Discussion
Our system grabs the NWS technical discussion each hour. This page is definitely for people with serious forecast needs, as the report is extremely technical. What it does do that other forecast products do not, however, is give you a sense of what the forecasters are thinking about and what larger weather patterns might be forming. If you’re a weather geek, you’ll find this interesting – else – “move along, nothing to see here” 
The NWS has a glossary of many of the terms and abbreviations used in the discussion forecast on this page.
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FXUS66 KMTR 181120
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
420 AM PDT FRI MAY 18 2012
.DISCUSSION...AS OF 3:15 AM PDT FRIDAY...AN UPPER LEVEL TROUGH
CONTINUES TO MOVE AWAY FROM THE DISTRICT. IN ITS WAKE THE AIRMASS
IS DRIER...PER THE LATEST OBS. EVEN THOUGH THERE IS NO MARINE
INVERSION TO SPEAK OF PER THE FT ORD PROFILER THERE ARE A FEW
PATCHES OF LOW CLOUDS...MAINLY SOUTH OF THE GOLDEN GATE AND INTO
THE SALINAS VALLEY.
THE GRADIENT PICTURE IS INDC A NORTHERLY GRADIENT OF 5.4 MB
BETWEEN ARCATA-SFO...A MODERATE ONSHORE GRADIENT OF 2.6 MB BETWEEN
SFO-SAC...AND A STRONG 16.7 MB GRADIENT BETWEEN SFO-LAS VEGAS. AS
A RESULT...WINDS ARE BRISK ALONG THE COAST AND IN THE PASSES.
PACHECO PASS IS GUSTING TO 29 MPH AS OF 3 AM AND THE ALTAMONT PASS
WAS GUSTING TO 44 MPH EARLIER LAST NIGHT.
MODELS ARE IN AGREEMENT IN BUILDING WEAK HIGH PRESSURE INTO THE
DISTRICT TODAY THROUGH THE WEEKEND. THIS WILL RESULT IN A GRADUAL
WARMING TREND STARTING TODAY AND LASTING THROUGH THE WEEKEND...
WITH NEAR NORMAL TEMPS EXPECTED THIS WEEKEND. AS WAS MENTIONED IN
THE EVENING DISCUSSION THERE WILL BE MINIMAL INLAND INTRUSION OF
LOW CLOUDS AS THE ONSHORE FLOW WILL BE WEAK AND THE MARINE
INVERSION...WHEN IT DEVELOPS...WILL BE SHALLOW.
AN UPPER TROUGH WILL MOVE TO THE COAST SUNDAY NIGHT INTO MONDAY.
THE DEEP MOISTURE AND DYNAMICS WILL STAY WELL TO THE NORTH OF THE
DISTRICT SO NO RAIN IS EXPECTED. THE MAIN EFFECT FROM THIS SYSTEM
WILL BE THE STRONG MARINE PUSH SUNDAY NIGHT AND MONDAY MORNING
RESULTING IN EXTENSIVE LOW CLOUDS AND COOLER TEMPS MONDAY AFTN.
NORTHWEST FLOW ALOFT WILL KEEP TEMPS COOL ON TUESDAY BEFORE WEAK
RIDGING BUILDS INTO THE DISTRICT FOR A LITTLE WARMING ON WEDNESDAY.
THE MEDIUM RANGE MODELS THEN DIVERGE THE END OF NEXT WEEK AND INTO
THE MEMORIAL DAY WEEKEND. THE ECMWF DROPS A STRONG UPPER LOW INTO
NORTHERN CA THURSDAY NIGHT AND FRIDAY WITH ANOTHER STRONG UPPER
LOW DROPPING TO OFF THE NORTHERN CA COAST ON SUNDAY. THE GFS ON
THE OTHER HAND ONLY HAS ONE UPPER LOW AND IS SLOWER MOVING IT
SOUTH INTO NORTHERN CA. THE ECMWF SOLUTION WOULD BE SIGNIFICANTLY
COOLER THURSDAY AND FRIDAY OF NEXT WEEK. AS OF NOW HAVE NOT
MENTIONED ANY SHOWER CHANCES BUT THIS WILL NEED TO BE WATCHED.
&&
.AVIATION...AS OF 4:15 AM PDT FRIDAY...VFR CONDITIONS WILL
PREVAIL...EXCEPT THROUGH THE MONTEREY BAY. SURFACE HIGH PRESSURE
WILL CONTINUE TO BUILD OVER THE TERMINALS...KEEPING THE REGION
MAINLY CLEAR. HOWEVER...MODERATE WEST WINDS WILL BE PRESENT THIS
AFTERNOON INTO THE EARLY EVENING HOURS AS A RESULT OF THIS HIGH
PRESSURE.
VICINITY OF KSFO...VFR CONDITIONS WILL PREVAIL. MODERATE WEST
WINDS EARLY THIS AFTERNOON THROUGH THE EVENING HOURS...WITH GUSTS
NEAR 30 KT. OTHERWISE...LITTLE CONFIDENCE WITH THE STRATUS
FORECAST FOR SATURDAY MORNING. A FEW OF THE SHORT TERM MODELS
INDICATE CIGS LATE SATURDAY MORNING...HOWEVER THEY WERE LEFT OUT
FOR THE MOMENT AND WILL BE RE-EVALUATED LATER IN THE DAY.
KSFO BRIDGE APPROACH...SIMILAR TO KSFO.
MONTEREY BAY AREA TERMINALS...MVFR AND OCCASIONAL IFR CIGS WILL BE
PRESENT THROUGH THE LATE MORNING/EARLY AFTERNOON HOURS. MODERATE WEST
WINDS THIS AFTERNOON AND AN EARLY RETURN TO CIGS THIS EVENING.
&&
.MARINE...AS OF 3:00 AM FRIDAY...SURFACE HIGH PRESSURE OVER THE
EASTERN PACIFIC RESULTED IN STRONG NORTHERLY WINDS THROUGH THE
WATERS. THESE STRONG WINDS GENERATED A STEEP FRESH SWELL OVER THE
REGION...WHICH WILL CONTINUE THROUGH AT LEAST THE BEGINNING OF THE
WEEKEND. A ROUGH BAR WAS ISSUED AFTER COORDINATION OVERNIGHT WITH
THE BAR PILOT...WHO REPORTED BREAKERS TO 12 FEET. THESE CONDITIONS
WILL SLOWLY IMPROVE LATE THIS MORNING INTO THE AFTERNOON HOURS.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.TDAY...SCA...MRY BAY
SCA...PIGEON PT TO PT PINOS 0-10 NM
SCA...PT ARENA TO PT REYES 0-10 NM
SCA...PT REYES TO PIGEON PT 0-10 NM
SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM
SCA...PT ARENA TO PIGEON PT 10-60 NM
SCA...PIGEON PT TO PT PIEDRAS BLANCAS 10-60 NM
SCA...ROUGH BAR ADVISORY FOR SF BAR UNTIL 3 PM
SCA...SF BAY FROM NOON
&&
PUBLIC FORECAST: STROBIN
AVIATION/MARINE: RILEY
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