875
FXUS66 KMTR 200532
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
1032 PM PDT WED JUN 19 2019
SYNOPSIS
SLIGHTLY COOLER TEMPERATURES ARE EXPECTED ONCE AGAIN
ON THURSDAY. WINDS SHIFT TO THE NORTH ON FRIDAY AND SATURDAY WHICH
WILL ALLOW FOR SLIGHTLY WARMER TEMPERATURES LEADING INTO THE
WEEKEND. THESE NORTHERLY WINDS HAVE THE POTENTIAL TO BE GUSTY
PARTICULARLY IN THE NORTH BAY HILLS FRIDAY AND SATURDAY MORNINGS.
DISCUSSION...AS OF 08:03 PM PDT WEDNESDAY
THE MARINE LAYER IS
TRICKLING INTO LOW LYING VALLEYS THIS EVENING AS IT COMPRESSES
DOWN TO A MODEST 1000FT AGL. IT WILL RETREAT ONCE AGAIN TO THE
COASTLINE TOMORROW AFTERNOON. THE EASTERN PACIFIC RIDGE IS
EXPECTED TO CONTINUE TO ERODE AS A TROUGH DESCENDS FROM THE
PACIFIC NORTHWEST TOMORROW AND INTO FRIDAY. THE BAY AREA WILL
REMAIN ON THE WEST SIDE OF THE TROUGH WHICH WILL KEEP SKIES MOSTLY
CLEAR, PROVIDING PLENTY OF SUNSHINE AND DRIER CONDITIONS. THIS
TROUGH WILL BRING NORTHERLY WINDS THAT WILL BE GUSTY, 30 MPH OR
MORE, PARTICULARLY IN HIGHER ELEVATIONS OF THE NORTH BAY ON
FRIDAY AND SATURDAY MORNING. THESE DOWNSLOPING WINDS WILL HELP
BRING WARMER TEMPERATURES TO THE BAY AREA FRIDAY AND INTO THE
WEEKEND. EXTENDED MODELS ARE SHOWING THE RETURN OF ONSHORE FLOW
AND A DEEPER MARINE LAYER EARLY NEXT WEEK WHICH WILL IN TURN BRING
COOLER TEMPERATURES.
PREV DISCUSSION...AS OF 1:48 PM PDT WEDNESDAY
SATELLITE IMAGERY
SHOWS LOW CLOUDS HAVE MOSTLY CLEARED TO THE COAST ACROSS THE
DISTRICT. THERE IS STILL SOME STRATUS AROUND THE MONTEREY BAY,
NEAR HALF MOON BAY, OVER PORTIONS OF SAN FRANCISCO, AND ALONG THE
SONOMA COUNTY COAST. CURRENT TEMPERATURE READINGS ARE RUNNING
COOLER THAN YESTERDAY AT THIS TIME WITH 60S TO LOWER 80S BEING
REPORTED AT AREA AIRPORTS. LOCATIONS IN THE SOUTHERN INTERIOR HAVE
WARMED INTO THE UPPER 80S AND LOWER 90S. THE MARINE LAYER HAS
INCREASED TO AROUND 2000 FEET AS OF NOON, AND THE ONSHORE SURFACE
PRESSURE GRADIENT IS A HEALTHY 2.9 MB, SO EXPECT LOW CLOUDS TO
SPREAD INLAND AGAIN OVERNIGHT.
AN UPPER LEVEL LOW DROPPING SOUTH FROM WESTERN CANADA INTO THE
PACIFIC NORTHWEST WILL AID IN CONTINUED COOLING OVER THE NEXT
COUPLE OF DAYS. THURSDAY WILL BE THE COOLEST DAY AS AN UPPER LEVEL
DISTURBANCE MOVES SOUTH ACROSS NEVADA WITH THE TROUGH AXIS MOVING
THROUGH OUR DISTRICT. THIS DISTURBANCE WILL TIGHTEN AN OFFSHORE
SURFACE PRESSURE GRADIENT WITH NORTH TO NORTHEAST WINDS INCREASING
THURSDAY NIGHT AS THIS TROUGH MOVES THROUGH. THE LATEST RUN OF
THE NAM12 MODEL STILL SHOWS 925 MB WINDS IN THE 25 TO 35 KT
RANGE...STRONGEST OVER THE HIGHER TERRAIN IN NAPA COUNTY. AFTER
WEAKENING DURING THE DAY FRIDAY THE NORTH TO NORTHEAST WINDS WILL
RAMP UP ONCE AGAIN FRIDAY NIGHT, ALTHOUGH WEAKER THAN THURSDAY
NIGHT. CURRENTLY THERE ARE NO WATCHES OR ADVISORIES FOR THE NORTH
AND EAST BAY HILLS BUT WILL CONTINUE TO MONITOR.
LONGER RANGE MODELS INDICATE A LONG-WAVE UPPER TROUGH OVER THE
EASTERN PACIFIC, WITH HIGH PRESSURE OVER THE ROCKY MOUNTAIN
STATES. THIS WILL MAINTAIN COOL TO NEAR SEASONALLY NORMAL TEMPS
NEXT WEEK.
AVIATION...AS OF 10:32 PM PDT WEDNESDAY
FOR 06Z TAFS. THE
MARINE LAYER HAS REBOUNDED TO OVER 2000 FT AGL PER THE FORT ORD
PROFILER. SATELLITE IMAGERY SHOWS LOW CLOUDS HAVE BEGUN TO MOVE
INLAND AND DOWN THE VALLEYS. CONDITIONS RANGE FROM VFR AT KSJC AND
KLVK TO IFR AT KSTS, KOAK, KMRY AND KSNS. EXPECT STRATUS TO
CONTINUE TO EXPAND OVERNIGHT WITH MVFR/IFR CONDITIONS TO PREVAIL
THROUGH TOMORROW MORNING. RIGHT NOW EXPECTING CLEARING GENERALLY
BETWEEN 17Z-19Z TOMORROW FOR MOST LOCATIONS. WINDS WILL CONTINUE
TO DIMINISH OVERNIGHT BEFORE INCREASING AND TURNING ONSHORE AGAIN
TOMORROW AFTERNOON.
VICINITY OF KSFO...SATELLITE SHOWS STRATUS SLOWLY CLOSING IN ON
THE TERMINAL. MVFR/IFR CIGS EXPECTED TO DEVELOP OVER THE NEXT
COUPLE OF HOURS AND THEN CONTINUE INTO LATE TOMORROW MORNING
(~17Z-19Z). WINDS WILL REMAIN LIGHT OVERNIGHT BEFORE ONSHORE
WINDS INCREASE TOMORROW AFTERNOON.
SFO BRIDGE APPROACH...PATCHES OF STRATUS HAVE DEVELOPED AROUND THE
BRIDGE. THE APPROACH MAY LOSE VISUALS BEFORE THE TERMINAL THIS
EVENING, OTHERWISE SIMILAR TO SFO.
MONTEREY BAY TERMINALS...IFR CIGS HAVE SETTLED IN FOR THE EVENING.
LIFR CONDITIONS MAY DEVELOP OVERNIGHT. LATEST GUIDANCE CONTINUES
TO SHOW STRATUS HANGING AROUND THE PENINSULA FOR MOST OF THE DAY
TOMORROW. IT IS POSSIBLE THAT MVFR/IFR CIGS CONTINUE AT KMRY ALL
DAY TOMORROW, BUT CONFIDENCE IS LOW. GENERALLY LIGHT WINDS
OVERNIGHT.
MARINE...AS OF 08:45 PM PDT WEDNESDAY
LIGHT SOUTHERLY WINDS
WILL PERSIST ALONG THE COAST SOUTH OF POINT REYES THROUGH TOMORROW
AS NORTHERLY WINDS INCREASE ACROSS THE NORTHERN OUTER WATERS
TONIGHT. GALE FORCE GUSTS WILL BE POSSIBLE STARTING TONIGHT OVER
THE OUTER WATERS NORTH OF POINT REYES THROUGH AT LEAST TOMORROW
NIGHT. ELEVATED WINDS WILL BECOME MORE WIDESPREAD, MAINLY OVER THE
OUTER WATERS, TOMORROW THROUGH FRIDAY. THESE WINDS WILL RESULT IN
STEEP FRESH SWELL CREATING HAZARDOUS SEAS CONDITIONS, ESPECIALLY
FOR SMALLER VESSELS.
MTR WATCHES/WARNINGS/ADVISORIES
.TNGT...GLW...PT ARENA TO PIGEON PT 10-60 NM
SCA...PT ARENA TO PT REYES 0-10 NM FROM 3 AM
PUBLIC FORECAST: DK
AVIATION: AS
MARINE: AS
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