Area Forecast Discussion
Issued by NWS Phoenix, AZ

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS65 KPSR 011143
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
442 AM MST SUN MAR 1 2015

.UPDATE...UPDATED AVIATION AND FIRE WEATHER DISCUSSIONS...

&&

...PROLONGED WET WINTER WEATHER EVENT ACROSS THE DESERT SOUTHWEST
SUNDAY THROUGH LATE MONDAY...

&&

.SYNOPSIS...
LOW PRESSURE WILL CONTINUE A SLOW APPROACH OF THE FORECAST
AREA...BRINGING MOISTURE INTO THE REGION ALONG WITH INCREASING
CHANCES OF SHOWERS TODAY AND MONDAY. PERIODS OF HEAVY RAIN ARE
POSSIBLE AT TIMES ESPECIALLY SUNDAY NIGHT THROUGH MONDAY AFTERNOON.
COOLER TEMPERATURES WILL ALSO ACCOMPANY THIS STORM WITH BELOW NORMAL
READINGS EXPECTED MONDAY THROUGH MID WEEK. A RETURN TO ABOVE NORMAL
TEMPERATURES IS LIKELY BY LATE WEEK.

&&

.DISCUSSION...
EARLY MORNING WATER VAPOR IMAGERY DEPICTS A SLOWLY RETROGRADING AREA
OF LOW PRESSURE OFF THE SOUTHERN CALIFORNIA COAST...WITH QUITE A BIT
OF MID AND HIGH CLOUD COVER DEVELOPING DOWNWIND OF THE COASTAL
MOUNTAINS ALONG THE LOWER COLORADO RIVER VALLEY. FINALLY AFTER MUCH
ANTICIPATION...PRECIP APPEARS TO BE DEVELOPING ACROSS THE WESTERN
PORTIONS OF THE FORECAST AREA AS RADAR RETURNS HAVE INCREASED
SUBSTANTIALLY SINCE 07Z. MOST THE THE PRECIP THAT IS REACHING THE
GROUND IS STILL CONFINED TO THE HIGHER TERRAIN NORTH OF PHOENIX BUT
NONETHELESS IT`S A GOOD SIGN THAT THE ATMOSPHERE IS RESPONDING TO
THE SUBTROPICAL MOISTURE THAT`S BEING ADVECTED INTO THE AREA.

LOW PRESSURE WILL CONTINUE ITS SLOW TREK DOWN THE CALIFORNIA COAST
TODAY...EVENTUALLY STALLING OUT WEST OF SAN DIEGO THIS AFTERNOON. IN
THE MEANTIME IT WILL CONTINUE TAPPING INTO THE ANOMALOUSLY MOIST
SUBTROPICAL PLUME OF MOISTURE THAT IS EVIDENT ON WATER VAPOR IMAGERY
SOUTH OF THE BAJA SPUR. RAIN SHADOWING DOWNWIND OF THE COASTAL
MOUNTAINS WILL PRECLUDE WIDESPREAD PRECIP FROM DEVELOPING THIS
MORNING...BUT EVENTUALLY ENOUGH MOISTURE WILL BUILD UP ACROSS
SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA THAT SHOWERS WILL BECOME
MORE WIDESPREAD IN NATURE. THE INHERITED FORECAST ALREADY DEPICTED
THIS SCENARIO AND I ONLY MADE MINOR CHANGES TO THE FORECAST FOR THE
WESTERN FORECAST AREA. TO THE EAST HOWEVER...IT STILL LOOKS LIKE
PRECIP WILL BE SLOW TO DEVELOP AROUND THE PHOENIX AREA...POSSIBLY
HOLDING OFF UNTIL SUNDAY EVENING/EARLY MONDAY MORNING. LATEST NAEFS
GUIDANCE AND THE PAST 2-3 RUNS OF THE SREF INDICATE THE BEST CHANCE
OF PRECIP WILL COME AFTER 00Z TONIGHT AND THUS I TRIMMED POPS A BIT
FOR TODAY. ONLY THINKING WE WILL SEE 20-30 PERCENT CHANCES AROUND
THE METRO...CERTAINLY LOOKING AT HIGHER CHANCES IN THE FOOTHILL
LOCATIONS NORTH/WEST/EAST OF PHOENIX BUT IT LOOKS MORE AND MORE
LIKELY THAT THE MORE WIDESPREAD RAIN WILL BE DELAYED A BIT.

THE QUASI-STATIONARY LOW WEST OF SAN DIEGO WILL GET KICKED THROUGH
THE AREA TOMORROW BY A RAPIDLY APPROACHING SECONDARY TROUGH MOVING
THROUGH NEVADA. THIS WILL BRING MORE WIDESPREAD PRECIP THROUGH THE
ENTIRE FORECAST AREA MONDAY MORNING/MONDAY AFTERNOON...WITH RAPID
CLEARING FROM WEST TO EAST MONDAY NIGHT. WHILE 500MB TEMPERATURE
FORECASTS HAVE RISEN OVER THE PAST FEW DAYS...BUFR SOUNDINGS
INDICATE ENOUGH INSTABILITY POTENTIAL COINCIDENT WITH THE PASSAGE OF
THE TROUGH TO WARRANT AT LEAST A SLIGHT CHANCE OF THUNDER. ONCE THE
TROUGH AXIS MOVES INTO NEW MEXICO MONDAY NIGHT...PRECIP CHANCES /AND
THE POTENTIAL FOR THUNDER/ WILL DROP CONSIDERABLY. AS FOR STORM
TOTAL PRECIP VALUES...ENSEMBLE MEAN IS AROUND 0.75 INCHES ALONG AND
NORTH OF I-10 WITH CLOSER TO 1-1.5 INCHES IN THE OROGRAPHICALLY
FAVORED UPSLOPE AREAS ACROSS NORTHERN LA PAZ COUNTY TO
WICKENBURG...CAVE CREEK...AND THE MOUNTAINS OF SOUTHERN GILA COUNTY.
MADE SOME SLIGHT ADJUSTMENTS TO STORM TOTAL QPF BASED ON THE SLOWER
ARRIVAL OF THE HEAVIER PRECIP BUT STILL ENOUGH TO KEEP THE FLOOD
WATCH INTACT.

THE IMPACTS ASSOCIATED WITH THE SECONDARY TROUGH ON TUESDAY HAVE
BEEN THE SOURCE OF MUCH DEBATE DUE TO VARYING MODEL SOLUTIONS...AND
INDIVIDUAL ENSEMBLE MEMBERS ARE STILL ALL OVER THE MAP THIS MORNING.
NO DOUBT THERE WILL BE SOME LINGERING MOISTURE IN THE AREA...THE
QUESTION IS IF THERE WILL BE ENOUGH FORCING WITH THIS SECONDARY
TROUGH TO TRIGGER SHOWERS ACROSS THE AREA. FELT IT PRUDENT TO KEEP
THE CHANCE OF PRECIP LINGERING ACROSS THE EASTERN HALF OF THE
FORECAST AREA ON TUESDAY ALTHOUGH MOST OF THE SHOWERS SHOULD BE TO
THE NORTH/EAST OF PHOENIX. 00Z DETERMINISTIC MODELS HAVE TRENDED
DRIER ON TUESDAY...WILL NEED TO SEE IF THIS TREND CONTINUES AND IF
THE ENSEMBLES PICK UP ON THIS DRIER SOLUTION.

FROM MID-WEEK ONWARD...RIDGING WILL TAKE HOLD ACROSS THE REGION AND
CONSEQUENTLY TEMPERATURES WILL ALSO CLIMB BACK ABOVE NORMAL BY LATE
WEEK INTO THE WEEKEND.

&&

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

A SLOW APPROACHING COLD FRONT WILL CONTINUE TO DRAW LOW LEVEL
MOISTURE INTO THE AREA FROM NORTHERN BAJA TODAY. ANY SHOWER ACTIVITY
THROUGH THIS AFTERNOON WILL MAINLY STAY TO THE NORTH AND WEST OF THE
PHOENIX TERMINALS...BUT A FEW LIGHT SHOWERS MAY AFFECT KSDL. CIGS
FOR NOW SHOULD STAY ABOVE 8KT FEET THROUGH THE AFTERNOON HOURS...BUT
IF ANY SHOWERS DO OCCUR...CIGS WOULD TEMPORARILY DROP TO AROUND 5-6K
FEET. THE COLD FRONT AND AREA OF RAIN WILL APPROACH THE PHOENIX AREA
SOMETIME LATE THIS EVENING INTO TONIGHT...BUT CONFIDENCE IN THE
EXACT TIME OF ARRIVAL OF THE RAIN...LOWER CIGS...AND ANY RESTRICTED
VISIBILITIES IS STILL SOMEWHAT LOW.

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

MID LEVEL CIGS WILL GRADUALLY LOWER THIS MORNING AND EVENTUALLY DROP
TO MVFR BY AROUND NOON AFTER SOME STEADY RAIN MOVES IN. CONFIDENCE
IS FAIRLY HIGH THAT A BAND OF LIGHT TO MODERATE RAIN WILL AFFECT
SOUTHEAST CALIFORNIA AND PORTIONS OF SOUTHWEST ARIZONA THIS
AFTERNOON INTO THIS EVENING. MAY SEE SOME MVFR VISIBILITIES AT TIMES
DUE TO THE RAIN AND POTENTIALLY IFR CIGS BRIEFLY DEPENDING ON HOW
STEADY THE RAIN ENDS UP BEING. RAIN SHOULD DIMINISH AFTER 09Z
TONIGHT WITH GRADUALLY IMPROVING CIGS BY 12Z MONDAY MORNING..

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
TUESDAY THROUGH SATURDAY...
COOL AND STILL RELATIVELY MOIST CONDITIONS WILL BE PRESENT ON
TUESDAY WITH LINGERING RAIN CHANCES ACROSS SOUTH-CENTRAL ARIZONA.
WEAK HIGH PRESSURE AND DRYING CONDITIONS WILL MOVE IN STARTING
WEDNESDAY. TEMPERATURES WILL WARM BACK TOWARD NORMALS BY THURSDAY
AND THEN A FEW DEGREES ABOVE NORMAL FOR FRIDAY AND SATURDAY. WINDS
WILL BE RELATIVELY LIGHT THROUGH THE PERIOD...BUT AFTERNOON
BREEZINESS IS EXPECTED ON WEDNESDAY THROUGH FRIDAY. MINIMUM
HUMIDITIES WILL DROP INTO THE 20S ON WEDNESDAY AND THEN INTO THE
TEENS EACH AFTERNOON STARTING THURSDAY.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...FLOOD WATCH FROM 5 PM TODAY THROUGH 5 PM MONDAY AZZ021>024.

CA...NONE.

&&

$$

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

DISCUSSION...LEINS
AVIATION...KUHLMAN
FIRE WEATHER...KUHLMAN







USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.