Dust Devil in Arizona, May 13, 2011

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
854 AM MST FRI MAY 13 2011

.SYNOPSIS...HIGH PRESSURE WILL BRING DRY CONDITIONS AND MUCH WARMER
TEMPERATURES TODAY AND SATURDAY. A TROUGH WILL PUSH THROUGH THE
REGION NORTH OF US NEXT WEEK...WITH BREEZY CONDITIONS AT TIMES ALONG
WITH TEMPERATURES NEAR SEASONAL AVERAGES.

&&

.DISCUSSION...WATER VAPOR IMAGERY SHOWS THE CENTER OF HIGH PRESSURE
WELL TO OUR SOUTH OVER THE EASTERN PACIFIC WATERS SEVERAL HUNDRED
MILES SOUTH SOUTHEAST OF THE SOUTHERN TIP OF BAJA. THE RIDGE AXIS
EXTENDS NORTHWARD THROUGH NORTHERN MEXICO AND ALONG THE ARIZONA NEW
MEXICO BORDER AND INTO UTAH. MEANWHILE...A WEAK SHORTWAVE TROUGH IS
CURRENTLY JUST OFF THE NORTHERN BAJA COAST AND MAKING ITS WAY TOWARD
THE PENINSULA AND THE DESERT SOUTHWEST. THIS SYSTEM WILL HAVE LITTLE
IMPACT ON ARIZONA AS IT MOVES THROUGH THE STATE LATE TONIGHT AND
EARLY SATURDAY.

THIS MORNINGS KTWC SOUNDING SHOWS A VERY DRY AIRMASS IN PLACE WITH A
PRECIPITABLE WATER VALUE OF ONLY 0.21 INCHES. FAIRLY LIGHT WINDS
FROM THE SURFACE TO AROUND 500MB. THE 24 HOUR TEMPERATURE CHANGE
PROFILE SHOWS SIGNIFICANT WARMING FROM THE SURFACE TO ABOUT
650MB...BUT WARMING THROUGHOUT THE ENTIRE COLUMN. THE FCST MAX TEMP
FROM THE SOUNDING SHOWS A HIGH OF 95 DEGS F AND THAT IS WHAT I HAVE
IN THE INHERITED MAX TEMP GRID.

AS OF 15Z TEMPERATURES ACROSS THE REGION RANGED FROM THE MID 60S TO
LOWER 70S FOR DESERT/VALLEY LOCATIONS AND THESE READINGS ARE RIGHT
ON TRACK WITH THE EXPECTED AFTERNOON HIGHS...SO NO CHANGES ARE
PLANNED AT THIS TIME.

VISIBLE SATELLITE IMAGERY SHOWS CLEAR SKIES ACROSS ALL OF ARIZONA
THIS MORNING AND THIS WILL CONTINUE THROUGH THIS AFTERNOON. BOTTOM
LINE IS THE FORECAST FOR THIS AFTERNOON IS RIGHT ON TRACK.

&&

.AVIATION...SKC CONDITIONS ACROSS SOUTHEAST ARIZONA THRU AT LEAST 00
SAT. NORMAL DIURNAL WIND TRENDS THRU THIS MORNING WITH SUSTAINED
SURFACE WINDS GENERALLY LESS THAN 10 KTS. SLY/SWLY SURFACE WINDS AT
10-15 KTS BETWEEN 17Z-00Z TODAY. AVIATION DISCUSSION NOT UPDATED
FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...DRY CONDITIONS AND A RAPID WARMING TREND IS EXPECTED
INTO THE WEEKEND AS HIGH PRESSURE ALOFT BUILDS ACROSS SOUTHEAST
ARIZONA. DAYTIME HUMIDITIES WILL GENERALLY BE IN THE SINGLE DIGITS
TO LOWER TEENS...WITH FAIR TO POOR NIGHTTIME RECOVERY. THERE WILL
ALSO BE LESS WIND THROUGH SATURDAY...ALTHOUGH LOCALLY GUSTY WINDS
WILL STILL OCCUR DURING THE AFTERNOON AND EARLY EVENING HOURS DUE TO
STRONG DAYTIME HEATING. AN INCREASE IN WIND IS EXPECTED LATE IN THE
WEEKEND AND EARLY NEXT WEEK AS A STORM SYSTEM MOVES INTO THE WEST
COAST AND THROUGH THE INTERMOUNTAIN WEST.

&&

.PREV DISCUSSION...A CLEAR SKY PREVAILED EARLY THIS MORNING ACROSS
SOUTHEAST ARIZONA. MUCH WARMER TODAY UNDER STRONG THICKNESS/HEIGHT
RISES. A WEAK UPPER LEVEL LOW...CURRENT APPROACHING NORTHERN BAJA
CALIFORNIA COAST...WILL PASS THROUGH ARIZONA TONIGHT AND BE IN THE
FOUR CORNERS REGION SATURDAY MORNING. HIGHS ON SATURDAY A FEW
DEGREES COOLER VERSUS TODAY.

COOLER AND BREEZY SUNDAY AND MONDAY AS A STRONGER PACIFIC LOW
PRESSURE SYSTEM MOVES INTO THE WEST COAST. COOLEST TEMPERATURES OF
THE FORECAST PERIOD...ALONG WITH STRONGER WINDS...WILL OCCUR NEXT
TUESDAY AS UPPER TROUGH MOVES INTO THE STATE. HIGHS FOR THE
REMAINDER OF NEXT WEEK WILL BE SLIGHTLY BELOW NORMAL.

&&

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

WEATHER.GOV/TUCSON