Flash Flood Watch 7, NWS San Diego, CA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
334 AM PDT WED AUG 20 2014

.SYNOPSIS...
A LOW PRESSURE SYSTEM WILL MOVE THROUGH SOUTHERN CALIFORNIA
THROUGH THURSDAY AND BRING CHANCES FOR SHOWERS AND THUNDERSTORMS
TO MUCH OF THE REGION. TEMPERATURES WILL BE BELOW NORMAL WITH
NIGHT AND MORNING LOW CLOUDS IN COASTAL AND VALLEY AREAS. FAIR
AND WARMER WEATHER WILL RETURN FRIDAY AS THE LOW PRESSURE EXITS
TO THE EAST...WITH FEWER LOW CLOUDS AND ONLY MINOR DAY TO DAY
FLUCTUATIONS IN TEMPERATURES OVER THE WEEKEND. FURTHER WARMING IS
POSSIBLE EARLY NEXT WEEK TO NEAR NORMAL LEVELS.

&&

.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...

THE UPPER LOW PRESSURE IS CENTERED NEAR THE CHANNEL ISLANDS EARLY
THIS MORNING. THIS FEATURE WILL BRIEFLY CUTOFF THROUGH THURSDAY
EVENING BEFORE BEING EJECTED EAST TOWARDS THE 4 CORNERS FRIDAY AND
OPENING UP. HI-RES MODELS IN GOOD AGREEMENT WITH THE UPPER LOW
FEATURE WITH A NARROW TAP OF SUBTROPICAL MOISTURE CONTINUING
THROUGH THURSDAY MORNING AND GENERATING SCATTERED CONVECTION AT
TIMES. THE THREAT OF CONVECTION WILL CONTINUE THIS MORNING ACROSS
THE COASTAL SECTOR AND THROUGH THE INLAND EMPIRE. WE EXPECT THE
AREA OF CONVECTION FOCUS TO TRANSITION TO THE INLAND MOUNTAINS AND
DESERTS LATER THIS AFTERNOON AND EVENING WITH DIURNAL HEATING
ALTHOUGH AN ISOLATED THUNDERSTORM CANNOT BE RULED OUT THROUGH
THURSDAY MORNING ACROSS THE COASTAL REGION TOO.

THE CONVECTION THIS MORNING HAS BEEN PERSISTENT SINCE ABOUT
MIDNIGHT AND ALONG A TRAINING BAND FROM THE NEARSHORE WATERS NEAR
SAN CLEMENTE ISLAND TO NEAR OCEANSIDE HARBOR...AND INLAND TO NEAR
ONYX PEAK. HI-RES CONVECTIVE PARAMETERS INDICATE SURFACE BASED
INSTABILITY WILL BE FAIRLY IMPRESSIVE ACROSS THE INLAND MOUNTAINS
THIS AFTERNOON WITH CAPE VALUES REACHING 1000+ J/KG. RESIDUAL
MOISTURE PRIMARILY FOR INLAND AREAS WILL CONTINUE THE THREAT OF
CONVECTION THROUGH THURSDAY MORNING BEFORE OUR REGION IS PLACED ON
THE BACKSIDE OF THE UPPER LOW.

ONSHORE FLOW...ALBEIT NOT AS STRONG...WILL CONTINUE THROUGH THE
WEEKEND. THIS WILL CONTINUE TO BRING SLIGHTLY BELOW NORMAL
TEMPERATURES ALONG THE COAST AND ACROSS THE COASTAL VALLEYS TOO.
THE HIGH PRESSURE ZONE WILL BUILD WEST FROM THE DESERT SOUTHWEST
AND BRING A MINOR WARMUP EARLY NEXT WEEK. TEMPERATURES WILL WARM
UP BUT ARE NOT EXPECTED TO EXCEED LATE AUGUST NORMALS THROUGH
EARLY NEXT WEEK.

&&

.AVIATION...
201000Z...PATCHY STRATUS...WITH BASES FROM 2100-2500 FT MSL AND TOPS
TO 3100 FT MSL...WILL CONTINUE ALONG PORTIONS OF THE COAST AND
COASTAL VALLEYS THIS MORNING. SCATTERED THUNDERSTORMS MOVING
NORTHEAST...STRETCHING FROM THE COASTAL WATERS NEAR KCRQ INLAND TO
THE MOUNTAINS NEAR KRIV...WILL CONTINUE SLOWLY SOUTHWARD THIS
MORNING. LIGHTNING...SMALL HAIL AND GUSTY WINDS WILL BE POSSIBLE
NEAR STORMS. THUNDERSTORMS CHANCES WILL CONTINUE THROUGH THURSDAY
MORNING ACROSS THE REGION. PATCHY STRATUS WILL CLEAR TOWARDS THE
COAST LATE THIS MORNING...THEN REDEVELOP ALONG THE COAST TONIGHT
WITH SLIGHTLY LOWER TOPS AND BASES.

&&

.MARINE...
300 AM...SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE TO MOVE
NORTHEAST ACROSS THE COASTAL WATERS THROUGH LATE THIS MORNING.
CLOUD-TO-WATER LIGHTNING...GUSTY WINDS...SMALL HAIL...ROUGH SEAS AND
ISOLATED WATERSPOUTS MAY ACCOMPANY STORMS. THE POSSIBILITY OF
SHOWERS AND THUNDERSTORMS WILL CONTINUE THROUGH THURSDAY MORNING. A
MARINE WEATHER STATEMENT REMAINS IN EFFECT FOR THUNDERSTORMS OVER
THE COASTAL WATERS THROUGH THURSDAY MORNING.

&&

.SKYWARN...
SKYWARN ACTIVATION MAY BE REQUESTED LATER TODAY DUE TO
THUNDERSTORMS. WEATHER SPOTTERS ARE ENCOURAGED TO REPORT ANY
OBSERVED SIGNIFICANT WEATHER CONDITIONS.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.

&&

PUBLIC...BROTHERTON
AVIATION/MARINE...JJT

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE SAN DIEGO CA
509 AM PDT WED AUG 20 2014

CAZ048-055-056-060-201300-
RIVERSIDE COUNTY MOUNTAINS-
SAN BERNARDINO COUNTY MOUNTAINS-
APPLE AND LUCERNE VALLEYS-
SAN BERNARDINO AND RIVERSIDE COUNTY VALLEYS -THE INLAND EMPIRE-
509 AM PDT WED AUG 20 2014

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHWESTERN SAN BERNARDINO AND
WESTERN RIVERSIDE COUNTIES UNTIL 600 AM PDT...

AT 503 AM PDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A
STRONG THUNDERSTORM NEAR SUN CITY...OR 11 MILES WEST OF HEMET...
MOVING NORTH AT 30 MPH.

HAIL UP TO THE SIZE OF NICKELS IS EXPECTED WITH THIS STORM...ALONG
WITH HEAVY RAIN AND FREQUENT DANGEROUS LIGHTNING.

AREAS AFFECTED BY THIS STORM INCLUDE...MORENO
VALLEY...YUCAIPA...BEAUMONT...MENTONE...AND FOREST FALLS.

THIS STORM MAY INTENSIFY...SO BE CERTAIN TO MONITOR LOCAL RADIO AND
TV STATIONS...AS WELL AS LOCAL CABLE TV OUTLETS...FOR ADDITIONAL
INFORMATION AND POSSIBLE WARNINGS FROM THE NATIONAL WEATHER SERVICE.

LAT...LON 3437 11698 3425 11669 3365 11712 3373 11731
TIME...MOT...LOC 1209Z 199DEG 25KT 3378 11717

JMB

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SAN DIEGO CA
547 AM PDT WED AUG 20 2014

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0515 AM     HAIL             SUN CITY                33.71N 117.20W
08/20/2014  E0.88 INCH       RIVERSIDE          CA   BROADCAST MEDIA

            LARGE HAIL CRACKED A WINDSHIELD NEAR MENIFEE. HAIL SIZE
            ESTIMATED.

&&

JABRO

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE SAN DIEGO CA
647 AM PDT WED AUG 20 2014

CAZ048-050-056-057-201445-
SAN DIEGO COUNTY VALLEYS-
RIVERSIDE COUNTY MOUNTAINS-
SANTA ANA MOUNTAINS AND FOOTHILLS-
SAN BERNARDINO AND RIVERSIDE COUNTY VALLEYS -THE INLAND EMPIRE-
647 AM PDT WED AUG 20 2014

...SIGNIFICANT WEATHER ADVISORY FOR EXTREME SOUTHWESTERN SAN
BERNARDINO...EXTREME EASTERN ORANGE...WESTERN RIVERSIDE AND EXTREME
NORTHWESTERN SAN DIEGO COUNTIES UNTIL 745 AM PDT...

AT 636 AM PDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A
LINE OF HEAVY SHOWERS WITH EMBEDDED THUNDERSTORMS BETWEEN TEMECULA
AND PERRIS...AFFECTING THE SOUTHERN INLAND EMPIRE...MOVING NORTHEAST
AROUND 30 MPH.

HAIL UP TO THE SIZE OF NICKELS IS POSSIBLE WITH THIS STORM...ALONG
WITH HEAVY RAIN.

AREAS AFFECTED BY THIS STORM INCLUDE...PERRIS...HEMET...AND
TEMECULA.

PLEASE REPORT SIGNIFICANT WEATHER OR DAMAGE TO THE NATIONAL WEATHER
SERVICE SAN DIEGO TWITTER AND FACEBOOK PAGES.

LAT...LON 3405 11711 3388 11678 3368 11686 3345 11709
      3341 11719 3359 11749
TIME...MOT...LOC 1345Z 213DEG 26KT 3386 11705

TS