194
FXUS65 KTWC 182019
AFDTWC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
119 PM MST SAT OCT 18 2025
SYNOPSIS
ONE MORE AFTERNOON OF BELOW NORMAL TEMPERATURES THEN
TEMPERATURES WARM TO NORMAL TO A FEW DEGREES ABOVE NORMAL TOMORROW
INTO THE MIDDLE OF NEXT WEEK. DRY CONDITIONS WILL ALSO PREVAIL
THROUGH TUESDAY WITH A SLIGHT CHANCE OF RAIN FOR MOUNTAIN AREAS EAST
OF TUCSON WEDNESDAY.
DISCUSSION
THIS AFTERNOON SOUTHEAST ARIZONA WAS SITUATED
BETWEEN A WEAK CLOSED UPPER LOW OFF THE COAST OF CALIFORNIA AND
BAJA CALIFORNIA AND A RIDGE OF HIGH PRESSURE BUILDING OVER CENTRAL
MEXICO. FEW TO SCATTERED HIGH CLOUDS EXPECTED THIS AFTERNOON WITH
HIGH TEMPERATURES RUNNING BELOW NORMAL BY AROUND 4 TO 8 DEGREES.
AS THE RIDGE OF HIGH PRESSURE CONTINUES TO BUILD, EXPECT
TEMPERATURES TO RISE ABOVE NORMAL INTO THE UPPER 80S TO AROUND 90
DEGREES TOMORROW RESULTING IN MINOR HEATRISK TO RETURN FOR VALLEY
LOCATIONS. CURRENT NBM PROBABILITIES FOR 90 DEGREES OR GREATER IN
TUCSON ARE 10 PERCENT SUNDAY AND MONDAY, 60 PERCENT ON TUESDAY,
50 PERCENT WEDNESDAY, AND DECREASING TO 5 PERCENT THURSDAY.
OTHERWISE, LITTLE TO NO WEATHER RELATED IMPACTS EXPECTED THIS
WEEKEND.
THE NEXT POTENTIAL FOR MINOR/NUISANCE IMPACTS WILL BE WEDNESDAY
AS THE AFOREMENTIONED UPPER LOW OPENS INTO A TROF AND PASSES OVER
CENTRAL ARIZONA. A MODEST INCREASE IN MID-LEVEL MOISTURE AND
FORCING FOR ASCENT AIDED BY TERRAIN WILL BRING SCATTERED TO BROKEN
CLOUDS TUESDAY THROUGH THURSDAY AND SLIGHT CHANCES (10-25%) FOR
SHOWERS MAINLY IN THE WHITE MOUNTAINS, CHIRICAHUA MOUNTAINS, AND
SKY ISLANDS WEDNESDAY. NOT MUCH IN THE WAY OF MEASURABLE RAINFALL
IS CURRENTLY ANTICIPATED WITH NBM QPF REMAINING UNDER 0.05".
LOCALLY BREEZY/GUSTY WINDS ARE POSSIBLE WITH THE PASSAGE OF THIS
SYSTEM PRIMARILY FOR WIND PRONE VALLEY LOCATIONS WEDNESDAY
AFTERNOON. ONLY LOCALIZED MINOR/NUISANCE IMPACTS ARE CURRENTLY
EXPECTED AS NBM PROBABILITIES FOR GUSTS OVER 25 MPH ARE LOW
(10-30%). THE TROF WILL EXIT THE AREA THURSDAY LEAVING SLIGHTLY
COOLER TEMPERATURES IN ITS WAKE.
LOOKING AHEAD AT THE EXTENDED FORECAST, THE CLIMATE PREDICTION
CENTER (CPC) DEPICTS TEMPERATURES TO LEAN ABOVE NORMAL AND
PRECIPITATION TO BE BELOW NORMAL FOR SOUTHEAST ARIZONA. ENSEMBLES
CURRENTLY AGREE THAT POSITIVE HEIGHT ANOMALIES WILL BE IN PLACE
THROUGH THE LAST WEEK OF OCTOBER WITH A RIDGE OF HIGH PRESSURE
BUILDING AND REMAINING IN PLACE OVER THE DESERT SOUTHWEST. THIS
SOLUTION WOULD SUPPORT CONTINUED WARM AND DRY CONDITIONS TO CLOSE
OUT OCTOBER.
AVIATION
VALID THROUGH 20/12/00Z.
FEW-SCT CLOUDS AOA 20K FT AGL. SFC WINDS WLY/NWLY AT 6-9 KTS THROUGH
19/03Z AND AGAIN AFTER 19/20Z. OTHERWISE, SFC WINDS LIGHT AND VRBL.
AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.
FIRE WEATHER
MINIMUM RH VALUES WILL BE IN THE 15-25 PERCENT
RANGE IN THE VALLEYS INTO NEXT WEEK. 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 BELOW NORMAL THIS AFTERNOON, WARMING TO NORMAL OR JUST ABOVE
NORMAL LEVELS TOMORROW INTO NEXT WEEK. EXPECT DRY CONDITIONS OVER
THE NEXT 7 DAYS WITH THE EXCEPTION OF THE WHITE MOUNTAINS WEDNESDAY,
WHICH WILL SEE A 20 PERCENT CHANCE FOR SHOWERS.
TWC WATCHES/WARNINGS/ADVISORIES
NONE.
DVS
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