FXUS65 KPSR 102101
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
201 PM MST THU DEC 10 2009
.SYNOPSIS...
A SERIES OF FAST MOVING WEATHER SYSTEMS WILL MOVE ACROSS THE REGION
THROUGH THIS WEEKEND. CLOUDS WILL INCREASE BEGINNING TODAY WITH
LIGHT RAIN POSSIBLE FRIDAY AND SATURDAY. THE LAST SYSTEM WILL COME
THROUGH SATURDAY NIGHT THROUGH SUNDAY NIGHT...BRINGING THE BEST
CHANCE FOR RAIN TO THE REGION BUT MAINLY IN THE MOUNTAINS OF
NORTHERN ARIZONA.
&&
.DISCUSSION...
ONLY SOME MID AND HIGH CLOUDS DRIFTING THROUGH THE REGION AS OF
20Z...SOME THICKER CLOUDS NOTED ACROSS CENTRAL/NORTHERN ARIZONA BUT
THE MAJORITY OF SOUTHERN ARIZONA/SOUTHEAST CALIFORNIA IS CLEAR.
WATER VAPOR IMAGERY REVEALS A SHORTWAVE TROUGH MOVING INTO SOUTHERN
CALIFORNIA. AT THIS POINT THIS WAVE DOES NOT LOOK LIKE A
PRECIP-MAKER AND SHOULD ONLY RESULT IN SOME ADDITIONAL MID AND HIGH
LEVEL CLOUD COVER. NOT MUCH OF A SURFACE REFLECTION WITH THIS
WAVE...PREVIOUS FORECAST WAS DRY AND I SEE NO REASON TO DEPART FROM
THIS THINKING. WITH ADDITIONAL CLOUD COVER TONIGHT I SUSPECT LOWS
WILL BE A FEW DEGREES WARMER ACROSS THE ENTIRE AREA. A SECOND TROUGH
WILL MOVE THROUGH NORTHERN ARIZONA ON SATURDAY...ISENTROPIC LIFT
WITH THIS WAVE IS QUITE WEAK AND CONCENTRATED ACROSS NORTHERN
ARIZONA AND ASIDE FROM SOME SLIGHT CHANCE POPS ACROSS THE HIGHER
TERRAIN...MAIN IMPACT WILL AGAIN BE SOME MID AND HIGH LEVEL CLOUD
COVER.
THE MAIN FOCUS TODAY WAS ON THE THIRD AND MOST SIGNIFICANT TROUGH
EXPECTED TO MOVE THROUGH THE DESERT SOUTHWEST ON SUNDAY. THE 12Z
EUROPEAN/12Z GFS/12Z CANADIAN ARE ALL SHOWING A TROUGH MOVING
THROUGH SUNDAY AFTERNOON/SUNDAY NIGHT. THIS IS JUST ABOUT 12 HOURS
SLOWER THAN THE MODELS WERE SHOWING YESTERDAY. GIVEN THE GOOD MODEL
AGREEMENT TODAY AND THE GOOD RUN TO RUN CONSISTENCY...I BUMPED UP
POPS AT ALL LOCATIONS SUNDAY AND SUNDAY NIGHT. THE BEST FORCING
WILL BE ACROSS NORTHERN ARIZONA SO I CONCENTRATED THE HIGHEST POPS
ACROSS THE HIGHER ELEVATIONS...HOWEVER I BROUGHT IN LOW CHANCE POPS
ALL THE WAY DOWN TO THE GREATER PHOENIX AREA. THIS SYSTEM DOES NOT
LOOK LIKE A HEAVY RAIN PRODUCER AT THIS POINT...GENERALLY SPEAKING
IT LOOKS LIKE A HIGH PROBABILITY OF A LIGHT PRECIP EVENT. NOT
ANTICIPATING ANY HYDRO CONCERNS WITH THIS SYSTEM...NOR AM I
EXPECTING SNOW ANYWHERE IN THE FORECAST AREA GIVEN SUFFICIENTLY HIGH
SNOW LEVELS. DRY WEATHER WILL RETURN ON MONDAY AS A STRONG H5 RIDGE
BUILDS ACROSS THE ENTIRE SOUTHWEST CONUS.
&&
AVIATION...
A VERY WEAK UPPER LEVEL SHORT WAVE TROUGH WILL MOVE THROUGH THE
REGION TODAY. EXPECT INCREASING MID/HIGH LEVEL CLOUDS...WITH NO REAL
THREAT FOR RAIN. A FEW VIRGA SHOWERS ARE NOT OUT OF THE QUESTION.
THUS...LIGHT IN-FLIGHT TURBULENCE WILL BE COMMON IN THESE AREAS.
OTHERWISE...ANTICIPATE SURFACE WIND SPEEDS TO BE RATHER LIGHT
THROUGH THE NEXT 24 HRS.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
FRIDAY THROUGH TUESDAY...
AN UNSETTLED WEATHER PATTERN WILL CONTINUE THROUGH SUNDAY...AS A
SERIES OF FAST MOVING WEATHER DISTURBANCES MOVE ACROSS THE REGION.
ANTICIPATE COOLER TEMPERATURES...LIGHT WINDS AND ELEVATED HUMIDITY
LEVELS. A SLIGHT CHANCE OF SHOWERS IS POSSIBLE AREA WIDE
FRIDAY...WITH A BETTER CHANCE OF RAIN EXPECTED SATURDAY NIGHT INTO
SUNDAY. HIGH PRESSURE WILL BEGIN TO BUILD OVER THE REGION MONDAY
INTO TUESDAY...RESULTING IN WARMER TEMPERATURES AND DRIER CONDITIONS.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE.
&&
$$
NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT
WEATHER.GOV/PHOENIX
DISCUSSION...LEINS
AVIATION...PADDOCK
FIRE WEATHER...PADDOCK
