489
FXUS65 KTWC 190827
AFDTWC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
127 AM MST SUN JUL 19 2026
SYNOPSIS
EXPECT SCATTERED SHOWERS AND THUNDERSTORMS MAINLY TO
THE EAST OF TUCSON THIS AFTERNOON INTO THIS EVENING. THESE
STORMS WILL HAVE THE POTENTIAL FOR HEAVY RAINFALL. OTHERWISE,
EXPECT A GENERAL UPTICK IN SHOWER AND THUNDERSTORM ACTIVITY THE
FIRST HALF OF THIS WEEK.
DISCUSSION
THE UPPER PATTERN EARLY THIS MORNING IS DEFINED BY
AN UPPER TROUGH OF LOW PRESSURE OVER WEST TEXAS AND AN
ANOMALOUSLY STRONG RIDGE OF HIGH PRESSURE EXTENDING FROM THE
GREAT BASIN EAST INTO THE HIGH PLAINS OF NEBRASKA. GENERALLY A
NORTHEAST FLOW HAS SETUP ACROSS SOUTHEAST ARIZONA THIS MORNING,
WITH A MID-LEVEL VORT MAX SPINNING ACROSS CENTRAL
ARIZONA...MOVING SW.
IN THE SHORT TERM, I WOULD EXPECT THIS FEATURE TO PROVIDE
ENOUGH SUPPORT TO KICK OFF SOME WIDELY SCATTERED SHOWERS WITH
EMBEDDED THUNDERSTORMS WEST OF TUCSON THROUGH DAYBREAK. GIVEN
THE DEEPER MOISTURE AVAILABLE (1.50 TO 1.70 INCHES OF PWAT IN
CENTRAL AND WESTERN PIMA), I WOULD EXPECT GENERALLY LESS THAN A
QUARTER INCH OF RAIN WITH LOCALIZED AREAS UP TO A HALF INCH
ACCOMPANYING THE STRONGER THUNDERSTORMS.
OTHERWISE, THE UPPER-FLOW BEGINS TO SHIFT FROM THE NE TO ENE
THIS AFTERNOON, RESULTING IN AN AREA OF MODEST LIFT/DEFORMATION
ALOFT MOVING WSW OFF OF THE ERN MOGOLLON RIM IN NM INTO
GREENLEE/GRAHAM COUNTIES AND THEN EVENTUALLY INTO EASTERN
COCHISE. DRIER AIR ALOFT WILL GET ENTRAINED INTO THE STORMS AS
THEY MOVE OFF THE TERRAIN INTO THE GILA RIVER VALLEY INCREASING
THE LIKELIHOOD FOR GUSTY OUTFLOW WINDS TO 40-45 MPH/BLOWING
DUST TO IMPACT THE GILA RIVER VALLEY AND SAN SIMON VALLEY.
ALTHOUGH PWATS EAST OF TUCSON WILL BE 1.30-1.50 INCHES, THAT IS
STILL 125-150% OF CLIMATOLOGY. THE COMBINATION OF THE UPPER
SUPPORT AND HIGHER MOISTURE WILL RESULT IN THE POTENTIAL FOR
HEAVY RAINFALL THIS AFTERNOON/EVENING, ESPECIALLY ALONG THE
ARIZONA AND NEW MEXICO BORDER. THIS IS SUPPORTED BY THE 19/00Z
HREF WHICH SHOWS A 30-70% NEIGHBORHOOD PROBABILITY FOR STORMS TO
PRODUCE IN EXCESS OF AN INCH OF RAIN ACROSS THE EASTERN 3
COUNTIES BETWEEN 20/00Z AND 20/06Z AND A 10% PROBABILITY FOR
RAINFALL IN EXCESS OF 3 INCHES ACROSS THE SAN SIMON VALLEY AT
20/03Z. THE WEATHER PREDICTION CENTER (WPC) INCLUDED THE 3
COUNTIES EAST OF TUCSON IN THE SLIGHT RISK FOR FLASH FLOODING ON
THEIR DAY 1 EXCESSIVE RAINFALL OUTLOOK FOR TODAY...AND THIS
FITS MY CONCEPTUAL MODEL.
THE WPC MAINTAINS THE SAME GENERAL AREA IN THEIR 'SLIGHT' RISK
FOR FLASH FLOODING IN THEIR DAY 2 ERO MONDAY. THAT PESKY UPPER-
LOW IN WRN TX THIS MORNING BECOMES AND INVERTED TROUGH AND BEGINS
TO NUDGE INTO THE EASTERN CWA MONDAY AFTERNOON, PROVIDING SOME
DYNAMICS TO THE MIX. I LIKE THE AREA DEFINED, AND WE MAY NEED TO
CONSIDER A FLASH FLOOD WATCH FOR GRAHAM/GREENLEE AND COCHISE
COUNTIES MONDAY...ESPECIALLY IF TODAY IS VERY ACTIVE ALONG THE
AZ/NM BORDER AND THE SOILS BECOME SATURATED INCREASING THE FLASH
FLOOD RISK MONDAY. THIS FEATURE WILL MAKE IT INTO EAST CENTRAL
ARIZONA TUESDAY AND LIFT THROUGH NORTHERN ARIZONA TUESDAY. THIS
WOULD LEAVE SOUTHEAST ARIZONA IN THE SUBSIDENT FIELD IN ITS
WAKE HINDERING THE POTENTIAL FOR WIDESPREAD HEAVY RAIN ACROSS
OUR NECK OF THE WOODS TUESDAY. IN ANY EVENT, THE NEXT SEVERAL
DAYS LOOK TO BE ACTIVE...ESPECIALLY EAST OF TUCSON.
AVIATION
VALID THROUGH 20/12Z. SCT-BKN 8-12K FT AGL BKN-OVC
12-15K FT AGL. WIDELY SCATTERED SHOWERS WITH EMBEDDED THUNDERSTORMS
GENERALLY WEST OF TUCSON THRU 19/15Z THIS MORNING. SCT CLOUDS 5-8K
FT AGL BKN-OVC 8-12K FT AGL AFTER 19/20Z THIS AFTERNOON WITH
SCATTERED SHOWERS AND THUNDERSTORMS WILL THEN DEVELOP AFTER
19/20Z ACROSS COCHISE, GRAHAM AND GREENLEE COUNTIES WITH 3-5SM
IN HEAVY RAIN. BLDU WILL ALSO BE POSSIBLE IN THE GILA RIVER
VALLEY AND SAN SIMON VALLEY AS STORMS THERE WILL BE CAPABLE OF
PRODUCING ERRATIC STRONG WIND GUSTS OF 35-40 KTS. OUTSIDE OF
THUNDERSTORMS, SURFACE WINDS GENERALLY UNDER 10 KTS. AVIATION
DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.
FIRE WEATHER
DAILY CHANCES FOR THUNDERSTORMS WILL CONTINUE
EACH AFTERNOON AND EVENING THROUGH THE NEXT 7 DAYS WITH DAY TO
DAY VARIABILITY. AN INCREASE IN THUNDERSTORM ACTIVITY IS
EXPECTED EAST OF TUCSON TODAY, THEN EXPAND IN COVERAGE THE FIRST
HALF OF THE WEEK. MINIMUM RELATIVE HUMIDITY 25-30 PERCENT IN
THE LOWER DESERT LOCATIONS AND ABOVE 40 PERCENT IN THE MOUNTAINS
THIS WEEK. WINDS THIS WEEK WILL REMAIN MAINLY LIGHT AND UNDER
15 MPH, THOUGH STRONG AND ERRATIC WINDS WILL BE POSSIBLE WITH
ANY THUNDERSTORM.
TWC WATCHES/WARNINGS/ADVISORIES
NONE.
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