Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 231322 AAA
AFDTWC

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE TUCSON AZ
622 AM MST THU JUL 23 2015

.SYNOPSIS...MOISTURE WILL CONTINUE TO INCREASE ACROSS SOUTHEAST
ARIZONA INTO FRIDAY. THIS WILL LEAD TO SCATTERED TO NUMEROUS SHOWERS
AND THUNDERSTORMS FOR MUCH OF SOUTHEAST ARIZONA TODAY INTO FRIDAY
BEFORE A DRYING TREND RETURNS OVER THE WEEKEND. ANOTHER UPSWING IN
THUNDERSTORM ACTIVITY IS THEN EXPECTED DURING THE EARLY TO
MIDDLE OF NEXT WEEK.

&&

.UPDATE...REVISED THE FORECAST AT BIT FOR THE NEXT COUPLE OF HOURS
TO ACCOUNT FOR SCATTERED SHOWERS OVER TUCSON METRO.

&&

.DISCUSSION...WATER VAPOR IMAGERY AND 23/00Z UPPER-AIR PLOTS SHOW A
BROAD FLAT RIDGE OVER THE SOUTHERN PLAINS WITH A TROUGH OVER THE
PACIFIC NORTHWEST. THIS SETUP WILL RESULT IN RETURN FLOW ON THE
WESTERN FLANK OF THE HIGH TO CONTINUE TO TRANSPORT MOISTURE
NORTHWARD TODAY THROUGH FRIDAY...AS EVIDENCED BY HIGHER MOISTURE TO
OUR SOUTH VIA VARIOUS OBSERVATIONAL SOURCES OF PRECIPITABLE WATER.
IN FACT...JUST IN THE PAST 24 HOURS OR SO...PW`S HAVE INCREASED
NEARLY A HALF INCH. MODELS INDICATE THAT PW`S WILL CONTINUE TO
INCREASE AND PEAK AT AROUND 1.6 - 1.8 INCHES BY LATE THIS
AFTERNOON INTO FRIDAY.

THE SWATH OF MID-UPPER LEVEL DRY AIR SEEN IN WV IMAGERY OVER MUCH OF
THE EASTERN PACIFIC...SOUTHERN CALIFORNIA...EXTREME NORTHWEST MEXICO
AND PARTS OF ARIZONA...NEVADA AND UTAH CONTINUES TO RECEDE FARTHER
TO THE NORTH AND WEST AS THE MOISTURE PLUME ON THE WESTERN FLANK OF
THE HIGH OVER THE SOUTHERN PLAINS CONTINUES ACROSS SONORA AND INTO
EXTREME SOUTHEAST ARIZONA AND PARTS OF NEW MEXICO.

IR SATELLITE IMAGERY SHOWS DEBRIS CLOUDS FROM EARLIER CONVECTION
OVER SONORA CONTINUING TO SPILL ACROSS SOUTHEAST ARIZONA. RADAR
MOSAIC SHOWS SOME WEAK RETURNS SOUTH OF NOGALES AND DOUGLAS...BUT
CONTINUE TO WEAKEN.

AS MOISTURE INCREASES AND DISTURBANCES EMBEDDED WITHIN THE SOUTH TO
SOUTHWEST FLOW ALOFT CONTINUE TO MOVE NORTH...EXPECT AN ENHANCEMENT
IN THUNDERSTORM ACTIVITY TODAY AND FRIDAY WITH A DOWNSWING OVER THE
WEEKEND IN RESPONSE TO THE HIGH SHIFTING FARTHER NORTH OVER THE
TEXAS PANHANDLE AND NEW MEXICO. THIS WILL RESULT IN AN INCREASE IN
TEMPERATURES OVER THE WEEKEND.

BY THE EARLY TO MIDDLE OF NEXT WEEK THE MODELS ADVERTISE AN INVERTED
TROUGH ON THE SOUTHERN PERIPHERY OF THE HIGH MAKING ITS WAY WEST OR
NORTHWEST ACROSS PARTS OF NORTHERN AND NORTHWEST MEXICO. THIS SHOULD
HELP INCREASE OUR CHANCES FOR SHOWERS AND THUNDERSTORMS DURING THAT
TIME FRAME AS MOISTURE INCREASES AS THIS FEATURE MOVES ACROSS THE
REGION.

FOR TUCSON...HIGH TEMPS WILL GENERALLY RANGE FROM 3 TO 5 DEGS BELOW
NORMAL TODAY AND FRIDAY...THEN 4 TO 6 DEGS ABOVE NORMAL SATURDAY
THROUGH MONDAY. THEREAFTER...HIGHS ABOUT 2 TO 3 DEGS ABOVE NORMAL.
LOW TEMPS ONLY SLIGHTLY ABOVE NORMAL FRIDAY AND SATURDAY
MORNINGS...THEN AROUND 3 TO 5 DEGS ABOVE NORMAL THROUGH THE
REMAINDER OF THE FORECAST PERIOD.

&&

.AVIATION...VALID THRU 24/12Z.

SCT-BKN CLOUDS AT 7-10K FT AGL FOR MOST AREAS THIS MORNING WITH AN
ISOLATED -SHRA PSBL NEAR KDUG/KALK/KFHU. SOME CLEARING IS POSSIBLE
DURING THE MID MORNING HOURS BEFORE CONVECTIVE BUILDUPS DEVELOP NEAR
TERRAIN. MOSTLY CLEAR SKIES WILL PREVAIL TO THE WEST OF KTUS.
CONVECTIVE ACTIVITY INCREASES AFTER 23/18Z WITH SCATTERED SHRA/TSRA
FOR MOST TERMINALS...AND NUMEROUS SHRA/TSRA EXPECTED NEAR KDUG/KOLS.
BRIEF MVFR CONDITIONS ALONG WITH VRB WIND GUSTS TO 35 KT WILL BE
POSSIBLE AROUND STRONGER STORMS. SHRA/TSRA COVERAGE WILL DIMINISH
AFTER 24/04Z...WITH -SHRA PSBL THROUGH THE END OF THE PERIOD MAINLY
NEAR THE INTERNATIONAL BORDER. OUTSIDE OF ANY TSRA GUSTINESS...
SURFACE WINDS WILL GENERALLY BE WESTERLY...TERRAIN DRIVEN AND LESS
THAN 12 KT. AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...INCREASED MOISTURE WILL RESULT IN SCATTERED TO
NUMEROUS AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS THROUGH
FRIDAY...ESPECIALLY NEAR THE INTERNATIONAL BORDER SOUTHEAST OF
TUCSON. SOMEWHAT DRIER AIR THIS WEEKEND WILL LIMIT PRECIPITATION TO
ISOLATED TO SCATTERED ACTIVITY...WITH THE MAJORITY OF CONVECTION
EXPECTED ACROSS EASTERN ZONES. MIGRATION OF HIGH PRESSURE TO A MORE
FAVORABLE LOCATION ALONG WITH ANOTHER PUSH OF MOISTURE FROM THE
SOUTH WILL BRING A SLIGHT UPTICK IN ACTIVITY... ESPECIALLY BY THE
MIDDLE OF NEXT WEEK.

20-FT WINDS WILL GENERALLY BE TERRAIN DRIVEN AND LESS THAN 15
MPH...WITH THE EXCEPTION OF SOME AFTERNOON GUSTINESS DUE TO DAYTIME
HEATING. AREAS IN AND AROUND STRONGER THUNDERSTORMS COULD SEE WIND
GUSTS OF 40 TO 45 MPH.

&&

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

&&

$$

PUBLIC...MOLLERE
AVIATION/FIRE WEATHER...FRENCH

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