Area Forecast Discussion
Issued by NWS Phoenix, AZ

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FXUS65 KPSR 022235
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
333 PM MST MON MAR 2 2015

.UPDATE...TO AVIATION DISCUSSION...

&&

.SYNOPSIS...
WIDESPREAD PRECIPITATION WILL CONTINUE TO SHIFT EASTWARD THIS
AFTERNOON AND INTO THE EVENING HOURS TONIGHT. PERIODS OF MODERATE TO
HEAVY RAIN ARE ANTICIPATED ACROSS SOUTH CENTRAL ARIZONA...ESPECIALLY
OVER THE HIGHER TERRAIN AND FOOTHILL LOCATIONS NORTH AND EAST OF
CENTRAL PHOENIX. THERE WILL ALSO BE A SLIGHT CHANCE OF THUNDERSTORMS
AS WELL THIS AFTERNOON AND EARLY EVENING. THERE WILL ALSO BE A
LINGERING SLIGHT CHANCE FOR SHOWERS OVER SOUTH CENTRAL ARIZONA
TUESDAY INTO WEDNESDAY AS THE SYSTEM SLOWLY EXITS TO THE EAST.
COOLER TEMPERATURES WILL ACCOMPANY THIS SYSTEM WITH BELOW NORMAL
READINGS EXPECTED THROUGH MID WEEK. A RETURN TO ABOVE NORMAL
TEMPERATURES IS LIKELY BY THURSDAY AS HIGH PRESSURE BUILDS INTO THE
DESERT SOUTHWEST.

&&

.DISCUSSION...
A RATHER COMPLICATED UPPER TROF ALONG THE WEST COAST CONTINUED TO
AFFECT THE DESERT SOUTHWEST...INCLUDING SERN CA AND ARIZONA...EARLY
THIS AFTERNOON. UPPER LOW CENTER CONTINUED TO SPIN ALONG THE FAR
SERN CA COAST...WHILE THE MAIN COLD FRONTAL BAND PUSHED EAST AND
INTO EAST-CENTRAL ARIZONA AT 130 PM. FRONT WAS MOVING PAST CENTRAL
PHOENIX AND INTO SOUTHERN GILA COUNTY...BUT WIDESPREAD SHOWERS
CONTINUED ACROSS MOST OF MARICOPA COUNTY AS WELL AS SOUTHERN GILA
COUNTY. RADAR AND GAGE REPORTS INDICATED THAT MOST RAINFALL TOTALS
SINCE NOON WERE LESS THAN ONE THIRD OF AN INCH...AND IN FACT MOST OF
THE GAGES IN THE MARICOPA COUNTY FLOOD CONTROL DISTRICT NETWORK
MEASURED WELL BELOW ONE QUARTER INCH SINCE 1230 PM. SO FAR WE HAVE
NOT SEEN THUNDERSTORM DEVELOPMENT ACROSS THE CENTRAL DESERTS...BUT
AN ISOLATED STORM IS POSSIBLE THIS AFTERNOON AND INTO THE EARLY
EVENING...AND ANY STORM THAT FORMS WILL LEAD TO LOCALLY MODERATE OR
HEAVY RAINFALL. AS A RESULT...WE WILL CONTINUE THE FLOOD WATCH FOR
MARICOPA COUNTY EASTWARD...AND WE HAVE DROPPED THE WATCH FOR ALL
AREAS WEST OF MARICOPA COUNTY.

FOR THE REST OF THIS AFTERNOON...WE MAY SEE A FEW SHOWERS OR EVEN A
THUNDERSTORM REDEVELOP OVER PORTIONS OF SERN AZ AS CONVECTION SPILLS
OVER THE COASTAL RANGES...AND MOVES INLAND AND AHEAD OF THE
WEAKENING UPPER LOW ALONG THE FAR SERN CA COAST. WE DO NOT EXPECT
SIGNIFICANT PRECIP WITH ANY SHOWERS/STORMS THAT MOVE THROUGH SERN CA
HOWEVER...BUT SOME SPOTS COULD SEE AMOUNTS IN EXCESS OF ONE QUARTER
INCH.

BY EARLY THIS EVENING...THE MAIN FOCUS OF THIS STORM SYSTEM...THE
FRONTAL BAND AND ASSOCIATED RAIN/RAIN SHOWER SHIELD...WILL PUSH EAST
AND INTO FAR EASTERN AZ AND NEW MEXICO. AT THE SAME TIME THE LOW
ALONG THE SERN CA COAST WILL WEAKEN AND BE MOVED INLAND AS A KICKER
LOW DROPS SOUTH ALONG THE CENTRAL CA COAST. AS SUCH THE CHANCES FOR
MEASURABLE PRECIP WILL DROP OFF SIGNIFICANTLY THIS EVENING...INTO
THE CHANCE CATEGORY OVER THE CENTRAL DESERTS WITH LINGERING LIKELY
POPS ACROSS SRN GILA COUNTY. AFTER MIDNIGHT TONIGHT WE EXPECT MAINLY
SINGLE DIGIT POPS ACROSS THE SWRN AZ DESERTS AS WELL AS SERN CA.
MODELS ARE CONSISTENT IN CALLING FOR THIS KICKER LOW TO DROP
SOUTHEAST TOWARDS THE NRN BAJA CA COAST TONIGHT...THEN SLOWLY DRIFT
EAST AND PASS BY ARIZONA TO THE SOUTH TUESDAY INTO WEDNESDAY. AS THE
LOW PASSES BY...DYNAMICS OVER SRN AZ BECOME WEAK...BUT SIGNIFICANT
LOW/MID LEVEL MOISTURE REMAINS IN PLACE AND AS SUCH WE WILL CONTINUE
A SLIGHT CHANCE FOR INSTABILITY SHOWERS OVER SOUTH CENTRAL AZ
TUESDAY AND TUESDAY NIGHT. IN FACT...INSTABILITY LOOKS TO BE A BIT
BETTER ON TUESDAY WITH LI VALUES GOING WEAKLY NEGATIVE AND THUS WE
HAVE A SLIGHT CHANCE FOR THUNDER IN THE FORECAST ACROSS SOUTH
CENTRAL AZ ON TUESDAY. BY WEDNESDAY AFTERNOON THE ONLY THREAT FOR
PRECIP WILL BE OVER THE HIGHER TERRAIN EAST OF PHOENIX...AND SKIES
WILL BECOME MOSTLY SUNNY FROM PHOENIX WESTWARD INTO SERN CA. TEMPS
TUESDAY AND WEDNESDAY WILLS STEADILY WARM BUT WILL REMAIN BELOW
SEASONAL NORMALS.

ONE ISSUE WE WILL CONTEND WITH TONIGHT WILL BE FOG POTENTIAL ACROSS
SOUTH CENTRAL ARIZONA. MANY LOCATIONS WILL SEE AT LEAST MODERATE
RAINFALL TOTALS TODAY...AND HUMIDITY LEVELS WILL REMAIN HIGH
OVERNIGHT. HOWEVER...WE EXPECT LINGERING LOW/MID CLOUD DECKS TONIGHT
INTO TUESDAY...REDUCING RADIATIONAL COOLING POTENTIAL. ALSO...
FORECAST SOUNDINGS ARE NOT CLASSICAL FOG SOUNDINGS. WINDS WILL BE
LIGHT BUT SHOULD NOT BE CALM FOR EXTENDED PERIODS. THUS...THERE MAY
BE PATCHY FOG WITH VISIBILITY DOWN BELOW 5 MILES AT TIMES BUT WE DO
NOT EXPECT SIGNIFICANT DENSE FOG. AS A COMPROMISE WE ADDED PATCHY
FOG TO OUR FORECAST ZONES EAST OF THE LOWER CO RIVER TONIGHT.

FOR THURSDAY...A DRYING AND SUBSIDENT NORTHERLY FLOW ALOFT WILL SET
UP ACROSS THE AREA AS HIGH PRESSURE ALOFT STARTS TO BUILD ALONG THE
CA COAST. THIS WILL LEAD TO SUNNY SKIES...AND CONTINUED WARMING
WITH HIGH TEMPS REACHING INTO THE LOW TO MID 70S...AND TOWARDS
SEASONAL NORMALS.

FRIDAY INTO THE WEEKEND...
A WARMING TREND IS EXPECTED TO CONTINUE THROUGH THIS PERIOD UNDER
MAINLY CLEAR SKIES AS HIGH PRESSURE STRENGTHENS OVER THE
REGION...WITH A DECENT CHANCE FOR HIGHS IN THE 80S ACROSS THE LOWER
DESERTS BY THE WEEKEND.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA AND KSDL...
MAIN RAIN SHOWER BAND REMAINS OVER THE EASTERN HALF OF THE PHX
METRO...WITH -SHRA/VCSH TO CONTINUE FOR KPHX...KIWA AND KSDL OVER
THE NEXT FEW HOURS. RAIN WILL CONTINUE TO TRANSITION EAST OF THE
AREA...WITH SHOWER CLEARING ALREADY NOTED ACROSS THE WESTERN
PORTIONS OF THE PHX METRO. WINDS TO GNLY HOLD POST-FRONTAL WEST TO
NORTHWEST HEADINGS WITH ELEVATED SPEEDS OF 10KTS AT LEAST...WITH
BRIEF PERIODS OF CALMER SPEEDS...UNDER 5KTS. MVFR CIGS REMAIN OVER
WESTERN MARICOPA COUNTY...DESPITE SHOWER ACTIVITY ENDING OVER THAT
AREA. CONFIDENCE IS MEDIUM IN PERIODS OF MVFR CIGS TO LINGER INTO
THE EVENING...BEFORE GRADUALLY LIFTING TOWARDS THE 5-7KFT LEVEL.
COULD SEE SOME ADDITIONAL STRAY SHOWERS DEVELOP ACROSS THE METRO
LATER IN THE EVENING...IN SIMILAR FASHION TO THE PAST COUPLE
NIGHTS...WARRANTING VCSH FOR THE EARLY EVENING.

FORECAST THOUGHTS NATURALLY TEND TOWARDS THE POTENTIAL FOR FOG
DEVELOPMENT FOR THE PHX TERMINALS...AND CRITICALLY KPHX...FOR
TUESDAY AM. WITH THE CURRENT FORECAST GUIDANCE AND SATELLITE
TRENDS...FEEL THAT WIDESPREAD SIGNIFICANT FOG DEVELOPMENT IS NOT
ANTICIPATED. SOME PATCHY FOG MAY DEVELOP FOR SOME OF THE SATELLITE
AIRFIELDS...BUT WITHIN THE PHX METRO DO NOT FEEL IFR/LIFR VSBYS WILL
BE REALIZED AT THE TERMINALS. FORECAST SOUNDINGS INDICATE SOME MID
LEVEL CLOUDS HELPING TO INSULATE OVERNIGHT TEMPERATURES...WHICH MAY
RESULT IN SOME STRATUS LAYERS ALONG NEARBY TERRAIN AND IN THE
VICINITY OF THE AIRFIELDS.

SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH...
INSTABILITY SHOWER AND ISOLATED THUNDER WILL CONTINUE ACROSS
SOUTHEAST CA IN RESPONSE TO THE ADVANCING UPPER LOW THROUGH THE
EARLY EVENING. ELEVATED WEST TO SOUTHWEST WINDS WILL ALSO PERSIST
INTO THE EVENING...WITH GUSTS UPWARDS OF 20KTS. AFTER 03/03Z OR
SO...SOME STRAY SHOWERS MAY LINGER BUT FEEL THE BULK OF THE PRECIP
ACTIVITY WILL BE WRAPPED. FEW-SCT CLOUDS 10KFT OR HIGHER MAY DRIFT
ACROSS THE AREA ALONG WITH DRIER AIR MOVING IN FROM THE WEST. THE
ADVANCE OF DRIER AIR AT THE SURFACE SHOULD HOLD OFF ANY FOG
DEVELOPMENT FOR THE MORNING HOURS...SO ATTM DO NOT HAVE ANY MENTION
IN THE TAFS.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
WEDNESDAY THROUGH SUNDAY...
STRONG HIGH PRESSURE AND MUCH DRIER CONDITIONS WILL MOVE BACK INTO
THE DISTRICT DURING THE LATTER HALF OF THE WEEK. TEMPERATURES WILL
REBOUND BACK INTO A NORMAL TO SLIGHTLY ABOVE NORMAL RANGE...WHILE
AFTERNOON HUMIDITY LEVELS RETURN INTO A 15 TO 25 PERCENT RANGE.
OVERNIGHT RECOVERY WILL BE GOOD. PERIODS OF GUSTY NORTH WINDS DOWN
THE COLORADO RIVER VALLEY WILL BE LIKELY WEDNESDAY AFTERNOON...WHILE
OCCASIONAL PERIODS OF STRONGER EASTERLY WINDS OVER RIDGE TOPS OF
CENTRAL ARIZONA MAY BE COMMON LATE IN THE WEEK.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...FLOOD WATCH THROUGH 8 PM TODAY AZZ022>024.

CA...NONE.

&&

$$

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

DISCUSSION...CB/PERCHA
AVIATION...NOLTE
FIRE WEATHER...MO






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