Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 030413
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
913 PM MST SAT MAY 2 2015

.SYNOPSIS...SOUTHEAST ARIZONA WILL EXPERIENCE COOLER TEMPERATURES
TOMORROW INTO NEXT WEEK. A WEAK WEATHER DISTURBANCE MOVING ACROSS THE
AREA WILL RESULT IN A SLIGHT CHANCE OF LIGHT SHOWERS AND
THUNDERSTORMS FROM TUCSON EAST ON SUNDAY. A STRONGER PACIFIC STORM
SYSTEM WILL THEN MOVE ACROSS THE AREA MONDAY...RESULTING IN A BETTER
CHANCE FOR SHOWERS AND THUNDERSTORMS ACROSS THE MAJORITY OF THE AREA
MONDAY INTO TUESDAY.

&&

.DISCUSSION...WATER VAPOR IMAGERY AND 03/00Z MODEL DATA AND UPPER-
AIR PLOTS SHOW A WEAK SHORTWAVE TROUGH OVER THE GENERAL VICINITY OF
SRN CALIFORNIA...NORTHERN GULF OF CALIFORNIA AND WESTERN ARIZONA. IR
SATELLITE IMAGERY SHOWS MOSTLY DEBRIS CLOUDINESS FROM EARLIER
CONVECTION...MAINLY NORTH OF A LINE FROM GILA BEND TO TUCSON TO
SIERRA VISTA. ALL OF THESE CLOUDS...AND LINGERING LIGHT SHOWERS ARE
CONTINUING TO MOVE TO THE NORTH. THESE SHOWERS WILL CONTINUE TO
DIMINISH THROUGHOUT THE REMAINDER OF THE EVENING. WILL UPDATE THE
FORECAST TO REFLECT A DECREASING THREAT FOR SHOWERS THROUGH THE
OVERNIGHT PERIOD.

AS OF 04Z (9 PM MST)...TEMPERATURES ACROSS THE REGION RANGED FROM
THE MID 60S TO 80 DEGREES. THE TUCSON INTL AIRPORT WAS REPORTING A
TEMP OF 80 DEGS...AFTER REACHING AN AFTERNOON HIGH OF 93 DEGS. THIS
WAS 6 DEGS ABOVE NORMAL FOR THIS DATE. WILL MAKE SOME ADJUSTMENTS TO
THE SHORT TERM HOURLY TEMP GRIDS TO REFLECT THE MOST RECENT TRENDS.
OTHERWISE...OVERNIGHT LOW TEMPS SEEM TO BE ON TRACK...BUT WILL
CONTINUE TO MONITOR.

FOR DETAILS REGARDING THE FORECAST BEYOND TONIGHT...PLEASE REFER TO
THE PREVIOUS DISCUSSION BELOW.

&&

.AVIATION...VALID THRU 04/06Z. ISOLATED TO SCATTERED -SHRA WILL
CONTINUE TO GRADUALLY DISSIPATE AS THEY MOVE TO THE NORTH TO
NORTHEAST...BUT POSSIBLY PERSISTING OVERNIGHT IN THE WHITE MOUNTAINS
NE OF KSAD. -SHRA/-TSRA WILL LIMITED TO AREAS NE OF KTUS SUNDAY
AFTN. SURFACE WINDS LIGHT AND VARIABLE OVERNIGHT...THEN SWLY/WLY AT
10-18 KTS WITH GUSTS TO 25 KTS SUNDAY AFTERNOON...THEN DIMINISHING
AGAIN SUNDAY EVENING. AVIATION DISCUSSION NOT UPDATED FOR TAF
AMENDMENTS.

&&

.FIRE WEATHER...EXPECT GUSTY WEST AND SOUTHWEST AFTERNOON WINDS THE
REMAINDER OF THIS WEEKEND ALONG WITH ISOLATED TO SCATTERED MAINLY
AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS FROM TUCSON
EASTWARD. SHOWERS AND STORMS WILL BE CAPABLE OF PRODUCING GUSTY
WINDS BUT CHANCES FOR RECEIVING MORE THAN A TENTH OF AN INCH OF
RAINFALL ARE LOW. THE CHANCE FOR WETTER STORMS SHOULD INCREASE
MONDAY AS A WEAK LOW PRESSURE SYSTEM APPROACHES FROM THE WEST
BRINGING HIGHER HUMIDITIES AND COOLER TEMPERATURES. A CHANCE OF
SHOWERS AND THUNDERSTORMS CONTINUES TUESDAY INTO WEDNESDAY NORTHEAST
OF TUCSON. DRY CONDITIONS WILL THEN PREVAIL THURSDAY AND FRIDAY
ALONG WITH AN UPTICK IN AFTERNOON WINDS AS A MORE SIGNIFICANT
WEATHER SYSTEM TAKES SHAPE ACROSS THE GREAT BASIN AREA TO OUR NORTH.

&&

.PREV DISCUSSION...A WEAK SHORTWAVE TROUGH OVER NORTHERN BAJA WILL
EJECT NORTHEAST THROUGH THE FORECAST AREA SUNDAY/SUNDAY NIGHT AS THE
MAIN UPPER TROUGH THEN MOVES INTO SOUTHERN CALIFORNIA. THE SOUTHERLY
FLOW AHEAD OF THIS FEATURE WILL IMPORT DEEPER MOISTURE INTO THE
STATE AT THE SAME TIME THE UPPER DIFLUENCE INTENSIFIES ACROSS SOUTH-
CENTRAL ARIZONA. THE BEST DYNAMICS SHIFT INTO CENTRAL AND NORTHERN
ARIZONA MONDAY AFTERNOON. THE BEST CHANCE FOR SHOWERS AND
THUNDERSTORMS ACROSS SOUTHEAST ARIZONA WILL BE EARLY MONDAY MORNING
INTO MONDAY EVENING. PRECIPITATION AMOUNTS WILL BE SOMEWHAT LOW WITH
THIS EVENT...GENERALLY AROUND A QUARTER TO THIRD INCH WITH ISOLATED
AMOUNTS UP TO THREE QUARTERS OF AN INCH IN THE HIGHER TERRAIN. THIS
SYSTEM FINALLY MOVES OUT OF THE STATE TUESDAY WITH DECREASING POPS
THROUGH THE DAY.

MEDIUM RANGE MODELS ARE ALL IN GOOD AGREEMENT WITH AN AMPLIFIED
RIDGE DEVELOPING IN THE EASTERN PACIFIC. I AM CONFIDENT THAT A DEEP
TROUGH WILL DEVELOP ALONG THE WEST COAST THE SECOND HALF OF THE WORK
WEEK...BUT NOT CONFIDENT THAT THIS WILL RESULT IN ANY PRECIPITATION
FOR OUR AREA. THIS PATTERN WILL LIKELY ONLY RESULT IN STRONGER WINDS.

&&

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

&&

$$

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