464
FXUS65 KTWC 282202
AFDTWC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
302 PM MST WED MAY 28 2025
SYNOPSIS
TEMPERATURES WILL BE SEVERAL DEGREES ABOVE NORMAL
THROUGH FRIDAY WITH GENERALLY DRY CONDITIONS PREVAILING. A WEATHER
SYSTEM THIS WEEKEND WILL BRING SOME MOISTURE INTO THE REGION,
INITIALLY WITH A SLIGHT CHANCE OF MAINLY DRY THUNDERSTORMS EAST OF
TUCSON FRIDAY, THEN CONTINUED SLIGHT CHANCES OF SHOWERS AND
THUNDERSTORMS SATURDAY AREA-WIDE. THE BEST CHANCES FOR SHOWERS AND
THUNDERSTORMS WILL OCCUR SUNDAY INTO EARLY MONDAY WITH DRY
CONDITIONS RETURNING THEREAFTER. BELOW NORMAL TEMPERATURES RETURN
SUNDAY INTO EARLY NEXT WEEK.
DISCUSSION
QUIET WEATHER TODAY AND TOMORROW THEN A MORE ACTIVE
WEATHER PATTERN SETS IN THE AREA THIS WEEKEND. TODAY, SOUTHWEST FLOW
ALOFT WITH WEAK RIDGING ALONG THE ARIZONA/ NEW MEXICO BORDER. CLEAR
SKIES THIS MORNING WILL BE REPLACED WHEN MID TO HIGH LEVEL
MOISTURE MOVES IN FROM THE WEST LEADING TO HIGH CLOUDS TO DEVELOP
THIS AFTERNOON WITH TYPICAL AFTERNOON BREEZES. HIGHS WILL BE A
FEW DEGREES ABOVE NORMAL TOPPING OUT RIGHT AROUND 100 IN TUCSON.
HEATRISK WILL BE MINOR THIS WEEK WITH POCKETS OF MODERATE ON
FRIDAY.
OUR WEATHER THIS WEEKEND WILL BE DOMINATED BY A TROUGH THAT MOVES IN
FROM THE SOUTHERN CALIFORNIA COAST THAT WILL TRANSITION INTO A
NEARLY STATIONARY CLOSED LOW OFF NORTHERN BAJA THURSDAY THROUGH
SATURDAY. THE ENSEMBLES ARE IN REALLY GOOD AGREEMENT THROUGH
SATURDAY ON THE PLACEMENT OF THIS SYSTEM. BEYOND THE UPPER LOW,
WE'VE GOT OUR EYE ON THE TROPICS WHERE A NEWLY NAMED TROPICAL
DEPRESSION ONE-E NEAR 10N/105W HAS FORMED. THE COMBINATION OF THE
UPPER LOW WHICH WILL PROVIDE A LONG DURATION SOUTH TO
SOUTHEASTERLY FLOW ON ITS EAST FLANK, AN ADDITIONAL MOISTURE INPUT
COURTESY OF THE TROPICAL CYCLONE WILL EVENTUALLY HELP PUSH OUR
PWAT LEVELS THIS WEEKEND TO AROUND 200-300 PERCENT OF NORMAL.
THIS SYSTEM WILL BEGIN TO PUSH MOISTURE INTO OUR AREA BEGINNING
THURSDAY NIGHT INTO FRIDAY MORNING THOUGH IT WILL MAINLY STAY IN
THE MID-LEVELS. THIS MAY LEAD TO SOME CLOUDS BUILDING UP. LOW
LEVEL MOISTURE WILL BE TOO LOW FOR ANY RAIN TO MAKE IT TO THE
SURFACE, THUS THE MAIN CONCERN IS DRY THUNDERSTORMS MAINLY EAST OF
TUCSON. BY SATURDAY, MORE MOISTURE WILL HAVE PUSHED INTO THE AREA
INCREASING PWATS TO 0.75" TO 1 INCH WHICH IS OVER 200 PERCENT OF
NORMAL. DESPITE THE INCREASE IN MOISTURE, THE RIDGING ALONG THE
ARIZONA/ NEW MEXICO BORDER LEADS TO A LOWER POSSIBILITY FOR DRY
THUNDERSTORMS TO DEVELOP IN THE AFTERNOON. FOR FRIDAY AND SATURDAY
ANY STORMS THAT DEVELOP MAY LEAD TO GUSTY WINDS AT THE SURFACE.
BY SUNDAY, THE CUT OFF LOW WILL HAVE FINALLY PUSHED EASTWARD
BRINGING THUNDERSTORM DYNAMICS AND MOISTURE FROM THE LOW AS WELL
AS MOISTURE THAT TROPICAL DEPRESSION ONE-E PUSHED NORTHWARD IN TO
OUR AREA. THERE IS SOME MODEL DIFFERENCES WITH THE LOCATION,
TIMING AND INTENSITY OF THE LOW AS IT MOVES INTO ARIZONA. THE
BIGGEST DISCREPANCY IS WHEN THE SHOWERS WILL OCCUR, EITHER SUNDAY
AFTERNOON OR SUNDAY NIGHT INTO MONDAY AND HOW WIDESPREAD THE
SHOWERS WILL BE. CURRENTLY, WE ARE FORECASTING THE LOW TO MOVE
ACROSS SOUTH-CENTRAL AZ BRINGING A WIDESPREAD CHANCE FOR SHOWERS
AND THUNDERSTORMS SUNDAY AFTERNOON INTO THE EVENING. ENSEMBLE
PRECIPITATION VALUES ARE GENERALLY AROUND 0.25 INCHES BUT THERE
ARE FEW OUTLIER MEMBERS THAT INDICATE LOCALLY HIGHER PRECIPITATION
AROUND 1 INCH, HIGHLIGHTING A CHANCE FOR SOME STORMS TO PRODUCE
HEAVIER RAINFALL.
ONCE THIS SYSTEM MOVES THROUGH MONDAY, DRY CONDITIONS WILL THEN
PREVAIL THROUGH THE MIDDLE OF NEXT WEEK WITH A RETURN TO
SOUTHWESTERLY FLOW ALOFT WITH WINDS THE NEXT CONCERN AS TROUGHING
BECOMES ESTABLISHED OVER THE GREAT BASIN. TEMPERATURES WILL BE 3
TO 7 DEGREES BELOW NORMAL EARLY NEXT WEEK.
AVIATION
VALID THROUGH 30/00Z.
SKC TO FEW CLOUDS AOA 20 TO 25K FT MSL. CLOUDS WILL BECOME FEW TO
SCT BY 29/00Z AOA 20 TO 25K FT MSL LASTING THROUGHOUT THE
FORECAST PERIOD. GENERALLY LIGHT AND TERRAIN DRIVEN WINDS LESS
THAN 12 KTS THROUGH THE FORECAST PERIOD WITH A WLY/SWLY AFTERNOON
GUSTS AROUND 15 KTS. AVIATION DISCUSSION NOT UPDATED FOR TAF
AMENDMENTS.
FIRE WEATHER
DRY CONDITIONS CONTINUE THROUGH THURSDAY
WEEK WITH SINGLE DIGIT MIN RH VALUES AT ALL ELEVATIONS, WITH POOR
OVERNIGHT RECOVERIES. EXPECT SEASONALLY TYPICAL AFTERNOON
BREEZES/GUSTS DUE TO STRONG DAYTIME HEATING.
A MORE VARIABLE WEATHER PATTERN DEVELOPS LATE IN THE WEEK AND INTO
EARLY NEXT WEEK AS A WEATHER SYSTEM TO OUR SOUTHWEST WILL DRAW
MOISTURE INTO THE AREA. THE MOISTURE INCREASE WILL INITIALLY
OCCUR IN THE MID LEVELS EAST OF TUCSON BY FRIDAY, WHERE BUILD- UPS
MAY RESULT IN DRY LIGHTNING. ADDITIONAL MOISTURE PUSHING INTO THE
AREA IS LIKELY THROUGH THE WEEKEND. SATURDAY MAY SEE ANOTHER DAY
OF BUILD-UPS FOR DRY LIGHTNING, THEN SUNDAY INTO MONDAY SHOULD
FEATURE ADEQUATE MOISTURE FOR MORE WIDESPREAD WETTING RAIN
OPPORTUNITIES. GUSTY AND ERRATIC WINDS WOULD OCCUR WITH ANY
THUNDERSTORM ACTIVITY. DRY WEATHER RETURNS BY NEXT TUESDAY.
TWC WATCHES/WARNINGS/ADVISORIES
NONE.
MALARKEY
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