Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 251000
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
259 AM MST MON AUG 25 2014

.SYNOPSIS...A SIGNIFICANT CHANGE IN THE WEATHER PATTERN WILL TAKE
PLACE TODAY AND TUESDAY AS DEEPER MOISTURE MOVES BACK INTO ARIZONA.
THIS WILL RESULT IN SHOWERS AND THUNDERSTORMS...SOME WITH VERY HEAVY
RAINFALL...LATER TODAY AND TUESDAY. IMPROVING WEATHER CAN BE
ANTICIPATED WEDNESDAY...WITH DAYTIME TEMPERATURES REBOUNDING TO
SLIGHTLY ABOVE NORMAL READINGS BY THE WEEKEND.

&&

.DISCUSSION...A BIG CHANGE IN THE WEATHER PATTERN WAS SHAPING UP FOR
THE NEXT COUPLE OF DAYS AS DEEPER MOISTURE RETURNS TO THE REGION.
LATEST MODELS CONTINUED TO SHOW 2 LARGE SCALE WEATHER FEATURES THAT
WILL BECOME A FACTOR IN BRINGING WIDESPREAD RAIN TO SOUTHEAST
ARIZONA LATER TODAY AND TUESDAY. HURRICANE MARIE POSITIONED WELL OFF
THE SOUTHERN TIP OF BAJA THIS MORNING WILL CONTRIBUTE TO THE
NORTHWARD PUSH OF MOISTURE POOLED SOUTH OF THE INTERNATIONAL BORDER
TODAY AND TUESDAY. RECENT SURFACE OBSERVATIONS SUGGESTED THAT THIS
MOISTURE INCREASE WAS ALREADY MATERIALIZING AS DEWPOINTS HAVE
CLIMBED INTO THE LOW TO MID 70S IN YUMA ALONG WITH READINGS IN THE
MID 60S BEING REPORTED IN TUCSON EARLY THIS MORNING. THIS DEEPER
MOISTURE WILL INTERACT WITH THE TAIL END OF A LOW PRESSURE SYSTEM
MOVING THROUGH NEVADA AND UTAH TONIGHT INTO EARLY WEDNESDAY. THERE
WAS A HIGH DEGREE OF CONFIDENCE THAT THE INGREDIENTS FOR HEAVY
RAINFALL AND SUBSEQUENT FLASH FLOODING WILL COME TOGETHER DURING THE
NEXT 12 TO 36 HOURS ACROSS SOUTHEAST ARIZONA. CONFIDENCE REMAINED
RATHER LOW...HOWEVER...ON THE TIMING OF THE HEAVIEST RAINFALL AS
MODEL SOLUTIONS DIFFER. SOME POINT TO TONIGHT AND OTHERS SUGGEST
TUESDAY AFTERNOON AND EVENING WILL BE THE HEAVIEST. THAT SAID...NOT
CONFIDENT ENOUGH ON THE TIMING TO JUSTIFY POSTING A FLASH FLOOD
WATCH ON THE MORNING FORECAST PACKAGE. FOR NOW...WILL BANK ON
TUESDAY AFTERNOON AND EARLY EVENING FOR BEING THE BEST TIME FRAME
FOR THE BULK OF THE HEAVY RAINFALL AREAWIDE. ALONG WITH THE
CLOUDINESS AND RAIN...COOLER DAYTIME TEMPERATURES CAN BE
ANTICIPATED. BY WEDNESDAY...THE RAPID DECREASE IN MOISTURE SHOULD
START THE DRYING TREND THROUGH THE WEEKEND. THIS DRYING TREND WILL
TRANSLATE TO A WARMING TREND AS WELL...WITH PROJECTED HIGH
TEMPERATURES REBOUNDING TO SLIGHTLY ABOVE NORMAL READINGS THIS
WEEKEND.

&&

.AVIATION...VALID THRU 26/12Z.
FEW-SCT CLOUDS AT 10-14K FT AGL AND SCT CLOUDS AOA 20K AGL THRU
25/17Z. BETWEEN 25/17Z AND 25/22Z...SCT CLOUDS AT 7-11K FT AGL AND
SCT-BKN CLOUDS AT 10-14K FT AGL. AFT 25/22Z...SCT-BKN CLOUDS AT
6-10K FT AGL AND BKN-OVC CLOUDS AT 10-14K FT AGL. INCREASING CHANCES
OF PRECIPITATION THROUGH THE FORECAST CYCLE...WITH A SLIGHT CHANCE
OF -SHRA/-TSRA THRU 25/19Z...THEN ISOLD-SCT SHRA/TSRA TIL 26/01Z.
AFT 26/01Z...SCT-NUMEROUS SHRA/TSRA. EXPECT MVFR VISIBILITIES AND
WIND GUSTS TO NEAR 45 KTS WITH THE STRONGER TSRA...ESPECIALLY THIS
AFTERNOON AND TONIGHT. OUTSIDE OF THUNDERSTORM OUTFLOWS...SURFACE
WIND WILL GENERALLY BE LESS THAN 10 KTS. AVIATION DISCUSSION NOT
UPDATED FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...A NOTICEABLE INCREASE IN SHOWER AND THUNDERSTORM
ACTIVITY WILL OCCUR TODAY THROUGH WEDNESDAY AS DEEPER MOISTURE
PUSHES BACK INTO SOUTHERN ARIZONA. EXPECT ISOLATED TO SCATTERED
AFTERNOON SHOWERS AND THUNDERSTORMS TODAY...WITH SCATTERED TO
NUMEROUS SHOWERS AND THUNDERSTORMS TONIGHT...TUESDAY...AND TUESDAY
NIGHT. A LITTLE LESS ACTIVITY IS THEN EXPECTED ON WEDNESDAY...WITH
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS. THE STRONGER
THUNDERSTORMS WILL PRODUCE STRONG...GUSTY AND ERRATIC WINDS. A
DRYING TREND WILL TAKE PLACE BY WEEKS END AND OVER THE UPCOMING
WEEKEND...WITH ONLY A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS
MAINLY OVER THE EASTERN MOUNTAINS.

&&

$$

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