANCE WHICH
INDICATES FAIRLY EARLY MIX OUT THIS MORNING. 24HOUR CHANGE IS
TRENDING WARMER AND DRIER AS HIGH PRESSURE BUILDS OVER PACIFIC
COASTLINE. GOES-W SATELLITE PRODUCTS SHOW THINNING OF MARINE LAYER
OFFSHORE OF THE STATE UNDER THE RIDGE WITH DEPTHS OF 1250FT OVER
THE BAY AREA AND JUST 750FT OFFSHORE. WIDESPREAD MVFR THROUGH
15-16Z THEN MIX OUT BETWEEN 17-19Z DEPENDING ON DISTANCE FROM
COAST. DEEPER MARINE LAYER RETURNS LATER THIS EVENING. ONSHORE
FLOW THROUGH THE PERIOD.

VICINITY OF KSFO... LOWER CONFIDENCE FORECAST. A THINNING
OFFSHORE MARINE LAYER WILL STRUGGLE TO FEED MOISTURE THROUGH THE
SAN BRUNO GAP AND COULD LEAD TO CLEARING AS EARLY AS 16-17Z. THAT
SAID... STILL POSSIBLE TO SEE MVFR THROUGH 19Z-20Z IF OFFSHORE
MARINE LAYER DEEPENS. ONSHORE FLOW 10-18 KT THROUGH THE
AFTERNOON. MVFR CIGS RETURN 04-05Z THU.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO. FOG PRODUCTS SHOWING SOME
CLEARING ALREADY OCCURRING OVER SOUTH BAY/KSMB AS OF 12Z THIS
MORNING... THIS TREND MAY CONTINUE UNABATED GIVEN CURRENT SET UP.

MONTEREY BAY AREA TERMINALS...MVFR CIGS THRU 18Z. SCT/BKN POSBL
THROUGH LATE MORNING THEN VFR UNTIL 04Z THU.

&&

.MARINE...AS OF 02:28 AM PDT WEDNESDAY...HIGH PRESSURE OVER THE
EASTERN PACIFIC WILL RESULT IN CONTINUED LIGHT ONSHORE FLOW AND
GENTLE SEA CONDITIONS THROUGH TONIGHT. WINDS VEER TOWARD THE
NORTHWEST AND INCREASE SLIGHTLY ON WEDNESDAY WITH GENTLE SEA
CONDITIONS EXPECTED THROUGH THE FORECAST PERIOD.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...NONE.

$$

PUBLIC FORECAST: BELL
AVIATION/MARINE: DRP

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.