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

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000
FXUS66 KMTR 191208
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
503 AM PDT SAT APR 19 2014

.SYNOPSIS...A SLIGHT WARMING TREND WILL CONTINUE THROUGH THE
REMAINDER OF THE WEEKEND ALONG WITH DRY CONDITIONS. A WEAK STORM
SYSTEM WILL THEN IMPACT THE REGION MONDAY NIGHT THROUGH TUESDAY
AND BRING CHANCES FOR PRECIPITATION AND COOLER TEMPERATURES. QUIET
WEATHER AND NEAR NORMAL TEMPERATURES RETURN FOR THE LATTER HALF OF
NEXT WEEK.

&&

.DISCUSSION...AS OF 04:38 AM PDT SATURDAY...LOW CLOUDS HAVE
INCREASED ACROSS THE REGION THIS MORNING AS A 2000 FT MARINE LAYER
REMAINS IN PLACE. STRATUS WILL LIKELY STICK AROUND THROUGH LATE
MORNING BEFORE BURNING OFF BY EARLY AFTERNOON. THIS WILL KEEP
TEMPERATURES COOLEST ALONG THE COAST WITH A GENERALLY WEAK ONSHORE
FLOW. DAYTIME TEMPERATURES ACROSS INLAND AREAS WILL LIKELY BE
WARMER THAN PREVIOUS DAYS AS THE MID/UPPER LEVEL RIDGE BUILDS
ACROSS THE REGION. SLIGHTLY WARMER CONDITIONS CAN THEN BE EXPECTED
ON SUNDAY WITH WEAKER ONSHORE FLOW AND INCREASED 850MB
TEMPERATURES.

THE NEXT MID/UPPER LEVEL SYSTEM WILL BEGIN TO APPROACH THE PACIFIC
NORTHWEST ON MONDAY AND SWEEP ACROSS THE STATE MONDAY NIGHT
THROUGH TUESDAY. THIS FAST MOVING SYSTEM WILL HAVE LIMITED
MOISTURE TO WORK WITH AND WILL LIKELY ONLY PRODUCE LIGHT RAINFALL
AMOUNTS ACROSS PORTIONS OF THE REGION MONDAY NIGHT INTO TUESDAY
MORNING. RAIN CHANCES DIMINISH BY TUESDAY AFTERNOON/EVENING WITH
NOTICEABLY COOLER TEMPERATURES EXPECTED FOR TUESDAY AND WEDNESDAY.

DAYTIME TEMPERATURES WILL REBOUND FOR THE LATTER HALF OF THE
UPCOMING WORKWEEK AS THE MID/UPPER LEVEL RIDGE REBUILDS ALONG THE
WEST COAST. WITH THE RIDGE ALOFT...DRY WEATHER WILL ALSO CONTINUE
FOR THE SECOND HALF OF NEXT WEEK.

MEDIUM RANGE FORECAST MODELS CONTINUE TO AGREE THAT A STRONGER AND
WETTER STORM SYSTEM WILL IMPACT THE AREA LATE FRIDAY THROUGH NEXT
WEEKEND. CHANCES CONTINUE TO INCREASE FOR WIDESPREAD RAINFALL AS A
SLOW MOVING MID/UPPER LEVEL SYSTEM MOVES ACROSS THE REGION.

&&

.AVIATION...AS OF 4:50 AM PDT SATURDAY...HIGH CLOUDS ARE OBSCURING
THE STRATUS CLOUDS THIS MORNING MAKING IT DIFFICULT TO FIGURE HOW
MUCH LOW CLOUD COVERAGE THERE IS AROUND THE AREA. THE TAF SITES
REPORT CEILINGS EXCEPT FOR KSJC. MOSTLY MVFR CIGS ARE REPORTED DUE TO
A RELATIVELY DEEPER MARINE LAYER NEAR 2000 FEET. KSTS ON THE OTHER
HAND REPORTS IFR.

THE STRATUS CLOUDS FILLED IN MORE SO THAN THE MOST RECENT WRF MODEL
HAD FORECASTED. KSFO FOR INSTANCE MAY BE RIGHT ON THE EDGE OF THE
CEILINGS AS THE 1 MINUTE OBS BACKED AWAY FROM OVC NOW SHOWING A
BKN CEILING. SAN MATEO BRIDGE REPORTS A BKN CLOUD CEILING. A VERY
WEAK AND DRY SHORTWAVE TROUGH WAS MOVING THROUGH THE MID LEVEL
RIDGE THIS MORNING. ONSHORE WINDS ARE A LITTLE MORE AMBITIOUS THIS
MORNING...DRIVEN BY A SFO-SAC GRADIENT AT 3.2 MB. 3.2 MB ONSHORE IS
A FAIRLY STRONG ONSHORE GRADIENT FOR THIS TIME OF THE DAY. THE NAM
MODEL FORECASTS THIS TO REACH ABOUT 4 MB BY AFTERNOON AND EVENING.
THE WINDS APPEAR TO BE HELPING WITH SOME MIXING ALREADY SO AN EARLY
CLEARING TO VFR IS POSSIBLE FOR BAY AREA TERMINALS BUT THIS IS A
LOW-MODERATE CONFIDENCE FORECAST. THE MODELS SHOW MORE BOUNDARY
LAYER HUMIDITY VERY LATE TONIGHT AND SUNDAY MORNING.

VICINITY OF KSFO...MVFR CEILING WILL LIKELY HOLD FOR A FEW MORE
HOURS BUT POTENTIAL IS THERE FOR THE CEILING TO MIX OUT TO FEW-SCT
BY 15Z. LOW CONFIDENCE. GUSTY WEST WINDS 20-28 KNOTS ARE FORECAST
NO LATER THAN 22Z.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...MARINE LAYER IS DEEP ENOUGH FOR MVFR
CEILINGS THIS MORNING. VFR IS FORECAST TO RETURN BY 19Z-20Z.

&&

.MARINE...AS OF 4:50 AM PDT SATURDAY...GUSTY NORTHWEST WINDS IN
THE SMALL CRAFT ADVISORY CRITERIA ARE STILL EXPECTED IN THE
SOUTHERN WATERS TODAY AND TONIGHT.

A HIGH SURF ADVISORY HAS BEEN ISSUED FROM 5 AM SUNDAY TO 5 AM MONDAY
MORNING FOR THE COAST FROM SONOMA COUNTY SOUTH TO MONTEREY COUNTY.
NORTHWEST SWELL WILL BUILD TO 13 TO 15 FEET WITH SWELL PERIODS 15 TO
16 SECONDS.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 10-60 NM

&&

$$

PUBLIC FORECAST: RGASS
AVIATION/MARINE: CANEPA

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