847
FXUS65 KTWC 192121
AFDTWC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
221 PM MST SUN OCT 19 2025
SYNOPSIS
ABOVE NORMAL HIGH TEMPERATURES THROUGH WEDNESDAY AND
NEAR NORMAL OR SLIGHTLY BELOW NORMAL THURSDAY AND FRIDAY. DRY
CONDITIONS WILL ALSO PREVAIL THROUGH MOST OF THE UPCOMING WEEK.
THE EXCEPTION WOULD BE TUESDAY NIGHT INTO WEDNESDAY WHERE THERE IS
A SLIGHT CHANCE OF SHOWERS FOR THE MOUNTAINS NORTHEAST OF TUCSON.
DISCUSSION
WATER VAPOR IMAGERY THIS AFTERNOON CLEARLY SHOWS
UPPER RIDGE BUILDING OVERHEAD OUT AHEAD OF A CUT-OFF UPPER LOW
THAT WAS LOCATED AROUND 700 MILES WEST OF THE BAJA SPUR. ABUNDANT
SUNSHINE TODAY WITH AFTERNOON TEMPERATURES RUNNING 5 TO 10 DEGREES
WARMER THAN YESTERDAY. MOST LOCATIONS LIKELY RECORDING THE FIRST
ABOVE NORMAL HIGH TEMPERATURE IN OVER A WEEK. SEE CLIMATE SECTION
BELOW. MOSTLY THIN HIGH CLOUDS WILL BE ON THE INCREASE TONIGHT
WITH OVERNIGHT LOWS SLIGHTLY WARMER THAN THIS MORNING.
THE FIRST HALF OF THE NEW WORK WEEK WILL BE WARM AS LOW-LEVEL
THICKNESSES VALUES RISE UNDER HIGH PRESSURE ALOFT. HIGHS IN THE
LOW TO MID 90'S LIKELY FOR THE LOW DESERT LOCALS WITH TUCSON
HAVING A LOW-END POTENTIAL OF 95 DEGREES ON TUESDAY. ADDITIONALLY
AS THE CUT-OFF UPPER LOW LIFTS TOWARD SOCAL ON TUESDAY, THE AREA
WILL SEE AN INCREASE IN MID-LEVEL MOISTURE AS PWATS RISING UP TO
0.80" WHICH RESULT IN PARTLY CLOUDY SKIES TUESDAY NIGHT INTO
WEDNESDAY WITH A SLIGHT CHANCE (10%-20%) OF SHOWERS, MAYBE AN
ISOLATED LIGHTNING STRIKE, FOR THE MOUNTAINS NORTHEAST OF TUCSON.
THE DETERMINISTIC 12Z ECMWF IS AN OUTLIER SHOWING 30-60% CHANCE
POPS ACROSS ERN PIMA AND SANTA CRUZ COUNTIES TUESDAY NIGHT/WED
MORNING. BREEZY CONDITIONS MOST LIKELY ON WEDNESDAY.
AS THE ABOVE MENTIONED CUT-OFF UPPER LOW MOVES ACROSS NORTHERN
ARIZONA ON THURSDAY, A COOLER AIR MASS WILL SETTLE IN WITH HIGHS
4 TO 10 DEGREES COOLER THAN WEDNESDAY OR 2 TO 6 DEGREES BELOW
NORMAL. HIGHS REBOUND AND WARM TO NEAR NORMAL BY SATURDAY.
AVIATION
VALID THROUGH 21/00Z.
SKC THRU 20/04Z THEN SCT-BKN CLOUDS AOA 20K FT AGL UNDER SLY/SWLY
FLOW ALOFT. SFC WINDS WLY/NWLY AT 5-10 KTS UNTIL 20/03Z THEN AGAIN
AFT 20/19Z. OTRW, SFC WINDS LIGHT AND VRBL BTWN 20/03Z AND 20/19Z.
AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.
FIRE WEATHER
MINIMUM RH VALUES WILL BE IN THE 15-25 PERCENT
RANGE IN THE VALLEYS THROUGH THE WORK WEEK, EXCEPT WEDNESDAY WHEN
RH VALUES INCREASE 5-10 PERCENT. 20-FOOT WINDS MAINLY 15 MPH OR
LESS, WITH OCCASIONAL GUSTS TO 20-25 MPH. CHANCE FOR BREEZY WINDS
WEDNESDAY AS A WEATHER SYSTEM MOVES THROUGH. HIGH TEMPERATURES
WILL BE AROUND NORMAL OR JUST ABOVE NORMAL LEVELS THROUGH THE
MIDDLE OF THE WEEK. EXPECT DRY CONDITIONS OVER THE NEXT 7 DAYS
WITH THE EXCEPTION THE MOUNTAINS NORTHEAST OF TUCSON WEDNESDAY,
WHICH WILL SEE UP TO A 20 PERCENT CHANCE FOR SHOWERS.
TWC WATCHES/WARNINGS/ADVISORIES
NONE.
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