Flash Flood in Arizona, August 23, 2003

SOUTHEAST ARIZONA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
220 PM MST SAT AUG 23 2003

.SYNOPSIS...HIGH PRESSURE OVER THE SOUTHERN ROCKIES WILL MAINTAIN A
FAVORABLE MOIST FLOW FOR SCATTERED SHOWERS AND THUNDERSTORMS FROM
TUCSON AND WEST...WITH LESS ACTIVITY OVER FAR EASTERN ARIZONA AGAIN
SUNDAY. INCREASING MOISTURE ASSOCIATED WITH REMNANTS OF TROPICAL
STORM IGNACIO...LOCATED SOUTH OF BAJA TODAY...WILL TRACK NORTHWARD
INTO THE REGION AROUND TUESDAY. THIS WILL BRING AN UPSWING IN
RAINFALL COVERAGE LATE MONDAY INTO TUESDAY.

.DISCUSSION...MODELS WERE HINTING AT A VERY ACTIVE NEXT FEW DAYS
RAINFALL WISE AS REMNANTS OF TROPICAL STORM IGNACIO JUST SOUTH OF
THE SRN TIP OF BAJA TODAY TRACK NORTHWARD BY TUESDAY. MODELS WERE
SHOWING A BROAD HIGH PRESSURE RIDGE OVER THE UNITED STATES WITH A
SECONDARY ANTICYCLONE CENTERED OVER THE SOUTHERN ROCKIES. THIS
GENERAL FLOW PATTERN WILL SUSTAIN THE PRESENT MOISTURE WHICH WILL
EVENTUALLY BE ENHANCED AROUND TUESDAY BY REMNANTS OF IGNACIO.
DAYTIME TEMPERATURES WILL BE IMPACTED BY THE BETTER CHANCES OF
PRECIP AND ASSOCIATED CLOUDINESS. THUS...WILL LOWER HIGH
TEMPERATURES A BIT FROM WHAT WAS PROJECTED EARLIER. IN A
NUTSHELL...THE BIG CHANGES WILL BE TO THE POPS ON TUESDAY BASED ON
THE GFS SOLUTION. OTHERWISE...WILL KEEP TYPICAL MODERATE PRECIP
CHANCES GOING THROUGH THE FORECAST PERIOD.

.TWC...NONE.

AZZ019-029>035-241400-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TUCSON AZ
1155 PM MST SAT AUG 23 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST ARIZONA

.DAY ONE...TODAY

SYNOPSIS...THE PROBABILITY OF RECEIVING PRECIPITATION IN EXCESS OF
ONE INCH WILL BE ABOVE CLIMATOLOGY ACROSS THE WESTERN DESERTS TODAY
AS HIGHER MOISTURE AND A FAVORABLE FLOW ALOFT RESIDES IN THIS AREA.
IN EASTERN COCHISE AND GRAHAM COUNTIES...DRIER LOW LEVELS WILL
INCREASE THE THREAT FOR DAMAGING THUNDERSTORM OUTFLOW WINDS BUT A
LOWER POSSIBILITY TO RECEIVE VERY HEAVY PRECIPITATION.

DISCUSSION...THE WATER VAPOR IMAGERY INDICATED THAT THE OVERALL
WEATHER PATTERN IS DEFINED BY AN UPPER LEVEL ANTICYCLONE STRETCHED
BETWEEN SOUTHERN AND NORTHEAST ARIZONA...AN INVERTED TROUGH
EXTENDING FROM EASTERN NEW MEXICO INTO NORTHERN CHIHUAHUA AND AN
EASTERLY WAVE PUSHING ACROSS NORTH CENTRAL MEXICO. SATELLITE
IMAGERY INDICATED THAT A JET STREAK ALONG THE WESTERN PERIPHERY OF
THE INVERTED TROUGH WILL CONTINUE TO PUSH WEST INTO SOUTHEAST
ARIZONA THIS AFTERNOON AND EVENING. THIS JET STREAK WILL INCREASE THE
OVERALL STRETCHING DEFORMATION THAT IS OCCURRING UNDER THE UPPER
ANTICYCLONE TODAY AS WELL AS FOCUS CONVECTION ALONG ITS BOUNDARY.

THE GOES-10 PRECIPITABLE WATER IMAGERY INDICATED A PLUME OF VERY
HIGH PW VALUES ACROSS THE WESTERN DESERTS WITH SLIGHTLY DRIER AIR
LOCATED ACROSS THE EASTERN BORDER WITH NEW MEXICO. THIS DRIER
AIRMASS ACROSS EASTERN COCHISE AND GRAHAM COUNTIES MAY LIMIT THE
OVERALL THUNDERSTORM ACTIVITY TODAY. HOWEVER...ANY STORMS THAT DO
DEVELOP IN THIS AREA WILL BE CAPABLE OF PRODUCING VERY STRONG WINDS
WITH THE DRY AIR IN THE LOW LEVELS.

STORMS WILL BEGIN TO DEVELOP OVER THE HIGHER TERRAIN IN THE SOUTH
AND EAST TODAY AND WILL PUSH WEST AT 15 MPH. THE THUNDERSTORMS THAT
DEVELOP LATER THIS AFTERNOON ACROSS THE WESTERN HALF OF THE FORECAST
AREA WILL BE CAPABLE OF PRODUCING VERY HEAVY RAINFALL GIVEN THE VERY
MOIST LOW TO MID LEVELS. THEREFORE...THE POSSIBILITY FOR RECEIVING
PRECIPITATION IN EXCESS OF ONE INCH INCREASES TOWARDS THE WEST
TODAY.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

THE MOIST AND UNSTABLE AIRMASS IN PLACE ACROSS SOUTHEAST ARIZONA
WILL BECOME MORE MOIST BEGINNING SUNDAY AND PERSISTING INTO WEDNESDAY
AS MOISTURE FROM THE REMNANTS OF TROPICAL STORM IGNACIO WILL MOVE
NORTH OVER THE DESERT SOUTHWEST. THIS WILL INCREASE THE POTENTIAL
FOR VERY HEAVY PRECIPITATION THE FIRST HALF OF THE WORK WEEK.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.