Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 250430
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
930 PM MST WED JUN 24 2015

.SYNOPSIS...THUNDERSTORM CHANCES WILL GRADUALLY INCREASE THROUGH
FRIDAY AS MOISTURE INCREASES ACROSS THE AREA. SOME STORMS THURSDAY
AND FRIDAY WILL GENERATE STRONG WINDS WITH AREAS OF BLOWING DUST
POSSIBLE. THE POTENTIAL EXISTS FOR AN ACTIVE THUNDERSTORM PERIOD
THIS WEEKEND AND EARLY NEXT WEEK WITH DAYTIME TEMPERATURES
MODERATING CLOSER TO SEASONAL NORMALS.

&&

.DISCUSSION...ISOLATED SHOWERS AND THUNDERSTORMS WERE ONGOING NEAR
THE NEW MEXICO BORDER AS WELL AS NEAR THE INTERNATIONAL BORDER
ADJACENT COCHISE COUNTY. IR SATELLITE IMAGERY DEPICTED CONVECTIVE
DEBRIS CLOUDINESS ACROSS SE ARIZONA AT THIS TIME. IR SATELLITE
IMAGERY ALSO DEPICTED A LARGE MCS OVER CENTRAL/SOUTHERN SONORA...
AND CLOUD TOPS HAVE BEEN GRADUALLY COOLING DURING THE PAST 1-2 HOURS
ACROSS NRN SONORA/FAR SRN ARIZONA.

BASED ON SATELLITE/RADAR TRENDS...THE 25/00Z NAM/GFS...THE 25/03Z
HRRR...AND SPC MESOSCALE ANALYSIS PRODUCTS...HAVE OPTED FOR A SLIGHT
CHANCE OF SHOWERS/TSTMS FROM TUCSON EWD/SWD THE REST OF TONIGHT.
PRECIP-FREE SHOULD CONTINUE THE REST OF TONIGHT ACROSS WRN/CENTRAL
PIMA COUNTY AND SOUTH CENTRAL PINAL COUNTY. THE POTENTIAL FOR GUSTY
WINDS DUE TO THUNDERSTORMS IS VIRTUALLY NIL THE REST OF TONIGHT.

PLEASE REFER TO THE ADDITIONAL SECTIONS FOR FURTHER DETAIL.

&&

.AVIATION...VALID THRU 26/06Z.
ISOLATED -TSRA/-SHRA EAST AND SOUTH OF KTUS WILL MOSTLY END AROUND
25/09Z OR SO. EXPECT ISOLATED -TSRA/-SHRA EAST OF KTUS DEVELOPING
LATE THURSDAY MORNING...THEN SCATTERED TO NUMEROUS -TSRA/-SHRA
SHOULD OCCUR ACROSS MUCH OF SOUTHEAST ARIZONA THURSDAY AFTERNOON AND
THURSDAY EVENING. THE POTENTIAL EXISTS FOR BRIEF WIND GUSTS MAINLY
IN THE 40-45 KT RANGE THURSDAY AFTERNOON. OTHERWISE...CLOUD DECKS
WILL GENERALLY BE AT OR ABOVE 10K FT AGL. SURFACE WIND OUTSIDE OF
-TSRA/-SHRA THURSDAY AFTERNOON WILL BE MAINLY NWLY AT 10-15 KTS...
THEN SURFACE WIND BECOMING ELY/SELY 10-15 KTS THURSDAY EVENING.
OTHERWISE...SURFACE WIND WILL BE LESS THAN 10 KTS. AVIATION
DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...MONSOONAL MOISTURE WILL BE DIRECTED INTO SOUTHEAST
ARIZONA FOR THE NEXT SEVERAL DAYS WITH THUNDERSTORM ACTIVITY
CONTINUING TO RAMP UP THROUGH THE WEEKEND. COVERAGE OF STORMS WILL
SPREAD WESTWARD EACH AFTERNOON THROUGH REST OF THE WEEK. INITIAL
THREAT FROM THUNDERSTORMS WILL BE STRONG GUSTY OUTFLOWS AND DRY
LIGHTNING THROUGH WEDNESDAY UNTIL MOISTURE BECOMES MORE ENTRENCHED.
WIND GUSTS OF 35-45 MPH WILL BE FAIRLY COMMON WITH THE POTENTIAL FOR
THE STRONGEST AFTERNOON AND EARLY EVENING STORMS TO PRODUCE WINDS IN
EXCESS OF 50 MPH.

&&

.PREV DISCUSSION /151 PM MST/...BROADSCALE RIDGING IS IN PLACE ALOFT
AND AT THE SURFACE OVER THE SOUTHWESTERN US...WITH THE SURFACE HIGH
DRAPED TO THE NORTH OF ARIZONA. AN AREA OF MID/UPPER LEVEL LOW
PRESSURE IS TRACKING SLOWLY NORTH ALONG THE CALIFORNIA COAST...AND
AN EASTERLY WAVE IS MOVING ACROSS WESTERN TEXAS AND NORTHERN MEXICO.
THE GRADIENT BETWEEN THE HIGH NORTH OF THE STATE AND THE LOW OFF THE
COAST OF CALIFORNIA IS GENERATING BROAD NORTH TO NORTHEAST FLOW
OVER THE AREA.

LOW LEVEL MOISTURE HAS BEEN INCREASING STEADILY OVER THE PAST 24
HOURS. THE COMBINATION OF THIS MOISTURE...HEATING...AND TERRAIN
HAS GENERATED SHOWERS AND THUNDERSTORMS ACROSS THE AREA. THE
STORMS ARE SLOWLY DRIFTING SOUTH TO SOUTHWEST. THUS FAR THE
STRONGEST STORMS HAVE LINGERED OVER HIGHER TERRAIN...HOWEVER...A
TRANSITION TO ACTIVITY OVER THE VALLEYS IS ANTICIPATED LATER THIS
AFTERNOON AND EVENING. STRONG GUSTY WINDS IS THE PRIMARY CONCERN
WITH VALUES IN EXCESS OF 50 MPH POSSIBLE WITH THE STRONGEST
STORMS. AREAS ALONG THE INTERSTATE 10 AND 19 CORRIDORS COULD BE
IMPACTED INCLUDING NOGALES AND TUCSON.

THE GENERAL WEATHER PATTERN WILL CHANGE LITTLE OVER THE NEXT
SEVERAL DAYS OTHER THAN AN AMPLIFICATION OF THE UPPER LEVEL RIDGE
OVER THE WESTERN US. THIS WILL KEEP THE MOISTURE TAP AIMED AT
ARIZONA THROUGH AT LEAST THE WEEKEND. AFTERNOON AND EVENING
THUNDERSTORMS ARE A STRONG POSSIBILITY EACH DAY. HEAVY RAINFALL
WILL BECOME A SIGNIFICANT THREAT BY THE WEEKEND. STRONG AND GUSTY
WINDS WILL REMAIN A THREAT THROUGHOUT AS WELL. EVERYONE SHOULD
KEEP AN EYE ON THE FORECAST TO GET THE LATEST DETAILS ON WHERE
STORM ARE EXPECTED TO INITIATE AND MIGRATE EACH DAY. ANYONE WITH
OUTDOOR PLANS THIS WEEKEND SHOULD ANTICIPATE THE POTENTIAL FOR
STRONG WINDS...HEAVY RAINFALL...AND FREQUENT LIGHTNING.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...YOUTUBE...AND AT WEATHER.GOV/TUCSON

FRANCIS
PREVIOUS DISCUSSION...CANTIN



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