083 
FXUS65 KPSR 290345
AFDPSR

AREA FORECAST DISCUSSION 
NATIONAL WEATHER SERVICE PHOENIX AZ
845 PM MST TUE JAN 28 2014

.SYNOPSIS...
STRONG HIGH PRESSURE ALOFT WILL ALLOW DRY CONDITIONS TO PREVAIL 
THROUGH THE WEEK WITH A CONTINUATION OF WELL ABOVE NORMAL 
TEMPERATURES THROUGH THURSDAY. A COOLING AND MOISTENING TREND IS 
EXPECTED BY FRIDAY...CONTINUING THROUGH THE WEEKEND WITH 
TEMPERATURES FINALLY FALLING BACK TO NORMAL BY SUNDAY.

&&

.DISCUSSION...
NO WEATHER PROBLEMS EXPECTED THROUGH THURSDAY. HIGH PRESSURE... 
PERIODS OF HIGH CLOUDS...AND MUCH ABOVE NORMAL TEMPERATURES WILL 
CONTINUE THROUGH THURSDAY.

A COLD DOWN IS STILL EXPECTED BEGINNING FRIDAY...AND CONTINUING THIS 
WEEKEND AS THE STORM TRACK PENETRATES THE WESTERN STATES AND EDGES 
CLOSER TO AZ. FORECAST DETAILS FOR FRI AND THE WEEKEND ARE FOUND 
BELOW IN THE PREVIOUS DISCUSSION. FORECASTS LOOK GOOD. NO WEATHER 
UPDATES PLANNED THIS EVENING.

PREVIOUS DISCUSSION...
DRY NORTHWESTERLY FLOW HAS TAKEN OVER ACROSS THE REGION WHILE A WARM 
AIRMASS REMAINS IN PLACE. THE FORECAST CHALLENGE OVER THE NEXT 
COUPLE DAYS WILL BE HOW MUCH CLOUD COVER WILL MOVE IN THROUGH THE 
UPPER RIDGE NOW TO OUR WEST AND HOW THEY MAY AFFECT AREA 
TEMPERATURES. THIS RIDGE WILL SHIFT EAST OVER THE NEXT COUPLE OF 
DAYS WITH 576-582DM 500MB HEIGHTS PEAKING OVER OUR FORECAST AREA BY 
WEDNESDAY AFTERNOON. AS AN UPSTREAM SHORTWAVE TROUGH DIVES 
SOUTHEASTWARD OFF THE PACIFIC NORTHWEST COAST...THE RIDGE WILL BEGIN 
TO FLATTEN WEDNESDAY NIGHT INTO THURSDAY. MODEL LAYER RH FORECASTS 
SUGGEST THAT HIGH CLOUDS WILL CONTINUE TO SPILL INTO THE 
REGION...BUT AT THIS TIME NOT EXPECTING TO HAVE ALL THAT MUCH OF AN 
AFFECT ON AFTERNOON HIGHS WEDNESDAY AND THURSDAY. MODELS SHOW 850MB 
TEMPS WARMING 2-4C DEGREES THROUGH THURSDAY...ESPECIALLY OVER 
SOUTHWEST AZ AND SOUTHEAST CA. ALTHOUGH 500MB HEIGHTS BEGIN DROPPING 
ON THURSDAY...THICKNESSES WILL BE SLOWER TO RESPOND AS WARMER AIR 
ADVECTS INTO THE CWA WITH SFC-850MB SOUTH TO SOUTHWESTERLY FLOW. 
DAYTIME TEMPERATURES WEDNESDAY WILL TOP OUT IN THE LOWER 80S ACROSS 
THE SOUTHEAST CALIFORNIA DESERTS AND MID TO UPPER 70S ACROSS THE 
SOUTH-CENTRAL ARIZONA DESERTS. THURSDAY IS EXPECTED TO BE THE 
WARMEST DAY WITH HIGHS IN THE LOWER 80S ACROSS NEARLY ALL THE LOWER 
DESERTS. THE CURRENT FORECAST HIGH OF 81 ON THURSDAY AT PHOENIX IS 
ONLY ONE OFF THE CURRENT RECORD OF 82 SET BACK IN 1935.

A LARGE SCALE PATTERN SHIFT WILL OCCUR FRIDAY AND PERSIST THROUGH 
THE WEEKEND AS THE PACIFIC JET BECOMES MORE ACTIVE AND THE EASTERN 
CONUS TROUGH WEAKENS. AS THIS HAPPENS...THE EASTERN PACIFIC RIDGE 
RETROGRADES OVER THE NORTH CENTRAL PACIFIC...AND ENERGY BEGINS TO  
UNDERCUT THE RIDGE AND PHASE WITH WAVES DIVING SOUTH FROM NORTHWEST 
CANADA...THUS BROADENING A TROUGH OVER THE WESTERN CONUS. MODELS ARE 
IN GOOD AGREEMENT AS TO THIS PATTERN DEVELOPMENT...BUT THE TIMING 
AND PLACEMENT OF SOME OF THE SHORT WAVE FEATURES THAT CARVE OUT THE 
TROUGH ARE STILL SKETCHY. THERE DOES APPEAR TO BE SOME MODEL 
AGREEMENT THAT SUBSEQUENT ENERGY DIGGING SOUTHWARD WILL BE CAPABLE 
OF TAPPING BETTER QUALITY MOISTURE AND ASCENT INTO THE REGION EARLY 
NEXT WEEK. SO THE TREND IS TOWARD COOLER TEMPERATURES...INCREASING 
MOISTURE...AND POSSIBLY SOME SLIGHT CHANCES OF PRECIPITATION MAINLY 
OVER THE HIGHER TERRAIN OF SOUTH-CENTRAL ARIZONA SUNDAY INTO MONDAY. 

&&

.AVIATION... 
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL...SOUTHWEST 
ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH...

THROUGH AT LEAST 20Z WED...VARIABLE HIGH CLDS AOA 25 THSD MSL. LIGHT 
WIND UNDER 7 KNOTS. 

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
THURSDAY THROUGH MONDAY...
HIGH PRESSURE WILL BEGIN TO WEAKEN THURSDAY AS A LOW PRESSURE SYSTEM 
PASSES TO THE NORTH. THIS WILL ALLOW FOR STRONGER WESTERLY WINDS 
ALOFT WHICH WILL TRANSLATE TO MODERATE BREEZINESS THURSDAY AND 
FRIDAY...MAINLY OVER SOUTHEAST CALIFORNIA AND AT RIDGETOPS 
ELSEWHERE. A COOLING TREND IS EXPECTED TO BEGIN FRIDAY AND CONTINUE 
INTO EARLY NEXT WEEK LEADING TO HIGH TEMPERATURES AT OR SLIGHTLY 
BELOW NORMAL BY MONDAY. THERE WILL ALSO BE A SLIGHT CHANCE OF 
SHOWERS MONDAY OVER THE HIGHER TERRAIN. MINIMUM HUMIDITIES WILL BE 
LOW THURSDAY THEN INCREASE CONSIDERABLY FRIDAY BEFORE TRENDING 
DOWNWARD AGAIN. MAXIMUM HUMIDITIES WILL REMAIN GOOD. 
 
&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

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DISCUSSION...VASQUEZ/KUHLMAN/MEYERS
AVIATION...VASQUEZ
FIRE WEATHER...AJ