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.
FXUS66 KMTR 121214
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA CA
414 AM PST FRI MAR 12 2010
.DISCUSSION…AS OF 4:00 AM PST FRIDAY…THE NEXT…AND APPARENTLY
LAST IN THE PRESENT SERIES OF PACIFIC WEATHER SYSTEMS TO AFFECT OUR
DISTRICT…IS NOW APPROACHING THE NORTHERN CALIFORNIA COAST.
CLOUDINESS OUT AHEAD OF IT IS SPREADING INTO THE SAN FRANCISCO BAY
REGION…AND SANTA ROSA HAS ALREADY REPORTED A TRACE OF RAIN. THIS
LEADING BIT OF PRECIPITATION IS ASSOCIATED WITH SOME MODEST WARM
ADVECTION AHEAD OF THE PRIMARY FRONTAL BAND. IN FACT…SOME
WIDELY SCATTERED SHOWERS ARE NOW EVIDENT ON KMUX RADAR FORMING OVER
OUR CENTRAL COASTAL WATERS AND MOVING NORTHEASTWARD AND INLAND. THE
FRONT ITSELF THOUGH…AND ASSOCIATED PRIMARY BAND OF RAIN…WILL MOVE
IN RAPIDLY FROM THE NORTHWEST DURING THE MORNING…AND SWEEP ENTIRELY
THROUGH THE DISTRICT BY LATE THIS EVENING. SHORT RANGE MODEL
PROJECTIONS ARE IN GOOD AGREEMENT IN INDICATING THE MAIN PERIOD OF
RAIN BEGINNING IN SAN FRANCISCO BY LATE MORNING…AND REACHING
MONTEREY BY AROUND 2 PM THIS AFTERNOON.
THIS FRONTAL SYSTEM APPEARS TO BE OF MODERATE INTENSITY IN ALL
RESPECTS. BREEZY CONDITIONS CAN BE EXPECTED AS THE FRONT MOVES
THROUGH…WITH STRONGEST GUSTS IN THE HILLS OF THE NORTHERN PART OF
THE DISTRICT…BUT EVEN THESE ARE EXPECTED TO REMAIN BELOW WIND
ADVISORY LEVELS. A FEW HOURS OF MODERATE TO LOCALLY EVEN HEAVY
RAIN WILL LIKELY ACCOMPANY THE FRONT…BUT AMOUNTS LOOK TO BE
INSUFFICIENT TO RAISE ANY CONCERNS OVER FLOODING. (OF COURSE BRIEF
PONDING IN ROADWAYS COULD LOCALLY OCCUR AND DRIVERS SHOULD EXERCISE
CAUTION.) MODEL OUTPUT SOUNDINGS SHOW ONLY MARGINALLY STABLE
CONDITIONS ON THE WARM AIR SIDE OF THE FRONT…CONSISTENT WITH THE
SHOWERS NOW DEVELOPING…BUT NO INDICATIONS OF SUFFICIENT
INSTABILITY TO RESULT IN ANY THUNDERSTORM ACTIVITY. AND THEN WITH AND
FOLLOWING THE FRONTAL PASSAGE…MID TROPOSPHERIC COLD AIR WILL
REMAIN TOO FAR TO THE NORTH FOR ANY CONVECTION TO OCCUR. CURRENTLY
EXPECT THE SYSTEM TOTAL RAINFALL…TODAY AND TONIGHT…TO RANGE
FROM AROUND 1.5 TO 2 INCHES IN THE WETTEST LOCATIONS IN THE NORTH
BAY COASTAL HILLS…TO ABOUT 0.75 INCHES ACROSS THE HEART OF THE SF
BAY AREA…AND IN THE NEIGHBORHOOD OF 0.5 INCHES IN THE LOWER
ELEVATIONS OF THE MONTEREY BAY REGION. EXPECT THE RAIN TO END PRETTY
QUICKLY FROM THE NORTH THIS EVENING…WITH VERY LIMITED IF ANY POST
FRONTAL BAND SHOWER ACTIVITY. IN FACT…WOULDN`T BE SURPRISED IF THE
RAIN HAD ENTIRELY ENDED IN SANTA ROSA BY LATE AFTERNOON AND SAN
FRANCISCO BY EARLY EVENING.
AND THEREAFTER IT APPEARS WE`LL GO DRY FOR A SIGNIFICANT PERIOD OF
TIME…AT LEAST FOR THE NEXT WEEK OR SO. ONE MINOR EXCEPTION IS THE
WEAK TAIL END OF A SYSTEM THE ECMWF AND GFS BRING INTO THE PACIFIC
NORTHWEST ON TUESDAY…BUT ALL CURRENT MODEL OUTPUT INDICATES NO MORE
THAN A SLIGHT CHANCE OF A LITTLE LIGHT RAIN FOR OUR NORTHERNMOST
ZONES TUES AND TUES NIGHT.
IT ALSO APPEARS WE`RE IN STORE FOR OUR FIRST APPRECIABLE WARMING
TREND OF THE YEAR. ALTHOUGH THE LOW LEVEL AIR MASS RIGHT BEHIND
THIS FRONT IS QUITE CHILLY…WITH 850 MB TEMPS AROUND -3 DEG C
SPREADING OVER US FRIDAY NIGHT AND SATURDAY MORNING…MODELS ARE IN
GOOD AGREEMENT IN WARMING THE AIR MASS SIGNIFICANTLY BEGINNING ON
SUNDAY. SO SATURDAY…ALTHOUGH DRY AND WITH PLENTIFUL SUNSHINE…
WILL BE ON THE CHILLY SIDE…BUT BY MONDAY AFTERNOON EXPECT WE`LL BE
SEEING WIDESPREAD LOWER 70S ACROSS OUR LOWER-ELEVATION INLAND AREAS.
&&
.AVIATION…AS OF 4:10 AM PST FRIDAY…MAIN WEATHER MAKER FOR TODAY
WILL BE A PASSING COLD FRONT. THE COLD FRONT WILL BRINGING MVFR
CONDITIONS WITH GUSTY S TO SE WINDS THIS AFTERNOON. EXPECT CIGS TO
LOWER AND RAIN TO DEVELOP N BAY EARLY MORNING…SF BAY LATE
MORNING/EARLY AFTERNOON…AND SJC AND MRY DURING THE AFTERNOON.
HOWEVER…RECENT KMUX IMAGERY DOES SHOW A FEW ROGUE SHOWERS MAY BE
POSSIBLE BEFORE THE MAIN RAIN BAND. AS WITH OTHER RECENT FROPAS
EXPECT SHOWERS TO END ABRUPTLY BEHIND THE FRONT WITH VFR CONDITIONS
DEVELOPING.
VICINITY OF KSFO…CIGS WILL REMAIN LOW END VFR(OCCASIONAL MVFR)
THROUGH 17-18Z. THERE AFTER CIGS WILL BE MVFR AS RAIN DEVELOPS. IN
ADDITION…SOUTHERLY WINDS WILL INCREASE WITH GUSTS IN THE 20-30KT
RANGE. CIGS WILL LIFT AND PRECIP WILL END AFTER 00-
02Z.
KSFO BRIDGE APPROACH…SAME AS KSFO.
MRY BAY AREA TERMINALS…VFR THIS MORNING. CONDITIONS
BECOMING MVFR IN THE AFTERNOON WITH WET RUNWAYS BY 21Z. RAIN
CHANGING TO SHOWERS IN THE EVENING WITH VFR CONDITIONS OVERNIGHT.
SOUTHERLY WINDS WILL ALSO INCREASE THIS AFTERNOON WITH GUSTS OVER 20
KT.
PROPOSED POLICY CHANGE…EFFECTIVE 15Z TUESDAY APRIL 6TH 2010 THE SAN
FRANCISCO BAY AREA OFFICE AT MONTEREY WILL BEGIN 3-HOURLY TAF
ISSUANCES FOR KSFO. THESE INTERMEDIATE TAFS AT 03Z…09Z…15Z…AND
21Z WILL BE ISSUED AS AMENDMENTS TO THE TAFS ISSUED AT 00Z…06Z…
12Z…AND 18Z. THE INTERMEDIATE TAFS WILL BE ISSUED DURING A 20-
MINUTE WINDOW BETWEEN 10 MINUTES BEFORE THE DESIGNATED ISSUANCE HOUR
AND 10 MINUTES AFTER THE HOUR. COMMENTS ON THIS PROPOSED RULE-MAKING
WILL BE ACCEPTED TO MARCH 19TH. COMMENTS CAN BE ADDRESSED TO THE
WEBMASTER AT THE NWS AT MONTEREY AT WWW.WEATHER.GOV/SANFRANCISCO.
&&
.MTR WATCHES/WARNINGS/ADVISORIES…
.TDA…SCA…PT ARENA TO PT PIEDRAS BLANCAS 10 TO 60 NM.
…SCA…PT ARENA TO PIGEON PT TO 10 NM.
…SCA…SF BAY BEGINNING AT NOON.
…SCA…SF BAR FOR ROUGH BAR.
&&
PUBLIC FORECAST: BLIER
AVIATION/MARINE: MEHLE
NWS ON THE WEB AT WEATHER.GOV/SANFRANCISCO
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