Area Forecast Discussion
Issued by NWS Phoenix, AZ

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000 FXUS65 KPSR 290301 AFDPSR AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PHOENIX AZ 805 PM MST MON JUL 28 2014 .SYNOPSIS... DRIER AIR WILL MOVE INTO THE REGION TUESDAY THROUGH LATE WEEK...WITH SIGNIFICANTLY REDUCED STORM CHANCES AND HOTTER TEMPERATURES. BETTER STORM CHANCES WILL EVENTUALLY INCREASE AGAIN FRIDAY INTO THE WEEKEND AS MOISTURE MOVES BACK INTO THE SOUTHWEST UNITED STATES. && .DISCUSSION... OTHER THAN AN ISOLATED SHRA/TS PERCOLATING OVER HIGHER TERRAIN OF NORTHERN PINAL COUNTY...ACTIVITY IS VIRTUALLY ABSENT OVER THE FORECAST AREA THIS EVENING. A LARGER CIRCULATION CENTER PROPAGATING NORTH INTO SOUTHERN NEVADA HAS BROUGHT A COMBINATION OF DEEPER SUBSIDENCE AND DRYING WESTERLY FLOW ALOFT INTO THE SOUTHWESTERN QUARTER OF ARIZONA. 00Z KTWC AND KPSR SOUNDING DATA SHOWS BOUNDARY LAYER MIXING RATIOS STILL LINGERING IN THE 9-11 G/KG RANGE WHILE TOTAL COLUMN PWATS SIT BETWEEN 1.25 AND 1.50 INCHES. HOWEVER...A NOTABLE SHIFT IN H7-H5 WINDS TO A WESTERLY DIRECTION AND INTRODUCTION OF LESS FAVORABLE MIDLEVEL LAPSE RATES PORTEND LITTLE ADDITIONAL SUPPORT FOR CONVECTIVE ACTIVITY AND MOSTLY QUIET CONDITIONS FOR THE REMAINDER OF THE NIGHT. THEREFORE...HAVE SIGNIFICANTLY REDUCED POPS THROUGH TUESDAY..WHILE ALSO MAKING SOME MODIFICATIONS OF HOURLY TEMPERATURES BASED ON CURRENT TRENDS. && .PREVIOUS DISCUSSION... /225 PM MST MON JUL 28 2014/ TUESDAY THROUGH SUNDAY...A DRAMATIC DECREASE THE AMOUNT OF CONVECTION ACROSS THE AREA...WITH THE FOCUS FOR ANY PRECIPITATION IN THE MOUNTAINS EAST OF PHOENIX THROUGH THE MIDDLE OF THE WEEK. MEAN BL MIXING RATIOS DROP TO AROUND 6 G/KG DURING THE MIDDLE PART OF THE WEEK AND EVEN CLIMO POPS MAY END UP BEING TOO HIGH. WITH DRIER AIR WORKING INTO THE AREA MID WEEK...TEMPS WILL LIKELY TAKE A RUN INTO THE 105-109 RANGE ACROSS THE DESERTS. CONSEQUENTLY...THERE SHOULD BE A SLIGHT DROP-OFF BY THE WEEKEND AS DEEPER MOISTURE MAKES ITS WAY BACK INTO THE AREA. STILL ABOVE 100 BUT SOMEWHAT LOWER THAN THE MID WEEK VALUES. MADE SLIGHT REDUCTIONS TO POPS ACROSS THE BOARD FROM TUESDAY THROUGH THURSDAY BASED ON LATEST GUIDANCE WITH THE HIGHEST VALUES DISPLACED WELL EAST OF THE DESERTS. THE MONSOON MOISTURE WONT BE TERRIBLY FAR AWAY...WINDS PER THE TWO-THREE MOST RECENT RUNS OF THE EUROPEAN AND GFS BRING INCREASED MIXING RATIOS BACK INTO THE AREA FRIDAY AND ALMOST CERTAINLY BY THE WEEKEND. PRECIP CHANCES ONCE AGAIN LOOK FAVORABLE FOR THE LATTER PORTIONS OF THE FORECAST PERIOD ALTHOUGH ITS STILL DIFFICULT TO HIGHLIGHT ONE DAY VS ANOTHER UNTIL WE GET A LITTLE CLOSER. && .AVIATION... SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL... ALTHOUGH AN ISOLATED TS WILL STILL BE POSSIBLE THIS EVENING SURROUNDING CNTRL ARIZONA...DIRECT IMPACTS ON TERMINALS ARE UNLIKELY. NO OTHER STORMS WERE NOTED IN THE SRN OR ERN PARTS OF THE STATE...AND LIGHT WESTERLY OR VARIABLE WINDS WILL LIKELY PREVAIL LONGER INTO THE OVERNIGHT HOURS THAN PREVIOUS NIGHTS. OTHERWISE...ONLY FEW/SCT MID/HIGH CLOUDS EXPECTED THROUGH TUESDAY...WITH STORM CHANCES TUESDAY AFTERNOON FAR LOWER THAN RECENT DAYS. SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH... NO AVIATION IMPACTS EXPECTED THROUGH TUESDAY AFTERNOON WITH ONLY OCCASIONAL MID/HIGH CLOUDS GENERALLY CLEARING THROUGH TUESDAY. STORM CHANCES WILL BE ALMOST NIL BEYOND THIS EVENING THROUGH TUESDAY. AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... THURSDAY THROUGH MONDAY... DRIER THAN NORMAL CONDITIONS EXPECTED THROUGH THURSDAY. STORM CHANCES WILL BE SLIGHT AND WILL BE LIMITED TO THE HIGHER TERRAIN OF EASTERN ARIZONA. LATE IN THE WEEK AND OVER THE WEEKEND...AN INCREASE IN MOISTURE AND ASSOCIATED HUMIDITIES IS ANTICIPATED AND STORM CHANCES...THOUGH SLIGHT...EXPAND TO THE LOWER ELEVATIONS. HIGH TEMPERATURES TREND DOWNWARD AS WELL. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...NONE. CA...NONE. && $$ VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX DISCUSSION...MO/MEYERS/LEINS AVIATION...MO FIRE WEATHER...HIRSCH/AJ

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