Area Forecast Discussion
Issued by NWS Tucson, AZ

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000
FXUS65 KTWC 170300
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
800 PM MST TUE SEP 16 2014

.SYNOPSIS...PERIODS OF SHOWERS AND THUNDERSTORMS CAN BE EXPECTED
TONIGHT THROUGH EARLY WEDNESDAY...WITH HEAVY RAINFALL POSSIBLE. THE
MOST WIDESPREAD AND HEAVIEST RAIN IS THEN EXPECTED WEDNESDAY AND
THURSDAY WITH THE POTENTIAL FOR FLOODING AND FLASH FLOODING ISSUES.
THEREAFTER...LINGERING TROPICAL MOISTURE WILL KEEP SCATTERED SHOWERS
AND THUNDERSTORMS IN THE FORECAST FRIDAY THROUGH THE WEEKEND.

&&

.DISCUSSION...SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS CONTINUE
TO LIFT NORTH ACROSS SOUTHEAST ARIZONA THIS EVENING. MOST OF THE
PRECIPITATION TODAY HAS BEEN ON THE LIGHT SIDE...WITH RAINFALL
TOTALS GENERALLY BETWEEN A COUPLE OF HUNDRETHS TO TWO-TENTHS OF AN
INCH. A FEW ISOLATED POCKETS OF HEAVIER RAINFALL WERE NOTED NEAR
CLIFTON AND SOUTH OF SAN SIMON...WITH RAINFALL AMOUNTS BETWEEN ONE
AND TWO INCHES. DEWPOINTS ARE CURRENTLY IN THE MID TO UPPER 60S
ACROSS THE SOUTHERN HALF OF ARIZONA IN THE LOWER ELEVATIONS...WITH
DEWPOINTS IN THE 50S IN THE HIGHER TERRAIN/MOUNTAINS. THE 00Z KTUS
SOUNDING INDICATES A VERY JUICY 1.82 INCHES OF PRECIPITABLE WATER...
OR 184 PERCENT OF NORMAL.

EXPECT SHOWERS AND THUNDERSTORMS TO INCREASE IN COVERAGE/INTENSITY
OVERNIGHT...WITH NUMEROUS SHOWERS AND ISOLATED THUNDERSTORMS
DEVELOPING AREAWIDE WEDNESDAY MORNING. ODILE/CIRCULATION CENTER
STILL ON FORECASTED TRACK...WITH ODILE MAKING LANDFALL ON THE
EASTERN SIDE OF THE GULF OF CALIFORNIA SOUTH OF ROCKY POINT/PUERTO
PENASCO AROUND 12Z WEDNESDAY...THEN REMNANT LOW TRACKING NORTHEAST
TO NEAR NOGALES BY 00Z THURSDAY...OVER TUCSON BY 06Z THURSDAY...AND
CONTINUED NORTHEAST TO NEAR SPRINGERVILLE BETWEEN 18Z THURSDAY/00Z
FRIDAY.

CURRENT FORECAST ON TRACK. NO UPDATES. FOR MORE INFORMATION ON THE
LATTER PERIODS OF THE FORECAST...PLEASE REFER TO THE PREV DISCUSSION
SECTION BELOW.

&&

.HYDROLOGY...TROPICAL STORM ODILE IS EXPECTED TO GENERATE HEAVY
RAINFALL ACROSS MUCH OF SOUTHEAST ARIZONA THROUGH THURSDAY WITH
STORM TOTAL RAINFALL AMOUNTS RANGING FROM 3 TO 6 INCHES POSSIBLE.
FLOODING ON CREEKS AND WASHES IS LIKELY WEDNESDAY AND THURSDAY WITH
MAIN STEM RIVER FLOODING POSSIBLE THROUGH THE WEEKEND. THE MAIN STEM
RIVERS OF CONCERN ARE THE GILA...SAN PEDRO...SANTA CRUZ...THE
RILLITO...AND THEIR TRIBUTARIES. SOME OF THE SMALLER CREEKS/WASHES
OF CONCERN INCLUDE BUT NOT LIMITED TO ARE: SABINO...ALAMO...
PANTANO...BRAWLEY...AND THE NOGALES WASH. FOR INDIVIDUAL RIVER
FORECASTS PLEASE REFER TO THE COLORADO BASIN RIVER FORECAST CENTER
WED SITE AT WWW.CBRFC.NOAA.GOV

&&

.AVIATION...VALID THRU 18/00Z
ISOLATED/SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WILL CONTINUE
TO INCREASE THIS EVENING...WITH NUMEROUS SHOWERS AND ISOLATED
THUNDERSTORMS WEDNESDAY AND THURSDAY. EXPECT LOWERING CEILINGS THIS
EVENING/TONIGHT...WITH CIGS OF 3-5K FT AGL DEVELOPING BETWEEN 17/03Z
AND 17/10Z...WITH MVFR CONDITIONS AREAWIDE EARLY WEDNESDAY THRU
THURSDAY. SURFACE WINDS GENERALLY LESS THAN 10 KTS...EXCEPT STRONGER
GUSTS/WINDS IN VICINITY OF THE STRONGER SHOWERS AND THUNDERSTORMS.
AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...INCREASING TROPICAL MOISTURE WITH WIDESPREAD SHOWER
AND THUNDERSTORM ACTIVITY DEVELOPING...ESPECIALLY LATE TONIGHT
THROUGH THURSDAY. EXPECT FLOODING ISSUES EARLY WEDNESDAY THROUGH
THURSDAY. ENOUGH RESIDUAL MOISTURE WILL BE IN PLACE FOR A CHANCE OF
SHOWERS AND THUNDERSTORMS FRIDAY INTO THE WEEKEND.

&&

.PREV DISCUSSION...AREAS OF LIGHT TO MODERATE SHOWERS CONTINUE TO
MOVE NORTH ACROSS THE REGION THIS AFTERNOON AS MOISTURE CONTINUES TO
SWEEP NORTH.  LIMITED SUNSHINE AND LACK OF DYNAMICS BETWEEN BANDS
HAS MELLOWED THE CONVECTION THUS FAR.  HOWEVER A BAND JUST TO THE
SOUTH IS HEADED OUR WAY AND WILL LIKELY GENERATE STEADIER
PRECIPITATION ACROSS THE AREA AS IT MOVES NORTH AND LIKELY AN
INCREASE IN INTENSITY.  HIRES MODELS SUGGEST SOME SIGNIFICANT CELLS
DEVELOPING LATER THIS EVENING AND OVERNIGHT ACROSS SOUTHERN AREAS AS
THIS BAND PASSES AND ODILE CONTINUES ITS SLOW MARCH NORTH.  WITH
THAT IN MIND HAVE MOVED UP THE TIME OF THE FLASH FLOOD WATCH FOR
SANTA CRUZ AND SOUTHERN PIMA COUNTIES BY 6 HOURS TO START THIS
EVENING JUST AS A PRECAUTION AS THERE IS POTENTIAL FOR LOCALLY HEAVY
RAINS TONIGHT FOR SOME LOCATIONS.  THAT SAID...THE MAIN TIME OF
CONCERN REMAINS LATER WEDNESDAY INTO EARLY THURSDAY.

TROPICAL STORM ODILE IS EXPECTED TO MAKE LANDFALL OVER NORTHWEST
SONORA MEXICO WEDNESDAY MORNING THEN MOVE NORTHEAST INTO CENTRAL
ARIZONA THROUGH THURSDAY MORNING WITH THE MAIN CONCERN HEAVY RAIN.
PERIODS OF HEAVY RAIN ARE ANTICIPATED NEAR AND TO THE RIGHT OF THE
TRACK OF THE SYSTEM WITH A FAIRLY SHARP CUTOFF TO THE WEST...SO THE
TRACK THAT ODILE DECIDES TO TAKE IS CRITICAL TO WHERE THE HEAVIEST
RAIN MAY FALL.

THE CURRENT THINKING IS THE STORM WILL PASS BY...NEAR OR JUST WEST
OF TUCSON WITH THE CORE OF THE HEAVIER RAIN IN THAT AREA AND TO THE
EAST...BUT STAY CURRENT WITH THE LATEST UPDATES AS THIS IS A VERY
DYNAMIC SITUATION.  AS IS NORMALLY THE CASE AND EXPECTED THIS TIME
AS WELL...RAINFALL AMOUNTS WILL BE HIGHLY VARIABLE ACROSS THE AREA
EVEN OVER SHORT DISTANCES.  THE POTENTIAL EXISTS FOR 3 TO 5 INCHES
OF RAIN THROUGH THURSDAY OVER SIGNIFICANT AREAS WITH LOCALLY HIGHER
AMOUNTS NOT OUT OF THE QUESTION.  OF NOTE IS THAT A SIGNIFICANT
PORTION OF THE HEAVY RAIN IS EXPECTED TO OCCUR WEDNESDAY NIGHT WITH
CREEK AND STREAM RISES OCCURRING DURING NIGHTTIME HOURS.

WITH THAT PATH IN MIND...THE AREAS OF BIGGEST THREAT FOR FLASH FLOOD
AND FLOOD ACTIVITY WOULD BE IN SANTA CRUZ...SOUTHERN AND EASTERN
PIMA...COCHISE...SOUTHERN GRAHAM...AND GREENLEE COUNTIES AND FLASH
FLOOD WATCHES ARE IN AFFECT.  PLEASE SEE THE HYDROLOGY SECTION
BELOW FOR MORE DETAILS ON RIVER AND CREEK FLOODING POTENTIAL.

DEPENDING ON HOW FAST THE REMAINS OF ODILE MOVES...THE STEADIER RAIN
WILL TAPER OFF DURING THE DAY THURSDAY FROM WEST TO EAST WITH
SCATTERED SHOWERS BEING LEFT IN ITS WAKE.  BY FRIDAY...A SHORT WAVE
RIDGE BUILDS OVER THE AREA AS WHATS LEFT OF ODILE MOVES INTO
NORTHERN TEXAS.  EVEN WITH THE RIDGE...A FAIR AMOUNT OF MOISTURE
REMAINS BEHIND FOR SCATTERED SHOWERS AND THUNDERSTORMS TO REMAIN IN
THE FORECAST.

THEN FOR THE WEEKEND AN UPPER LOW OFF THE SOUTHERN CALIFORNIA COAST
WILL SLOWLY LIFT NE THROUGH MONDAY MAINTAINING A MOIST SOUTHERLY
FLOW OVER THE REGION.  THUS WE WILL LIKELY HAVE SCATTERED CONVECTION
THROUGH THE WEEKEND WITH AN AFTERNOON AND EVENING FOCUS.  BEYOND
THAT THERE IS NO SIGNIFICANT DRYING TREND UNTIL WEDNESDAY WITH
LINGERING CONVECTION THROUGH AT LEAST THEN.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
  FLASH FLOOD WATCH FROM WEDNESDAY MORNING THROUGH THURSDAY
  AFTERNOON FOR AZZ501-505-506-509-510.

  FLASH FLOOD WATCH THROUGH THURSDAY AFTERNOON FOR
  AZZ502>504-AZZ507>508-511>515.

&&

$$

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