Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 010337
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
840 PM MST THU JUL 31 2014

.SYNOPSIS...SCATTERED SHOWERS AND THUNDERSTORMS THROUGH TONIGHT
FOLLOWED BY A BETTER CHANCE OF SHOWERS AND THUNDERSTORMS FRIDAY AND
OVER THE WEEKEND. GUSTY WINDS FROM THUNDERSTORMS COULD PRODUCE AREAS
OF BLOWING DUST...ESPECIALLY FRIDAY AFTERNOON IN DUST PRONE
LOCATIONS. PERIODS OF HEAVY RAINFALL CAN BE ANTICIPATED THROUGH THE
WEEKEND.

&&

.DISCUSSION...RIDGE AXIS NEARLY OVERHEAD BUT SIGNIFICANT WEAKNESSES
IN THE FLOW. PRECIPITABLE WATER VALUES BETWEEN 1.4 AND 1.6 INCHES AS
PER 00Z KTWC SOUNDING AND BLENDED TOTAL PW SATELLITE TRENDS.
SOUTHEASTERLY IMPULSE TRACKING ACROSS THE NORTHERN GULF ENHANCING
STORMS IN CENTRAL TO NORTHERN SONORA AS IT LIFTS TO THE
NORTHWEST...AND WILL PROBABLY KEEP ACTIVITY GOING OVERNIGHT ACROSS
WESTERN AREAS. STRONG OUTFLOW FROM ORGANIZED CONVECTION IN WESTERN
NEW MEXICO NOW PUSHING DEEP INTO SOUTHEAST ARIZONA WITH STORMS
INCREASING THROUGH SOUTHERN GREENLEE...EASTERN GRAHAM AND EASTERN
COCHISE COUNTIES AS A DIRECT RESULT. THIS IS A DEEP AND SUSTAINED
OUTFLOW THAT COULD PUSH INTO EASTERN PIMA COUNTY IN THE LATE EVENING
AND EARLY MORNING HOURS.

EXPECT DEEP MOISTURE TO COMBINE WITH PERSISTENT ORGANIZATION FROM
ONE IMPULSE NEAR SOUTHERN NEW MEXICO AND ANOTHER NEAR NORTHWEST
SONORA FOR WIDESPREAD THUNDERSTORM ACTIVITY INTO THE WEEKEND.

&&

.AVIATION...VALID THRU 02/03Z.
ACTIVE SHOWERS AND THUNDERSTORMS WILL CONTINUE THROUGH THE LATE
EVENING INTO THE EARLY MORNING HOURS. STORMS MAY IMPACT
TERMINALS...WITH KOLS HAVING THE HIGHEST CHANCE DURING THE NEXT 6 TO
12 HOURS. HEAVY RAINFALL MAY REDUCE VISIBILITIES AND CREATE PERIODS
OF MVFR CONDITIONS. SCATTERED SHOWERS/THUNDERSTORMS WITH THE
POTENTIAL FOR HEAVY RAIN AND GUSTY WINDS WILL BE THE RULE INTO THE
EARLY PART OF THE WEEKEND. AVIATION DISCUSSION NOT UPDATED FOR TAF
AMENDMENTS.

&&

.FIRE WEATHER...SHOWER AND THUNDERSTORM ACTIVITY WILL BE ON THE
INCREASE THROUGH THE NEXT 48 TO 72 HOURS AS MONSOON MOISTURE SURGES
IN FROM THE SOUTH. EXPECT STRONG...GUSTY AND ERRATIC WINDS WITH THE
STRONGER THUNDERSTORMS. INCREASING MOISTURE WILL ALSO TRANSLATE INTO
PERIODS OF HEAVY RAINFALL AND COOLER TEMPERATURES THIS
WEEKEND...PARTICULARLY SATURDAY. THEREAFTER...A DRYING TREND WITH
WARMER TEMPERATURES WILL PREVAIL BY THE MIDDLE OF NEXT WEEK.

&&

.PREV DISCUSSION...THE OVERALL TREND SUGGESTED BY THE MODELS WILL BE
AN INCREASE IN RAIN CHANCES THROUGH THE WEEKEND. SHOWERS AND
THUNDERSTORMS WERE REDEVELOPING THIS AFTERNOON FOLLOWING A LULL IN
THE ACTIVITY THIS MORNING. THIS ACTIVITY CAN BE EXPECTED TO INCREASE
IN COVERAGE BY THIS EVENING WITH LOCALLY HEAVY DOWNPOURS AND STRONG
WINDS BEING THE MAIN THREATS THIS EVENING AND FOR THE MOST PART
THROUGH THE WEEKEND. AREAS OF BLOWING DUST WILL BE POSSIBLE...MAINLY
EARLY THIS EVENING AND AGAIN FRIDAY IN DUST PRONE SPOTS. BASED ON
THE LATEST QPF GUIDANCE...MULTIPLE DAYS OF HEAVY RAINFALL ACROSS THE
AREA AND IN SONORA MEXICO AND WESTERN NEW MEXICO COULD RESULT IN
ELEVATED FLOWS IN SOME OF THE LARGER WASHES AND STREAMS. THIS WILL
ESPECIALLY BE THE CASE FOR SANTA CRUZ...GREENLEE...EASTERN GRAHAM
AND THE SOUTHERN ONE-HALF OF COCHISE COUNTIES BY SUNDAY AFTERNOON.
MODELS SUGGESTED THAT BE BEST TIME FRAME FOR MORE WIDESPREAD HEAVY
RAINFALL WILL BE SATURDAY AFTERNOON INTO SUNDAY MORNING AS AN UPPER
LOW TRACKS NORTHWARD INTO SOUTHWEST ARIZONA. OTHERWISE...MORE
LOCALIZED HEAVY RAINFALL AND RUNOFF PROBLEMS CAN BE ANTICIPATED
TODAY AND FRIDAY. THE BEST UPPER LEVEL DYNAMICS TO SUPPORT SHOWERS
AND THUNDERSTORMS WILL BE OVER NORTHERN ARIZONA BY SUNDAY AFTERNOON.
THEREFORE...WOULD EXPECTED CLEARING ACROSS SOUTHEAST ARIZONA SUNDAY
MORNING WITH DRIER AIR SPREADING INTO THE AREA EARLY NEXT WEEK. THIS
DRIER AIR WILL LIMIT THUNDERSTORM ACTIVITY BY THE MIDDLE OF NEXT
WEEK.

&&

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

&&

$$

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