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 121501
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
800 AM MST FRI SEP 12 2014

.SYNOPSIS...EXPECT SCATTERED THUNDERSTORMS ESPECIALLY EAST OF TUCSON
THIS AFTERNOON AND EVENING. STRONG AND GUSTY EAST WINDS WILL DEVELOP
TONIGHT INTO SATURDAY...THEN SEVERAL DEGREES OF COOLING ALONG WITH A
REDUCED CHANCE OF STORMS THIS WEEKEND. THE CHANCE FOR THUNDERSTORMS
WILL INCREASE EARLY NEXT WEEK AS MOISTURE INCREASES ACROSS THE AREA
FROM THE SOUTH...ESPECIALLY TUESDAY AND WEDNESDAY.

&&

.DISCUSSION...SUNNY SKIES FROM TUCSON WWD AND A FEW MID-LEVEL CLOUDS
FOR MOSTLY SUNNY SKIES ACROSS ERN SECTIONS AT THIS TIME. DEWPOINTS
AT LOWER ELEVATIONS VALID 15Z WERE MOSTLY IN THE MID-UPPER 50S...AND
THESE TEMPS WERE ABOUT IDENTICAL TO 24 HOURS AGO. SURFACE TEMPS
VALID 15Z WERE GENERALLY 1-3 DEGS F WARMER VERSUS THIS TIME THUR.
12/12Z KTWC SOUNDING TOTAL PRECIP WATER VALUE WAS 1.20 INCHES...AN
INCREASE OF NEARLY 0.20 INCH VERSUS 24 HOURS AGO. THE ENVIRONMENT
WAS MODERATELY UNSTABLE...WITH LIFTED INDEX OF MINUS 4 AND UNMODIFIED
SBCAPE OF 1099 J/KG. 12/12Z UPPER AIR PLOTS DEPICTED RIDGE AXIS
EXTENDING FROM SRN CALIFORNIA EWD INTO THE SERN CONUS...AND TROUGH
WAS OVER THE UPPER MISSISSIPPI RIVER VALLEY REGION. VERY LIGHT MOSTLY
SELY/SLY FLOW PREVAILED IN THE 850-500 MB LAYER...AND VERY LIGHT WLY
FLOW WAS OBSERVED ABOVE 500 MB.

THE OFFICIAL FORECAST CONTINUES WITH SCATTERED SHOWERS/TSTMS ACROSS
ERN SECTIONS THIS AFTERNOON/EVENING...AND ISOLATED SHOWERS/TSTMS
SHOULD OCCUR FOR THE TUCSON METRO AREA WWD INTO THE TOHONO O`ODHAM
NATION. DRY CONDITIONS SHOULD CONTINUE THIS AFTERNOON/EVENING ACROSS
WRN PIMA COUNTY. GUSTY EAST WINDS ARE FORECAST TO START ACROSS THE
TUCSON METRO AREA TONIGHT AND CONTINUE SAT IN RESPONSE TO A VERY
TIGHT SURFACE PRESSURE GRADIENT.

THERE ARE NO UPDATES PLANNED AT THIS TIME. PLEASE REFER TO THE
ADDITIONAL SECTIONS FOR FURTHER DETAIL.

&&

.AVIATION...VALID THRU 13/12Z.
AN EASTERLY WIND WILL IMPORT HIGHER MOISTURE TO LOCATIONS MAINLY
EAST OF TUCSON TODAY. THIS WILL RESULT IN SCATTERED LOW-LEVEL
CLOUDS /7-11K FT AGL/ AND SCATTERED TO BROKEN MID-LEVEL CLOUDS
/12-16K FT AGL/ WITH SCATTERED AFTERNOON AND EVENING SHRA/TSRA.
SURFACE WIND GENERALLY LESS THAN 10 KTS...EXCEPT GUSTY IN THE
VICINITY OF SHRA/TSRA. GUSTY EAST WINDS WILL DEVELOP THIS EVENING
AND CONTINUE INTO SATURDAY MORNING...WITH SOME GUSTS APPROACHING
35 KTS. AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...THERE IS A CHANCE OF SHOWERS AND THUNDERSTORMS
ACROSS THE EASTERN HALF OF THE FORECAST AREA THIS AFTERNOON AND
EVENING. WINDS WILL GENERALLY BE OUT OF THE EAST TODAY...WITH EXCEPT
ERRATIC OUTFLOWS ASSOCIATED WITH THUNDERSTORMS. STRONGER EAST TO
SOUTHEAST WINDS WILL OCCUR TONIGHT INTO SATURDAY DUE TO A BACKDOOR
FRONTAL PASSAGE. EXPECT WIND SPEEDS TO BE ELEVATED INTO SUNDAY...
GENERALLY BETWEEN 10 AND 20 MPH...WITH SOME LOCALLY HIGHER SPEEDS
POSSIBLE. PRECIPITATION CHANCES WILL LOWER DURING THIS WEEKEND INTO
THE SLIGHT CHANCE CATEGORY. TROPICAL MOISTURE WILL THEN BE ON THE
INCREASE NEXT WEEK...WITH TROPICAL STORM ODILE INFLUENCE REACHING
THE FORECAST AREA. EXPECT AN INCREASE IN SHOWER AND THUNDERSTORM
ACTIVITY AND AREAL COVERAGE BY THE MIDDLE OF THE UPCOMING WEEK.

&&

.PREV DISCUSSION...DECENT SYSTEM PUSHING THROUGH THE NORTHERN AND
CENTRAL PLAINS WITH TRAILING FRONTAL BOUNDARY INTO NEW MEXICO.
EXPECT AN EASTERLY GRADIENT AS THE PERIPHERY OF THIS AIR MASS TRIES
TO BACK INTO THE AREA FROM THE EAST TONIGHT INTO SATURDAY WITH A
SURFACE HIGH BUILDING DOWN THE FRONT RANGE. BREEZY TO LOCALLY WINDY
EAST TO SOUTHEAST WINDS TONIGHT THROUGH THE FIRST HALF OF THE
WEEKEND. EXPECT ELEVATED OVERNIGHT LOWS SATURDAY MORNING AS MANY
VALLEY LOCATIONS FROM TUCSON EASTWARD FAIL TO DECOUPLE. THIS WILL
TAMP DOWN THE MOISTURE A BIT AND FILTER IN SOME RELATIVELY COOLER
AIR INTO EASTERN ZONES SATURDAY. AN EXAGGERATED SPATIAL TREND IN
TEMPERATURES SATURDAY WITH VERY LITTLE COOLING OUT WEST CONTRASTED
WITH AROUND 10 DEGREES OF COOLING IN EASTERN ZONES.

TROPICAL STORM ODILE CURRENTLY DOWN AROUND 15.5N 104.9W OR ABOUT 245
MILES SOUTH OF MANZANILLO WILL CONTINUE TO STRENGTHEN AND PUSH
NORTHWEST TOWARD THE TIP OF BAJA OVER THE NEXT 5 DAYS. SHE WILL
LIKELY HELP PROVIDE A MOISTURE INCREASE FOR BETTER SHOWER AND
THUNDERSTORM COVERAGE FOR OUR AREA AROUND TUESDAY AND WEDNESDAY OF
NEXT WEEK...BUT SHE DOESN`T HAVE ALL OF THE ADVANTAGES NORBERT DID.
FOR ONE...THERE IS A DEVELOPING RIDGE AXIS THAT WILL PROBABLY BE A
LITTLE TOO DOMINANT OVER THE DESERT SOUTHWEST EARLY NEXT WEEK. FOR
NORBERT THE RIDGE WAS SET UP EAST OF OUR AREA WITH STRONGER AND
DEEPER SOUTHERLY TO SOUTHEASTERLY FLOW AROUND IT. ANOTHER FACTOR IS
NORBERT ALSO WAS ABLE TO HELP GUIDE ADDITIONAL TROPICAL MOISTURE
FROM A DECAYING GULF OF MEXICO SYSTEM INTO OUR AREA...AND WE DON`T
REALLY HAVE THAT THIS TIME. ODILE WILL VERY LIKELY ENHANCE OUR
MOISTURE WITH INCREASED STORM COVERAGE FOLLOWING...BUT AT THIS POINT
IT DOESN`T LOOK LIKE IT WILL BE QUITE AS SIGNIFICANT AS NORBERT WAS.

SO...INCREASING MOISTURE FOR BETTER STORM COVERAGE FROM TUCSON
EASTWARD TODAY...GUSTY EAST WINDS TONIGHT INTO SATURDAY WITH BELOW
AVERAGE TEMPERATURES SATURDAY...THEN ENHANCED MOISTURE FOR MUCH
BETTER STORM COVERAGE BY TUESDAY AND WEDNESDAY.

&&

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

&&

$$

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

FRANCIS
PREVIOUS DISCUSSION...MEYER




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