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 040555
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
1055 PM PDT TUE MAY 3 2016

.SYNOPSIS....HIGH CLOUDS WILL PUSH INTO THE AREA TODAY AS A SYSTEM
APPROACHES FROM THE PACIFIC. THIS WILL BRING COOLER TEMPERATURES
TO THE AREA BEGINNING WEDNESDAY ALONG WITH A POSSIBILITY OF
SHOWERS AND A RISK OF AFTERNOON THUNDERSTORMS...THESE CONDITIONS
ARE EXPECTED TO PERSIST INTO THE WEEKEND.

&&

.DISCUSSION...AS OF 9:00 PM PDT TUESDAY...MID AND UPPER LEVEL
CLOUDS MOVING IN AHEAD OF AN APPROACHING UPPER LEVEL TROUGH HAVE
BLANKETED THE REGION THIS EVENING. TEMPERATURES ARE RUNNING
ABOUT THE SAME AS YESTERDAY IF NOT A FEW DEGREES WARMER WHICH IS
LIKELY DUE TO THE INCREASED CLOUD COVER OVER THE DISTRICT. WINDS
REMAIN LIGHT WITH GRADIENTS AND MARINE LEVEL DEPTH OF 2000 FEET
ALMOST IDENTICAL TO YESTERDAY AT THIS TIME.

MODELS REMAIN IN FAIRLY GOOD AGREEMENT WITH RESPECT TO THE
APPROACHING SYSTEM WITH ALL INDICATIONS OF THE TROUGH FORMING A
CLOSED LOW BY WEDNESDAY EVENING. THE FORECAST REMAINS ON TRACK
WITH SHOWERS ANTICIPATED TO BEGIN WEDNESDAY WITH GREATEST CHANCES
ACROSS THE NORTHERN HALF OF THE CWA. AS THE SYSTEM NEARS AND THE
COOL UNSTABLE AIRMASS MOVES INTO OUR AREA THE CHANCE OF ISOLATED
AFTERNOON THUNDERSTORMS WILL INCREASE. CURRENT THINKING IS THAT
THE SHOWERS WILL MOVE IN ACROSS THE NORTH BAY WEDNESDAY MORNING
WITH INCREASING INSTABILITY AND DAYTIME HEATING LEADING TO A
CHANCE OF ISOLATED THUNDERSTORM ACROSS THE NORTHERN HALF OF THE
WARNING AREA IN THE AFTERNOON. AS THE LOW MOVES OVER THE NORTHERN
AND CENTRAL CALIFORNIA COAST ON THURSDAY SHOWERS WILL SPREAD
ACROSS THE ENTIRE DISTRICT. THE POTENTIAL FOR CONVECTION INCREASE
THURSDAY AFTERNOON INTO FRIDAY AS THE CENTER OF THE LOW MOVES
SOUTHEAST INTO SOUTHERN CALIFORNIA. UPPER LEVEL LOWS ARE DIFFICULT
TO PREDICT AS THEIR MOVEMENT CAN BE A BIT UNPREDICTABLE THEREFORE
THE CHANCE OF SHOWERS AND THUNDERSTORMS HAS BEEN BROAD BRUSHED
ACROSS THE REGION. SHOWERS ARE ANTICIPATED TO TAPER SATURDAY
EVENING AS THE LOW MOVES INLAND TOWARD THE FOUR-CORNERS REGION.

FROM PREVIOUS DISCUSSION...ALTHOUGH THERE WILL BE A CHANCE OF
RAIN EACH DAY, AMOUNTS WILL BE VERY LIGHT. IN FACT, RAINFALL
TOTALS FROM THE CNRFC THROUGH THE WEEKEND INDICATE LESS THAN 1/4"
FOR MOST URBAN LOCATIONS. HIGHER ELEVATIONS COULD LOCALLY SEE UP
TO 1/2". ALL AREAS WILL SEE COOLER TEMPERATURES WITH HIGHS IN THE
UPPER 50S TO NEAR 70 EXPECTED TOMORROW THROUGH FRIDAY. THIS WOULD
TRANSLATE TO A DROP OF UP TO 20 DEGREES COMPARED TO THE HEAT LAST
SUNDAY.

LONGER RANGE OUTLOOK FOR NEXT WEEK FAVORS A RIDGE RETURNING WITH
WARMER THAN NORMAL TEMPERATURES AND DRIER THAN NORMAL CONDITIONS.

&&

.AVIATION...AS OF 10:54 PM PDT TUESDAY...THE SOUTHERN END OF AN
ELONGATED UPPER LEVEL TROUGH OVER THE EASTERN PACIFIC WILL
GRADUALLY MOVE EAST AND BECOME A CLOSED LOW WEDNESDAY. SATELLITE
SHOWS AREAS OF LOW CLOUDS MOSTLY OVER THE COASTAL WATERS WHILE
MID-HIGH LEVEL CLOUDS CONTINUE TO STREAM IN OFF THE EASTERN
PACIFIC. MARINE LAYER INVERSIONS ARE LIKELY TO STEADILY DEEPEN AND
WEAKEN TONIGHT AND WEDNESDAY AS DEEP LAYERED COOLING TAKES PLACE
IN THE ATMOSPHERE DUE TO THE APPROACHING EPAC TROUGH.

THE WINDS FORECAST IS LOW CONFIDENCE THIS PERIOD. CIGS FORECAST LOW
TO MODERATE CONFIDENCE TONIGHT AND WEDNESDAY.

VICINITY OF KSFO...VFR TO MVFR CIGS LATE TONIGHT AND WEDNESDAY
MORNING. VICINITY SHOWERS AFTER 17Z WEDNESDAY.

SFO BRIDGE APPROACH...SIMILAR AS KSFO.

MONTEREY BAY TERMINALS...MVFR CIGS GRADUALLY DEVELOPING THIS EVENING.
LOW CONFIDENCE IFR CIGS FORECAST TONIGHT. PARTIAL CLEARING RETURNS
BY LATE WEDNESDAY MORNING. VICINITY SHOWERS WEDNESDAY AFTERNOON.

&&

.MARINE...AS OF 8:39 PM PDT TUESDAY...A LOW PRESSURE AREA OVER THE
EASTERN PACIFIC WILL MOVE TOWARD THE BAY AREA THROUGH MID-WEEK THEN
MOVE TO SOCAL BY THIS WEEKEND. COLDER UNSTABLE AIR WITH THIS LOW
WILL LEAD TO A CHANCE OF SHOWERS AS WELL AS A SLIGHT CHANCE OF
THUNDERSTORMS THROUGH MID-LATE WEEK. WINDS AND SEAS WILL GRADUALLY
INCREASE LATE THIS WEEK.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...NONE.

$$

PUBLIC FORECAST: CW
AVIATION/MARINE: CANEPA


VISIT US AT WWW.WEATHER.GOV/SANFRANCISCO

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



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