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

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000
FXUS66 KMTR 190400
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
900 PM PDT FRI APR 18 2014

.SYNOPSIS...DRY WEATHER WILL CONTINUE THROUGH THE WEEKEND.
LITTLE CHANGE IN TEMPERATURES IS FORECAST FOR SATURDAY...BUT
WARMER WEATHER IS EXPECTED ON SUNDAY AS ONSHORE FLOW DECREASES. A
WEAK WEATHER SYSTEM WILL ARRIVE ALONG THE NORTHERN CALIFORNIA
COAST BY LATE MONDAY AND BRING COOLER CONDITIONS ALONG WITH SHOWER
CHANCES MONDAY NIGHT AND TUESDAY. RAINFALL AMOUNTS WILL BE LIGHT.
DRY WEATHER WITH NEAR NORMAL TEMPERATURES WILL RETURN FOR THE
SECOND HALF OF NEXT WEEK.

&&

.DISCUSSION...AS OF 9:00 PM PDT FRIDAY...SIMILAR TO LAST
EVENING...COASTAL LOW CLOUDS LARGELY CLEARED OUT LATE IN THE DAY
AS BRISK NORTHWEST WINDS OVER THE COASTAL WATERS PRODUCED GOOD LOW
LEVEL MIXING. EXPECT STRATUS EVOLUTION TONIGHT TO BE SIMILAR TO
WHAT OCCURRED LAST NIGHT...WITH LOW CLOUDS FILLING IN ALONG MUCH
OF THE COASTLINE LATE TONIGHT AS COASTAL WINDS EASE. LOW CLOUDS
WILL ALSO DEVELOP INLAND BY SUNRISE SATURDAY. THE DIFFERENCE
THIS EVENING COMPARED TO LAST EVENING IS A WEAKER N-S SURFACE
GRADIENT WHICH SHOULD MEAN GREATER INLAND DEVELOPMENT OF LOW
CLOUDS AROUND SF BAY LATE TONIGHT COMPARED TO LAST NIGHT.

AN UPPER RIDGE OFF THE COAST OF SOUTHERN CA WILL BEGIN TO BUILD
NORTHWARD ON SATURDAY AND PREVENT THE WEATHER SYSTEM CURRENTLY
APPROACHING THE PAC NW FROM IMPACTING OUR AREA IN ANY WAY. THE
BUILDING RIDGE SHOULD COMPRESS THE MARINE LAYER A BIT TOMORROW SO
WE MAY SEE SLIGHT WARMING INLAND. BUT MODERATE ONSHORE FLOW AND
MORNING MARINE LAYER CLOUDS WILL KEEP COASTAL TEMPS NEAR
PERSISTENCE. WARMING IS FORECAST FOR ALL AREAS ON SUNDAY AS THE
UPPER RIDGE STRENGTHENS A BIT MORE AND ONSHORE FLOW WEAKENS.

THE LONGWAVE UPPER TROUGH CURRENTLY CENTERED IN THE GULF OF ALASKA
IS FORECAST TO DIG TO THE SOUTHEAST OFF THE WEST COAST ON SUNDAY
AND MONDAY AND THEN SWING INLAND ACROSS CALIFORNIA LATE MONDAY
NIGHT AND TUESDAY. ALTHOUGH THIS SYSTEM LOOKS RELATIVELY ROBUST
WITH GOOD COLD ADVECTION FORECAST FROM MONDAY EVENING INTO
TUESDAY...THE MODELS AGREE THAT IT WILL BE LACKING IN MOISTURE.
ONLY SCATTERED LIGHT QPF IS FORECAST BY THE MODELS FROM LATE
MONDAY INTO MONDAY NIGHT WITH DRY CONDITIONS DEVELOPING BY TUESDAY
ONCE THE UPPER TROUGH AXIS MOVES THROUGH. BASED ON LATEST MODEL
DATA...THE SYSTEM IS MOVING MORE QUICKLY THAN PREVIOUSLY FORECAST
SO WE MAY NEED TO CONSIDER ADDING POPS FOR LATE MONDAY. IN
ADDITION...POPS MAY NEED TO BE REDUCED FOR TUESDAY. THERE NO
LONGER APPEARS TO BE ANY THREAT OF THUNDER WITH THIS SYSTEM. RAIN
TOTALS FROM LATE MONDAY INTO EARLY TUESDAY WILL PROBABLY NOT
EXCEED A TENTH OF AN INCH. ALSO...MUCH OF OUR AREA MAY NOT PICK
UP ANY MEASURABLE PRECIP FROM THIS SYSTEM.

DRY AND MILD WEATHER IS FORECAST FOR THE SECOND HALF OF NEXT WEEK
AS A SHORTWAVE RIDGE BUILDS IN FOR A FEW DAYS.

BASED ON GOOD AGREEMENT AMONG THE MEDIUM RANGE MODELS...CONFIDENCE
IS INCREASING THAT OUR AREA WILL SEE WIDESPREAD RAINFALL FROM A
RELATIVELY STRONG AND WET LATE SEASON STORM SYSTEM BEGINNING LATE
NEXT FRIDAY AND CONTINUING INTO THE FINAL WEEKEND OF APRIL AND
BEYOND.

&&

.AVIATION...AS OF 4:50 PM PDT FRIDAY...THE CURRENT VISIBLE
SATELLITE IMAGE IS SHOWING MOSTLY CLEAR SKIES FROM ROUGHLY SANTA
CRUZ NORTH WITH OVERCAST SKIES ENGULFING SOUTHERN MONTEREY BAY AND
PUSHING INTO THE SALINAS VALLEY. THE BAY AREA SODARS REALLY ARE
NOT SHOWING A DEFINITIVE MARINE LAYER. WITH THIS IN MIND I DON`T
EXPECT AN EARLY RETURN OF STRATUS IF IT RETURNS AT ALL TO THE BAY
AREA IT WILL BE LATE. ONE THE OTHER HAND THE MARINE LAYER IS A
SOLID 2000 FEET DEEP ON THE FORT ORD PROFILER AND STRATUS IS
SHOWING NO SIGNS OF CLEARING ANYTIME SOON IN MONTEREY.

VICINITY OF KSFO...VFR IS EXPECTED TO PERSIST THROUGH THE NEXT 24
TO 36 HOURS. PATCHY STRATUS MAY DEVELOP TO THE NORTH AND EAST OF
THE TERMINAL LATE TONIGHT. WEST WINDS 20 KT GUSTING TO 27 KT WILL
SUBSIDE TO AROUND 10 KT LATER THIS EVENING.

MODERATE CONFIDENCE.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO WITH STRATUS POSSIBLE LATE
TONIGHT EAST OF THE APPROACH.

MODERATE CONFIDENCE

MONTEREY BAY AREA TERMINALS...MVFR CIGS ARE EXPECTED TO PREVAIL
THROUGH 1200Z TONIGHT AT WHICH CIGS WILL FALL TO AROUND OVC007.
CIGS WILL IMPROVE TO OVC015 BY 1700Z SATURDAY MORNING. WEST
SOUTHWEST WINDS 10 TO 12 KT WILL DIMINISH TO AROUND 5 KT THIS
EVENING.

HIGH CONFIDENCE.

&&

.MARINE...AS OF 12:45 PM PDT FRIDAY...SMALL CRAFT ADVISORIES CONTINUE
ACROSS ALL PACIFIC WATERS AND MONTEREY BAY WITH NORTHWEST WINDS OF
20-30 KTS. WINDS WILL GRADUALLY DIMINISH OVERNIGHT FROM N TO S AND
WILL CONTINUE WITH SCA IN SOUTHERN WATERS THROUGH LATE SATURDAY
MORNING DUE TO MODERATE NORTHWEST WINDS. INCREASING CONFIDENCE IN
ARRIVAL OF LARGE NW SWELL ON SUNDAY TO PRODUCE HAZARDOUS BEACH
CONDITIONS FROM ELEVATED RIP CURRENT THREAT. WILL MONITOR
CONDITIONS FOR POSSIBLE ISSUANCE OF BEACH HAZARD STATEMENT AS
EVENT APPROACHES.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 10-60 NM
             SCA...MONTEREY BAY UNTIL 11 PM
             SCA...PT REYES TO PIGEON PT 0-10 NM UNTIL 11 PM
             SCA...PIGEON PT TO PT PINOS 0-10 NM UNTIL 11 PM
             SCA...PIGEON PT TO PT PINOS 10-60 NM UNTIL 11 PM
             SCA...PT ARENA TO PT REYES 0-10 NM UNTIL 3 AM
             SCA...PT ARENA TO PT REYES 10-60 NM UNTIL 3 AM
             SCA...PT REYES TO PIGEON PT 10-60 NM UNTIL 3 AM

&&

$$

PUBLIC FORECAST: DYKEMA
AVIATION: LARRY
MARINE: JOHNSON

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