Area Forecast Discussion
Issued by NWS Phoenix, AZ

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
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 252133
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
233 PM MST SAT APR 25 2015

.SYNOPSIS...
A STRONG COLD FRONT WILL MOVE THROUGH THE REGION EARLY TONIGHT
BRINGING GUSTY WINDS AND GOOD CHANCES FOR RAIN. CHANCES FOR
SHOWERS AND THUNDERSTORMS WILL INCREASE THIS EVENING AND INTO
TONIGHT...BUT MAINLY ACROSS PORTIONS OF SOUTHWEST AND SOUTH CENTRAL
ARIZONA. LINGERING SHOWERS ARE EXPECTED SUNDAY OVER EASTERN
ARIZONA...WITH CLEARING OVER SOUTHEAST CALIFORNIA AND SOUTHWEST
ARIZONA. DRIER AND MUCH WARMER WEATHER IS EXPECTED NEXT WEEK.

&&

.DISCUSSION...

...POTENT UPPER TROUGH AND FRONTAL PASSAGE ACROSS THE REGION THIS
EVENING AND TONIGHT WITH STRONG GUSTY WINDS AND THUNDERSTORM
CHANCES...

TODAY THUS FAR HAS BEEN FAIRLY QUIET ACROSS THE AREA EXCEPT FOR SOME
LIGHT SHOWERS PASSING THROUGH RIVERSIDE AND LA PAZ COUNTIES WITH
SOME RECENT DEVELOPMENT JUST TO OUR NORTH IN YAVAPAI COUNTY. THESE
SHOWERS WERE IN RESPONSE TO A WEAKENING SHORTWAVE TROUGH MOVING INTO
CENTRAL ARIZONA OUT AHEAD OF THE MAIN TROUGH THAT WILL AFFECT THE
AREA LATER TODAY AND TONIGHT. CURRENT WATER VAPOR AND UPPER HEIGHT
ANALYSIS SHOWS A RATHER IMPRESSIVE UPPER TROUGH APPROACHING FROM THE
NORTHWEST WITH THE MAIN SHORTWAVE TROUGH JUST WEST OF LAS VEGAS.
DIFLUENT FLOW ALOFT OVER SOUTHERN NEVADA AND UTAH ALONG WITH STRONG
500MB HEIGHT FALLS CENTERED OVER THE SIERRAS ARE HELPING TO SPARK
OFF SCATTERED SHOWERS AND THUNDERSTORMS. WINDS AHEAD OF AN ADVANCING
COLD FRONT HAVE BECOME GUSTY ACROSS SOUTHEAST CALIFORNIA WITH SOME
GUSTS TO AROUND 35 KNOTS. AS THE FRONT MOVES THROUGH THIS
EVENING...CAN EXPECT SOME WIND GUSTS UP TO 40-45 KNOTS IN SOME
LOCALIZED SPOTS ALONG WITH THE POTENTIAL FOR SOME BLOWING DUST.

THE MAIN SHORTWAVE TROUGH AND COLD FRONT WILL QUICKLY DIVE
SOUTHEASTWARD THROUGH THE REST OF TODAY...REACHING SOUTH-CENTRAL
ARIZONA AROUND 06Z THIS EVENING. STILL EXPECTING SCATTERED TO
WIDESPREAD SHOWERS AND THUNDERSTORMS TO DEVELOP AHEAD OF THESE
FEATURES DURING THE EVENING TIME FRAME WITH BEST CHANCES STRETCHING
FROM NORTHERN LA PAZ COUNTY THROUGH MUCH OF MARICOPA COUNTY...INTO
SOUTHERN GILA COUNTY. CONDITIONS REMAIN RATHER MOIST BETWEEN 8-10K
FEET...BUT FURTHER MOISTENING IN THE MID LEVELS WILL OCCUR AS THE
TROUGH AND COLDER AIR MOVES IN FROM THE NORTHWEST. THE MOIST
CONDITIONS...WEAK UPSLOPE LOW LEVEL FLOW...AND STRONG FORECAST MODEL
OMEGA FOR THIS EVENING ACROSS SOUTH-CENTRAL ARIZONA...WILL ALL COME
INTO PLAY TO AID IN SHOWER AND THUNDERSTORM DEVELOPMENT. STRONGER
SHOWERS OR THUNDERSTORMS WILL HAVE THE POTENTIAL TO BRING SOME GUSTY
WINDS DOWN TO THE SURFACE...SO SOME STRONGER SUB-SEVERE GUSTS ARE
POSSIBLE.

BY SUNDAY MORNING...THE MAIN SHORTWAVE TROUGH WILL BE MOVING INTO
WESTERN NEW MEXICO WITH SUBSIDENCE ALOFT WORKING INTO OUR WESTERN
ZONES. CHANCES FOR LINGERING SHOWERS WILL BE POSSIBLE THROUGH SUNDAY
MORNING FROM AROUND PHOENIX EASTWARD WITH BEST CHANCES OVER THE
HIGHER TERRAIN OF EAST-CENTRAL ARIZONA. BY MID TO LATE SUNDAY
AFTERNOON...THE DRIER AIR BEHIND THE TROUGH WILL HAVE MIXED OUT THE
LOW LEVELS ENOUGH TO BASICALLY KEEP ANY REMAINING SHOWER CHANCES
OVER HIGHER TERRAIN AREAS. OUR WESTERN ZONES SHOULD CLEAR OUT FAIRLY
QUICKLY ON SUNDAY WITH HIGHS REBOUNDING BACK INTO THE LOW TO MID
80S. ELSEWHERE...TEMPERATURES SHOULD ONLY PEAK OUT IN THE UPPER 70S
ACROSS THE SOUTH-CENTRAL ARIZONA DESERTS.

FOR THE COMING WORK WEEK...A LARGE RIDGE IS FORECAST TO TAKE OVER
WITH DRY CONDITIONS AND WARMING TEMPERATURES. HIGHS BY MONDAY SHOULD
REACH NEAR NORMALS AND ONCE THE UPPER LEVEL RIDGE FINALLY TAKES
OVER...TEMPERATURES WILL HEAT UP EVEN MORE WITH FORECAST HIGHS IN
THE MIDDLE TO UPPER 90S FOR WEDNESDAY AND THURSDAY ACROSS THE
DESERTS. THOUGH THERE ARE SOME MODEL DIFFERENCES BEYOND NEXT
THURSDAY...THE GENERAL CONSENSUS IS THAT LARGE SCALE TROUGHING WILL
PUSH THE RIDGE OUT THE REGION ALLOWING FOR SOME MODERATION IN
TEMPERATURES...BUT CONTINUING WITH THE DRY CONDITIONS.

&&

AVIATION...

SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL...
APPROACHING UPPER-LEVEL LOW CENTER...AND ASSOCIATED SFC FRONT IS
STILL EXPECTED TO BRING STRONG...AND GUSTY WINDS TO THE PHX AREA
TERMINALS THIS AFTERNOON/EVENING AS SFC PRESSURE GRADIENTS INCREASE
OVER THE REGION. SUSTAINED WINDS...FROM A WESTERLY DIRECTION...ARE
EXPECTED TO INCREASE INTO THE 20-25KT RANGE...WITH GUSTS IN THE 30-
35KT RANGE BY THIS EVENING...WITH PERHAPS A SHORT BURST OF EVEN
STRONGER WINDS FOR A HOUR OR SO AROUND 02-03Z AS THE SFC FRONT
PASSES. ALONG WITH THE WINDS...SCATTERED-NUMEROUS SHOWERS AND FEW
THUNDERSTORMS ARE ALSO EXPECTED TO DEVELOP ALONG/JUST AHEAD OF THE
FROM...WITH ENOUGH CONFIDENCE TO INCLUDE THEM IN THE TAFS BETWEEN
06Z AND 12Z. DRIER AIR PUSHING IN FROM THE WEST WILL THEN CLEAR
SKIES FAIRLY RAPIDLY SUNDAY MORNING AS THE MAIN UL TROF MOVES OFF TO
THE EAST. GUSTY WESTERLY WINDS TO REDEVELOP SUN AFTERNOON AS SFC
HIGH PRESSURE OVER THE GREAT BASIN KEEPS SFC PRESSURE GRADIENTS
RATHER TIGHT OVER THE REGION.

SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA INCLUDING KIPL AND
KBLH... APPROACHING UL TROUGH WILL KEEP STRONG WESTERLY WINDS GOING
ACROSS THE REGION THROUGH THE EVENING HOURS...WITH GUSTS AS HIGH AS
40KT EARLY THIS EVENING. PERIODS OF BLOWING DUST REDUCING VISIBILITY
DOWN TO 2SM WILL BE COMMON WITH THE STRONGER WINDS...ESPECIALLY
ACROSS IMPERIAL COUNTY AND NEAR YUMA. 18Z TAFS TAKE AIRFIELD VSBYS
DOWN TO 5SM BUT CANNOT RULE OUT LOCALLY LOWER VALUES FOR SHORTER
PERIODS. SLANT VSBYS LIKELY IMPACTED DUE TO LOFTED DUST. THE
STRONGEST WINDS TO ABATE LATER INTO THE EVENING BUT REMAIN ELEVATED
IN THE 10-15KT RANGE WITH GUSTS STILL TOWARDS 20KTS. STRONGER WINDS
TO RETURN SUN AFTERNOON AS SFC HIGH PRESSURE OVER THE GREAT BASIN
KEEPS SFC PRESSURE GRADIENTS RATHER TIGHT OVER THE REGION.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
MONDAY THROUGH FRIDAY...
IN THE WAKE OF THE DEPARTING TROUGH...NEXT WEEK WILL SEE THE ARRIVAL
OF A STRONG UPPER RIDGE OVER THE SOUTHWESTERN CONUS FROM MONDAY
THROUGH MOST OF THE WEEK. TEMPERATURES WILL WARM SUBSTANTIALLY AND
APPROACH THE TRIPLE DIGIT MARK FOR THE LATTER PART OF THE WEEK.
AFTERNOON HUMIDITIES WILL DROP INTO THE LOWER TEENS AND UPPER SINGLE
DIGITS WITH FAIR OVERNIGHT RECOVERIES EXPECTED. WINDS WILL BE GNLY
LIGHT AND SHOULD FOLLOW TYPICAL DIURNAL PATTERNS.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.

CA...WIND ADVISORY UNTIL 9 PM PDT TODAY FOR CAZ030>033.

&&

$$

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

DISCUSSION...KUHLMAN
AVIATION...NOLTE
FIRE WEATHER...NOLTE/LEINS



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