000 FXUS65 KPSR 110440 AFDPSR AZZ020>028-CAZ030>033-111045- SOUTHWEST ARIZONA/SOUTHEAST CALIFORNIA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PHOENIX AZ 940 PM MST FRI MAY 10 2002 .SYNOPSIS... WINDY CONDITIONS...WITH SOME BLOWING DESERT SAND AND DUST...ARE FORECAST THROUGH THIS EVENING AS A LOW PRESSURE SYSTEM FROM NEVADA APPROACHES. THE DRY SOUTHERN END OF THIS SYSTEM WILL MOVE EAST ACROSS ARIZONA WITH SOME COOLING AND BREEZY CONDITIONS SATURDAY. STRONG HIGH PRESSURE ALOFT FROM THE SOUTHWEST WILL MOVE EAST ACROSS THE SOUTHWESTERN UNITED STATES WITH SIGNIFICANTLY WARMER WEATHER EARLY NEXT WEEK. ANOTHER WEAKER PACIFIC LOW PRESSURE SYSTEM WILL RESULT IN PARTLY CLOUDY SKIES TUESDAY AND WEDNESDAY...AND DROP TEMPERATURES SOMEWHAT LATE NEXT WEEK. .DISCUSSION... A RATHER STRONG YET DRY LOW PRESSURE SYSTEM CONTINUED TO DEVELOP OVER THE GREAT BASIN TODAY...AND AS OF THIS EVENING THE MAIN UPPER LOW WAS LOCATED OVER WESTERN AND CENTRAL NV...WITH H5 TEMPS OF MINUS 25C. AZ WAS ON THE SERN EDGE OF THIS LOW...UNDER A RATHER STRONG DRY SWLY TO WLY WINDFLOW. GOES PWAT IMAGERY AND PLOT DATA SHOW HOW DRY AZ IS ATTM...AND SURFACE DEWPOINTS OVER SRN AZ MOSTLY ARE IN THE TEENS AND 20S...WITH SOME MID 30S SEEN OVER FAR SERN CA. IR SATELLITE IMAGERY DEPICTS VIRTUALLY CLEAR SKIES STATEWIDE AT 9 PM. STRONG GRADIENTS ASSOCD WITH THIS APPROACHING LOW CAUSED BREEZY TO WINDY CONDITIONS THIS AFTERNOON AND EVENING...WITH GUSTS OVER 30 MPH COMMON OVER THE SRN AZ DESERTS EARLIER...AND SOME OF THESE STRONGER GUSTS CAUSED BLOWING DUST PROBLEMS EARLIER THIS AFTERNOON IN THE CASA GRANDE AREA. THIS PROMPTED THE ISSUANCE OF A BLOWING DUST WARNING FOR THAT AREA...MAINLY SOUTH OF THE GILA RIVER...WITH ISOLD SPOTS SEEING VSBYS GOING DOWN TO NEAR ZERO MILES AT TIMES. AS OF 8 PM MOST OF THE WINDS OVER THE SCNTRL AZ DESERTS HAD DROPPED OFF TO BELOW 25 MPH AND THUS THE WARNING WAS ALLOWED TO EXPIRE. STRONGER WINDS WERE SEEN OVER SERN CA...MAINLY IN THE IMPERIAL AREA...AND AS OF 9 PM GUSTS FROM 35 TO AROUND 40 MPH WERE BEING RECORDED AT EL CENTRO ...IMPERIAL AND TWENTY NINE PALMS NEAR JOSHUA TREE NATIONAL PARK. RATHER TIGHT SURFACE GRADIENT STILL EXISTS IN THAT AREA...AND IS KEEPING THE WINDS GOING STRONG. WIND ADVISORY REMAINS IN EFFECT FOR OUR CA ZONES TIL 11 PM TONIGHT...AND AT 9 PM ISSUED A FOLLOW UP STATEMENT ON THIS WIND EVENT. EXPECT WINDS TO TAPER OFF IN THE ADVY AREA BY MIDNIGHT OR SHORTLY THEREAFTER AS THE GRADIENTS RELAX. UPPER LOW FORECAST BY ETA AND NGM TO KEEP MOVING ESEWD NEXT 24 HOURS WITH THE UPPER LOW INTO FAR NRN AZ AND UT BY SAT AFTN/EVE. GRADIENTS NOT QUITE AS STRONG TOMORROW SO THERE WILL BE LESS WIND...BUT CERTAINLY THERE WILL BE ENOUGH FOR BREEZY CONDITIONS MOSTLY PLACES BY AFTERNOON. VERY DRY ATMOSPHERE CONTINUES...AS OUR AREA REMAINS ON THE SOUTHERN PERIPHERY OF THIS LOW...WHICH IS ALMOST ALWAYS A DRY SCENARIO FOR US. THUS GENLY CLEAR SKIES WILL CONTINUE TONIGHT AND SUNNY SKIES AWAIT OVER THE WEEKEND. HAVE AMENDED ZONES EARLIER TO BACK OFF ON THE WINDS A BIT OVER THE AZ ZONES...AND WILL KEEP AN EYE ON THE WINDS OVER SERN CA TO SEE IF WIND ADVISORY NEEDS EXTENDING BEYOND 11 PM. OTHERWISE FORECASTS LOOK OK. 11 .PSR...WIND ADVISORY FOR SOUTHEAST CALIFORNIA ZONES 30...32...AND 33...JOSHUA TREE NATIONAL PARK...RIVERSIDE COUNTY EASTERN DESERTS...AND IMPERIAL COUNTY UNTIL 11 PM PDT...0600 GMT THIS EVENING.