Area Forecast Discussion
Issued by NWS Phoenix, AZ

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000
FXUS65 KPSR 261010
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
310 AM MST MON JAN 26 2015

.SYNOPSIS...
A LOW PRESSURE SYSTEM WILL AFFECT THE REGION TODAY AND TONIGHT
BRINGING AN INCREASE IN MOISTURE AND A PERIOD OF LIGHT RAIN.
THIS DISTURBANCE WILL MOVE NORTH OF THE REGION ON TUESDAY...AND IN
ITS WAKE ABOVE NORMAL TEMPERATURES AND HIGHER THAN NORMAL HUMIDITIES
WILL PREVAIL. ANOTHER LOW PRESSURE SYSTEM WILL BRING ADDITIONAL
MOISTURE AND ANOTHER CHANCE FOR PRECIPITATION LATE IN THE WEEK AND
INTO THE WEEKEND.

&&

.DISCUSSION...
AN UPPER LEVEL LOW CENTERED WELL WEST OF BAJA CONTINUES TO WOBBLE TO
THE WEST-NORTHWEST WHILE STRONG SOUTHEASTERLY MID LEVEL FLOW OVER
NORTHERN MEXICO STREAMS MOISTURE NORTHWARD INTO ARIZONA. CURRENT IR
IMAGERY SHOWS AN EXTENSIVE BAND OF CLOUDS OVER SOUTHERN ARIZONA AND
NORTHERN MEXICO. AS THE UPPER LOW CENTER AND A JET STREAK POSITIONED
OVER NORTHERN BAJA AND SOUTHERN CALIFORNIA LIFT NORTHWESTWARD OVER
THE NEXT 12 HOURS...THE BAND OF CLOUDS AND MOISTURE WILL GET
STRETCHED AND EVENTUALLY LIFT NORTHWARD INTO CENTRAL ARIZONA BY THIS
AFTERNOON. ANTICIPATING A BAND OF RAIN SHOWERS TO DEVELOP BY MID
MORNING IN AN AREA OF FAVORED VERTICAL ASCENT OVER SOUTHWEST ARIZONA
AND SOUTHEAST CALIFORNIA. MODEL QPF ALONG WITH HIGH-RES MODEL
FORECAST REFLECTIVITY PAINT A LARGE AREA OF RAIN AFFECTING THE
AFOREMENTIONED AREAS THROUGH AROUND NOON. THE STRONGEST MID LEVEL
OMEGA OVER SOUTHEAST CALIFORNIA BETWEEN 12-18Z AND PRECIPITABLE
WATER VALUES QUICKLY INCREASING TO JUST OVER ONE INCH BOTH SUPPORT
THIS AREA OF EXPECTED RAIN.

AS THE BULK OF THE MOISTURE GRADUALLY SHIFTS NORTHWARD INTO CENTRAL
ARIZONA BY LATE IN THE AFTERNOON AHEAD OF A NORTHWARD MOVING
SHORTWAVE TROUGH...AM EXPECTING ANOTHER RAIN BAND TO FORM FURTHER TO
THE EAST AND EVENTUALLY SWING THROUGH THE PHOENIX AREA SOMETIME THIS
EVENING. THE LATEST MODEL RUNS HAVE BACKED OFF SLIGHTLY ON QPF
AMOUNTS OVER SOUTH-CENTRAL ARIZONA AS THE BEST AREA OF VERTICAL
ASCENT HAS SHIFTED TO THE WEST A BIT. STILL THINKING NEARLY ALL THE
CWA WILL COME AWAY WITH AT LEAST SOME LIGHT RAIN. BY THE TIME THE
RAIN ENDS SOMETIME TUESDAY MORNING...STORM TOTAL RAINFALL AMOUNTS
SHOULD VARY BETWEEN 0.10-0.25 INCHES IN MOST AREAS WITH POSSIBLY
SOME LOCALIZED HALF INCH AMOUNTS OVER FAR SOUTHWEST ARIZONA AND
SOUTHEAST CALIFORNIA. THE TEMPERATURE FORECAST FOR TODAY IS A BIT
TRICKY WITH RAIN AFFECTING THE AREA. WENT 60-65 IN LOWER DESERT
SPOTS ACROSS SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA AND CLOSER
TO 70 IN PHOENIX SINCE THE RAIN WILL LIKELY HOLD OFF UNTIL THE EARLY
EVENING.

MUCH DRIER AIR ALOFT WILL SURGE IN LATE TONIGHT AND EARLY
TUESDAY...BUT AMPLE LOW LEVEL MOISTURE SHOULD INITIALLY KEEP SOME
LINGERING STRATO-CU CLOUDS OVER PARTS OF THE AREA THROUGH AROUND
NOON TUESDAY. FEEL WE SHOULD HAVE ENOUGH SUN ON TUESDAY TO WARM
THINGS BACK UP TO ABOVE NORMAL WITH MOST LOWER DESERT AREAS BREAKING
70 DEGREES. THE UPPER LEVEL LOW WILL QUICKLY SHIFT INTO THE GREAT
BASIN ON TUESDAY LEAVING A BRIEF PERIOD OF RIDGING OVER THE DESERT
SOUTHWEST. THIS SHOULD LAST THROUGH WEDNESDAY PROVIDING ANOTHER WARM
DAY WITH MOSTLY CLEAR SKIES. HOWEVER...ANOTHER UPPER LOW TRAILING
BEHIND THIS FIRST ONE WILL MOVE INTO OUR REGION STARTING WEDNESDAY
NIGHT. INITIALLY THIS SYSTEM WILL JUST BE A WEAK OPEN WAVE AS IT
NEARS THE SOUTHWESTERN COAST...BUT WE WILL START TO SEE A GOOD DEAL
OF MID AND UPPER LEVEL MOISTURE STREAMING IN FROM THE SOUTHWEST BY
THURSDAY MORNING.

THE SYSTEM FOR LATE THIS WEEK WILL FORM IN AN UPPER LEVEL SPLIT FLOW
SYNOPTIC REGIME AND BY LATE FRIDAY A SUPPORTING JET STREAK WILL DIVE
SOUTHWARD INTO THE BACK SIDE OF THE DEVELOPING TROUGH ALLOWING THE
TROUGH DO DEEPEN. AT THIS POINT...MOISTURE SEEMS TO BE A BIT MORE
LIMITED THIS TIME AROUND AS THE LOW AND MID LEVEL FLOW REMAIN OUT OF
THE SOUTHWEST. HOWEVER...INITIALLY THERE SHOULD BE ENOUGH MOISTURE
AND DYNAMICS TO BRING SOME RAINFALL TO PORTIONS OF OUR AREA SOMETIME
FRIDAY. FOR NOW IT SEEMS BEST CHANCES WILL BE ACROSS SOUTH-CENTRAL
AND EASTERN ARIZONA. EXACT TIMING OF THE RAIN IS HARD TO NAIL DOWN
AT THIS POINT...BUT FEEL BEST CHANCES WILL BE DURING THE DAYTIME
HOURS FRIDAY. WOULD NOT BE SURPRISED IF WE HAVE LINGERING SHOWERS
THROUGH MUCH OF SATURDAY AS THE UPPER LOW COULD BE STATIONARY OVER
THE REGION FOR A DAY OR SO. HAVE DECREASED HIGHS BY A FEW DEGREES ON
FRIDAY OVER SOUTH-CENTRAL ARIZONA GIVEN THE HIGHER CONFIDENCE OF
RAIN AND KEPT FAIRLY SIMILAR VALUES FOR SATURDAY.

CONFIDENCE FOR THIS COMING WEEKEND IS STILL FAIRLY LOW AS MODELS
HAVE HAD SOME DIFFICULTY OVER THE PAST FEW MODEL RUNS...BUT IN
GENERAL IT WOULD SEEM THINGS MAY DRY OUT BY SATURDAY NIGHT OR EARLY
SUNDAY. SLIGHT CHANCE POPS REMAIN IN THE FORECAST INTO SATURDAY
NIGHT...BUT HAVE TRIMMED POPS ON SUNDAY WITH THE ONLY SLIGHT CHANCE
POPS NOW OVER THE HIGHER TERRAIN EAST OF PHOENIX.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA AND KSDL...

LITTLE TO NO AVIATION IMPACTS REST OF TONIGHT...WITH JUST SOME
MAINLY HIGH CLOUDINESS SPREADING OVER THE PHX AREA FROM THE SOUTH.
CIGS ARE THEN EXPECTED TO LOWER TO AROUND 10K FEET MONDAY
MORNING...WITH THESE CIGS HOLDING NEAR THESE LEVELS THROUGH MONDAY
AFTERNOON AS LOW PRESSURE BEGINS TO APPROACH FROM THE SOUTH. LIGHT
RAIN...WITH CIGS AOB 6K FT TO FINALLY MOVE INTO THE REGION BY EARLY
EVENING ON MONDAY. WINDS TO REMAIN MAINLY EASTERLY THROUGH THE THIS
PERIOD WITH SPEEDS MAINLY AOB 6 KNOTS...PERHAPS EVEN BECOMING RATHER
LIGHT/VARIABLE AT TIMES. MAY SEE CIGS LOWER TO NEAR OR EVEN BELOW
4-5K FEET OVERNIGHT MONDAY AND INTO EARLY TUESDAY MORNING AS LOW
LEVELS SATURATE.

FOR PLANNING PURPOSES...LIGHT RAIN THAT IS EXPECTED TO MOVE INTO
THE PHX AREA EARLY MONDAY EVENING TO CONTINUE INTO EARLY TUES
MORNING. CIGS DURING THIS PERIOD ARE EXPECTED TO REMAIN MAINLY IN
THE 4-6K FT RANGE...WITH FEW-SCT SCUD LAYERS DROPPING AS LOW AS 2-3K
FT AT TIMES. ALTHOUGH THE RAIN IS EXPECTED TO END TUES MORNING...
LIGHT WINDS AND A VERY MOIST AIRMASS IS EXPECTED TO ALLOW CIGS AOB
5K FT TO LINGER THROUGH AT LEAST MIDDAY TUES...WITH ONLY SLOW
CLEARING EXPECTED ON TUES AFTERNOON. WINDS TO REMAIN ON THE LIGHT
SIDE...MAINLY AOB 6 KTS THROUGH TUESDAY MIDDAY...MAINLY BLOWING FROM
AN EASTERLY DIRECTION.

SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH...

NO AVIATION IMPACTS THROUGH MONDAY MORNING WITH INCREASING CLOUDS
OVERNIGHT TONIGHT AND CIGS LOWERING TO 12-15K FEET BY SUNRISE. WINDS
WILL REMAIN LIGHT AND GENERALLY FAVOR A WESTERLY OR NORTHERLY
DIRECTION. RAIN AND LOWER CIGS WILL THEN MOVE INTO THE KIPL AREA BY
LATE MONDAY MORNING...AND INTO THE KBLH AREA BY MIDDAY OR EARLY AFTN
MON AS LOW PRESSURE APPROACHES FROM THE SOUTH...WITH CIGS AS LOW AS
3-5K FT AND VIS AS LOW AS 3-5 MILES AT TIMES DURING THIS RAIN
EVENT...WITH WINDS FAVORING AT NORTHERLY DIRECTION AT KBLH...AND
WESTERLY AT KIPL. CLEARING FROM THE SOUTH/SOUTHWEST EXPECTED MONDAY
NIGHT AS THE SHORTWAVE LIFTS TO THE NORTH.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
TUESDAY THROUGH SATURDAY...
NEAR TO SLIGHTLY ABOVE NORMAL TEMPERATURES EXPECTED THROUGH THE
PERIOD WITH WEDNESDAY AND THURSDAY BEING THE WARMEST DAYS. FAIRLY
MOIST CONDITIONS WILL EXIST AS SOUTHERLY FLOW PERSISTS ACROSS
THE DESERT SOUTHWEST. AN EXITING LOW PRESSURE SYSTEM EARLY TUESDAY
WILL BRING LINGERING RAIN CHANCES THROUGH TUESDAY AFTERNOON...WHILE
ANOTHER LOW PRESSURE SYSTEM IS FORECAST TO BRING MORE RAIN CHANCES
FOR THURSDAY NIGHT THROUGH POSSIBLY SATURDAY. THE MOIST CONDITIONS
WILL ONLY LEAD TO MINIMUM HUMIDITIES EACH AFTERNOON IN THE 25 TO 45
PERCENT RANGE. WITH THE EXCEPTION OF SOME OCCASIONAL EARLY MORNING
OR AFTERNOON BREEZINESS...WINDS WILL REMAIN LIGHT THROUGH THE ENTIRE
PERIOD.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...KUHLMAN
AVIATION...PERCHA/CB
FIRE WEATHER...KUHLMAN











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