Area Forecast Discussion
Issued by NWS Tucson, AZ

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000
FXUS65 KTWC 200425
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
925 PM MST TUE AUG 19 2014

.SYNOPSIS...SCATTERED MAINLY AFTERNOON AND EVENING THUNDERSTORMS
WILL CONTINUE THROUGH FRIDAY. SOME STORMS WILL PRODUCE HEAVY
RAINFALL AND GUSTY WINDS. A GRADUAL DRYING IS EXPECTED TO OCCUR
THIS WEEKEND INTO EARLY NEXT WEEK. HOWEVER...ENOUGH MOISTURE WILL
REMAIN FOR ISOLATED TO SCATTERED THUNDERSTORMS. BELOW NORMAL DAYTIME
TEMPERATURES WILL PREVAIL THROUGH FRIDAY FOLLOWED BY A WARMING TREND
THIS WEEKEND.

&&

.DISCUSSION...KEMX WSR-88D DETECTED SCATTERED 30-45 DBZ ECHOES
ACROSS FAR ERN PIMA/NWRN COCHISE/NERN SANTA CRUZ COUNTIES AT 0420Z.
OTHER ISOLATED 30-45 DBZ ECHOES WERE ACROSS SOUTH CENTRAL PINAL
COUNTY. THE REST OF SE AZ WAS VOID OF PRECIP ECHOES AT THIS TIME.
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS HAVE DIMINISHED
CONSIDERABLY IN INTENSITY DURING THE PAST HOUR ACROSS EAST CENTRAL
PIMA COUNTY.

THUS...THE FLASH FLOOD WARNING WAS REPLACED WITH A SMALL STREAM
FLOOD ADVISORY UNTIL 1030 PM MST. ALSO...THE FLASH FLOOD WATCH HAS
BEEN LIMITED TO ESSENTIALLY COCHISE COUNTY...AND REMAINS IN EFFECT
UNTIL 11 PM MST. THE FAVORED LOCALES FOR ANY RAINFALL OF
SIGNIFICANCE SHOULD BE ACROSS COCHISE COUNTY UNTIL AROUND MIDNIGHT
OR SO...AS PER RADAR TRENDS AND THE 20/00Z NAM.

FOR THE REST OF TONIGHT...HAVE MAINTAINED A SLIGHT CHANCE OF SHOWERS
AND THUNDERSTORMS ESSENTIALLY FROM TUCSON EWD TO THE NEW MEXICO
BORDER. MOSTLY CLEAR SKIES SHOULD PREVAIL ACROSS WRN PIMA COUNTY.

PLEASE REFER TO THE ADDITIONAL SECTIONS FOR FURTHER DETAIL.

&&

.AVIATION...VALID THRU 21/06Z.
EXPECT SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS SOUTH TO
SOUTHEAST OF KTUS UNTIL AROUND 20/06Z FOLLOWED BY ISOLATED COVERAGE
OF -TSRA/-SHRA MAINLY NEAR THE NEW MEXICO BORDER LATE TONIGHT INTO
WEDNESDAY MORNING. ISOLATED TO SCATTERED TSRA/SHRA WILL OCCUR
WEDNESDAY AFTERNOON AND WEDNESDAY EVENING. MVFR VISIBILITIES AND
WIND GUSTS OF 35-45 KTS WILL OCCUR WITH THE STRONGER TSRA.
OTHERWISE...CLOUD DECKS WILL MAINLY BE AT 6-12K FT AGL AND SURFACE
WIND WILL GENERALLY BE LESS THAN 10 KTS THRU WEDNESDAY EVENING.
AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...EXPECT SCATTERED MAINLY AFTERNOON AND EVENING
THUNDERSTORMS THROUGH FRIDAY. SOMEWHAT LESS COVERAGE OF
THUNDERSTORMS IS FORECAST TO OCCUR THIS WEEKEND AND EARLY NEXT WEEK.
ENOUGH MOISTURE WILL CONTINUE FOR ISOLATED TO SCATTERED MAINLY
AFTERNOON AND EVENING THUNDERSTORMS. OTHERWISE...20-FOOT WINDS WILL
EXHIBIT NORMAL DIURNAL TRENDS AND WILL BE MOSTLY LESS THAN 15 MPH.

&&

.PREV DISCUSSION...AS THE UPPER LOW CONTINUES TO APPROACH THE REGION
IT WILL PUSH SOME DRIER AIR IN OVERNIGHT FROM THE WEST BEHIND THE
MAIN AREA OF SHOWERS AND THUNDERSTORMS WHICH WILL RESULT IN A
DECREASE IN THE CONVECTION ACROSS THE REGION FROM WEST TO EAST. AS A
RESULT OF THE DRIER AIR MOVING IN ALOFT AND LIMITED FORCING...THERE
WILL BE LESS AREAL COVERAGE OF STORMS ON WEDNESDAY...BUT THANKS TO
PLENTY OF NEAR SURFACE MOISTURE IT SHOULD REMAIN SOMEWHAT ACTIVE.
LIKELY SIMILAR TO A TYPICAL AVERAGE MONSOON DAY WITH CONVECTION
FIRING OFF THE HIGHER TERRAIN AND DRIFTING TO THE NORTH-NORTHEAST.

BEYOND THAT THE OPERATIONAL MODELS ARE COMING IN LINE WITH THE UPPER
LOW OVER SOUTHERN CALIFORNIA...AT LEAST MORE IN LINE. THE GFS IS
STILL THE SLOWER MODEL BUT ITS COMING AROUND TO THE OTHER SOLUTIONS.
WITH THE IDEA OF LEANING SLOWER...THE LOW WOULD LIFT NE THROUGH
CENTRAL AND/OR NORTHERN ARIZONA THURSDAY NIGHT INTO EARLY FRIDAY.
THIS COULD MAKE FOR AN INTERESTING THURSDAY AFTERNOON AND EVENING.
I TWEAKED POPS UP A BIT THAT TIME FRAME BUT THEY MAY END UP HIGHER
YET FOR THAT TIME PERIOD. BELOW NORMAL HIGH TEMPERATURES EXPECTED
THROUGH AT LEAST THURSDAY THANKS TO THE ENHANCED CONVECTION.

DRIER AIR MOVES INTO NORTHERN AREAS FRIDAY ONWARD WITH DEEP MOISTURE
HANGING NEAR THE INTERNATIONAL BORDER AND SOUTH OF THERE AS WESTERLY
FLOW DEVELOPS OVER THE STATE. WITH THAT THOUGHT WILL LIKELY HAVE A
DECENT DOWNTURN IN THE CONVECTION OVER THE REGION WITH THE POSSIBLE
EXCEPTION OF ALONG THE BORDER AREA. THE RELATIVE LACK OF CONVECTION
WILL ALLOW AFTERNOON TEMPERATURES TO RETURN TO NORMAL LEVELS ACROSS
THE REGION SATURDAY ONWARD.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
   FLASH FLOOD WATCH UNTIL 11 PM MST THIS EVENING FOR AZZ507-508-
   512-513.

&&

$$

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

FRANCIS
PREVIOUS DISCUSSION...CERNIGLIA




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