Area Forecast Discussion
Issued by NWS Tucson, AZ

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000
FXUS65 KTWC 061620
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
920 AM MST MON JUL 6 2015

.SYNOPSIS...A PACIFIC LOW PRESSURE SYSTEM OFF THE CALIFORNIA COAST
WILL BRING DRIER AIR FROM THE WEST THE NEXT COUPLE OF DAYS. THIS
WILL RESULT IN A GENERAL DECREASE IN THUNDERSTORM ACTIVITY. DAYTIME
TEMPERATURES WILL MAINLY BE A FEW DEGREES BELOW AVERAGE THIS WEEK.

&&

.DISCUSSION...VISIBLE SATELLITE IMAGERY AND SURFACE OBSERVATIONS
INDICATED SUNNY SKIES ACROSS WESTERN PIMA COUNTY...AND MOSTLY SUNNY
TO PARTLY CLOUDY SKIES ELSEWHERE. THERE IS STILL AMPLE MOISTURE
ACROSS SE ARIZONA THIS MORNING...WITH DEWPOINTS AT LOWER ELEVATIONS
VALID 16Z MOSTLY IN THE LOWER-MID 60S F. 06/12Z KTWC SOUNDING PRECIP
WATER VALUE WAS 1.62 INCHES...DOWN NEARLY 0.10 INCH VERSUS 24 HOURS
AGO. A FAIRLY UNSTABLE ENVIRONMENT WAS ALSO OBSERVED...WITH SURFACE
BASED CAPE OF 1618 J/KG...AND LIFTED INDEX OF MINUS 5. HOWEVER...
THIS SOUNDING DEPICTED A CONSIDERABLY DRIER REGIME ABOVE 500 MB
VERSUS SUN MORNING. 06/12Z UPPER AIR PLOTS DEPICTED 592 DM HIGH
PRESSURE CENTERED OVER CHIHUAHUA WITH RIDGE AXIS EXTENDING NWWD
ACROSS THE GREAT BASIN. A WEAK UPPER LOW WAS ALSO CENTERED WEST OF
THE NRN CALIFORNIA COAST NEAR 37N/129W. LIGHT TO MODERATE SWLY FLOW
PREVAILED ABOVE 500 MB ACROSS SE ARIZONA.

A GRADUAL DRYING TREND FROM WEST-TO-EAST WILL OCCUR ACROSS THE AREA
STARTING TODAY AND CONTINUING DURING THE NEXT SEVERAL DAYS. THERE
APPEARS TO BE ENOUGH MOISTURE TO SUPPORT SCATTERED TO PERHAPS
SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND EVENING FROM TUCSON
EASTWARD/SOUTHWARD TO THE NEW MEXICO/INTERNATIONAL BORDERS. THE MAIN
IMPACT WILL CONTINUE TO BE LOCALLY HEAVY RAINFALL...AND PERHAPS
BRIEF STRONG AND GUSTY WINDS.

THEREAFTER...THE INHERITED OFFICIAL FORECAST DEPICTS ISOLATED TO
SCATTERED MAINLY AFTERNOON/EVENING SHOWERS AND THUNDERSTORMS FROM
TUCSON EWD/SWD TUESDAY INTO THIS WEEKEND. 06/12Z NAM IS MORE
VIGOROUS WITH THE DRYING TREND VERSUS THE 06/06Z GFS AND 06/00Z
ECMWF. IF THE NAM IS REALITY...THIS FORECAST AREA MAY BE PRECIP-FREE
PERHAPS AS EARLY AS WED. FOR NOW...WILL GIVE MORE CREDENCE TOWARD
THE GFS/ECMWF SOLUTIONS. SWLY FLOW ALOFT MAY BECOME INCREASINGLY SLY
OR PERHAPS SELY NEXT WEEKEND AND EARLY NEXT WEEK AS HIGH PRESSURE
ALOFT OVER THE SERN CONUS BECOMES POSITIONED OVER NEW MEXICO/WEST
TEXAS.

HIGH TEMPS DURING THE UPCOMING WEEK WILL GENERALLY BE A FEW DEGS
BELOW NORMAL.

&&

.AVIATION...VALID THRU 07/18Z.
SCATTERED -TSRA/-SHRA WILL OCCUR FROM KTUS VICINITY EASTWARD AND
SOUTHWARD TO THE NEW MEXICO/INTERNATIONAL BORDERS THIS AFTERNOON AND
EVENING. THE BULK OF THIS PRECIPITATION IS EXPECTED TO END AROUND
MIDNIGHT TONIGHT. LOCAL MVFR CONDITIONS AND BRIEF WIND GUSTS OF
25-35 KTS MAY ACCOMPANY THE STRONGER TSRA. ISOLATED TO SCATTERED
-TSRA/-SHRA WILL THEN BE CONFINED MAINLY TO LOCATIONS EAST AND SOUTH
OF KTUS TUESDAY AFTERNOON. OTHERWISE...CLOUD BASES WILL GENERALLY BE
AROUND 5-9K FT AGL AND SURFACE WIND WILL BE LESS THAN 10 KTS.
AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...EXPECT SCATTERED SHOWERS AND THUNDERSTORMS THIS
AFTERNOON AND EVENING MAINLY FROM TUCSON EASTWARD AND SOUTHWARD TO
THE NEW MEXICO/INTERNATIONAL BORDERS. THEREAFTER...REDUCED COVERAGE
OF SHOWERS AND THUNDERSTORMS WILL PREVAIL TUESDAY THROUGH FRIDAY...
AND PERHAPS CONTINUING INTO THIS WEEKEND. ISOLATED TO SCATTERED
SHOWERS AND THUNDERSTORMS SHOULD BE LIMITED TO LOCATIONS EAST AND
SOUTH OF TUCSON. GENERALLY LIGHT TERRAIN DRIVEN WINDS WILL OCCUR
OUTSIDE OF THUNDERSTORM INFLUENCES.

&&

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

&&

$$

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

FRANCIS


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