Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 241631
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
930 AM MST SUN MAY 24 2015

.SYNOPSIS...A FEW SHOWERS MAY OCCUR FROM NEAR TUCSON EASTWARD TO THE
NEW MEXICO BORDER THIS AFTERNOON AND EVENING. A CHANCE OF SHOWERS
CONTINUES MEMORIAL DAY ACROSS THE WHITE MOUNTAINS. A WARMING TREND
WILL PREVAIL INTO TUESDAY FOLLOWED BY DRY CONDITIONS WITH NEAR
NORMAL DAYTIME TEMPERATURES WEDNESDAY THROUGH FRIDAY.

&&

.DISCUSSION...WEAK UPPER LOW WITH ASSOCIATED CYCLONIC CLOUD MASS
TWIST WAS EVIDENT VIA VISIBLE SATELLITE IMAGERY OVER FAR SW ARIZONA/
SE CALIFORNIA AT THIS TIME. THIS UPPER LOW WILL MOVE EWD ACROSS SE
ARIZONA THIS AFTERNOON AND EVENING. 24/12Z NAM/GFS AND 24/15Z RUC
HRRR DEPICT LIGHT RAIN AMOUNTS TO DEVELOP GENERALLY FROM NEAR THE
TUCSON METRO AREA EWD ACROSS NRN COCHISE/SRN GRAHAM COUNTIES...AND
ERN SANTA CRUZ/SWRN COCHISE COUNTIES AROUND 21Z-22Z THIS AFTERNOON.
THE BULK OF THIS ACTIVITY IS THEN DEPICTED TO BE NEAR THE CATALINA/
RINCON MOUNTAINS EWD TO NEAR THE NEW MEXICO BORDER THIS EVENING.

HAVE NOTED THAT THE 24/12Z GFS MOS POPS HAVE TRENDED UPWARD VERSUS
PREVIOUS SOLUTIONS. WILL MODIFY THE 21Z-00Z GRIDDED DATA POPS TO
DEPICT A SLIGHT CHANCE OF SHOWERS FOR THE TUCSON METRO AREA.
OTHERWISE...A CHANCE OF SHOWERS EXISTS THIS EVENING ACROSS THE WHITE
MOUNTAINS...AND A SLIGHT CHANCE OF SHOWERS MAINLY FROM TUCSON EWD
ACROSS NRN COCHISE/SRN GRAHAM COUNTIES. ANY SHOWERS SHOULD BE EAST
OF THIS FORECAST AREA BY AROUND MIDNIGHT TONIGHT AS THE MID-LEVEL
TROUGH AXIS MOVES INTO SWRN NEW MEXICO.

RAINFALL AMOUNTS ASSOCIATED WITH THIS WEAK UPPER LOW WILL BE QUITE
LIGHT...GENERALLY RANGING FROM A TRACE UPWARD TO AROUND ONE TENTH OF
AN INCH OR SO. HOWEVER...ANY RAINFALL ON MAY 24 IS QUITE UNUSUAL. A
SLIGHT CHANCE OF SHOWERS CONTINUES ACROSS THE WHITE MOUNTAINS MON.

THEREAFTER...FLAT RIDGE OVER THE AREA TUE WILL MOVE EWD INTO THE
CENTRAL CONUS PLAINS WED IN RESPONSE TO THE NEXT DEEPENING UPPER
TROUGH WEST OF THE AREA. THE GFS/ECMWF/CMC WERE SIMILAR WITH MOVING
THIS UPPER TROUGH EWD INTO THE CENTRAL/SRN ROCKIES FRIDAY. IN SPITE
OF THE PRESENCE OF THIS UPPER TROUGH...APPEARS THAT PRECIP-FREE
CONDITIONS WILL OCCUR TUE-FRI. UPPER RIDGE IS THEN PROGGED TO
AMPLIFY OVER THE WRN CONUS SAT FOR CONTINUED DRY CONDITIONS.

HIGH TEMPS TODAY WILL BE A FEW DEGS WARMER VERSUS TEMPS ACHIEVED
SAT...THEN ABOUT 5 DEGS OR SO OF DAILY WARMING WILL OCCUR MON-TUE.
EXPECT ONLY VERY MINOR CHANGES IN DAYTIME TEMPS TUE-FRI...WITH
DAYTIME TEMPS TO BE QUITE CLOSE TO NORMAL FOR LATE MAY. HIGH TEMPS
SAT MAY THEN BECOME A FEW DEGS TO SEVERAL DEGS ABOVE NORMAL IN
RESPONSE TO INCREASED HEIGHTS/THICKNESSES OVER THE AREA.

&&

.AVIATION...VALID THRU 25/18Z.
A WEAK LOW PRESSURE SYSTEM ALOFT WILL MOVE EASTWARD ACROSS SE
ARIZONA THIS AFTERNOON AND EVENING. EXPECT ISOLATED TO SCATTERED
-SHRA AND PERHAPS A FEW -TSRA FROM KTUS VICINITY EASTWARD TO THE NEW
MEXICO BORDER THIS AFTERNOON AND EVENING. THE BEST PERIOD FOR THIS
ACTIVITY APPEARS TO BE FROM 21Z THIS AFTERNOON TO AROUND 06Z MONDAY.
OTHERWISE...CLEAR SKIES THE REST OF THIS MORNING THEN SCATTERED TO
BROKEN CLOUDS AT 8-12K FT AGL THIS AFTERNOON AND THIS EVENING.
CLEARING SKIES FROM WEST-TO-EAST LATE TONIGHT AND EARLY MONDAY
MORNING. SURFACE WIND THIS AFTERNOON WILL BE SWLY TO NWLY AT 10-18
KTS WITH GUSTS OF 20-25 KTS. SURFACE WIND WILL BE LESS THAN 10 KTS
AT OTHER TIMES. AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...THERE IS A CHANCE OF SHOWERS MAINLY ACROSS THE WHITE
MOUNTAINS THIS AFTERNOON AND EVENING AND AGAIN MONDAY. A FEW SHOWERS
MAY ALSO OCCUR THIS AFTERNOON AND EVENING MAINLY FROM NEAR TUCSON
EASTWARD ACROSS COCHISE COUNTY. ANY RAINFALL IS EXPECTED TO BE QUITE
LIGHT...WITH AMOUNTS TO RANGE FROM A TRACE UPWARD TO AROUND ONE
TENTH OF AN INCH. OTHERWISE...DRY CONDITIONS WILL PREVAIL THIS WEEK.
EXPECT NORMAL DIURNAL WIND TRENDS...WITH GUSTS DURING THE AFTERNOON
HOURS DUE TO DAYTIME HEATING. A WARMING TREND WILL OCCUR THROUGH
TUESDAY FOLLOWED BY NO SIGNIFICANT CHANGE IN DAYTIME TEMPERATURES
WEDNESDAY THROUGH FRIDAY.

&&

.CLIMATE...THERE HAVE ONLY BEEN FIVE OCCURRENCES OF MEASURABLE
RAINFALL ON MAY 24 FOR TUCSON SINCE RECORDS STARTED IN 1894. TWO
OTHER OCCURRENCES HAD TRACE AMOUNTS OF RAINFALL. THE LAST RECORDED
RAINFALL ON MAY 24 WAS 1994 WITH 0.14 INCH.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...YOUTUBE...AND AT WEATHER.GOV/TUCSON

FRANCIS



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