794
FXUS65 KTWC 062018
AFDTWC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
119 PM MST TUE OCT 6 2026
SYNOPSIS
TEMPERATURES WILL BE 3 TO 10 DEGREES ABOVE NORMAL
THROUGH THE WORK WEEK. WINDS PICK UP AGAIN OUT OF THE EAST
THURSDAY INTO THE WEEKEND. SLIGHT CHANCES FOR PRECIPITATION IN
THE WHITE MOUNTAINS ON WEDNESDAY AND THURSDAY AFTERNOON. BETTER AND
MORE WIDESPREAD RAIN CHANCES RETURN THIS WEEKEND THROUGH EARLY NEXT
WEEK.
DISCUSSION
MOSTLY SUNNY TO PARTLY CLOUDY SKIES ACROSS SOUTHEAST
ARIZONA WITH ABOVE NORMAL TEMPERATURES CONTINUING AS BROAD RIDGING
ALOFT REMAINS IN CONTROL. MOISTURE LEVELS ARE STILL RELATIVELY
ELEVATED FOR THIS TIME OF YEAR WITH SURFACE DEWPOINTS IN THE MID 50S
TO LOW 60S RESULTING IN SOME CUMULUS CLOUDS. THESE WON'T REALLY
DEVELOP INTO ANYTHING IN TERMS OF PRECIPITATION CHANCES AS VERY DRY
AIR AND SUBSIDENCE DOMINATES ABOVE 500 MB. THERE IS A WEAK
DISTURBANCE/UPPER LOW WITHIN THE BROADER RIDGING THAT WILL MOVE
TOWARDS THE WHITE MOUNTAINS FROM THE NORTH TO RESULT IN A SLIGHT
CHANCE (10 TO 20 PERCENT) OF SHOWERS AND THUNDERSTORMS BOTH
WEDNESDAY AND THURSDAY AFTERNOON. THE REST OF SOUTHEAST ARIZONA
WILL REMAIN DRY WITH CONTINUED ABOVE NORMAL TEMPERATURES.
A FAIRLY BENIGN WEATHER PATTERN WILL CONTINUE THURSDAY AND FRIDAY
WITH AN UPTICK IN EASTERLY WINDS. FOR THIS WEEKEND, OUR FOCUS WILL
TURN TOWARDS THE TROPICS AS HURRICANE RACHEL (WELL WEST OF SOUTHERN
BAJA) MAKES AN ABRUPT 90 DEGREE RECURVATURE TO THE NORTHEAST AS A
STRONG TROUGH APPROACHES THE WEST COAST. LATEST NHC FORECAST SHOWS
RACHEL RAPIDLY BECOMING POST-TROPICAL ON SATURDAY, SHORTLY AFTER IT
MAKES ITS TURN TO THE NORTHEAST. THERE IS STILL SOME SPREAD IN THE
ENSEMBLE GUIDANCE ON WHERE THE REMNANTS OF RACHEL WILL END UP WITH
THE MOST LIKELY TRAJECTORY NOW BEING TOWARDS BAJA CALIFORNIA OR EVEN
AS FAR NORTH SOUTHERN CALIFORNIA. REGARDLESS, THE REMAINS OF RACHEL
WILL HELP SEND ABOVE NORMAL MOISTURE LEVELS INTO THE SOUTHWEST US
INCLUDING OUR FORECAST AREA. THESE ABOVE NORMAL MOISTURE LEVELS IN
COMBINATION WITH FORCING AND LIFT FROM TROUGHING ALOFT WILL RESULT
IN AN EXTENDED PERIOD OF RAIN CHANCES. WHILE POPS (AROUND 20%) GET
INTRODUCED AS EARLY AS SATURDAY AFTERNOON, RECENT TRENDS POINT
TOWARDS A PERIOD OF 20% TO 50% RAIN CHANCES (WITH POTENTIAL FOR A
FEW THUNDERSTORMS AS WELL) FROM SUNDAY THROUGH TUESDAY. MOST OF THE
ENSEMBLES KEEP QPF IN OUR AREA AT REASONABLE LEVELS (0.25" TO 0.75")
DURING THIS TIME FRAME BUT THERE ARE A FEW OUTLIERS ON THE HIGHER
SIDE (1 TO 2"+) THAT SHOWS THE HIGHER END/WORST CASE POTENTIAL.
STILL HAVE TIME TO SORT THESE DETAILS OUT AND HAVE A BETTER HANDLE
ON THE INTERACTION OF THE TROUGH WITH REMNANTS FROM RACHEL AND WHERE
THE HEAVIEST PRECIPITATION WILL LINE UP. OTHERWISE, STARTING SUNDAY,
COOLER TEMPERATURES WILL MOVE IN AS WELL WITH HIGHS BELOW NORMAL
EARLY NEXT WEEK.
AVIATION
VALID THRU 08/00Z.
FEW-SCT CLOUDS 7K-10K FT AGL THRU 07/03Z, THEN BECOMING SKC WITH FEW-
SCT CLOUDS AGAIN AFT 07/18Z, ESPECIALLY IN THE WHITE MOUNTAINS. SFC
WINDS MAINLY NW 5-10 KTS THRU 07/04Z, THEN BECOMING VARIABLE MAINLY
8 KTS OR LESS THROUGH THE END OF VALID PERIOD. AVIATION DISCUSSION
NOT UPDATED FOR TAF AMENDMENTS.
FIRE WEATHER
WINDS WILL BE LESS THAN 15 MPH AND TERRAIN
DRIVEN THROUGH WEDNESDAY. MINIMUM RELATIVE HUMIDITY VALUES WILL
REMAIN 15-30 PERCENT IN LOWER ELEVATIONS AND ABOVE 40 PERCENT IN
HIGH ELEVATION TERRAIN THROUGH THE WORK WEEK. THERE IS A SLIGHT
CHANCE FOR STORMS OVER THE WHITE MOUNTAINS WEDNESDAY AND THURSDAY
AFTERNOONS. BREEZY EASTERLY WINDS RETURN THURSDAY INTO SATURDAY WITH
THE STRONGEST WINDS IN THE GILA RIVER VALLEY.
A WEATHER SYSTEM WILL BEGIN TO MOVE IN THIS WEEKEND BRINGING A
20-50 PERCENT CHANCE FOR RAIN LATE SATURDAY INTO EARLY NEXT
WEEK.
TWC WATCHES/WARNINGS/ADVISORIES
NONE.
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