Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 211600
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
900 AM MST MON JUL 21 2014

.SYNOPSIS...EXPECT ISOLATED TO SCATTERED THUNDERSTORMS MOSTLY EAST
AND SOUTH OF TUCSON THROUGH THE MIDDLE OF THIS WEEK. MUCH HOTTER
TEMPERATURES WILL OCCUR TUESDAY THROUGH THURSDAY...WITH NEAR RECORD
HIGHS POSSIBLE. AN INCREASE IN THUNDERSTORM ACTIVITY SHOULD OCCUR
LATE IN THE WEEK AND INTO THE WEEKEND.

&&

.DISCUSSION...WATER VAPOR IMAGERY AND 21/12Z UPPER-AIR PLOTS SHOW A
RIDGE CENTERED IN THE GENERAL VICINITY OF EASTERN NEW MEXICO AND THE
TEXAS PANHANDLE. THIS IS RESULTING IN SOUTHWESTERLY FLOW IN THE MID
TO UPPER LEVELS. FLOW FROM THE SFC-500MB IS GENERALLY VERY LIGHT AT
5 TO 10 KNOTS. VISIBLE SATELLITE IMAGERY SHOWS A MCV OVER EXTREME NE
SONORA AND NW CHIHUAHUA MEXICO AS A RESULT OF THE COMPLEX THAT
DEVELOPED OVER SONORA MEXICO YESTERDAY EVENING. EXTENSIVE CLOUDINESS
ASSOCIATED WITH THIS MCV COVER A LARGE SWATH ALONG THE AZ/NM BORDER
AND WELL SOUTH INTO NORTHERN MEXICO. THESE CLOUDS ARE STREAMING TO
THE NORTH NORTHEAST AND SHOULD SLOWLY ERODE DURING THE DAY.

THIS MORNINGS KTWC UNMODIFIED SOUNDING INDICATED A PRECIPITABLE
WATER VALUE OF 1.12 INCHES...WITH A LIFTED INDEX OF ZERO AND A CAPE
OF AROUND 40 J/KG. MODIFYING THE SOUNDING USING T=102;TD=41 YIELDS A
LI OF PLUS 1 AND NO APPRECIABLE CAPE. NEEDLESS TO SAY...WE SHOULDN`T
SEE ANY CONVECTION THIS AFTERNOON OR EVENING. WILL LIKELY SEE SOME
ACTIVITY AGAIN TODAY SOUTH OF THE BORDER. THAT SAID...I WILL TRIM
BACK POPS FOR THIS AFTERNOON AND EVENING...BUT WILL KEEP A SLIGHT
CHANCE OF SHOWERS AND THUNDERSTORMS RIGHT ALONG THE INTERNATIONAL
BORDER FROM NOGALES TO DOUGLAS...AND ALSO OVER THE EASTERN MOST
MOUNTAINS.

AS OF 15Z (8 AM MST)...TEMPERATURES ACROSS THE REGION RANGED FROM
THE MID 70S TO THE MID 80S...WITH THE TUCSON INTL AIRPORT REPORTING
A TEMP OF 84 DEGS AFTER A MORNING LOW OF 81 DEGS. THESE READINGS
SEEM TO BE ON TRACK WITH EXPECTED AFTERNOON HIGH TEMPERATURES...BUT
WILL CONTINUE TO MONITOR. WILL MAKE SOME MINOR ADJUSTMENTS TO THE
SHORT TERM HOURLY TEMPERATURE GRIDS TO REFLECT THE LATEST TEMP
TRENDS.

FOR DETAILS REGARDING THE FORECAST BEYOND TODAY...PLEASE REFER TO
THE PREVIOUS DISCUSSION BELOW.

&&

.AVIATION...THERE WILL BE A SLIGHT CHANCE OF -TSRA/-SHRA IN THE
WHITE MOUNTAINS NE OF KSAD...AND SOUTH/SOUTHEAST OF KTUS IN THE
VICINITY OF THE KOLS/KDUG TERMINALS. BRIEF WIND GUSTS TO NEAR 35 KTS
MAY OCCUR WITH THIS ACTIVITY. OTHERWISE...CLOUD DECKS FROM KTUS
EWD/SWD WILL MOSTLY BE ABOVE 10K FT AGL OUTSIDE OF TSRA. MOSTLY
CLEAR SKIES ARE EXPECTED WEST OF KTUS. BREEZY SURFACE WIND IN THE
GILA RIVER VALLEY IN THE VICINITY OF KSAD...WITH WLY/NWLY SURFACE
WIND AT 12-17 KTS THIS AFTERNOON/EARLY EVENING. OTHERWISE...SURFACE
WIND OUTSIDE OF ANY TSRA OUTFLOW INFLUENCES WILL GENERALLY BE 12 KTS
OR LESS. AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...THERE WILL BE A SLIGHT CHANCE OF THUNDERSTORMS TODAY
AND TUESDAY MAINLY NEAR THE INTERNATIONAL BORDER FROM NOGALES TO
DOUGLAS AND IN THE EASTERN MOUNTAINS ALONG THE NEW MEXICO BORDER.
STRENGTHENING HIGH PRESSURE ALOFT WILL RESULT IN HOTTER TEMPERATURES
TUESDAY THROUGH THURSDAY. THEREAFTER...INCREASED THUNDERSTORM
ACTIVITY SHOULD OCCUR STARTING ON WEDNESDAY AND CONTINUING INTO NEXT
WEEKEND. BREEZY WINDS ARE EXPECTED ONCE AGAIN TODAY IN THE UPPER
GILA RIVER VALLEY AROUND SAFFORD.

&&

.PREVIOUS DISCUSSION...DEEP MOISTURE NEEDED TO SUPPORT THUNDERSTORMS
WILL BE RATHER LIMITED THE NEXT FEW DAYS. THIS LACK OF MOISTURE
COMBINED WITH THE STRENGTHENING OF HIGH PRESSURE ALOFT WILL RESULT
IN RECORD OR NEAR RECORD HIGH TEMPERATURES AROUND WEDNESDAY AND
THURSDAY. THE CURRENT FORECAST STILL CALLS FOR HIGH TEMPERATURES TO
BE ABOUT 5 DEGREES WARMER THAN MOS GUIDANCE. THIS PROJECTION LOOKED
REASONABLE BASED ON FORECAST THICKNESS VALUES WHICH TEND TO
CORRELATE WELL WITH HIGH TEMPERATURES. THE ONLY QUESTION WILL BE THE
AMOUNT OF MOISTURE WHICH WILL BE ON THE INCREASE AS THE UPPER HIGH
BUILDS AND BECOMES CENTERED AROUND EAST-CENTRAL ARIZONA. AT ANY
RATE...THE EXCESSIVE HEAT IN COMBINATION WITH A MORE FAVORABLE FLOW
PATTERN FOR THUNDERSTORMS WILL BRING ELEVATED RAIN CHANCES BY THE
END OF THE WEEK.

&&

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

&&

$$

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