Area Forecast Discussion
Issued by NWS Tucson, AZ

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000
FXUS65 KTWC 191604
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
905 AM MST FRI SEP 19 2014

.SYNOPSIS...LINGERING MOISTURE WILL MAINTAIN A CHANCE OF SHOWERS AND
THUNDERSTORMS INTO THIS WEEKEND. HIGH PRESSURE ALOFT COULD PROVIDE
REDUCED RAINFALL CHANCES NEXT WEEK. EXPECT GRADUALLY WARMER DAYTIME
TEMPERATURES INTO THIS WEEKEND.

&&

.DISCUSSION...WATER VAPOR IMAGERY SHOWS RIDGING TO OUR SOUTH OVER
MEXICO...WITH AN APPROACHING PACIFIC TROUGH THAT EXTENDS FROM THE
NORTHERN ROCKIES THROUGH NORTH CENTRAL CALIFORNIA AND INTO THE
COASTAL WATERS. PLENTY OF DRY MID TO UPPER LEVEL AIR COVERS MUCH OF
THE DESERT SOUTHWEST...NORTHERN MEXICO AND THE EASTERN PACIFIC
WATERS. THIS IS REFLECTED IN THIS MORNINGS KTWC SOUNDING WHICH SHOWS
SIGNIFICANT DRYING ABOVE 600MB COMPARED TO 24 HOURS AGO. THE
UNMODIFIED SOUNDING INDICATED A PRECIPITABLE WATER (PW) VALUE OF
1.65 INCHES COMPARED TO 1.94 INCHES FROM THURSDAY MORNING. THE
LIFTED INDEX WAS MINUS 2...WITH A CAPE OF AROUND 1900 J/KG.
MODIFYING THE SOUNDING USING T=90;TD=64 YIELDS A SIMILAR LI...BUT A
CAPE OF AROUND 1500 J/KG. THAT SAID...WE SHOULD STILL SEE SCATTERED
TO LOCALLY NUMEROUS SHOWERS AND THUNDERSTORMS CONTINUE TO
DEVELOP...ESPECIALLY IF WE START TO SEE MORE SUN PEEK THROUGH THE
CLOUDINESS.

IR AND VISIBLE SATELLITE IMAGERY CONTINUE TO SHOW EXTENSIVE LOW AND
MID LEVEL CLOUDINESS COVERING A LARGE PART OF THE FORECAST
AREA...BUT WE SHOULD BEGIN TO SEE SOME OF THE CLOUDINESS ERODE AS
THE DAY PROGRESSES.

THE LATEST RADAR MOSAIC SHOWS A FEW ISOLATED SHOWERS MAINLY OVER
EASTERN PIMA COUNTY AT THIS TIME. EARLIER THIS MORNING THESE SHOWERS
WERE AFFECTING PORTIONS OF THE TUCSON METRO. PRIOR TO SUNRISE A
SHOWER PRODUCED CONSIDERABLE RAIN AT THE SALCIDO PLACE GAUGE...WHICH
IS EAST OF VAIL AND NORTH OF INTERSTATE 10 NEAR THE COCHISE COUNTY
LINE...WHEN IT PICKED UP 1.89 INCHES IN THE PAST 6 HOURS.

SO...EXPECT TO SEE SHOWERS AND THUNDERSTORMS INCREASE THROUGH THE
DAY...WITH THE FOCUS MAINLY SOUTH AND EAST OF TUCSON...BUT MOSTLY
SCATTERED IN NATURE.

THE INHERITED FORECAST SEEMS TO BE ON TRACK...SO NO CHANGES ARE
PLANNED AT THIS TIME...BUT WILL CONTINUE TO MONITOR SATELLITE AND
RADAR TRENDS.

&&

.AVIATION...VALID THRU 20/18Z.
EXPECT ISOLATED TO SCATTERED -SHRA/-TSRA TO REDEVELOP ACROSS SE AZ
THIS AFTERNOON AND CONTINUE UNTIL ABOUT 20/02Z. MVFR CIGS AND VSBYS
PRESENT THIS MORNING WILL MAINLY BE CONFINED TO MORE INTENSE SHOWERS
THIS AFTERNOON...A FEW AREAS OF MVFR CIGS AND MT OBSCURATIONS COULD
DEVELOP AGAIN TOWARD SATURDAY MORNING. SURFACE WINDS WILL BE MAINLY
LESS THAN 10 KTS. AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...MOISTURE WILL REMAIN IN PLACE INTO NEXT
WEEK..FUELING CHANCES FOR ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS.

&&

.CLIMATE...THE TUCSON AIRPORT HAS RECORDED 3 STRAIGHT DAYS WITH
HIGHS LESS THAN 85 DEGREES. THIS IS THE LONGEST SEPTEMBER STRETCH
SINCE 1985.

&&

.PREVIOUS DISCUSSION...THE WEAK UPPER LOW OFF THE CENTRAL CALIFORNIA
COAST WILL DROP SOUTH TODAY BEFORE BOTTOMING OUT WEST OF LOS ANGELES
THEN LIFT NE INTO NEVADA BY SUNDAY MORNING. ISOLATED TO SCATTERED
MAINLY AFTERNOON/EVENING STORMS WITH BEST CHANCES FROM TUCSON EAST.

POTENTIALLY DRIER AIR COULD MOVE OVER THE AREA EARLY NEXT WEEK
UNDER WLY FLOW ALOFT WITH UPPER HIGH CENTERED TO OUR SOUTH. HIGHS
WILL BE AT OR NEAR NORMALS NEXT WEEK.

&&

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

&&

$$

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

PUBLIC...MOLLERE
AVIATION/FIRE WEATHER...DROZD





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