Severe Thunderstorm Warning 1, NWS San Francisco Bay Area, CA

753 
WWUS56 KMTR 202230
SVSMTR

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
330 PM PDT SUN JUL 20 2014

CAC069-202300-
/O.CON.KMTR.SV.W.0001.000000T0000Z-140720T2300Z/
SAN BENITO CA-
330 PM PDT SUN JUL 20 2014

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 400 PM PDT
FOR SAN BENITO COUNTY...

AT 327 PM PDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO
INDICATE A SEVERE THUNDERSTORM CAPABLE OF PRODUCING QUARTER SIZE 
HAIL AS WELL AS HEAVY DOWNPOURS AND POSSIBLY FLASH FLOODING. THIS 
STORM WAS LOCATED OVER SAN BENITO COUNTY...OR 28 MILES EAST OF 
PINNACLES NATIONAL PARK. THIS STORM WAS MOVING EAST AT 5 MILES PER HOUR.

THE SEVERE THUNDERSTORM WILL OTHERWISE REMAIN OVER MAINLY RURAL AREAS
OF THE INDICATED COUNTY.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THIS IS A DANGEROUS STORM. IF YOU ARE IN ITS PATH...PREPARE
IMMEDIATELY FOR DAMAGING WINDS...DESTRUCTIVE HAIL...AND DEADLY CLOUD
TO GROUND LIGHTNING. PEOPLE OUTSIDE SHOULD MOVE TO A SHELTER...
PREFERABLY INSIDE A STRONG BUILDING BUT AWAY FROM WINDOWS.

&&

LAT...LON 3648 12087 3653 12071 3637 12064 3634 12077
TIME...MOT...LOC 2229Z 180DEG 0KT 3638 12070

$$

CANEPA

249 
WWUS56 KMTR 202250
SVSMTR

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
350 PM PDT SUN JUL 20 2014

CAC069-202259-
/O.CAN.KMTR.SV.W.0001.000000T0000Z-140720T2300Z/
SAN BENITO CA-
350 PM PDT SUN JUL 20 2014

...THE SEVERE THUNDERSTORM WARNING FOR SAN BENITO COUNTY HAS BEEN 
CANCELLED...

THIS THUNDERSTORM HAS WEAKENED BELOW SEVERE LIMITS BUT IT'S STILL 
CAPABLE OF PRODUCING SMALL HAIL AS WELL AS HEAVY DOWNPOURS THROUGH 5 
PM. 

LAT...LON 3648 12087 3653 12071 3637 12064 3634 12077
TIME...MOT...LOC 2249Z 180DEG 0KT 3638 12070

$$

CANEPA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
140 PM PDT SUN JUL 20 2014

.SYNOPSIS...MONSOON MOISTURE WILL CONTINUE TO SPREAD HIGH
CLOUDS...SPRINKLES AND A SLIGHT CHANCE OF THUNDERSTORMS ACROSS THE
DISTRICT THROUGH TONIGHT. A DRYING TREND WILL DEVELOP BY MONDAY AS
ONSHORE FLOW RETURNS TO THE REGION. LOOK FOR DRY AND SEASONABLE
WEATHER TO LAST THROUGH WEDNESDAY WITH AN INLAND WARMING TREND BY
LATER IN THE WEEK AS STRONG HIGH PRESSURE BUILDS OVER THE REGION.

&&

.DISCUSSION...AS OF 1:40 PM PDT SUNDAY...CLIMATOLOGY SHOWS THAT
LIGHTNING IS SCARCE IN THE GREATER BAY AREA AND TODAY WE ARE
SEEING WHY. AT FIRST GLANCE THINGS LOOK ABOUT AS IDEAL AS ONE CAN
IMAGINE FOR TRIGGERING AT LEAST ISOLATED T-STORMS. WE'VE GOT A
WELL DEFINED SHORTWAVE ROTATING INTO THE EASTERN CWA UNDER A
GENERAL SOUTHEAST (I.E. MOIST) WIND FLOW. THE OLD RULE OF THUMB
FOR CALIFORNIA IS THAT SOUTHEAST FLOW WILL BRING MONSOONSAL
MOISTURE. OF COURSE THIS IS TRUE BUT IT SEEMS THAT IF YOU WANT TO
SEE CONVECTION ACROSS THE BAY AREA THE MORE IDEAL SCENARIO IS
STORMS COMING IN FROM THE PACIFIC WITH A SHORTWAVE OFFSHORE AND
VERY WARM SURFACE TEMPS. ANYWAY IN ADDITION TO THE
SHORTWAVE...ABUNDANT MOISTURE...JULY SUN ANGLE WE ALSO HAVE AT
LEAST MARGINAL INSTABILITY WITH MODIFIED TOTAL TOTALS IN EXCESS OF
30. ALL OF THIS HAS LEAD TO CONTINUAL RETURNS ALOFT ON THE RADAR
BUT ONLY TRACE AMOUONTS OF PRECIP AND NO LIGHTNING...SO FAR.

AS WE MOVE THROUGH THE REMINDER OF THE AFTERNOON THE FORECAST WILL
CONTINUE TO SHOW SPRINKLES WITH SLIGHT CHANCE OF T-STORMS MAINLY
OVER EASTERN MONTEREY AND SAN BENITO COUNTY.

IT APPEARS THAT AFTER TONIGHT THE MONSOON MOISTURE AND ASSOCIATED
PRECIP CHANCES WILL SHIFT NORTH OF OUR CWA AS THE SYNOPTIC FLOW
TURNS MORE WSW WITH A WEAK TROUGH SOUTHWEST OF POINT CONCEPTION.

THE FORECAST FOR THE START OF THE WORK WEEK WILL FEATURE
SEASONABLE TEMPERATURES. ONE INTERESTING ITEM IS HOW MILD THE SEA
SURFACE TEMPERATURES (SST) OFF THE COAST ARE. BUOY 28 NEAR POINT
PIEDRAS BLANCAS WAS UP TO 68 DEGREES SST YESTERDAY AND TODAY MOST
OF THE COASTAL BUOYS ARE RUNNING IN THE LOW TO MID 60S AND EVEN BODEGA
BAY BUOY IS 59 (MILD FOR THEM). THIS IS ALL DO TO A LACK OF
UPWELLING WHICH IS FORECAST TO CONTINUE AS LIGHT SOUTHERLY WINDS
CONTINUE ACROSS THE COASTAL WATERS AT LEAST THROUGH MIDWEEK. THESE
MILD SST WILL KEEP ARE OVERNIGHT LOWS FAIRLY MILD.

ONSHORE FLOW THROUGH WEDS WILL KEEP TEMPERATURES SEASONABLY MILD
WITH CONTINUED QUIET WEATHER. THE TREND FOR THE SECOND HALF OF THE
WEEK WILL FEATURE INLAND WARMING AS THE FOUR-CORNERS HIGH EXPANDS
WESTWARD AS THE MIDWEEK SHORTWAVE THAT WILL BRING WIND TO THE
PACNW WILL PASS INTO THE NORTHERN ROCKIES. THIS PATTERN SHOULD
BRING MORE WIDESPREAD INLAND 90S AND LOWER 100S BY THURSDAY AND
FRIDAY. LONG RANGE FORECAST WILL HAVE TO MONITOR ANOTHER WEAK
SHORTWAVE BY NEXT WEEKEND THAT WILL LIKELY HAVE IMPACTS FOR THE
MOUNTAINS OUTSIDE OUR CWA.

&&

.AVIATION...AS OF 10:45 AM PDT SUNDAY...VFR CONDITIONS EXPECTED
THROUGH MUCH OF THE AFTERNOON AND EARLY EVENING HOURS WITH
CONTINUED HIGH CLOUDS STREAMING ACROSS THE REGION. ISOLATED
SHOWERS REMAIN POSSIBLE THROUGH THE DAY WITH A POSSIBLE
THUNDERSTORM OR TWO THIS AFTERNOON...GENERALLY LOW CONFIDENCE FOR
THUNDERSTORMS. LOWERING CIGS EXPECTED LATE TONIGHT INTO EARLY
MONDAY MORNING.

VICINITY OF KSFO...VFR CONDITIONS WITH WESTERLY WINDS INCREASING
TO 10 TO 15 KT THIS AFTERNOON WITH GUSTS TO 22 KT. VICINITY
SHOWERS POSSIBLE THROUGHOUT THE DAY...YET LITTLE IMPACT EXPECTED.
POSSIBLE RETURN OF MVFR/IFR CIGS EARLY MONDAY MORNING. LOW
CONFIDENCE ON STRATUS RETURN OVER TERMINAL.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO. HIGHER CONFIDENCE ON
STRATUS RETURN OVER APPROACH MONDAY MORNING.

MONTEREY BAY AREA TERMINALS...VFR CONDITIONS WITH VICINITY SHOWERS
POSSIBLE LATER THIS AFTERNOON AND EVENING. MVFR/IFR CIGS RETURN
LATE TONIGHT AND CONTINUE THROUGH MONDAY MORNING. MODERATE
CONFIDENCE.

&&

.MARINE...AS OF 10:45 AM PDT SUNDAY...A WEAK SURFACE PRESSURE
GRADIENT ACROSS THE COASTAL WATERS WILL MAINTAIN LIGHT WINDS AND
GENTLE SEAS THROUGH EARLY NEXT WEEK. NORTHWESTERLY WINDS WILL
INCREASE BY MIDWEEK AS A THERMAL TROUGH DEVELOPS OVER INTERIOR
CALIFORNIA.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...SCA...SF BAY NORTH OF THE BAY BRIDGE UNTIL 8 PM

&&

PUBLIC FORECAST: RWW
AVIATION/MARINE: RGASS

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.SANFRANCISCOBAYAREA.GOV
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA