National Weather Service National Headquarters

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS66 KSGX 171024
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
324 AM PDT FRI MAY 17 2013

.SYNOPSIS...
A TROUGH OF LOW PRESSURE ALOFT WILL MOVE ACROSS THE REGION TODAY.
A DEEPER MARINE LAYER MAY LEAK SOME PATCHY DRIZZLE AT TIMES...AND
A FEW SHOWERS ARE POSSIBLE IN THE MOUNTAINS THROUGH THIS EVENING
WITH THE PASSAGE OF THE TROUGH. OTHERWISE...DRY AND COOLER WITH
GUSTY WESTERLY WINDS IN THE MOUNTAINS AND DESERTS. BUILDING HIGH
PRESSURE SATURDAY NIGHT AND SUNDAY WILL BRING DRYING AND WARMING...
ALONG WITH A SHALLOWER MARINE LAYER THROUGH EARLY NEXT WEEK. COOLER
AGAIN FOR THE LATTER HALF OF NEXT WEEK AS THE MARINE LAYER DEEPENS
AND ONSHORE FLOW INCREASES.

&&

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

STRONG ONSHORE PRESSURE GRADIENTS OVERNIGHT CONTINUED GUSTY WESTERLY
WINDS THROUGH THE MOUNTAINS AND INTO THE DESERTS. LOCAL GUSTS IN THE
35 TO 40 MPH RANGE SHOULD GRADUALLY SUBSIDE THROUGH THE MORNING.
SATELLITE IMAGERY SHOWS A BAND OF HIGH CLOUDS SWEEPING THROUGH THE
REGION FROM THE NW...PARTIALLY OBSCURING THE LOWER MARINE CLOUDS
SURGING INLAND. A COASTAL EDDY WAS PRODUCING SE WINDS ALONG THE
COAST AT 3 AM PDT. NO PCPN HAS BEEN DETECTED OR REPORTED...EXCEPT
FOR THE HIGHEST ELEVATIONS OF RIVERSIDE COUNTY WHERE TORO PEAK
REPORTED .01 INCH.

A BROAD LOW PRESSURE TOUGH ALOFT WILL SWING THROUGH CA TODAY...
SWEEPING THE HIGHER CLOUDS OFF TO THE EAST. THE MARINE LAYER CLOUDS
MAY GET DEEP AND THICK ENOUGH TO LEAK SOME DRIZZLE WEST OF THE
MOUNTAINS...AND A FEW SCATTERED...LIGHT RAINSHOWERS COULD DEVELOP
EAST INTO THE MOUNTAINS THROUGH THIS EVENING...BUT CONFIDENCE IS LOW
AND LITTLE ACCUMULATION IS EXPECTED. THE TROUGH WILL SLIDE EAST FRI
NIGHT/SAT. SETTING US UP IN A NW FLOW ALOFT BETWEEN A STRONG UPPER-
LEVEL RIDGE PARKED OVER THE EASTPAC...AND A BROAD LOW PRESSURE
TROUGH LINGERING OVER THE GREAT BASIN. IT WILL BE WARMER EACH DAY
SAT THROUGH MON AS HEIGHTS/THICKNESS RISE OVER SOCAL.

THE WARMING TREND WILL GET SNUFFED OUT MIDWEEK AS ONSHORE FLOW
STRENGTHENS. THE RIDGE OFF THE COAST WILL WEAKEN...AS A CUT-OFF LOW
DEVELOPS OVER THE PACNW LATE TUE. THE BROAD CIRCULATION AROUND THIS
COLD LOW WILL KEEP CYCLONIC FLOW ALOFT OVER ALL OF CA AND ONSHORE
FLOW AT THE SURFACE FOR THE REMAINDER OF NEXT WEEK. BY THU OR FRI
THE MARINE LAYER MAY BE DEEP ENOUGH FOR SOME LIGHT PCPN. TEMPS WILL
BE ABOVE NORMAL FOR THE FIRST HALF OF THE WEEK...MAINLY
INLAND...THEN BELOW NORMAL FOR THE SECOND HALF. COASTAL AREAS WILL
BE CLOSE TO MID MAY NORMALS.

WEATHER CONCERNS WILL BE FOR GUSTY WESTERLY WINDS IN THE MOUNTAINS
AND DESERTS LATER THIS AFTERNOON AND EVENING...AND FOR SOME POSSIBLE
LIGHT PCPN ALONG AND WEST OF THE MOUNTAINS. LATEST MODEL GUIDANCE
KEEPS THE SFC LOW OVER THE DESERTS WEAKER TODAY THAN YESTERDAY...AND
CONSEQUENTLY...FORECAST SPEEDS ARE LOWER AND BELOW ADVISORY
CRITERIA. STILL COULD SEE A FEW GUSTS IN THE WINDER SPOTS THROUGH
AND BELOW THE BANNING PASS TO AROUND 45 MPH BY EVENING. IN TERMS OF
PCPN...MODELS HAVE BEEN VERY STINGY GENERATING ANY ACCUMULATIONS...
AND RISING CLOUD BASES ARE NOT SUPPORTIVE...SO WILL MENTION PATCHY
DRIZZLE THIS MORNING AND AGAIN SAT AM WITH A MODERATE EDDY
CIRCULATION NEAR SHORE. A SLIGHT CHANCE OF SHOWERS IS CONTINUED
FOR...MAINLY THE COASTAL SLOPES LATE TODAY AND OVERNIGHT WITH THE
00Z NAM4 GENERATING SOME PATCHY LIGHT ACCUMULATIONS.

&&

.AVIATION...
170900Z...LOW CLOUDS FILLED THE COASTAL BASIN WITH CIGS 2000-2500
FEET ASL EARLY THIS MORNING. TOPS WILL GROW FROM 3000 FEET TO AROUND
4500 FEET AND PATCHY DRIZZLE IS POSSIBLE THIS MORNING. RANDOM AND
PARTIAL SCATTERING OUT OF CLOUDS IS EXPECTED...BUT MOST LIKELY
BETWEEN 18-00Z TODAY. CLOUDS WILL REFILL THE COASTAL BASIN THIS
EVENING THROUGH TONIGHT AT ABOUT THE SAME LEVEL. A FEW LIGHT SHOWERS
ARE POSSIBLE ON COASTAL MOUNTAIN SLOPES THIS AFTERNOON AND EVENING.
SOME COASTAL SLOPE TERRAIN WILL BE OBSCURED AT TIMES IN CLOUDS AND
FOG...MAINLY BETWEEN 2500-4500 FEET THIS MORNING AND AGAIN TONIGHT.

WESTERLY WINDS WILL CONTINUE TO GUST AROUND 40 MPH THROUGH MOUNTAIN
PASSES AND ADJACENT DESERT SLOPES THROUGH TONIGHT.

&&

.MARINE...
STRONG NORTHWEST WINDS AND A VERY SHORT PERIOD WIND SWELL WILL
DEVELOP IN THE OUTER COASTAL WATERS THIS AFTERNOON AND EVENING AND
CONTINUE OVERNIGHT. A FEW GUSTS WILL REACH 25 KT WHILE COMBINED SEAS
UP TO 7 FEET ARE EXPECTED...ESPECIALLY AROUND SAN CLEMENTE ISLAND.
WINDS AND SEAS WILL DIMINISH SATURDAY MORNING.

&&

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

PZ...SMALL CRAFT ADVISORY FOR THE OUTER WATERS FROM NOON FRIDAY TO 5
AM SATURDAY.

&&

$$

PUBLIC...JAD
AVIATION/MARINE...MM