EXTREME SOUTHWESTERN CALIFORNIA AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
AFDSAN 230 PM PST SAT JAN 15 2000
...SYNOPSIS...
A STORM SYSTEM GOING BY TO THE NORTH...COMBINED WITH HIGH LEVELS OF
MOISTURE WILL BRING SOME LIGHT RAIN TO THE AREA SUNDAY INTO MONDAY.
AMOUNTS SHOULD BE LIGHT...RANGING FROM A FEW HUNDREDTHS OF AN INCH
ALONG THE SAN DIEGO COAST TO OVER 1/2 INCH ON THE SOUTH SLOPES OF
THE SAN BERNARDINO MOUNTAINS. TEMPERATURES WILL BE COOLER SUNDAY AND
MONDAY...YET STILL NEAR OR SLIGHTLY ABOVE NORMAL. HIGH PRESSURE
ALOFT WITH WARM AND FAIRLY MOIST SOUTHWEST FLOW WILL BRING HIGH
CLOUDS AND WARM WEATHER TUESDAY AND WEDNESDAY.
...DISCUSSION...
A FAIRLY VIGOROUS SYSTEM WILL MOVE THROUGH CENTRAL/NORTHERN
CALIFORNIA SUNDAY...BUT THE DYNAMICS ARE MOSTLY LACKING DOWN HERE.
IN FACT...THE NGM ACTUALLY HAS SOME ANTI-CYCLONIC FLOW WHEN THE
MOISTURE IS AT ITS HIGHEST. 850 MB MOISTURE IS ABOVE 70 PERCENT
SUNDAY INTO MONDAY ON ALL THE MODELS...AND THIS WOULD FAVOR AT LEAST
SOME RAIN. PER DISCUSSION WITH OXNARD...IT APPEARS THE MODELS MIGHT
BE A LITTLE BIT TOO HIGH ON THE LOW-LEVEL MOISTURE...ESPECIALLY
GIVEN HOW DRY WE ARE AT THE SURFACE AND THAT WE ARE STRUGGLING TO
EVEN TURN WEAKLY ONSHORE SO FAR. MOST RAINFALL SHOULD BE LIGHT SINCE
THE DYNAMICS/INSTABILITY ARE LIMITED...SO THE MAIN THING WE WILL
HAVE IS OROGRAPHICS. LOCAL SEA TEMPS WILL NOT HELP MUCH AS THE COLD
ANOMALY WILL INCREASE THE LOW-LEVEL STABILITY SLIGHTLY. ALSO...OUR
HEIGHTS STAY AROUND 576 OR HIGHER...NOT LOW AT ALL...AND THE SURFACE
PRESSURE GRADIENTS STAY WEAK FROM THE LA AREA SOUTH. AT LEAST THE
COLDEST AIR IN THE SYSTEM...ACCORDING TO THE IR IMAGE...IS SHIFTING
MORE SE...VERSUS THE SW SHIFT FRIDAY.
700 MB WINDS DO INCREASE AT TIMES TO 50 KNOTS ON THE MODELS...BUT WE
HAVE RATHER WEAK COLD AIR ADVECTION AND NO INVERSION EXPECTED...SO
SIGNIFICANT MOUNTAIN WAVE ACTIVITY IS NOT EXPECTED. STRONGEST WINDS
SHOULD BE EARLY SUNDAY AND SO THE WINDS SHOULD BE MOSTLY 25-35 IN
THE NORTHERN MOUNTAINS WITH SOME HIGHER GUSTS AND OVER THE
APPLE/YUCCA VALLEYS. ACARS SOUNDINGS ARE SHOWING 30 KNOT WINDS NOW
AT THOSE LEVELS...AND SOME OF THAT IS SHOWING UP IN THE OBS...LIKE
AT GRANITE MOUNTAIN.
MONDAY STILL LOOKS A BIT MOIST...SO SOME LINGERING SHOWERS ARE
POSSIBLE THEN...WITH THE BEST PRECIP AMOUNTS OVER THE MOUNTAINS.
ECM/MRF ARE POINTING TO A VERY MILD PERIOD NEXT WEEK...AROUND
TUE/WED AS THE HIGH ALOFT OVER NW MEXICO EXPANDS N AND W. WE WILL
LIKELY MIMIC THE WARMTH OF THE PAST 2-3 DAYS THEN. THE STORM TRACK IS
STILL AIMED AT N CAL THEN...AND THE FLOW OVER US STAYS SOMEWHAT
MOIST...SO HIGH CLOUDS WILL DOMINATE. LATE WEDNESDAY OR
THURSDAY...ANOTHER SYSTEM WILL MOVE BY TO THE NORTH. IT IS
BORDERLINE AS TO WHETHER OR NOT WE GET ANY RAIN...THE PERFORMANCE OF
THE SUNDAY SYSTEM WILL GUIDE US...IN ADDITION TO FUTURE MODEL RUNS.
NEVERTHELESS...THURSDAY WILL BE COOLER AS TEMPS ALOFT DROP AND WE
BECOME MORE ONSHORE.
SAN -454
.SAN...NONE.
MAXWELL