Funnel Cloud in California, May 7, 2015

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
443 AM PDT THU MAY 7 2015

.SYNOPSIS...AN UPPER LEVEL LOW OVER NORTHERN CALIFORNIA WILL
RESULT IN SHOWERS AND ISOLATED THUNDERSTORMS OVER PORTIONS OF THE
DISTRICT TODAY AND EARLY FRIDAY. DRY WEATHER CONDITIONS AND
SLIGHTLY WARMER TEMPERATURES RETURN FOR THE WEEKEND AS THE SYSTEM
SHIFTS INLAND AND HIGH PRESSURE BUILDS OVER THE REGION.

&&

.DISCUSSION...AS OF 3:42 AM PDT THURSDAY...THE UPPER
LOW...CURRENTLY CENTERED OVER NORTHERN CALIFORNIA...IS PRODUCING
A FEW SHOWERS OVER THE SACRAMENTO VALLEY AS WELL AS ON THE WEST
SLOPES OF THE SIERRA. SOME ECHOES ARE CUTTING ACROSS NORTHERN NAPA
COUNTY AT THIS TIME. SO FAR...THERE NO REPORTS OF MEASURABLE
RAINFALL IN OUR AREA FROM THESE CELLS. THESE ECHOES ARE MOVING
FROM WEST TO EAST. AS THE UPPER LOW MOVES SOUTH...THE AREA OF
POTENTIAL SHOWER/THUNDERSTORM ACTIVITY WILL SPREAD TO INCLUDE THE
EASTERN AND SOUTHERN TWO THIRDS OF THE DISTRICT TODAY WITH THE
BEST CHANCES FOR CONVECTIVE ACTIVITY ALONG THE EASTERN SECTIONS.
SHOWER CHANCES TO DIMINISH LATE TONIGHT AS THE UPPER LOW MOVES
TOWARDS LAS VEGAS...BUT A FEW SHOWERS COULD LINGER INTO FRIDAY
MORNING...MAINLY OVER THE SOUTHERN COUNTIES.

BY SATURDAY THE UPPER LOW IS PROGGED TO BE LOCATED OVER NORTHERN
ARIZONA AND HIGH PRESSURE WILL REBUILD ALONG THE WEST COAST. THIS
WILL BRING IN A WARMING TREND FOR THE WEEKEND...AT LEAST OVER
INLAND AREAS. NEAR-COASTAL LOCATIONS WILL REMAIN COOL WITH A
CONTINUED ONSHORE FLOW. ANOTHER TROUGH OF LOW PRESSURE WILL MOVE
TOWARDS THE PACIFIC NORTHWEST COAST EARLY NEXT WEEK WITH ANOTHER
UPPER LOW FORECAST TO DROP SOUTH OVER THE EASTERN PACIFIC AND WEST
OF COASTAL CALIFORNIA BY LATE NEXT WEEK. SO FAR THESE FEATURES ARE
NOT EXPECTED TO BRING US ANY RAIN...BUT COOLER TEMPERATURES ARE
LIKELY.

&&

.AVIATION...AS OF 4:33 AM PDT WEDNESDAY...IMPRESSIVE N-S GRADIENT
AT ALMOST 7 MB. AS ONE WOULD EXPECT CLEAR SKIES PREVAIL OVER THE
COASTAL WATERS. HOWEVER...SIMILAR TO THE LAST FEW MORNINGS THERE
ARE A FEW PATCHY LOW CLOUDS AROUND SF BAY. MORE CLOUDS EXIST FROM
THE SAN MATEO COAST SOUTHWARD. THAT BEING SAID...CLOUD COVERAGE IS
SLIGHTLY LESS THAN YESTERDAY MORNING. LOCATIONS THAT HAVE CIGS
WILL LIKELY LAST THROUGH MID MORNING BEFORE MIXING OUT AS THE
UPPER LOW DRIFTS SOUTH. CONF IS MEDIUM TO LOW.

VICINITY OF KSFO...VFR CONDITIONS PREVAIL FOR KSFO AND KOAK...BUT
A FEW CLOUDS DO LINGER TO THE WEST AND OVER THE SE BAY. FOR NOW
WILL NOT INCLUDE ANY CIGS...BUT WILL MONITOR CLOSELY. WINDS WILL PICK UP
THURSDAY AFTERNOON WITH SUSTAINED WINDS AROUND 15 TO 20 KT WITH
GUSTS AROUND 25 KT.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO. A FEW PATCHY CLOUDS AROUND
1500 FEET THIS MORNING.

MONTEREY BAY AREA TERMINALS...MVFR CIGS ARE EXPECTED THROUGH THIS
AFTERNOON. WILL ALLOW FOR A FEW HOURS OF SCT AS THE UPPER LOW
MOVES OVERHEAD. LIGHT SOUTHWESTERLY WINDS WILL PREVAIL TROUGH THE
NIGHT. WINDS WILL PICKING UP IN THE AFTERNOON WITH SUSTAINED WINDS
OF 10 TO 15 KT WITH GUSTS TO AROUND 20 KT.

&&

.MARINE...AS OF 02:21 AM PDT THURSDAY...MODERATE TO STRONG
NORTHERLY WINDS WILL CONTINUE OVER THE COASTAL WATERS TODAY AS
HIGH PRESSURE REMAINS OVER THE NORTHERN PACIFIC. THE STRONGEST
WINDS WILL BE OVER THE OUTER WATERS NORTH OF POINT REYES. THE
STRONG WINDS WILL PRODUCE HAZARDOUS CONDITIONS WITH STEEP WIND
WAVES AND FRESH SWELL. NORTHERLY FLOW WILL GRADUALLY WEAKEN
TONIGHT AND FRIDAY.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...SCA...PIGEON PT TO PT PINOS 0-10 NM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM
             SCA...PT ARENA TO PT REYES 10-60 NM FROM 3 PM
             GLW...PT ARENA TO PT REYES 10-60 NM UNTIL 3 PM
             SCA...PT REYES TO PIGEON PT 10-60 NM FROM 9 AM
             GLW...PT ARENA TO PT REYES 0-10 NM UNTIL 9 AM
             GLW...PT REYES TO PIGEON PT 10-60 NM UNTIL 9 AM
             SCA...PIGEON PT TO PT PINOS 10-60 NM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 10-60 NM
             SCA...PT ARENA TO PT REYES 0-10 NM FROM 9 AM
             SCA...PT REYES TO PIGEON PT 0-10 NM
             SCA...ROUGH BAR ADVISORY FOR SF BAR UNTIL 3 PM

&&

PUBLIC FORECAST: SIMS
AVIATION/MARINE: MM

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