Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 300357
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
857 PM MST FRI AUG 29 2014

.SYNOPSIS...MOSTLY CLEAR...HOT AND DRY CONDITIONS WILL CONTINUE
THROUGH THE HOLIDAY WEEKEND. THEN...SOME MOISTURE WILL SNEAK INTO
AREAS NEAR THE INTERNATIONAL BORDER FOR A SLIGHT CHANCE OF
THUNDERSTORMS TUESDAY AND WEDNESDAY. THE MOISTURE IS EXPECTED TO
BECOME MORE PRONOUNCED LATE IN THE WEEK WITH AN INCREASE IN SHOWER
AND THUNDERSTORM ACTIVITY.

&&

.DISCUSSION...WATER VAPOR IMAGERY AND 30/00Z UPPER-AIR PLOTS SHOW
HIGH PRESSURE TO OUR SOUTH EXTENDING FROM JUST OFF THE SOUTHERN
CALIFORNIA/NORTHERN BAJA COASTS THROUGH NORTHERN BAJA AND INTO
NORTHERN SONORA. THAT SAID...DRY WEST TO NORTHWEST MID TO UPPER
LEVEL FLOW RESIDES ACROSS SOUTHEAST ARIZONA AS EVIDENCED BY THE
30/00Z KTWC SOUNDING. PLENTY OF DRY MID TO UPPER LEVEL AIR IN PLACE
WITH WV IMAGERY SHOWING A LARGE SWATH OF DRY AIR THAT EXTENDS OVER
MUCH OF NORTHERN MEXICO AND INTO SOUTHERN PORTIONS OF ARIZONA...NEW
MEXICO AND WEST TEXAS.

IR SATELLITE IMAGERY SHOWS CLEAR SKIES ACROSS SOUTHERN ARIZONA WITH
MOSTLY HIGH LEVEL CLOUDINESS SPILLING OVER THE TOP OF THE HIGH
ACROSS PORTIONS OF NORTH CENTRAL CALIFORNIA INTO MUCH OF NEVADA AND
UTAH...AS WELL AS NORTHERN PORTIONS OF ARIZONA. EXPECTING SKIES TO
REMAIN CLEAR OVERNIGHT...SO INHERITED SKY CONDITION FORECAST FOR THE
REMAINDER OF TONIGHT LOOKS GOOD.

AS OF 03Z (8 PM MST)...TEMPERATURES ACROSS THE REGION RANGED FROM
THE MID 70S TO THE LOWER 90S...WITH THE TUCSON INTL AIRPORT
REPORTING A TEMP OF 93 DEGS...AFTER REACHING AN AFTERNOON HIGH OF
102 DEGS...WHICH WAS 4 DEGS ABOVE NORMAL FOR THIS DATE. THE CURRENT
TEMP READINGS SEEM TO BE ON TRACK WITH THE INHERITED/EXPECTED
OVERNIGHT LOW TEMPERATURES...SO NO CHANGES PLANNED AT THIS
TIME...BUT WILL CONTINUE TO MONITOR AND WILL MAKE CHANGES IF NEEDED.
OTHERWISE...THE FORECAST FOR THE REMAINDER OF TONIGHT SEEMS TO BE IN
GOOD SHAPE.

FOR DETAILS REGARDING THE FORECAST BEYOND TONIGHT...PLEASE REFER TO
THE PREVIOUS DISCUSSION BELOW.

&&

.AVIATION...VALID THRU 31/06Z.
EXPECT SKC CONDITIONS OVERNIGHT AND EARLY SATURDAY THROUGH AROUND
30/18Z. A FEW CUMULUS CLOUDS WITH BASES AROUND 8-12K FT AGL WILL
DEVELOP FROM AROUND 30/18Z THROUGH 31/02Z...THEN SKC AFTER 31/02Z.
SURFACE WINDS WILL BE MAINLY LESS THAN 10 KTS THRU SATURDAY...EXCEPT
FOR OCCASIONAL GUSTS TO AROUND 20 KTS DURING THE MID TO LATE
AFTERNOON HOURS. AVIATION DISCUSSION NOT UPDATED FOR TAF
AMENDMENTS.  CERNIGLIA

&&

.FIRE WEATHER...DRY CONDITIONS WILL PREVAIL THROUGH MONDAY WITH
WARMER THAN NORMAL TEMPERATURES AND LOWER THAN NORMAL HUMIDITY
LEVELS.  THE UPPER LEVEL HIGH WILL REPOSITION ITSELF EAST EARLY NEXT
WEEK TO WHERE MOISTURE IS EXPECTED TO MOVE INTO SOUTHEAST PARTS OF
THE AREA FOR A SLIGHT CHANCE OF THUNDERSTORMS MAINLY NEAR THE
INTERNATIONAL BORDER SOUTH TO SOUTHEAST OF TUCSON TUESDAY.  THE
MOISTURE WILL LIKELY SPREAD A BIT WEDNESDAY AND MORE SO THURSDAY
THROUGH FRIDAY FOR INCREASING CHANCES OF CONVECTION.  EXPECT LIGHT
TERRAIN DRIVEN WINDS INTO EARLY NEXT WEEK.  GUSTY OUTFLOWS
ASSOCIATED WITH THUNDERSTORMS WILL THEN OCCUR DURING THE LATTER PART
OF NEXT WEEK.  CERNIGLIA

&&

.PREVIOUS DISCUSSION...THE UPPER LEVEL HIGH CURRENTLY OFF THE
CALIFORNIA COAST WILL BUILD EAST LATE THIS WEEKEND AND SET UP JUST
TO OUR EAST MONDAY THEN GRADUALLY CONTINUE EAST THROUGH THE WEEK.
THIS WILL BEGIN TO ALLOW SOME MOISTURE TO ADVECT NEARBY MONDAY THEN
OVER SOUTHEAST PORTIONS OF THE FORECAST AREA TUESDAY AND WEDNESDAY
RESULTING IN A THREAT OF CONVECTION SOUTHEAST PART OF THE AREA THOSE
TWO DAYS.  SHOULD ALSO SEE AFTERNOON HIGH TEMPERATURES COOLING A
DEGREE OR TWO AS WELL.

BEYOND THAT...THE QUESTION BECOMES HOW MUCH MOISTURE DO WE GET OVER
THE AREA.  WHILE DETAILS DIFFER WHICH IS USUAL...MID RANGE MODEL
FIELDS CONTINUE TO INDICATE A NICE FETCH OF MOISTURE MOVING INTO THE
REGION ON SOUTHEAST FLOW.  OVER THE LAST FEW DAYS THE EC HAS BEEN
THE MOST CONSISTENT WITH THIS SCENARIO AND WOULD RAMP UP THE
MOISTURE THURSDAY AND ESPECIALLY FRIDAY INTO SATURDAY RESULTING IN
AN UPTICK IN CONVECTION ACROSS THE AREA.  HAVE LEANED ON THAT IDEA
AND TWEAKED THE FORECAST BY ADJUSTING TO POPS UPWARD BY AT LEAST
BRINGING THEM UP CLIMATOLOGY FOR THE EARLY PART OF SEPTEMBER.  WITH
THE IDEA OF MORE CLOUDS AND POTENTIAL SHOWERS I ALSO TWEAKED
AFTERNOON TEMPS DOWN A BIT AS WELL.  WILL HAVE TO SEE HOW THIS ALL
PANS OUT.  CERNIGLIA

&&

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

&&

$$

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