Area Forecast Discussion
Issued by NWS Tucson, AZ

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000
FXUS65 KTWC 171635
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
935 AM MST SUN AUG 17 2014

.SYNOPSIS...AMPLE MOISTURE WILL PROVIDE SCATTERED THUNDERSTORMS
THIS WEEK. SOME STORMS WILL PRODUCE GUSTY WINDS AS WELL AS HEAVY
RAIN THAT MAY LEAD TO FLASH FLOODING.

&&

.DISCUSSION...ISOLATED SHOWERS WERE OCCURRING IN AN ARC FROM ORACLE
TO PICACHO PEAK TO JUST WEST OF SELLS. THE REST OF SE AZ WAS
PRECIP-FREE AT THIS TIME. IR/VISIBLE SATELLITE IMAGERY INDICATED
MOSTLY SUNNY SKIES ACROSS FAR ERN SECTIONS...AND PARTLY CLOUDY TO
MOSTLY CLOUDY SKIES ELSEWHERE. DEWPOINTS AT LOWER ELEVATIONS VALID
16Z RANGED FROM THE UPPER 50S-MID 60S F...AND THESE TEMPS WERE
GENERALLY 2-5 DEGS F LOWER VERSUS 24 HOURS AGO. SURFACE TEMPS FROM
TUCSON WWD VALID 16Z WERE ABOUT 3-8 DEGS F COOLER VERSUS 24 HOURS
AGO. SURFACE TEMPS ELSEWHERE WERE NEARLY IDENTICAL TO THIS TIME SAT.

1501Z BLENDED TOTAL PRECIP WATER PRODUCT YIELDED VALUES RANGING FROM
AROUND 0.75 INCHES ACROSS THE WHITE MOUNTAINS TO NEARLY 1.40 INCHES
ACROSS WRN PIMA COUNTY. 17/12Z UPPER AIR PLOTS DEPICTED BROAD RIDGE
OVER THE SWRN CONUS WITH 594 DM HIGH PRESSURE CENTERED OVER NERN AZ.
LIGHT GENERALLY ELY MID-LEVEL STEERING FLOW PREVAILED OVER SE AZ.

THE ISOLATED SHOWERS ACROSS WRN SECTIONS ARE EXPECTED TO MOVE WWD
AND WEAKEN DURING THE NEXT 1-2 HOURS AS PER THE 17/14Z RUC HRRR AND
17/12Z NAM SOLUTIONS. SCATTERED SHOWERS/TSTMS SHOULD DEVELOP BY
EARLY THIS AFTERNOON ACROSS THE HIGHER TERRAIN OF GREENLEE/GRAHAM/
COCHISE COUNTIES. THESE SHOWERS/TSTMS WILL THEN MOVE WWD THIS
AFTERNOON AND INTO THIS EVENING. THERE ARE SOME DIFFERENCES BETWEEN
THE NAM...RUC HRRR...AND UNIV OF AZ WRF-NAM REGARDING THE WWD EXTENT
OF CELL MIGRATION INTO THIS EVENING.

HOWEVER...THESE SOLUTIONS ARE SIMILAR WITH LIMITING ANY RAINFALL OF
SIGNIFICANCE MOSTLY TO AREAS EAST OF TUCSON THIS AFTERNOON. APPEARS
THAT SHOWERS/TSTMS THAT OCCURRED LAST NIGHT ACROSS ERN PIMA COUNTY
WERE SUFFICIENT TO INHIBIT CONVECTIVE DEVELOPMENT THIS AFTERNOON.
THUS...FORECAST CONFIDENCE IS SUFFICIENTLY HIGH AT THIS TIME TO
LOWER POPS FOR THE TUCSON METRO AREA AND ADJACENT LOWER ELEVATION
LOCALES THIS AFTERNOON.

THE OFFICIAL FORECAST WILL BE UPDATED TO REFLECT THIS SCENARIO. WILL
ALSO FAVOR THE DRIER RUC HRRR SOLUTION TO REDUCE POPS ACROSS WRN
SECTIONS THIS AFTERNOON. OTHERWISE...SCATTERED SHOWERS/TSTMS WILL
OCCUR THIS AFTERNOON ACROSS ERN SECTIONS. THE MAIN IMPACTS WILL BE
LOCALLY HEAVY RAINFALL AND BRIEF STRONG WIND GUSTS.

PLEASE REFER TO THE ADDITIONAL SECTIONS FOR FURTHER DETAIL.

&&

.AVIATION...VALID THRU 18/18Z.
SCATTERED -TSRA/-SHRA WILL DEVELOP ACROSS THE HIGHER TERRAIN EAST OF
KTUS BY EARLY THIS AFTERNOON. THESE SHOWERS/THUNDERSTORMS WILL THEN
MOVE WWD ACROSS SE AZ THRU THIS EVENING AND LATER TONIGHT. THE BULK
OF ANY -TSRA/-SHRA IS THEN EXPECTED TO BE WEST OF KTUS MONDAY
MORNING. MVFR VISIBILITIES AND BRIEF WIND GUSTS TO NEAR 50 KTS WILL
OCCUR WITH THE STRONGER TSRA. OTHERWISE...CLOUD DECKS WILL MAINLY BE
AT 6-12K FT AGL AND SURFACE WIND WILL GENERALLY BE LESS THAN 10 KTS
THRU MONDAY MORNING. AVIATION DISCUSSION NOT UPDATED FOR TAF
AMENDMENTS.

&&

.FIRE WEATHER...SCATTERED THUNDERSTORMS WILL OCCUR THIS WEEK AS
AMPLE MOISTURE REMAINS ACROSS SOUTHEAST ARIZONA. THE STRONGER
THUNDERSTORMS WILL PRODUCE STRONG...GUSTY AND ERRATIC WINDS.
OTHERWISE...AFTERNOON MINIMUM RELATIVE HUMIDITIES ARE FORECAST TO BE
MOSTLY IN THE 25-40 PERCENT RANGE AT LOWER ELEVATIONS FOLLOWED BY
GOOD TO EXCELLENT OVERNIGHT RECOVERIES. 20-FOOT WINDS WILL EXHIBIT
NORMAL DIURNAL TRENDS AND BE MOSTLY LESS THAN 15 MPH.

&&

.PREV DISCUSSION...MONDAY...E-SE FLOW ALOFT WITH UPPER HIGH OVER NRN
NM. PRECIPITABLE WATER VALUES ARE FORECAST TO BE A TICK WETTER THAN
TODAY. LOOKING AT ANOTHER ROUND OF SCATTERED STORMS WITH A FEW
LINGERING INTO THE OVERNIGHT HOURS. FURTHER UPSTREAM ON MONDAY AN
UPPER LEVEL TROF WHICH IS OVER THE PACIFIC NW TODAY...WILL DROP INTO
NRN CA AND DEVELOP INTO A CLOSED LOW OFF NRN CA CST. THIS FEATURE
WILL BE A PLAYER IN OUR FORECAST LATER IN THE WEEK.

TUESDAY...SOUTHERLY FLOW INCREASES AS THE ABOVE MENTIONED NRN CA
UPPER LOW DROPS S ALONG THE CA CST AND BE OFF LA BASIN LATE IN THE
AFTERNOON. PRECIPITABLE WATER VALUES ARE FORECAST TO BE IN THE
1.50"-1.80" RANGE.

CHAOS REIGNS FOR THE REMAINDER OF THE WEEK WITH RESPECT TO WHERE
THE ABOVE MENTIONED CUT-OFF LOW WILL MOVE AND HOW MUCH THE TROPICS
START TO BE PLAYER. AT THIS TIME...AND WITH THE MEDIUM RANGE MODELS
ALONG WITH THE ENSEMBLES HAVE MANY SOLUTIONS...HAVE DECIDED TO GO
WITH CLIMO POPS ACROSS THE AREA STARTING WEDNESDAY THROUGH SATURDAY.

SURE LOOKS LIKE IT WILL BE A WET WEEK ACROSS SE ARIZONA.

&&

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

&&

$$

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

FRANCIS
PREVIOUS DISCUSSION...GLUECK




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