Severe Thunderstorm Warning 70, NWS Tucson, AZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
910 AM MST TUE OCT 26 2004

SOUTHEAST ARIZONA FORECAST DISCUSSION

.SYNOPSIS...A STRONG LOW PRESSURE SYSTEM NEAR THE CALIFORNIA COAST
WILL APPROACH ARIZONA BY THURSDAY. ISOLATED SHOWERS WILL OCCUR TODAY
AND WEDNESDAY AHEAD OF THIS SYSTEM...AND ESPECIALLY FOR AREAS NORTH
AND EAST OF TUCSON. RAIN CHANCES WILL INCREASE PARTICULARLY ON
THURSDAY AS THE LOW PRESSURE SYSTEM MOVES ACROSS THE GREAT BASIN
REGION.

&&

.DISCUSSION...IR SATELLITE IMAGERY INDICATED GENERALLY BROKEN
MID/HIGH LEVEL CLOUDS ACROSS MUCH OF SE AZ AT THIS TIME. THE
EXCEPTION WAS FAR WRN PIMA COUNTY WHERE MAINLY CLEAR SKIES
PREVAILED. DEWPOINTS WERE GENERALLY IN THE 50S F WHICH WERE NEARLY
2-6 DEGS F HIGHER VERSUS 24 HOURS AGO. 26/12Z KTUS SOUNDING
REFLECTED A SOMEWHAT MOIST ENVIRONMENT AS WELL WITH PRECIP WATER
VALUE NEAR 0.65 INCH. HOWEVER SOME DRYING WAS EVIDENT VERSUS 24
HOURS AGO PARTICULARY IN THE MID/UPPER LEVELS. PROFILE INDICATED A
SOMEWHAT UNSTABLE ENVIRONMENT WITH LIFTED INDEX VALUE OF MINUS 2 AND
UNMODIFIED SURFACE-BASED CAPE OF 594 J/KG. ANALYSES OF 26/12Z UPPER
AIR PLOTS INDICATED LOW PRESSURE CENTERED JUST OFF THE OREGON COAST
NEAR 45N/126W WITH N-S RIDGE AXIS OVER THE ERN CONUS...GENERALLY
FROM THE GREAT LAKES TO THE GULF OF MEX. SWLY FLOW PREVAILED OVER
SRN AZ.

INHERITED FORECAST OF ISOLATED SHOWERS ACROSS ALL BUT FAR WRN PIMA
COUNTY/TOHONO OODHAM NATION APPEARS REASONABLE GIVEN THE ABOVE
DIAGNOSTICS. WILL NEED TO MONITOR FOR POSSIBILITY OF AN ISOLATED
THUNDERSTORM AS WELL GIVEN THE AFOREMENTIONED STABILITY INDICES.
26/12Z ETA AND QUICK GLANCE AT GFS INDICATE THAT THE IMPACT ON SE AZ
WEATHER FROM THE W COAST SYSTEM MAY BE DELAYED ABOUT 6 HOURS OR SO.
IN OTHER WORDS THE BEST CHANCE OF MEASURABLE PRECIP NOW APPEARS TO
BE LATE THUR/THUR NIGHT/FRI PERIOD. WILL COORD WITH WFO/S PSR/FGZ
BEFORE MAKING ANY ADJUSTMENTS TO INHERITED FORECASTS HOWEVER. WILL
ELABORATE FURTHER IN AFTERNOON DISCUSSION. NO CHANGES TO INHERITED
FORECASTS AT THIS TIME.

&&

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

&&

BF

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TUCSON AZ
700 AM MST TUE OCT 26 2004

AZZ019-029>035-271400-
NORTHERN GREENLEE COUNTY-SOUTHEAST PINAL COUNTY-
UPPER GILA RIVER VALLEY-WESTERN PIMA COUNTY-
TOHONO OODHAM NATION-TUCSON METRO/MARANA/GREEN VALLEY-
SANTA CRUZ COUNTY-COCHISE COUNTY-
700 AM MST TUE OCT 26 2004

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST ARIZONA

.DAY ONE...TODAY

MOISTURE BEING PULLED IN FROM THE SOUTH TODAY WILL BRING ISOLATED
SHOWERS OR THUNDERSTORMS TO AREAS MAINLY EAST OF TUCSON.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

THE MOISTURE ACROSS SOUTHEAST ARIZONA AND NORTHERN MEXICO WILL
SPREAD NORTH AND WEST THROUGH THE MIDDLE OF THE WEEK WHICH WILL
INTERACT WITH A STRONG PACIFIC STORM SYSTEM MOVING INTO ARIZONA FROM
THE PACIFIC NORTHWEST ON THURSDAY.

THIS SYSTEM WILL BE PRECEDED BY STRONG...GUSTY SOUTH TO SOUTHWEST
WINDS OF 15 TO 25 MPH WITH GUSTS TO 35 MPH ON WEDNESDAY AND
THURSDAY. MUCH COOLER TEMPERATURES AND THE BEST CHANCE OF WIDESPREAD
VALLEY RAIN AND HIGH ELEVATION SNOW SHOWERS WILL MOVE INTO THE AREA
ON THURSDAY. DAYTIME HIGH TEMPERATURES ON THURSDAY ARE EXPECTED TO
RANGE FROM 8 TO 12 DEGREES BELOW SEASONAL NORMALS. RAINFALL AMOUNTS
IN THE DESERTS AND VALLEYS WILL GENERALLY RANGE FROM A QUARTER TO A
THIRD OF AN INCH WITH ISOLATED AMOUNTS OF AROUND A HALF INCH
POSSIBLE. THE HIGHEST PEAKS IN THE WHITE MOUNTAINS WILL SEE TOTAL
SNOW ACCUMULATIONS OF AROUND 3 TO 4 INCHES. SHOWERS WILL DECREASE
FROM WEST TO EAST THURSDAY NIGHT AND FRIDAY WITH DRY CONDITIONS
EXPECTED TO RETURN TO THE AREA ON THE WEEKEND.

.SPOTTER INFORMATION STATEMENT...

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