Special Weather Statement, NWS Tucson, AZ

AREA FORECAST DISCUSSION...UPDATE
NATIONAL WEATHER SERVICE TUCSON AZ
640 PM MST FRI JUL 17 2015

.SYNOPSIS...SHOWERS AND THUNDERSTORMS WILL INCREASE IN COVERAGE
EARLY SATURDAY AS TROPICAL MOISTURE MOVES NORTH ACROSS THE AREA.
SHORT BURSTS OF VERY HEAVY RAINFALL WILL BE POSSIBLE THROUGH
SATURDAY BRINGING ABOUT THE POTENTIAL FOR LOCAL FLASH FLOODING.  A
SLOW DRYING TREND WILL THEN BEGIN EARLY NEXT WEEK...WITH THE BEST
CHANCES FOR THUNDERSTORMS MAINLY EAST AND SOUTH OF TUCSON BY
WEDNESDAY.

&&

.DISCUSSION...A COMBINATION OF LIMITED SOLAR INSOLATION AND SOME
STABILIZATION OF THE ATMOSPHERE HAS SEEN LIMITED THUNDERSTORM
DEVELOPMENT FROM TUCSON EASTWARD...WITH VERY ACTIVE WESTERN AREAS. A
MERGING COMPLEX WEST OF TUCSON...CENTERED OVER THE TOHONO O'ODHAM
NATION...IS TRYING TO SQUEEZE ACTIVITY EASTWARD TOWARD TUCSON...BUT
THE 00Z SOUNDING IS SHOWING A BLEAK PICTURE FOR CONVECTIVE
POTENTIAL...WITH ABOUT 2 DEGREES OF WARMING IN MID LEVELS. WE
UPDATED THE FORECAST OVERNIGHT TO LIMIT MOST OF THE WIDESPREAD HEAVY
RAINFALL.

WITH ADDITIONAL MOISTURE SPREADING IN FROM THE WEST AND
SOUTHWEST...ALONG WITH A FAVORABLE UPPER LEVEL DIFFLUENT AREA
SHIFTING FROM SONORA INTO SOUTHEAST ARIZONA IN THE EARLY MORNING
HOURS...WE STILL EXPECT TO SEE MORE WIDESPREAD COVERAGE OF SHOWERS
AND THUNDERSTORMS BEGINNING EARLY SATURDAY. PROBABLY INCREASING FROM
THE SOUTH AFTER 4 AM...ALTHOUGH MESOSCALE MODELS CONTINUE TO
STRUGGLE TO GET A HANDLE ON THINGS. UNTIL THEN...OUTSIDE OF WESTERN
AREAS COVERAGE OF STRONG STORMS WILL LIKELY BE LIMITED.

PLEASE SEE THE PREVIOUS DISCUSSION BELOW FOR ADDITIONAL DETAILS.

&&

.AVIATION...VALID THRU 19/00Z.
BKN-OVC CLOUDS AT 8-15K FT AGL WILL GENERALLY PREVAIL THROUGH THE
FORECAST PERIOD. EXPECT SCATTERED +SHRA/+TSRA TO CONTINUE THIS
EVENING...INCREASING SATURDAY MORNING. CIGS WILL BRIEFLY LOWER TO 4-
6K FT NEAR TSRA'S. SURFACE WIND WILL MAINLY BE LESS THAN 10 KTS
THROUGH THE PERIOD OUTSIDE OF ANY GUSTS FROM TSRA'S. AVIATION
DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS WITH
LOCALLY HEAVY RAIN IS EXPECTED THROUGH SATURDAY WITH SHOWER AND
THUNDERSTORM COVERAGE JUST A LITTLE BIT LESS ON SUNDAY. BY EARLY
NEXT WEEK...EXPECT A DRYING TREND WILL LIMIT SHOWERS AND
THUNDERSTORMS TO MAINLY EAST AND SOUTH OF TUCSON INTO THE MIDDLE OF
NEXT WEEK.

&&

.PREV DISCUSSION...MORNING SHOWERS AND EXTENSIVE CLOUD COVER HAD
DELAYED THE REDEVELOPMENT OF SHOWERS AND THUNDERSTORMS TODAY. BASED
ON THE BLENDED TOTAL PRECIP WATER PRODUCT...DEEPER MOISTURE
CONTINUED TO ADVECT NORTHWARD UP THE GULF OF CALIFORNIA INTO THE
DESERTS OF ARIZONA. A WEAK CIRCULATION FROM A THUNDERSTORM COMPLEX
THAT DEVELOPED LAST NIGHT WELL SOUTH OF THE INTERNATIONAL BORDER WAS
BRUSHING FAR SOUTHEAST COCHISE COUNTY EARLY THIS AFTERNOON. THIS
FEATURE WAS HELPING TRIGGER A FEW SHOWERS AND THUNDERSTORMS IN
COCHISE COUNTY. SOME THINNING OF THE CLOUD COVER THIS MORNING FROM
TUCSON WESTWARD HAD PROVIDED ENOUGH SURFACE HEATING TO SUPPORT A FEW
LIGHT SHOWERS OVER THE TOHONO O'ODHAM NATION SO FAR TODAY. ALTHOUGH
DELAYED SIGNIFICANTLY...SCATTERED SHOWERS AND THUNDERSTORMS CAN
STILL BE ANTICIPATED LATER TODAY. BECAUSE OF THE INCREASED
MOISTURE...JUST ABOUT ANY STRONG THUNDERSTORM THAT MANAGES TO
DEVELOP WILL BE CAPABLE OF PRODUCING VERY HEAVY RAINFALL IN A SHORT
PERIOD OF TIME. THUS...WILL KEEP THE FLASH FLOOD WATCH GOING THROUGH
SATURDAY. OTHERWISE...A TREND TOWARD A GRADUAL DAILY REDUCTION IN
THE COVERAGE OF SHOWERS AND THUNDERSTORMS CAN BE ANTICIPATED MONDAY
INTO WEDNESDAY OF NEXT WEEK. DAYTIME TEMPERATURES WILL REBOUND
MONDAY AND TUESDAY TO NEAR NORMAL READINGS.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
   FLASH FLOOD WATCH FROM THRU SATURDAY EVENING FOR MOST OF SOUTHEAST
   ARIZONA...INCLUDING ZONES AZZ501>509-511>515

&&

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

MEYER

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE TUCSON AZ
713 PM MST FRI JUL 17 2015

AZZ502-504-180300-
TUCSON METRO AREA INCLUDING TUCSON/GREEN VALLEY/MARANA/VAIL AZ-
TOHONO O'ODHAM NATION INCLUDING SELLS AZ-
713 PM MST FRI JUL 17 2015

...SIGNIFICANT WEATHER ADVISORY FOR NORTH CENTRAL PIMA COUNTY UNTIL
800 PM MST...

AT 712 PM MST...DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM NEAR
TO JUST SOUTHWEST OF AVRA VALLEY...MOVING NORTHEAST AT 5 MPH.

WINDS IN EXCESS OF 40 MPH WILL BE POSSIBLE WITH THIS STORM ALONG
WITH VERY HEAVY RAINFALL.

LOCATIONS IMPACTED INCLUDE...
AVRA VALLEY AND PICTURE ROCKS.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

EXTREMELY HEAVY RAINFALL IS ALSO OCCURRING WITH THIS STORM...AND MAY
LEAD TO FLASH FLOODING. DO NOT DRIVE YOUR VEHICLE THROUGH FLOODED
ROADWAYS.

&&

LAT...LON 3226 11138 3240 11150 3249 11130 3238 11115
TIME...MOT...LOC 0212Z 239DEG 9KT 3238 11137

MEYER