Severe Thunderstorm Warning 25, NWS Flagstaff, AZ

NORTHERN ARIZONA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
245 PM MST WED JUL 30 2003

.SYNOPSIS...THE ATMOSPHERE WILL REMAIN MOIST AND UNSTABLE INTO THE
EARLY PART OF NEXT WEEK. LOOK FOR DAILY SHOWER AND THUNDERSTORM
ACTIVITY TO CONTINUE...AND FOR TEMPERATURES TO REMAIN NEAR NORMAL
VALUES.

.DISCUSSION...CONVECTIVE ACTIVITY QUITE VIGOROUS TODAY ALONG THE RIM
AND IN THE EAST-CENTRAL ZONES WHERE SOLAR HEATING WAS NOT HAMPERED
BY EARLY MORNING CLOUDS. EXPECTING THIS ACTIVITY TO CONTINUE INTO
THE EVENING WITH A SLOW DECREASE OVERNIGHT AS AIRMASS REMAINS VERY
UNSTABLE AND NEARLY MOIST ADIABATIC. FLOW BEGINS TO SHIFT TO THE
SOUTHEAST OVERNIGHT AND INTO THURSDAY AND FRIDAY. THIS WILL FOCUS
THE CONVECTION ON THE RIM AND AREAS NORTH AND NORTHWEST INSTEAD OF
AREAS WEST OF THE RIM. THIS WILL ALSO ALLOW SOME OF THE VERY DEEP
MOISTURE OVER SOUTHERN ARIZONA TO ADVECT EVEN FARTHER NORTHWARD INTO
THE WEEKEND. GFS SUGGESTING A DRYING TREND BY DAYS 6 OR 7 AS SOUTH
FLOW TURNS TO SOUTHWEST FLOW. WE ARE NOT BUYING THIS TREND YET AS
OTHER MODELS NOT ANYWHERE NEAR AS AGGRESSIVE. EVEN IF A TROUGH
DEVELOPS OVER THE WEST COAST...THIS TIME OF YEAR IT MAY LEAD TO A
SURGE OR MAKE THE ATMOSPHERE MORE BAROCLINIC. ALTHOUGH PW VALUES MAY
DECREASE...CONVECTION WOULD NOT. SO...WITH MODEL UNCERTAINTY AND
THE REASONS JUST STATED...WILL SHOW VERY LITTLE CHANGE IN THE OUT
PERIODS. PETERSON.

.FGZ...NONE.

.CODED TEMPERATURES/POPS FOR SELECTED CITIES IN NORTHERN ARIZONA

CITY             TEMPERATURES LO/HI           PROBABILITY OF PRECIP
                 TON THU   FRI     SAT        TON THU   FRI     SAT
FLAGSTAFF        057/078 055/080 056/080      040 050 040 050 040 040
WINSLOW          066/088 065/090 065/090      030 030 030 030 020 020
PRESCOTT         064/084 063/086 064/086      050 040 040 040 030 040
PAGE             075/095 074/096 075/096      020 020 020 030 020 020
WINDOW ROCK      062/083 059/085 059/085      030 030 030 030 020 030
CANYON DE CHELLY 072/089 069/091 069/091      030 030 030 030 030 030
COTTONWOOD       072/095 071/097 072/097      040 030 030 030 020 030
GRAND CANYON     056/080 054/082 055/082      040 050 040 050 040 040
GREER            053/074 051/076 052/076      050 050 040 050 040 040
HEBER            058/083 056/085 057/085      040 050 040 050 040 040
JACOB LAKE       057/076 055/078 056/078      040 040 040 050 040 040
NAVAJO N.M.      066/083 063/085 063/085      030 030 030 040 030 030
PAYSON           065/089 064/091 065/091      040 040 030 040 030 030
SEDONA           070/093 069/095 070/095      040 030 030 030 020 030
SELIGMAN         057/087 056/089 057/089      050 040 040 040 030 030
SHOW LOW         065/084 063/086 064/086      050 050 040 050 040 040
ST. JOHNS        061/082 060/084 060/084      040 040 040 040 040 040
WUPATKI N.M.     069/090 068/092 068/092      030 030 030 030 020 020

AZZ004>018-037>040-310200-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
935 AM MST WED JUL 30 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR APACHE...COCONINO...NORTHERN
GILA...NAVAJO...AND YAVAPAI COUNTIES IN NORTHERN ARIZONA.

.DAY ONE...TODAY

A MOISTURE RICH AIRMASS REMAINS OVER THE STATE TODAY. SCATTERED
SHOWERS AND THUNDERSTORMS ARE ALREADY IN PROGRESS ACROSS NORTHERN
SECTIONS OF THE STATE...WITH MORE DEVELOPMENT EXPECTED OVER SOUTHERN
AND CENTRAL SECTIONS LATER THIS MORNING.

STRONG THUNDERSTORMS ARE EXPECTED BY EARLY AFTERNOON MAINLY ALONG
THE WESTERN EDGE OF THE MOGOLLON RIM AND POINTS WEST IN NORTHERN
GILA AND YAVAPAI COUNTIES. STORMS WILL BE MOVING TO THE WEST AT
AROUND 20 MPH TODAY...SO HEAVY RAINFALL WILL BE LIMITED UNLESS
MULTIPLE STORMS FORM OVER THE SAME LOCATION.

MOSTLY SMALL HAIL CAN BE EXPECTED WITH THE STRONGER STORMS
TODAY...ISOLATED STORMS MAY PRODUCE SEVERE HAIL.

DUE TO THE FREQUENCY OF RAIN EVENTS ALONG AND WEST OF THE RIM...THE
POTENTIAL FOR URBAN AND SMALL STREAM FLOODING REMAINS MODERATE TODAY.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

LITTLE CHANGE IS SEEN IN THE MOIST AND UNSTABLE ATMOSPHERE OVER THE
REGION THROUGH THE PERIOD. THUNDERSTORMS ARE EXPECTED TO DEVELOP
EACH DAY...ALTHOUGH WINDS BY THURSDAY AND FRIDAY WILL BE OUT OF THE
SOUTHEAST...INSTEAD OF THE EAST.

THIS DIRECTION WILL FAVOR MORE OF THE RIM COUNTRY NORTH TO THE GRAND
CANYON...WITH LESS ACTIVITY IN YAVAPAI COUNTY. THE THREAT FOR HEAVY
RAINFALL AMOUNTS AND THE POTENTIAL FOR SMALL STREAM FLOODING STILL
REMAINS.

.SPOTTER INFORMATION STATEMENT...

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

DEFINITION OF HAZARDOUS WEATHER...A WEATHER EVENT POSING A THREAT
TO LIFE AND PROPERTY.