FXUS65 KPSR 022255
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
355 PM MST WED DEC 2 2009
.SYNOPSIS...
A DRY FLOW ALOFT FROM THE NORTHWEST WILL RESULT IN CLEAR SKIES
TONIGHT AND SUNNY SKIES THURSDAY WITH TYPICAL TEMPERATURES FOR EARLY
DECEMBER. A DRY COLD FRONT FROM THE NORTH WILL BRING BREEZY WEATHER
TO SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA THURSDAY INTO FRIDAY
AND SOUTH-CENTRAL ARIZONA BY FRIDAY ALONG WITH COLDER AND VERY DRY
AIR. SOME FREEZING TEMPERATURES ARE EXPECTED IN COLDER DESERT AREAS
THURSDAY NIGHT WITH MORE WIDESPREAD FREEZING TEMPERATURES FRIDAY
NIGHT. HIGH CLOUDINESS IS EXPECTED TO INCREASE FRIDAY NIGHT INTO
SATURDAY...FOLLOWED BY UNSETTLED WEATHER AND A CHANCE OF RAIN NEXT
WEEK AS PACIFIC STORMS MOVES INTO OUR AREA.
&&
.DISCUSSION...
SOME MOSTLY THIN HIGH CLOUDINESS FROM THE NORTHWEST WAS MOVING
SOUTHEAST ACROSS THE AREA TODAY. THE HIGH CLOUDINESS WAS NOT AS
THICK AS PREVIOUSLY EXPECTED AND SKIES WERE MOSTLY SUNNY ACROSS THE
AREA TODAY. TEMPERATURES WERE GENERALLY CLOSE TO THE SAME TO A
DEGREE OR TWO COOLER EARLY THIS AFTERNOON COMPARED WITH THE SAME
TIME YESTERDAY...EXCEPT 3 TO 5 DEGREES COOLER IN SOUTHEAST
CALIFORNIA INCLUDING EL CENTRO. DEW POINT TEMPERATURES IN THE LOWER
50S AT YUMA WERE MORE THAN 30 DEGREES HIGHER EARLY THIS AFTERNOON
COMPARED WITH THE SAME TIME YESTERDAY...AND GENERALLY 8 TO 30 DEGREES
HIGHER IN SOUTHEAST CALIFORNIA. THIS MOISTURE WAS RESULTING IN SOME
LOW CLOUDS OVER SOUTHERN YUMA COUNTY INCLUDING YUMA LATE THIS
MORNING AND MOSTLY EAST OF YUMA EARLY THIS AFTERNOON. WINDS WERE
GENERALLY CALM OR LIGHT.
A FLOW ALOFT FROM THE NORTHWEST IS EXPECTED TO BE DRY WITH MOSTLY
CLEAR SKIES TONIGHT AND SUNNY SKIES THURSDAY. TYPICAL TEMPERATURES
FOR EARLY DECEMBER ARE ALSO EXPECTED.
THE VERY DRY FAR SOUTHWEST END OF A VERY LARGE LOW PRESSURE SYSTEM
ALOFT CENTERED OVER THE UPPER MIDWEST AND ASSOCIATED COLD FRONT WILL
MOVE SOUTHEAST ACROSS OUR AREA THURSDAY AFTERNOON AND THURSDAY NIGHT.
STRONG SURFACE HIGH PRESSURE BEHIND THIS SYSTEM IS EXPECTED TO BUILD
OVER NEVADA AND UTAH WITH BREEZY WINDS FROM THE NORTH IN SOUTHEAST
CALIFORNIA AND SOUTHWEST ARIZONA THURSDAY INTO FRIDAY...ESPECIALLY
DOWN THE LOWER COLORADO RIVER VALLEY. ALSO...AN INCREASE IN
BREEZINESS FROM THE NORTHEAST IS EXPECTED IN SOUTH-CENTRAL ARIZONA
BY FRIDAY MORNING AND EARLY AFTERNOON. THESE WINDS WILL BRING COLDER
AND VERY DRY AIR INTO OUR AREA WITH SINGLE DIGIT MINIMUM AFTERNOON
RELATIVE HUMIDITY FRIDAY.
SOME FREEZING TEMPERATURES ARE EXPECTED IN COLDER DESERT AREAS
THURSDAY NIGHT WITH MORE WIDESPREAD FREEZING TEMPERATURES FRIDAY
NIGHT. PROTECTION FOR THE MORE FROST SENSITIVE PLANTS WILL BE
NECESSARY PERHAPS EARLY FRIDAY MORNING...BUT MORE LIKELY BY LATE
FRIDAY NIGHT AND EARLY SATURDAY MORNING.
A WEAK PACIFIC LOW PRESSURE SYSTEM FROM THE WEST IS EXPECTED TO
SPREAD CONSIDERABLE HIGH CLOUDINESS OVER OUR AREA FRIDAY NIGHT AND
SATURDAY.
A HIGH PRESSURE SYSTEM ALOFT IS EXPECTED TO BECOME ANCHORED OVER THE
GULF OF ALASKA AND ALASKA THIS COMING WEEKEND AND MUCH OF NEXT WEEK.
AT THE SAME TIME A STRONG AND COLD LOW PRESSURE SYSTEM IS EXPECTED
TO DEVELOP NEAR THE PACIFIC NORTHWEST COAST BY SUNDAY INTO MONDAY.
THERE IS MUCH UNCERTAINTY REGARDING WHAT TRACK THIS LOW PRESSURE
SYSTEM WILL TAKE. IT COULD MOVE SOUTHEAST AND RESULT IN MOST OF THE
RAINFALL THAT OCCURS NEXT WEEK ON MONDAY NIGHT AND TUESDAY. HOWEVER
A LOW PRESSURE SYSTEM FROM THE WEST AND MOISTURE ASSOCIATED WITH THE
SUBTROPICAL JET STREAM WILL PROBABLY BRING MOST OF NEXT WEEKS
RAINFALL SOMETIME BETWEEN WEDNESDAY NIGHT AND FRIDAY. IN OTHER
WORDS...AS IS TYPICAL THAT FAR OUT IN TIME...THE TRACK AND TIMING IS
UNCERTAIN...BUT IT DOES LOOK AS IF OUR WEATHER WILL BECOME UNSETTLED
WITH A CHANCE OF RAIN NEXT WEEK. THE SNOW LEVEL IS EXPECTED TO MOSTLY
BE ABOVE 7 THOUSAND FEET.
THERE IS A POTENTIAL FOR SIGNIFICANT RAIN IN OUR AREA NEXT WEEK...
ESPECIALLY IN SOUTH-CENTRAL ARIZONA NORTH AND EAST OF PHOENIX.
HOWEVER...THERE IS STILL MUCH UNCERTAINTY THIS FAR OUT IN TIME. FOR
THE TIME BEING...HAVE KEPT THE PRECIPITATION FORECAST INHERITED BY
THE PREVIOUS SHIFT. STAY TUNED.
&&
AVIATION...
SOUTHEAST CALIFORNIA...SOUTHWEST AND SOUTH-CENTRAL AZ...INCLUDING
KPHX...KIWA...KIPL...AND KBLH.
CLEAR OR THIN CIFM CLOUDS. WINDS LIGHT THRU 12Z THURSDAY. KPHX
WILL SEE A TYPICAL LGT WEST BREEZE DEVELOPING AFT 21Z.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
FRIDAY THROUGH TUESDAY...
A LOW PRESSURE SYSTEM WILL MOVE THROUGH THE SOUTHERN ROCKIES BY
FRIDAY. THE ASSOCIATED COLD FRONT WILL BRING AN INCREASE IN THE WIND
LATE THURSDAY...AND INTO FRIDAY. MUCH DRIER AIR WILL SPREAD ACROSS
ALL ZONES ON FRIDAY...WITH MINIMUM RH VALUES DROPPING INTO THE
SINGLE DIGITS THROUGHOUT THE DESERTS. AT THIS TIME...CRITICAL FIRE
WEATHER THRESHOLDS ARE NOT EXPECTED TO BE REACHED.
INCREASING CLOUDS AND HUMIDITY ARE EXPECTED LATE IN THE WEEKEND...AS
A MAJOR CHANGE IN THE PATTERN DEVELOPS. A SERIES OF PACIFIC STORMS
ARE EXPECTED TO MOVE ACROSS THE REGION...FOR AN INCREASING CHANCE
OF SHOWERS PARTICULARLY MONDAY AND TUESDAY.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE.
&&
$$
NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT
WEATHER.GOV/PHOENIX
DISCUSSION...ELLIS
AVIATION...SIPPLE
FIRE WEATHER...SIPPLE
