Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 310451
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
930 PM PDT WED JUL 30 2014

.SYNOPSIS...
FAIR WEATHER WILL PREVAIL THROUGH THURSDAY NIGHT WITH PATCHY NIGHT
AND MORNING LOW CLOUDS AND FOG NEAR THE COAST. TEMPERATURES WILL
CONTINUE TO BE A LITTLE ABOVE SEASONAL NORMALS IN MOST AREAS.
MOISTURE WILL INCREASE FROM THE SOUTHEAST FRIDAY AND SATURDAY AND
COMBINE WITH A WEAK LOW PRESSURE SYSTEM ALOFT TO BRING INCREASING
CHANCES OF THUNDERSTORMS OVER THE MOUNTAINS AND DESERTS...MAINLY IN
THE AFTERNOONS AND EVENINGS. A FEW THUNDERSTORMS COULD STRAY WEST
INTO THE VALLEYS...MAINLY SATURDAY. A FEW THUNDERSTORMS WILL LINGER
SUNDAY...THEN FAIR WEATHER WILL RETURN MONDAY THROUGH WEDNESDAY OF
NEXT WEEK.

&&

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

SKIES WERE MOSTLY CLEAR EXCEPT FOR A FEW PATCHES OF STRATUS FORMING
ALONG THE BEACHES. MOISTURE FROM THE REMNANTS OF HERNAN WAS MOSTLY
NORTH OF OUR AREA AS THAT HELPED TO PRODUCE THUNDERSTORMS THIS
AFTERNOON OVER CENTRAL CALIFORNIA...INCLUDING THE SIERRA...THOUGH
NONE FORMED OVER OUR FORECAST AREA TODAY. PATCHY STRATUS WILL OCCUR
NEAR THE COAST OVERNIGHT...WITH SOME FOG POSSIBLE LATE OVER HIGHER
COASTAL TERRAIN AND THE SAN DIEGO COUNTY MESAS...THOUGH ANY DENSE
FOG SHOULD BE QUITE LOCAL. THE TEMP PROFILE WILL BE SIMILAR THU...SO
ANOTHER HOT DAY WILL OCCUR INLAND...WITH LOWER DESERT TEMPS AS HIGH
AS AROUND 115.

MOISTURE ALOFT WILL GRADUALLY INCREASE THE NEXT FEW DAYS. 00Z NKX
SOUNDING SHOWED 1.21 IN OF PRECIPITABLE WATER...SIMILAR TO 24 HOURS
AGO...AND NOAA GPS PW SENSORS SHOW ONLY SLIGHTLY HIGHER VALUES IN
THE LOWER DESERTS. THE MCS OVER SOUTHERN SONORA COULD POTENTIALLY
PRODUCE SOME SOUTHEAST-TO-NORTHWEST FLOW FOR THU MORNING...AND IF
THIS IS STRONG ENOUGH...THEN FUTURE SHIFTS MIGHT RECONSIDER
THUNDERSTORM CHANCES FOR THU. HOWEVER...THE MOST LIKELY SCENARIO IS
FOR ENOUGH MOISTURE IN THE 700-500 MB LAYER AND SURFACE BASED
INSTABILITY FOR SCATTERED TSTORMS FRIDAY. MODELS HAVE BEEN SHOWING A
WEAK UPPER LOW MOVING FROM SOUTHEAST TO NORTHWEST INTO SOUTHEASTERN
CALIFORNIA AROUND SATURDAY NIGHT OR SUNDAY. MODELS ARE TYPICALLY
LOW-CONFIDENCE WITH THIS KIND OF UPPER LOW IN SUMMER...BUT IT WOULD
HAVE THE POTENTIAL TO CREATE DYNAMICS TO COMBINE WITH MOISTURE AND
SOME ELEVATED CAPE AND PRODUCE THUNDERSTORMS OUTSIDE OF THE NORMAL
MTN/DESERT LOCATIONS AND OUTSIDE THE NORMAL AFTERNOON/EVENING TIME
FRAMES. MODELS HAVE TRENDED A BIT TO THE EAST IN RECENT RUNS...SO
CHANCES OF COASTAL THUNDERSTORMS DO NOT LOOK HIGH ENOUGH TO PUT IN
THE FORECAST...BUT INLAND VALLEYS COULD HAVE A STRAY THUNDERSTORM.
RIGHT NOW...SATURDAY LOOKS LIKE THE BEST DAY FOR THUNDERSTORMS DUE
TO THE BEST MOISTURE AS MOISTURE DECREASES A BIT SUNDAY. SOMEWHAT
LOWER TEMPS OVER THE WEEKEND IN THE DESERTS WILL BE OFFSET BY THE
HIGHER HUMIDITY WHICH WILL KEEP DAYTIME HEAT INDEX VALUES SIMILAR TO
THOSE OF TODAY OR THURSDAY.

DRIER WEST FLOW DEVELOPS AROUND MONDAY AS THE HIGH BUILDS A BIT OVER
NORTHERN MEXICO AND SOME TROUGHING DEVELOPS OVER THE INTERIOR
WEST...PARTLY FROM THAT UPPER LOW FROM THE WEEKEND. WEAK UPPER LOWS
MOVING BY THE NORTH NEXT WEEK SHOULD MAINTAIN THE WEST FLOW THROUGH
AT LEAST WED OR THU AND KEEP THE REGION DRY...AND HAVE A PATTERN
CONDUCIVE TO NIGHT AND MORNING STRATUS NEAR THE COAST. TEMPS WILL BE
MOSTLY SEASONAL.

&&

.AVIATION...
310330Z...COASTS/VALLEYS...STRATUS WITH BASES 800-1000 FT MSL AND
TOPS 1200 FT MSL WILL DEVELOP OVER THE COASTAL WATERS TONIGHT. THIS
PATCHY LOW CLOUD DECK WILL MOVE INLAND 5-10 SM BETWEEN
03/0900-1400Z...POSSIBLY AFFECTING KSNA...KCRQ...KSAN. VISIBILITY
MAY BE LOCALLY REDUCED TO 1 MILE OR LESS WHERE THE CLOUDS INTERSECT
THE TERRAIN ON THE LOWER COASTAL MESAS. CONFIDENCE OF TIMING AND
COVERAGE OF STRATUS IS LOW. THE LOW CLOUDS WILL ERODE TO THE BEACHES
BY 31/1500Z. ANOTHER STRATUS DECK...SLIGHTLY DEEPER...WILL MOVE FROM
THE COAST INLAND THURSDAY NIGHT AFT 01/0900Z.

MOUNTAINS/DESERTS...SKC CONDS WITH LIGHT TO MODERATE DIURNALLY
DRIVEN WINDS.

&&

.MARINE...
900 PM PDT...NO HAZARDOUS MARINE WEATHER EXPECTED THROUGH SUNDAY.

&&

.SKYWARN...
SKYWARN ACTIVATION IS NOT REQUESTED. HOWEVER WEATHER SPOTTERS ARE
ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS.


&&

.SGX WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

PUBLIC...MAXWELL
AVIATION/MARINE...JT






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