609
FXUS65 KPSR 091324 AAB
AFDPSR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PHOENIX AZ
624 AM MST TUE FEB 9 2010
UPDATE
MINOR UPDATE TO THE FORECAST FOR TODAY. APPEARS THAT THE STRONG
FORCING WITH THE INCOMING SYSTEM IS CAUSING SOME ISOLATED SHOWERS TO
DEVELOP ACROSS SRN NV AND SRN CA. THIS IS LIKELY IN RESPONSE TO A
LIFTING WARM FRONT /SRN NV/ AND AN INCOMING PV ANOMALY ON THE
STRENGTHENING JET OVERHEAD. WITH THE PV ANOMALY FORECAST TO MOVE
THROUGH THE WRN CWA THIS MORNING I ADDED SOME SLIGHT CHANCE POPS TO
THAT AREA. KEPT THE LOW POPS INTO THE AFTN HOURS AS SOLAR HEATING
COULD LEAD TO A FEW CONVECTIVE SHOWERS. NO OTHER UPDATES.
SYNOPSIS
EXPECT AN INCREASE IN MAINLY HIGH CLOUDS TODAY AS A LOW PRESSURE
SYSTEM APPROACHES FROM THE NORTHWEST. RAIN AND MOUNTAIN SNOW
SHOWERS...AS WELL AS A SLIGHT CHANCE OF A THUNDERSTORM...WILL OCCUR
OVER FAR SOUTHEAST CALIFORNIA AND THE LOWER COLORADO RIVER VALLEY
TONIGHT INTO EARLY WEDNESDAY...AND MAINLY OVER SOUTHWEST AND SOUTH-
CENTRAL ARIZONA WEDNESDAY. DRIER CONDITIONS WILL PREVAIL THURSDAY AS
THE LOW MOVES OFF TO OUR EAST...THOUGH IT WILL REMAIN RATHER COOL.
WARMER WEATHER WILL SLOWLY RETURN HEADING INTO THE WEEKEND WITH
ABOVE NORMAL TEMPERATURES LIKELY BY SATURDAY.
DISCUSSION
IMPRESSIVE LOW IS QUICKLY DIVING ALONG THE NRN CA COAST THIS
MORNING...PRETTY MUCH AS EXPECTED. SOUTHERN BRANCH OF THE JET IS
ALSO RESPONDING TO THE INCOMING LOW AS CAN BE SEEN WITH THE FLARE-UP
IN PWAT AND IR IMAGERY...AGAIN AS EXPECTED.
00Z MODELS APPEAR TO HAVE A PRETTY GOOD HANDLE ON THE SYSTEM AND
REMAIN IN GENERALLY GOOD AGREEMENT AS IT TRAVERSES OUR CWA THOUGH
THERE REMAIN MINOR IMPORTANT DIFFERENCES. MODELS HAVE TAKEN A
NOTICEABLE SW JOG WITH THE SYSTEM...NOT SURPRISING GIVEN IT IS A BIT
COLDER AND STRONGER THEN EXPECTED. IT NOW APPEARS THE STRONGEST
FORCING WILL IMPACT OUR WRN CWA...THEN SWING SOUTH AND EAST OF OUR
AREA. OVERALL SYSTEM REMAINS VERY IMPRESSIVE WITH IT/S FORCING
FIELDS.
MOISTURE REMAINS THE BIG MISSING INGREDIENT AND BASED ON LATEST
SATELLITE DATA I DON/T THINK WE/LL GET ANY SIGNIFICANT MOISTURE
INFLUX. SO THE SYSTEM WILL HAVE TO WORK WITH WHAT IT HAS...RESULTING
IN QPF OF ROUGHLY 1/10 TO 1/4 INCH MOST AREAS. SNOW LEVELS WILL FALL
TO AROUND 4000 FEET ACROSS SE CA. FORECAST SNOW AMOUNTS ARE 2-4
INCHES IN THE JOSHUA TREE NATIONAL PARK TUESDAY EVENING THROUGH
WEDNESDAY MORNING. I/LL BE CONVERTING THE WINTER STORM WATCH TO A
WINTER WEATHER ADVISORY BASED ON THE FORECAST.
STRONGEST FORCING...WHICH WILL BE WANING...SHIFTS INTO SE AZ AND
SONORA DURING THE DAY WEDNESDAY. I ADJUSTED THE POPS DOWN A BIT
BASED ON THE MORE SOUTHERLY TRACK AND THE STILL MISSING MOISTURE.
SOME MINOR SNOW ACCUMULATION WILL BE POSSIBLE IN SRN GILA COUNTY
PRIMARILY ABOVE 5000 FEET /2-4 INCHES/. TEMPERATURES WILL BE NEARLY
10 DEG BELOW 30 YEAR NORMALS WEDNESDAY.
STRONG RIDGING DEVELOPS BEHIND THE LOW THURSDAY WHICH WILL QUICKLY
BRING THE THREAT OF PRECIP TO AN END. MODELS IN GOOD AGREEMENT THAT
A BROAD H5 RIDGE WILL BUILD OVER THE ERN PAC AND EXTEND INTO THE SW
STATES. FINE WARMING TREND WILL DEVELOP THROUGH THE WEEKEND WITH
SOME GUIDANCE OFFERING HIGHS IN THE 80S ON THE LOWER DESERTS BY
EARLY NEXT WEEK. WILL HOLD OFF ON THAT MUCH OPTIMISM AT THIS TIME
BUT MID 70S LOOK LIKE A GOOD BET.
AVIATION
KPHX AND KIWA...
LIGHT WINDS FROM THE EAST THIS MORNING ARE EXPECTED TO BECOME
VARIABLE AFTER 2000 TO 2200 GMT THIS AFTERNOON...THEN FROM THE EAST
AGAIN AFTER ABOUT 0400 GMT AT KIWA AND 0800 GMT AT KPHX TONIGHT.
HIGH CLOUDINESS IS EXPECTED TO INCREASE FROM THE SOUTHWEST BY THIS
AFTERNOON AND TONIGHT WITH A FEW TO SCATTERED CLOUDS NEAR 7 AND 14
THOUSAND FEET.
KIPL AND KBLH...
LIGHT AND VARIABLE WINDS ARE EXPECTED THIS MORNING BECOMING FROM THE
SOUTH AROUND 10 KNOTS LATE THIS MORNING AND/OR THIS AFTERNOON...THEN
FROM THE SOUTHWEST AND WEST TONIGHT. INCREASING AND LOWERING
CLOUDINESS IS EXPECTED THROUGH THE PERIOD WITH CEILINGS LOWERING TO
6 THOUSAND FEET AFTER 0800 GMT TONIGHT AND AS LOW AS 4 THOUSAND FEET
AFTER 1000 GMT WITH VISIBILITY DROPPING TO NEAR 5 MILES IN SHOWERS.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
FIRE WEATHER
WEDNESDAY NIGHT THROUGH MONDAY...
SOME LINGERING SHOWERS ARE EXPECTED WEDNESDAY NIGHT...MAINLY EAST OF
PHOENIX. HIGH PRESSURE ALOFT FROM THE PACIFIC WILL BRING A RETURN TO
RELATIVELY DRIER AIR AND A RECOVERY OF TEMPERATURES THURSDAY AND
FRIDAY WITH FURTHER WARMING THIS COMING WEEKEND. MINIMUM RELATIVE
HUMIDITY IS EXPECTED TO GENERALLY REMAIN ABOVE 20 PERCENT WITH GOOD
TO EXCELLENT RECOVERY AT NIGHT. SOME BREEZINESS FROM THE NORTH AND
NORTHEAST IS EXPECTED THIS WEEKEND...ESPECIALLY DOWN THE LOWER
COLORADO RIVER VALLEY.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...WINTER WEATHER ADVISORY FROM 8 PM THIS EVENING TO 10 AM PST
WEDNESDAY CAZ030.
NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT
WEATHER.GOV/PHOENIX
DISCUSSION...INIGUEZ
AVIATION...ELLIS
FIRE WEATHER...ELLIS
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