Area Forecast Discussion
Issued by NWS Tucson, AZ

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS65 KTWC 250414
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
915 PM MST MON AUG 24 2015

.SYNOPSIS...EXPECT A DAILY CHANCE OF SHOWERS AND THUNDERSTORMS
ACROSS THE AREA INTO WEDNESDAY. FOR THE SECOND HALF OF THE
WEEK...BUILDING HIGH PRESSURE WILL TEND TO SUPPRESS THUNDERSTORM
COVERAGE WHILE BRINGING HOTTER TEMPERATURES TO THE AREA. NEAR RECORD
HIGHS ARE POSSIBLE FOR THE UPCOMING WEEKEND.

&&

.DISCUSSION...MID LEVEL WARMING PUT A CAP ON VALLEY STORMS FOR MOST
OF THE DAY...WITH THE 00Z KTWC SOUNDING SHOWING AN H5 TEMPERATURE OF
ABOUT -5C AT THE BASE OF A SMALL INVERSION. WE WERE SEEING MORE
STABLE AIR WEST OF TUCSON WITH LESS STABLE ATMOSPHERE EAST OF
TUCSON. BY LATE AFTERNOON WE WERE SEEING NEUTRAL TO CONDITIONALLY
UNSTABLE CONDITIONS OVER THE VALLEY THAT WAS ABLE TO TAKE ADVANTAGE
OF THE EASTERLY FLOW BETWEEN 500-700MB TO CARVE OUT SOME ELEVATED
CONVECTIVE POTENTIAL. BRING IN SOME OUTFLOW FROM THE CONVECTION EAST
OF THE AREA AND WE MANAGED SOME NICE STORMS OVER EASTERN PIMA COUNTY.

THIS ACTIVITY WILL PROPAGATE INTO DEEPER MOISTURE WEST OF TUCSON
WITH A STRONG POTENTIAL FOR OUTFLOWS INCREASING STORM ORGANIZATION
ACROSS THE TOHONO O`ODHAM NATION OVERNIGHT. ELSEWHERE...SCATTERED
SHOWERS WITH ISOLATED EMBEDDED THUNDERSTORMS WILL HANG ON INTO THE
EARLY MORNING HOURS.

AS FOR TUESDAY...LARGE SCALE CONDITIONS WILL CONTINUE TO FAVOR ABOVE
AVERAGE THUNDERSTORM COVERAGE AND ORGANIZATION AS IT HAS FOR THE
PAST FEW DAYS. MY FIRST GUESS IS THAT WE WILL ONCE AGAIN SEE
SIGNIFICANT DELAY IN VALLEY STORM DEVELOPMENT. HOWEVER...AT LEAST
FROM TUCSON EASTWARD...THE STORM LEVEL FLOW IS PROBABLY STRONG
ENOUGH TO RESET THE ATMOSPHERE BY LATE IN THE DAY AND EARLY EVENING
TO ONCE AGAIN RESPOND WELL TO OUTFLOWS.

&&

.AVIATION...VALID THRU 26/06Z.
SCT-BKN CLOUDS AT 6 TO 10 KFT AGL AND ISOLATED TO SCATTERED
SHRA/TSRA THROUGH 25/09Z. GRADUAL DECREASE IN COVERAGE THEREAFTER
WITH MULTIPLE CLOUD LAYERS ABOVE 10 KFT AGL. SCT SHRA/TSRA WILL
ONCE AGAIN DEVELOP LATER TUESDAY. BRIEF MVFR CONDITIONS IN AND
AROUND STRONGER TSRA ALONG WITH GUSTY AND ERRATIC WINDS TO 45 KTS.
AWAY FROM TSRA...SURFACE WINDS TERRAIN DRIVEN AND GENERALLY LESS
THAN 12 KTS OUTSIDE OF TYPICAL AFTERNOON GUSTINESS. AVIATION
DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS ARE
EXPECTED THIS AFTERNOON AND EVENING WITH DECENT STORM CHANCES
REMAINING ON TUESDAY. DRIER AIR WILL BEGIN TO MOVE INTO THE REGION
STARTING WEDNESDAY...BUT WE SHOULD HOLD ONTO ENOUGH MOISTURE FOR AT
LEAST ISOLATED SHOWER AND STORM COVERAGE. THEREAFTER...AN UPPER
RIDGE WILL BUILD OVER THE AREA LATE IN THE WEEK INTO NEXT WEEKEND
RESULTING IN A SIGNIFICANT DECREASE IN SHOWERS AND THUNDERSTORMS
WITH TEMPERATURES RISING TO NEAR RECORD LEVELS FRIDAY AND THROUGH
THE WEEKEND. OUTSIDE OF POTENTIALLY STRONG THUNDERSTORM
WINDS...WINDS WILL BE TYPICAL FOR MID AUGUST AND GENERALLY LESS THAN
15 MPH WITH AFTERNOON GUSTINESS...ESPECIALLY IN THE GILA RIVER
VALLEY.

&&

.PREV DISCUSSION...ITS BEEN A STRUGGLE THIS AFTERNOON WITH ONLY
ISOLATED STORMS. AS MENTIONED IN THE MORNING DISCUSSION 12Z UOFA WRF
NAM WAS MUCH MORE GUNG HO ON CONVECTION TODAY VERSUS THE WRF GFS. AT
THIS TIME IT APPEARS THAT THE WRF-GFS MAY BE THE MODEL TO GO WITH
AND OUR FORECAST IS A LITTLE OVERDONE FOR THIS AFTERNOON. FOR THE
TONIGHT PERIOD...WILL GO WITH A LOW-MID SCATTERED AREAL COVERAGE OF
STORMS.

A CHANCE OF AFTERNOON AND EVENING SHOWERS ON TUESDAY AND WEDNESDAY
WITH EITHER DAY BEING MORE ACTIVE THAN THE OTHER.

THURSDAY INTO THE WEEKEND WILL SEE A DOWNTURN IN CHANCES FOR
THUNDERSTORMS AS DRIER AIR MOVES IN AND HIGH PRESSURE STRENGTHENS
OVER THE AREA. HIGHS UP WILL BE NEAR RECORD HIGHS FOR LATE AUGUST.
INTERESTING TO NOTE THAT 12Z ECMWF 850-700 MB THICKNESS VALUES ARE
LOWER THAN PAST MODEL RUNS. AT THIS TIME RAN WITH CURRENT FORECAST
HIGHS WHICH ARE NEAR WHAT GFS IS HINTING AT.

&&

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

&&

$$

MEYER/LADER/CARLAW

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



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.