090
FXUS65 KPSR 151214
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
514 AM MST SUN SEP 15 2019
UPDATE
UPDATED AVIATION DISCUSSION.
SYNOPSIS
AN UPPER LEVEL DISTURBANCE ACROSS EASTERN ARIZONA WILL SUPPORT
WIDESPREAD SHOWERS AND A FEW THUNDERSTORMS THROUGH THIS AFTERNOON
ACROSS THE HIGH TERRAIN WELL EAST OF PHOENIX. THE LOWER DESERTS
WILL STAY DRY TODAY AS HIGHS REACH NEAR NORMAL READINGS. A LOW
PRESSURE SYSTEM MOVING INTO THE GREAT BASIN MONDAY INTO TUESDAY
WILL ALLOW FOR PERIODIC SHOWER CHANCES ACROSS THE HIGHER TERRAIN
NORTH AND EAST OF PHOENIX. THE LATTER HALF OF THE WEEK SHOULD
MOSTLY BE DRY AS TEMPERATURES REMAIN NEAR SEASONAL NORMALS.
DISCUSSION
A WELL DEFINED MID AND UPPER LEVEL LOW IS CURRENTLY SEEN IN WATER
VAPOR IMAGERY CENTERED JUST EAST OF PHOENIX, VERY SLOWLY DRIFTING
NORTH NORTHEAST. EASTERN ARIZONA WILL REMAIN IN A FAVORABLE UPPER
LEVEL ASCENT REGION FOR MUCH OF TODAY WITH MAINLY SHOWERS
PERSISTING MAINLY EAST OF A TUCSON TO GLOBE LINE. THE EXTENSIVE
CLOUDINESS TODAY SHOULD LIMIT INSTABILITY OVERALL, BUT A FEW
THUNDERSTORMS WILL BECOME POSSIBLE MAINLY ALONG THE MOGOLLON RIM
THIS AFTERNOON. EASTERN SECTIONS OF GILA COUNTY COULD PICK UP AN
ADDITIONAL HALF TO ONE INCH OF RAIN THROUGH THIS AFTERNOON, BUT
HEAVY RAINFALL SHOULD BE LIMITED AND ONLY MINOR LOCALIZED FLOODING
WILL BE POSSIBLE. FURTHER WEST, NORTHERLY DOWNSLOPING FLOW INTO
SOUTH-CENTRAL THIS MORNING WILL BECOME MORE WESTERLY WITH DRIER
AIR CONTINUING TO WORK INTO THE AREA WHILE LIKELY INHIBITING
CONVECTION ALTOGETHER OVER THE LOWER DESERTS. ASIDE FROM THE
MOSTLY CLOUDY SKIES AND SHOWERS ACROSS THE HIGHER TERRAIN, THE
REST OF ARIZONA SHOULD MOSTLY SEE SUNNY SKIES BY LATE MORNING AND
HIGHS JUST SHY OF NORMAL.
THE COMPACT UPPER LEVEL LOW WILL FINALLY EXIT INTO NEW MEXICO
THIS EVENING WHILE BROAD CYCLONIC FLOW BECOMES MORE PRONOUNCED TO
OUR NORTHWEST AHEAD OF APPROACHING PACIFIC TROUGH. THE MAIN
SHORTWAVE WITH THIS TROUGH IS STILL FORECAST TO TRACK WELL TO OUR
NORTH, BUT WE WILL AT LEAST SEE SOME WEAK JET SUPPORTED ASCENT ON
MONDAY. THE COMBINATION OF THE LINGERING MOISTURE, UPPER LEVEL
DYNAMICS, AND WEAK UPSLOPE SOUTHWESTERLY LOW LEVEL FLOW SHOULD
SUPPORT SCATTERED SHOWERS AND ISOLATED STORMS OVER AREAS MAINLY
NORTH AND EAST OF PHOENIX MONDAY AFTERNOON INTO MONDAY NIGHT. WE
CANNOT RULE OUT A FEW ISOLATED SHOWERS OR STORMS ACROSS THE SOUTH-
CENTRAL ARIZONA DESERTS AS FORECAST SOUNDINGS INDICATE SUFFICIENT
INSTABILITY, BUT CHANCES FOR THIS ARE NOT VERY HIGH. BY TUESDAY,
DRIER WESTERLY FLOW WILL SPREAD ACROSS ALL OF ARIZONA, LIKELY
LIMITING RAIN CHANCES TO ONLY THE HIGHEST PEAKS IN EASTERN
ARIZONA. VERY LITTLE CHANGE IN AIRMASS EARLY THIS WEEK WILL KEEP
TEMPERATURES RIGHT AROUND NORMALS, OR HIGHS IN THE UPPER 90S IN
PHOENIX TO JUST OVER 100 ACROSS THE WARMER WESTERN DESERTS.
FORECAST CONFIDENCE IS SLIGHTLY LOWER FOR THE REST OF THE WEEK AS
MODELS SOMEWHAT DIFFER IN AVAILABLE MOISTURE FOR ANOTHER PACIFIC
TROUGH LIKELY PASSING BY TO OUR NORTH ON THURSDAY. AT THIS POINT,
THE OPERATIONAL GFS IS AN OUTLIER COMPARED TO THE REST OF ITS
ENSEMBLE MEMBERS AND THE EUROPEAN MODEL SUITE AS IT BRINGS TOO
MUCH MOISTURE BACK INTO EASTERN ARIZONA LATE WEDNESDAY INTO
THURSDAY. LATEST MODEL RUNS SHOW THE TROUGH DIGGING FARTHER SOUTH
INTO CENTRAL CALIFORNIA THEN PREVIOUS TROUGHS, SO WE CANNOT RULE
OUT THE POSSIBILITY OF SUFFICIENT MOISTURE BEING DRAWN NORTHWARD
TO AT LEAST SUPPORT LIMITED RAIN CHANCES OVER THE HIGHER TERRAIN.
THE CONTINUED BROAD TROUGHING OVER THE WESTERN U.S. DURING THE
LATTER HALF OF THE WEEK SHOULD KEEP TEMPERATURES NEAR SEASONAL
NORMALS.
AVIATION
UPDATED AT 1205Z.
SOUTH-CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
EXPECT SOME LINGERING ISOLATED SPRINKLES IN THE EAST VALLEY EARLY
IN THE PERIOD ON SUNDAY MORNING WITH MOSTLY LIGHT TO OCCASIONALLY
MODERATE EASTERLY WINDS. SKIES THIS MORNING WILL BE PARTLY CLOUDY
WITH MID TO HIGH LEVEL CLOUD CIGS NEAR 14-21KFT AND FEW LOW
CLOUDS AT 7-8KFT. WINDS WILL TREND WESTERLY BY MID AFTERNOON WITH
DECREASING CLOUDINESS AS ISOLATED AFTERNOON THUNDERSTORMS DEVELOP
AND REMAIN OVER THE HIGH TERRAIN TO THE DISTANT EAST AND NORTH OF
PHOENIX. THERE IS A FAIR CHANCE OF LIGHT TO MODERATE
NORTHEASTERLY OUTFLOW FROM HIGH COUNTRY CONVECTION REACHING THE
TERMINALS AROUND 02-03Z THIS EVENING WITH WIND SPEEDS NEAR 7-12KT
AS SOME HIGH CLOUD CIGS MOVE BACK INTO THE AREA.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
LOOK FOR LIGHT TO MODERATE WINDS FAVORING THE SOUTHEAST AT KIPL
TODAY TO SWITCH OVER TO THE WEST EARLY THIS EVENING. AT KBLH
MOSTLY MODERATE WINDS WILL FAVOR THE SOUTH TO SOUTHWEST BY MID
MORNING. SKIES WILL BE CLEAR TO MOSTLY CLEAR THIS MORNING WITH
INCREASING HIGH CLOUD CIGS AND FEW MID CLOUDS MOVING IN FROM THE
WEST DURING THE COURSE OF THE AFTERNOON AND INTO THIS EVENING.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
FIRE WEATHER
TUESDAY THROUGH SATURDAY:
A SERIES OF LOW PRESSURE SYSTEMS WILL MOVE THROUGH GREAT BASIN NEXT
WEEK GRADUALLY PUSHING MOISTURE AND STORM CHANCES FROM THE
DISTRICTS. RESIDUAL LINGERING MOISTURE MAY SUPPORT SOME UPSLOPE
SHOWERS DURING THE MIDDLE OF THE WEEK, HOWEVER MUCH DRIER AIR WILL
ENCOMPASS THE REGION BY THE END OF THE WEEK. THESE STORM SYSTEMS
WILL ALLOW TEMPERATURES TO HOVER AROUND THE SEASONAL AVERAGE WHILE
THE DRIER AIRMASS WILL PULL AFTERNOON HUMIDITY LEVELS INTO A 10-25%
RANGE. A FEW PERIODS OF BREEZY CONDITIONS WILL BE POSSIBLE WITH THE
PASSAGE OF THESE WEATHER DISTURBANCES.
SPOTTER INFORMATION STATEMENT
SPOTTERS SHOULD FOLLOW STANDARD REPORTING PROCEDURES.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...NONE.
DISCUSSION...KUHLMAN
AVIATION...SAWTELLE
FIRE WEATHER...MO
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