Area Forecast Discussion
Issued by NWS Phoenix, AZ

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000 FXUS65 KPSR 271105 AAA AFDPSR AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE PHOENIX AZ 405 AM MST THU NOV 27 2014 .UPDATE...UPDATED AVIATION AND FIRE WEATHER DISCUSSIONS... && .SYNOPSIS... A WARM AND DRY STRETCH OF WEATHER WILL AFFECT THE REGION THROUGH THE UPCOMING WEEKEND UNDER HIGH PRESSURE ALOFT. HIGH TEMPERATURES WILL BE THE WARMEST TODAY...PEAKING IN THE UPPER LOWER 80S... AND THEN SLOWLY COOL THROUGH EARLY NEXT WEEK WHILE STILL REMAINING WELL ABOVE SEASONAL NORMALS. A LOW PRESSURE SYSTEM EXPECTED FOR EARLY OR MID NEXT WEEK WILL BRING CHANCES FOR RAIN AND COOLER TEMPERATURES. && .DISCUSSION... ANOTHER QUIET DAY UNDER CLEAR SKIES IS IN STORE FOR TODAY...BUT WITH MUCH WARMER TEMPERATURES. HIGHS FOR TODAY SHOULD BREAK 80 DEGREES IN MOST LOWER DESERT LOCATIONS WHICH IS AROUND 10 DEGREES ABOVE NORMAL. THE PACIFIC RIDGE OF HIGH PRESSURE IN PLACE OVER THE WESTERN UNITED STATES BRINGING THE WARM CONDITIONS WILL PERSIST INTO THE COMING WEEKEND...BUT GRADUALLY FLATTEN OUT AS AN UPSTREAM TROUGH DIGS INTO THE PACIFIC NORTHWEST LATE FRIDAY INTO SATURDAY. 500MB HEIGHTS OF 572-576DM STARTING FRIDAY AND LIKELY LASTING INTO EARLY NEXT WEEK WILL PROVIDE FOR CONTINUED ABOVE NORMAL TEMPERATURES ACROSS THE REGION. EXPECTING TO SEE SOME GRADUAL COOLING AFTER TODAY...BUT LOWER DESERT HIGHS IN THE MID TO UPPER 70S SHOULD PERSIST AT LEAST THROUGH NEXT MONDAY. A MUCH MORE COMPLEX SYNOPTIC PATTERN IS IN STORE FOR THE EASTERN PACIFIC AND WESTERN UNITED STATES FOR NEXT WEEK AS MODELS CONTINUE TO ADVERTISE A DEEP CUT-OFF LOW OVER THE EASTERN PACIFIC FOR EARLY NEXT WEEK. OVERALL...LONG RANGE MODELS AGREE THERE WILL BE A STRONG POLAR JET DIGGING SOUTHWARD THIS WEEKEND ACROSS THE EASTERN PACIFIC GIVING RISE TO A DEEP CLOSED LOW BY SUNDAY NIGHT INTO MONDAY. THIS DEEP LOW SITUATED WELL OFF THE CALIFORNIA COAST LOOKS LIKE IT WILL ALSO INTERACT WITH A STRENGTHENING SUB-TROPICAL JET AND MOISTURE FEED. BEYOND MONDAY...MODELS DISAGREE WITH THE EVOLUTION OF THE LOW AND HOW MUCH MOISTURE WILL EVENTUALLY MAKE ITS WAY INTO THE DESERT SOUTHWEST VIA THE SUB-TROPICAL JET. BEST RAIN CHANCES FOR OUR REGION STILL LOOKS TO BE LATER TUESDAY INTO EARLY WEDNESDAY MOST LIKELY RESULTING FROM THE POTENTIAL STRONG MOISTURE SURGE FROM THE SUB-TROPICAL JET INFLUENCE AND BROAD BUT WEAK ASCENT ALOFT. THE LAST FEW MODEL RUNS HAVE TRENDED TOWARD A SLOWER EVOLUTION OF THE LOW AND A BIT DRIER SOLUTION. THE OPERATIONAL GFS AND GFS ENSEMBLE GENERALLY POINTS TOWARD A STRONGER MOISTURE FEED AND BETTER RAIN CHANCES STARTING SOMETIME TUESDAY AND LIKELY ENDING EARLY WEDNESDAY. THE EUROPEAN HAS BEEN TRENDING TOWARD A DRIER OR EVEN COMPLETELY DRY SOLUTION...KEEPING THE CLOSED LOW FURTHER OFF THE COAST WHILE ALSO BRINGING MUCH LESS MOISTURE NORTHWARD. GIVEN THE OVERALL DRYING TREND...HAVE TRIMMED POPS SLIGHTLY FOR TUESDAY AND WEDNESDAY...BUT KEPT SLIGHT CHANCE AND CHANCE POPS FAIRLY WIDESPREAD ACROSS THE CWA. TEMPERATURES HAVE BEEN EDGED HIGHER TO SLIGHTLY ABOVE NORMAL VALUES THROUGH THE MIDDLE OF NEXT WEEK. && .AVIATION... SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL... SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA...INCLUDING KIPL AND KBLH... UPPER LEVEL RIDGE OVER THE DESERT SOUTHWEST WILL ALLOW FOR MOSTLY CLEAR SKIES AND LIGHT WINDS AT ALL TERMINALS THROUGH AT LEAST FRIDAY. WINDS WILL FAVOR TYPICAL DIURNAL TRENDS AT ALL SITES...GENERALLY 5 KTS OR LESS. REGARDING THE MULCH FIRE NEAR LUKE AIR FORCE BASE...THIS SHOULD ONLY HAVE AN IMPACT ON SLANT VSBYS AS WINDS SHOULD BE TOO LIGHT TO CARRY DENSE SMOKE TO ANY OF THE MAIN PHOENIX TERMINALS. AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... SATURDAY THROUGH WEDNESDAY... HIGH PRESSURE WILL REMAIN IN CONTROL THROUGH MONDAY...RESULTING IN A CONTINUED PERIOD OF MOSTLY CLEAR SKIES AND DRY CONDITIONS. SINGLE DIGIT HUMIDITIES WITH FAIR OVERNIGHT RECOVERIES WILL BE COMMON THROUGH THE WEEKEND. STILL MONITORING THE POTENTIAL FOR A LARGE UPPER LEVEL STORM SYSTEM TO MOVE THROUGH THE AREA BY THE MIDDLE OF NEXT WEEK. SOME MODEL DIFFERENCES HAVE BECOME MORE AND MORE EVIDENT OVER THE PAST FEW RUNS...THUS CONFIDENCE IN EXACTLY HOW THE FORECAST WILL EVOLVE NEXT WEEK IS LOW. STILL HANGING ONTO THE IDEA OF INCREASING RAIN CHANCES AND ELEVATED HUMIDITIES BY TUESDAY/WEDNESDAY. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...NONE. CA...NONE. && $$ VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX DISCUSSION...KUHLMAN AVIATION...LEINS FIRE WEATHER...LEINS

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