Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 011112
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
410 AM MST WED JUL 1 2015

.SYNOPSIS...EXPECT SCATTERED MAINLY AFTERNOON AND EVENING
THUNDERSTORMS INTO EARLY NEXT WEEK. DAYTIME TEMPERATURES WILL REMAIN
CLOSE TO SEASONAL NORMALS INTO THIS HOLIDAY WEEKEND.

&&

.DISCUSSION...IT WAS QUITE AN ACTIVE DAY ACROSS SE AZ ON TUESDAY
WITH MULTIPLE THUNDERSTORMS PRODUCING SEVERE HAIL...THE LARGEST OF
WHICH WERE GOLF BALL SIZE. KEMX WSR-88D IS CURRENTLY SHOWING
SCATTERED SHOWERS AND THUNDERSTORMS CONTINUING TO ROLL WESTWARD
ACROSS MAINLY WESTERN PIMA COUNTY AT THIS HOUR...ALTHOUGH THESE
STORMS ARE NO LONGER SHOWING SEVERE CHARACTERISTICS. RADAR ESTIMATES
ACROSS THE AREA SHOW THE HEAVIEST RAINFALL AMOUNTS ACROSS
SOUTHEASTERN PIMA AND SANTA CRUZ COUNTIES...WITH TOTALS SINCE 30/18Z
IN THE 1 TO 2 INCH RANGE AND A FEW SPOTS IN EXCESS OF 3 INCHES.

WV IMAGERY THIS MORNING SHOWS WRN AZ/NRN BAJA CA IMPINGED BETWEEN
HIGH PRESSURE CENTERED OVER THE GREAT BASIN AND LOW PRESSURE
CENTERED NEAR 25N/123W. THIS SETUP HAS CREATED A SE/NW ORIENTED JET
WHICH IS FUNNELING DEEPER MOISTURE INTO THE AREA FROM BOTH THE GULF
OF MEXICO AND FROM THE GULF OF CALIFORNIA. IN FACT...THE GFS/NAM
LAYER PWAT IS SHOWING VALUES CLOSE TO 2 INCHES NEARING THE WRN
AZ/MEXICO BORDER LATER ON THIS MORNING.

IR IMAGERY SHOWS SOME RESIDUAL CLOUD COVER IN THE WAKE OF EARLIER
CONVECTION. THIS SHOULD HELP TO MODERATE TEMPERATURES A DEGREE OR
TWO TODAY...WITH THE EXCEPTION OF THE WHITE MOUNTAINS WHERE VERY
LITTLE CONVECTION OCCURRED TODAY. LAST SEVERAL RUNS OF HI-RES MODELS
INCLUDING THE HRRR/RUC ARE CURRENTLY SHOWING CONVECTION BEGINNING TO
REDEVELOP NEAR THE AZ/MEXICO BORDER AROUND 01/19Z AND GRADUALLY
FILLING IN TOWARD THE NORTH AND WEST THROUGH THE AFTERNOON HOURS.
LATEST RUNS OF THE NAM/RUC MODELS INDICATE THE PRESENCE OF 1000-2000
J OF CAPE AT THE SAME TIME WITH FAIRLY LITTLE CIN...SO IT SHOULD NOT
TAKE MUCH FOR STORMS TO GET GOING TODAY ONCE DAYTIME HEATING BEGINS.

STORM MOTION IS EXPECTED TO BE SLIGHTLY MORE TOWARD THE NORTHWEST
TODAY AS COMPARED TO TUESDAY...WITH HAIL AND DAMAGING WINDS THE MAIN
THREAT. STEERING FLOW WILL BE SLIGHTLY WEAKER...SO WILL NEED TO BE
MORE AWARE OF LOCALIZED FLASH FLOODING TODAY...ESPECIALLY FOR AREAS
WHICH RECEIVED THE HEAVIEST RAINFALL OVER THE LAST 24 HOURS.

FRIDAY THROUGH THE WEEKEND WILL SEE THE REORIENTATION OF THE RIDGE
AXIS FROM CHIHUAHUA THROUGH EASTERN BORDER AREAS AND THEN INTO
UTAH...CREATING A LONG SOUTHERLY FETCH INSTEAD OF EASTERLY. THESE
PATTERNS TEND TO EMPHASIZE HEAVIER RAINFALL AS WELL AS MORE
WIDESPREAD CONVECTIVE ORGANIZATION IMMEDIATELY UPSTREAM IN SONORA.
AS SUCH...IT SEEMS THAT DAILY CHANCES FOR SHOWERS AND THUNDERSTORMS
WILL CONTINUE FOR THE NEXT SEVERAL DAYS...AND ONLY SLIGHT
MODIFICATIONS HAVE BEEN MADE TO THE POP GRIDS AT THIS TIME. LOCATION
OF THE HEAVIEST RAINFALL/BEST CHANCES FOR CONVECTION WILL BE HIGHLY
DEPENDENT ON THE CONDITIONS WHICH OCCURRED DURING THE PREVIOUS 12 TO
24 HOURS...SO IT IS LIKELY THAT MINOR TWEAKS WILL OCCUR WITH EACH
FORECAST PACKAGE.

LOOKING A LITTLE FURTHER AHEAD...IT SEEMS WE MAY HAVE A SLIGHT
DOWNTURN IN THUNDERSTORM ACTIVITY AND A REDUCTION IN DAYTIME
TEMPERATURES BY THE MIDDLE OF NEXT WEEK...AS MORE SWLY FLOW IMPACTS
THE AREA. STAY TUNED.

&&

.AVIATION...VALID THRU 02/12Z.
ISOLD TSRA/SHRA WILL CONT ACROSS WRN PIMA COUNTY THRU 02/12Z. DEBRIS
CLOUDS SLOWLY DIMINISHING THIS MORNING BECOMING SCTD EARLY THIS
AFTERNOON. ISOLD TO SCTD TSRA/SHRA AFT 02/19Z. BRIEF WIND GUSTS OF
45 KTS WILL BE POSSIBLE WITH THE STRONGEST STORMS. SURFACE WIND WILL
BE LESS THAN 12 KTS OUTSIDE OF ANY TSRA. AVIATION DISCUSSION NOT
UPDATED FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...ADEQUATE MOISTURE AND A FAVORABLE FLOW PATTERN WILL
CONTINUE TO PROVIDE A CHANCE OF MAINLY AFTERNOON AND EVENING SHOWERS
AND THUNDERSTORMS INTO THE UPCOMING HOLIDAY WEEKEND WITH HIGH
TEMPERATURES WITHIN A FEW DEGREES OF NORMAL.

&&

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

&&

$$

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