Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 282123
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
220 PM MST MON JUL 28 2014

.SYNOPSIS...WE STILL HAVE GOOD MOISTURE IN PLACE FOR A CHANCE OF
SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND EVENING. SOME STORMS
WILL GENERATE LOCALLY HEAVY RAINFALL. FEWER STORMS ARE EXPECTED
AROUND MID WEEK AS HIGH PRESSURE BUILDS OVERHEAD ACCOMPANIED BY
SEVERAL DEGREES OF HEATING BY TUESDAY OR WEDNESDAY. A STRONGER
CHANCE OF THUNDERSTORMS RETURNS ONCE AGAIN TO END THE WEEK AND TAKE
US INTO NEXT WEEKEND.

&&

.DISCUSSION...SLOW DEVELOPMENT IN NORTHERN PARTS OF OUR AREA BEHIND
EXITING MCV FROM LAST NIGHT. ELSEWHERE WE HAVE GREAT MOISTURE BUT
MEAGER FLOW. WIND PROFILE NOT OPTIMAL FOR GOOD STORM STRUCTURE. SLOW
MOVING STORMS THAT INITIALLY ARE CHOKING BEFORE REACHING MID CYCLE.
WE SHOULD MANAGE BETTER COVERAGE LATER IN THE AFTERNOON AND EARLY
EVENING...BUT STORMS WILL TEND TO STRUGGLE AWAY FROM TERRAIN
ENHANCEMENT. WEAK UPPER LEVEL DIFFLUENCE ON THE EASTERN FLANK OF A
FEATURE PUSHING NORTH THROUGH FAR SOUTHWEST ARIZONA AND SOUTHERN
CALIFORNIA COULD ENHANCE SOME OF THE STORM ACTIVITY JUST WEST OF
TUCSON. ANOTHER IMPULSE IN FAR NORTHERN SONORA WILL PROBABLY ENHANCE
SOME OF THE STORMS IN COCHISE COUNTY THIS AFTERNOON. THAT ONE WILL
ALSO TEND TO KEEP STORMS GOING INTO THE EARLY MORNING HOURS EAST OF
TUCSON. WET STORMS WITH LOCALIZED FLASH FLOODING THE MAIN STORY.

OVERALL RIDGE AXIS JUST EAST AND/OR NORTHEAST OF THE AREA COMBINED
WITH GULF SURGE A COUPLE OF DAYS AGO HAS SERVED SOUTHEAST ARIZONA
WELL OVER THE PAST 3 DAYS. DOWNTURN EXPECTED STARTING AS SOON AS
TUESDAY AS A SECONDARY HIGH CENTER CONSOLIDATES NEARLY OVERHEAD TO A
LITTLE SOUTH AND SOUTHWEST OF OUR AREAS. THIS WILL TEND TO PUSH
STORM ACTIVITY BACK TO BORDER AND MOUNTAIN AREAS WHILE WE HEAT UP
SEVERAL DEGREES (PERHAPS AGAIN CLIMBING TO A FEW DEGREES SHY OF
RECORD LEVELS). ONE CAVEAT TO THIS IS THE  MOISTURE TRANSPORT TRENDS
UP THE GULF ARE ONCE AGAIN INCREASING...ENHANCED SOMEWHAT BY THAT
NICE COMPLEX THAT PUSHED INTO THE MOUTH OF THE GULF LAST NIGHT FROM
WESTERN MEXICO AROUND 23N. WE SHOULD MANAGE TO AT LEAST KEEP
INTERNATIONAL BORDER AREAS ACTIVE OVER THE NEXT FEW DAYS.

LATE IN THE WEEK THE SEGMENT OF THE RIDGE OVER OUR AREA SHOULD
WEAKEN AS WE SEE SOME WEAK TROUGHINESS TENDENCIES NEAR THE CENTRAL
AND NORTHERN COAST. THAT ALLOW A DEGREE OR TWO OF COOLING IN MID
LEVELS WHILE ALSO ALLOWING DEEPER MOISTURE IMPORT ONCE AGAIN. ECMWF
KEYS ON A NICE IMPULSE ROTATING IN FROM NORTHERN MEXICO FRIDAY
AFTERNOON FOR A STRONG UPTICK IN THUNDERSTORM COVERAGE THAT SHOULD
TAKE US INTO THE WEEKEND.

&&

.AVIATION...VALID THRU 29/21Z.
SCATTERED TSRA/SHRA THIS AFTERNOON INTO THIS EVENING. MVFR
CONDITIONS WILL OCCUR WITH THE STRONGER TSRA ALONG WITH WIND GUSTS
TO AROUND 45 KTS. CLOUD DECKS WILL GENERALLY BE AT 7-12K FT AGL INTO
TONIGHT. ISOLD STORMS POSSIBLE EAST OF KTUS OVERNIGHT...INCLUDING
THE KDUG AREA. SOME CLEARING TUESDAY MORNING ESPECIALLY FROM KTUS
WESTWARD. AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...SCATTERED THUNDERSTORMS WILL OCCUR THIS AFTERNOON
AND EVENING. EXPECT STRONG...GUSTY AND ERRATIC WINDS ASSOCIATED WITH
THE STRONGER STORMS. DRIER CONDITIONS WILL THEN PROVIDE DECREASED
THUNDERSTORM ACTIVITY FOR MUCH OF THE AREA TUESDAY THROUGH
THURSDAY...EXCEPT FOR AREAS NEAR THE INTERNATIONAL BORDER AND NEW
MEXICO BORDER AREAS. THEREAFTER...SCATTERED MOSTLY AFTERNOON AND
EVENING THUNDERSTORMS WILL PREVAIL FRIDAY THROUGH SUNDAY AS DEEPER
MOISTURE RETURNS TO THE AREA. OTHERWISE...NORMAL DIURNAL WIND TRENDS
WILL OCCUR WITH OCCASIONAL GUSTS DURING THE AFTERNOON HOURS DUE TO
DAYTIME HEATING.

&&

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

&&

$$

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

MEYER/GLUECK





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