Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 021647
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
930 AM MST THU JUL 2 2015

.SYNOPSIS...THERE WILL BE FEW THUNDERSTORMS AROUND TODAY...OTHERWISE
EXPECT SCATTERED MAINLY AFTERNOON AND EVENING THUNDERSTORMS INTO
EARLY NEXT WEEK. SLOWER MOVING STORMS WILL START TO INCREASE HEAVY
RAINFALL CONCERNS WITH WET MICROBURSTS POSSIBLE. DAYTIME
TEMPERATURES WILL REMAIN CLOSE TO SEASONAL NORMALS INTO THIS HOLIDAY
WEEKEND.

&&

.DISCUSSION...THE ATMOSPHERE IS TEMPORARILY BECOMING MORE STABLE
WITH A MUCH WEAKER FLOW AS THE RIDGE AXIS REORIENTS FROM A POSITION
NORTH OF OUR AREA TO ONE THAT IS MORE TYPICALLY AMPLIFIED EAST OF
OUR AREA. AS THIS HAPPENS THE BRISK EASTERLY FLOW IS TURNING INTO AN
INCREASING AND DEEPENING SOUTHERLY FLOW. SO FOR TODAY...NOT MUCH.
FRIDAY WILL START TO INCREASE A BIT AS THE NEW FLOW REGIME SETS
UP...THEN INCREASING THUNDERSTORMS FOR THE WEEKEND INTO EARLY NEXT
WEEK. THESE WILL BE MORE TYPICAL SUMMER THUNDERSTORMS WITH HEAVY
RAIN AND ISOLATED WET MICROBURST CONCERNS...NOT THE STRONG
MESOCYCLONES OF TUESDAY. WE TWEAKED THE CURRENT FORECAST TO PUSH
CHANCES OF THUNDERSTORMS EVEN LOWER TODAY AND THIS EVENING. FOR
ADDITIONAL DETAILS PLEASE SEE THE PREVIOUS DISCUSSION BELOW.

&&

.AVIATION...VALID THRU 03/18Z. MOSTLY CLEAR THROUGH THE MORNING HOURS
WITH ISOLATED THUNDERSTORMS DEVELOPING IN THE AFTERNOON...MAINLY
NEAR THE MOUNTAINS SOUTH AND EAST OF KTUS. BRIEF WIND GUSTS OF 30-45
KTS AND MVFR CONDITIONS POSSIBLE NEAR THE STRONGEST STORMS.
OTHERWISE EXPECT NORMAL DIURNAL WIND TRENDS. AVIATION DISCUSSION NOT
UPDATED FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...NOT AS MANY STORMS AROUND TODAY...OTHERWISE 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.

&&

.PREV DISCUSSION...QUITE A DIFFERENT SCENE ACROSS SEAZ EARLY THIS
MORNING COMPARED TO 24 HRS AGO...WITH NO RETURNS EVIDENT ON KEMX
RADAR. IR SATELLITE IMAGERY SHOWS CLEAR TO MOSTLY CLEAR SKIES...WITH
SOME DEBRIS CLOUDINESS PUSHING SWD INTO THIS CWA FROM THE DECAYING
COMPLEX LOCATED OVER NRN AZ...AND ALSO A FEW CLOUDS POPPING UP ALONG
THE INTERNATIONAL BORDER. WATER VAPOR IMAGERY AND 02/00Z UPPER-AIR
PLOTS SHOW HIGH PRESSURE CENTERED OVER THE GREAT BASIN WITH EAST TO
SOUTHEAST STEERING FLOW OVER ARIZONA. 02/09Z SFC PLOTS INDICATE
TEMPERATURES WERE GENERALLY IN THE 60S AND 70S...WITH DEWPOINTS
HOLDING STEADY IN THE 50S AND 60S.

THE HIGH PRESSURE CENTER WILL CONTINUE TO MIGRATE SOUTH AND EAST
OVER THE NEXT SEVERAL DAYS...FROM ERN NEVADA TO ERN NEW MEXICO. THIS
MEANS A TRANSITION IN THE LARGE SCALE FLOW OVER AZ FROM AN ELY
DIRECTION TO A SLY DIRECTION. FOR THE NEXT 24 HOURS THIS SHOULD SHOW
ITSELF AS A SLOW WARMING TREND IN THE MID LEVELS AND WEAKENING STORM
LEVEL FLOW.

CURRENTLY ANTICIPATING TODAY TO BE A DOWN DAY FOR STORMS IN BOTH
INTENSITY AND COVERAGE. THE BEST CHANCE FOR RAIN THIS AFTERNOON IS
EXPECTED NEAR TERRAIN FOR AREAS MAINLY SOUTH TO EAST OF TUCSON AND
ALSO THE WHITE MOUNTAINS...WITH SOME STORMS MAKING IT INTO THE
VALLEYS. ACTIVITY SHOULD THEN INCREASE A BIT ON FRIDAY AS SLY FLOW
DEEPENS THROUGH THE COLUMN AND INTENSIFIES. THIS SETUP WILL FEED
PLENTY OF MOISTURE FROM THE GULF OF CALIFORNIA INTO THE AREA BY
SATURDAY...MAKING FOR A BUSY HOLIDAY WEEKEND WEATHER-WISE WITH SLOW
MOVING AND HEAVY RAINING STORMS.

UPPER LEVEL FLOW WILL THEN GRADUALLY BECOME SWLY BY THE MIDDLE OF
NEXT WEEK AS LOW PRESSURE...CURRENTLY LOCATED NEAR 28N/126W...MOVES
NWD AND CONSOLIDATES OFF THE NRN CA COAST AND THE HIGH PRESSURE
RIDGE FLATTENS OUT EWD OVER THE CONUS. THIS WILL FEED SLIGHTLY DRIER
AIR INTO AZ...CAUSING A SLIGHT DOWNTURN IN CONVECTIVE ACTIVITY FOR A
COUPLE OF DAYS. STILL A LITTLE FAR OUT TO PINPOINT THE EXACT TIMING
AND DURATION OF THIS LULL...BUT PLENTY OF TIME TO IRON OUT THESE
DETAILS OVER THE COMING DAYS.

NO BIG CHANGES IN TEMPERATURES FOR THE NEXT WEEK...AS HIGHS SHOULD
TOP OUT IN THE UPPER 90S WITH PERHAPS A 100 OR TWO...WITH LOWS IN
THE UPPER 70S EACH MORNING.

&&

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

&&

$$

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MEYER/LADER



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