Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 032214
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
300 PM MST FRI JUL 3 2015

.SYNOPSIS...ANOTHER CHANCE OF SHOWERS AND THUNDERSTORMS OVERNIGHT
FOLLOWED BY A STEADY INCREASE IN THE NUMBER OF STORMS INTO THIS
WEEKEND. SLOWER MOVING STORMS WILL START TO INCREASE HEAVY RAINFALL
CONCERNS WITH WET MICROBURSTS POSSIBLE. DAYTIME TEMPERATURES WILL
REMAIN CLOSE TO SEASONAL NORMALS.

&&

.DISCUSSION...SLOW DEVELOPMENT WITH VERY WEAK FLOW FOR STORM
STRUCTURE. EVEN DELAYED MOUNTAIN DEVELOPMENT WITH CONVECTIVE
INHIBITION INCREASING AS WE SEE WARMER TEMPERATURES FROM H5 TO H6
BEHIND A WEAK SOUTHEASTERLY IMPULSE. STORM STRUCTURE EVEN STRUGGLING
IN THE SKY ISLANDS...MUCH LESS VALLEY LOCATIONS. THE RIM IS FIRING
NICELY BUT FLOW DOES NOT FAVOR A DEEP OUTFLOW INTO OUR LOWER
ELEVATIONS.

INITIAL CONVECTIVE DEVELOPMENT JUST SOUTH OF THE BORDER THROUGH
NORTHEAST SONORA AND NORTHWEST CHIHUAHUA CONTINUES TO TRACK WELL
WITH THE IDEA OF A STRONG CONVECTIVE COMPLEX ASSOCIATED WITH THE H7
THETA-E RIDGE STRENGTHENING THROUGH THAT REGION. THIS SHOULD SPREAD
INTO BORDER AREAS THIS EVENING AND FAVOR COCHISE AND SANTA CRUZ
COUNTIES BETWEEN 03Z AND 08Z.

WITH THE RIDGE AXIS SOLIDLY EAST OF OUR AREA SATURDAY THE DEEPER
SOUTHERLY FLOW WILL KEEP ABOVE AVERAGE MOISTURE OVER THE AREA WHILE
ALSO ALLOWING THE FLOW TO ORGANIZE JUST ENOUGH FOR BETTER STORM
STRUCTURE. ADD IN MID LEVELS COOLING BACK TO LEVELS MORE FAVORABLE
FOR STORM ENVIRONMENT AND WE SHOULD SEE AN INCREASE IN THUNDERSTORM
COVERAGE SATURDAY (UNLESS THE COMPLEX DEVELOPING TO OUR SOUTH
BECOMES MORE OF AN ISSUE THAN CURRENTLY EXPECTED). KEEPING FINGERS
CROSSED TO START SHUTTING DOWN CONVECTION AFTER SUNSET SATURDAY.

FOR SUNDAY THE ECMWF AND GFS ARE BOTH HINTING AT BUILDING A BIG DAY
AROUND A REMNANT CIRCULATION LIFTING UP FROM THE SOUTH. WITH
MOISTURE THAT DEEP WHO AM I TO ARGUE. WATCH FOR A BUSY AND WET
SUNDAY WITH HEAVY RAIN AND POTENTIAL FLASH FLOOD ISSUES A CONCERN.

BY TUESDAY...MAJOR FEATURES ARE TRYING TO GIVE A WESTERLY COMPONENT
TO OUR SOUTHERLY FLOW. A BIG DIFFERENCE BETWEEN 170 DEGREES AND 200
DEGREES FOR AREAS OF STORM DEVELOPMENT. WE WILL SHOW A DIMINISHING
THUNDERSTORM TREND SPREADING IN FROM THE WEST BY MID WEEK.

&&

.AVIATION...VALID THRU 05/00Z.
EXPECT SCATTERED TO NUMEROUS -TSRA/-SHRA EAST AND SOUTH OF KTUS INTO
THIS EVENING. THERE IS ALSO A SLIGHT CHANCE OF -TSRA/-SHRA FOR KTUS
INTO THIS EVENING...BUT THE CHANCE OF OCCURRENCE IS TOO LOW TO
INCLUDE IN THE TAF. ISOLATED TO SCATTERED -TSRA/-SHRA SHOULD PREVAIL
LATE TONIGHT INTO SATURDAY MORNING...THEN SCATTERED TO NUMEROUS
-TSRA/-SHRA WILL RETURN SATURDAY AFTERNOON. THE BEST PERIOD FOR
BRIEF WIND GUSTS OF 35-45 KTS WILL BE SATURDAY AFTERNOON.
OTHERWISE...CLOUD DECKS WILL MAINLY BE AT OR ABOVE 8K FT AGL AND
SURFACE WIND GENERALLY LESS THAN 10 KTS. AVIATION DISCUSSION NOT
UPDATED FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...SCATTERED SHOWERS AND THUNDERSTORMS WILL OCCUR
MAINLY EAST AND SOUTH OF TUCSON INTO SATURDAY MORNING. FAIRLY SLOW
STORM MOTIONS WILL GIVE A GREATER POTENTIAL FOR HEAVY RAINFALL. DRY
CONDITIONS WILL PREVAIL ACROSS WESTERN PIMA COUNTY WEST OF TUCSON
INTO SATURDAY MORNING. THEREAFTER...EXPECT INCREASED COVERAGE OF
SHOWERS AND THUNDERSTORMS STARTING SATURDAY AFTERNOON AND CONTINUING
SUNDAY. THE MAIN CONCERN WILL BE THE COMBINATION OF BRIEF STRONG AND
GUSTY WINDS AND HEAVY RAINFALL. A CHANCE OF MAINLY AFTERNOON AND
EVENING THUNDERSTORMS WILL THEN CONTINUE DURING THE UPCOMING WEEK.

&&

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

&&

$$

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

MEYER/FRANCIS



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