NWS Forecast Discussion
000
FXUS66 KSGX 152032
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
230 PM PDT WED OCT 15 2008
.SYNOPSIS...HIGH PRESSURE ALOFT AND WEAK OFFSHORE FLOW WILL CONTINUE
WARM DAYS WEST OF THE MOUNTAINS THROUGH FRIDAY. UPPER LEVEL LOW
PRESSURE WILL BRING MORE CLOUDS AND COOLING THIS WEEKEND.
&&
.DISCUSSION...FOR SOUTHWEST CALIFORNIA INCLUDING SAN DIEGO...
ORANGE...SOUTHWEST SAN BERNARDINO AND WEST RIVERSIDE COUNTIES.
.SHORT TERM (TODAY-SAT)...SKIES WERE CLEAR EXCEPT FOR A FEW HIGH
CLOUDS. EARLY AFTERNOON ACARS SOUNDINGS INDICATED A NEAR SURFACE
BASED INVERSION WITH NE WINDS TO ABOUT 15 KTS IN THE LOW LEVELS AND
W TO SW WINDS ALOFT. OFFSHORE GRADIENTS WITH ABOUT -8 MB SAN-TPH.
A WEAK UPPER LOW WILL MEANDER SW OF SAN DIEGO AS HIGH PRESSURE
BUILDS ALOFT INTO FRI. THIS WILL MAINTAIN CLEAR SKIES EXCEPT FOR
A FEW HIGH CLOUDS AT TIMES. THE LOW WILL GET PICKED UP BY A TROUGH
IN THE NE PAC WITH A VORT MAX SKIRTING PAST JUST TO OUR W AND N ON
SAT. THE WEAKENING OFFSHORE FLOW AND HIGH ALOFT WILL CONTINUE HOT
AND DRY DAYS INLAND THROUGH FRI WITH MAX TEMPS IN THE 90S IN MOST
INLAND VALLEYS. THERE WILL STILL BE LOCAL GUSTY OFFSHORE WINDS BUT
THEY WILL GENERALLY BE DECREASING IN STRENGTH AND WILL REMAIN BELOW
ADVISORY STRENGTH. CLEAR AND DRY NIGHTS WILL ALLOW EXCELLENT
RADIATIONAL COOLING IN AREAS PROTECTED FROM THE WINDS. AREAS WITH
SOME WINDS AND MIXING SUCH AS THE LOWER FOOTHILL LOCATIONS WILL STAY
WARMER EACH NIGHT. PATCHY STRATUS COULD RETURN TO THE BEACHES AS
EARLY AS FRIDAY AFTERNOON OR EVENING. THIS SHOULD BRING A LITTLE
COOLING TO THE BEACHES FRIDAY AFTERNOON. A SHALLOW MARINE LAYER WILL
DEVELOP BY SAT MORNING. MAX TEMPS WILL DROP ABOUT 10-15 DEGREES IN
MOST AREAS W OF THE MOUNTAINS SAT WITH LOWERING HEIGHTS AND STRONGER
ONSHORE GLOW. IF THE UPPER LOW TO OUR SW PICKS UP MORE MOISTURE THEN
THERE COULD EVEN BE A FEW LIGHT SHOWERS LATE SAT...MAINLY IN THE NRN
AREAS. WILL INDICATE SOME LOW LEVEL POPS BUT PROBABILITIES TOO LOW
TO INCLUDE IN THE ZONES AT THIS TIME.
LOCAL CRITICAL FIRE WEATHER CONDITIONS WILL CONTINUE INTO FRI IN THE
INLAND VALLEYS AND MOUNTAINS DUE TO LOW HUMIDITIES. SEE THE FIRE
WEATHER DISCUSSION BELOW FOR DETAILS.
&&
.LONG TERM (SUN-WED)...THE TROUGH WILL MOVE THROUGH SUN WITH FLAT
FLOW OR WEAK RIDGING MON. ANOTHER TROUGH SHOULD MOVE PAST TO THE N
TUE. WHILE THE MARINE LAYER WILL DEEPEN...IT SHOULD REMAIN CONFINED
TO THE COASTAL AREAS AND WRN SAN DIEGO INLAND VALLEYS. OFFSHORE FLOW
COULD DEVELOP AFTER THE TROUGH MOVES THROUGH TOWARD THE MIDDLE OF
NEXT WEEK...BUT THE STRENGTH IS UNCERTAIN.
&&
.AVIATION...
152300Z...CLEAR. WEAK LOCALLY MODERATE OFFSHORE FLOW THROUGH
THURSDAY...BECOMING WEST TO NORTHWEST ONSHORE FLOW DURING THE
AFTERNOON. LIGHT TO MODERATE UP AND DOWNDRAFTS IN THE MORNING
NEAR THE MOUNTAINS.
&&
.FIRE WEATHER...
THIS AFTERNOON...WIND SPEEDS HAVE DECREASED SIGNIFICANTLY IN ALL
AREAS WITH THE WIND PRONE AREAS REPORTING GUSTS OF 25 TO 35 MPH.
WEAKER OFFSHORE WINDS WILL CONTINUE INTO FRIDAY...MAINLY DURING THE
MORNINGS FOR SOUTHERN AREAS FAVORED FOR EASTERLY OFFSHORE FLOW. HIGH
PRESSURE ALOFT WILL BRING WARMER DAYTIME TEMPERATURES ABOVE SEASONAL
AVERAGES THROUGH FRIDAY. COMBINED WITH A VERY DRY ATMOSPHERE...THERE
WILL BE SEVERAL HOURS OF RELATIVE HUMIDITIES BELOW 10 PERCENT WITH
LITTLE OVERNIGHT RECOVERY FOR SOME INLAND AREAS THROUGH FRIDAY. IN
THE COASTAL AREAS...A WEAK AFTERNOON SEA BREEZE COULD KEEP
HUMIDITIES ABOVE CRITICAL LEVELS. FOR THE WEEKEND...A TROUGH OF LOW
PRESSURE MOVING INLAND THROUGH SOUTHERN CALIFORNIA WILL BRING
COOLING AND HIGHER HUMIDITIES.
A RED FLAG WARNING IS CURRENTLY IN EFFECT FOR MOST OF EXTREME
SOUTHWEST CALIFORNIA...EXCLUDING THE DESERTS...UNTIL FRIDAY NIGHT
DUE TO LONG DURATION LOW RELATIVE HUMIDITIES CONTINUING THROUGH
FRIDAY ALTHOUGH THE WINDS WILL BE WEAKER.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...RED FLAG WARNING FOR THE MOUNTAINS...INLAND VALLEYS AND ORANGE
COUNTY COASTAL AREAS UNTIL 10 PM TONIGHT AND CONTINUING FOR THE
MOUNTAINS AND INLAND VALLEYS UNTIL 10 PM FRI.
&&
$$
PUBLIC...ATKIN
AVIATION...SMALL
FIRE WEATHER...PG
NWS SGX Office Area Forecast Discussion
