Damaging Wind in Arizona, July 18, 2001

SOUTHEAST ARIZONA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
205 PM MST WED JUL 18 2001

SYNOPSIS...DEEP MOISTURE AND LIGHT WINDS ALOFT WILL BRING SCATTERED
THUNDERSTORMS THIS EVENING WITH LOCALLY HEAVY RAIN. HIGH PRESSURE
ALOFT WILL GRADUALLY MOVE WESTWARD FROM THE SOUTHERN PLAINS TO NEW
MEXICO THROUGH EARLY NEXT WEEK. THUS EXPECT AN INCREASE IN
THUNDERSTORM ACTIVITY WEST OF TUCSON WITH LITTLE CHANGE IN THE EAST.

DISCUSSION...NOT MUCH CHANGE IN THOUGHT FOR THE FIRST 36 HOURS OF THE
FORECAST FROM THIS MORNING. LIGHT WINDS AT THE 700/850 MB LEVEL...AN
OVERLAP OF THE THETA E RIDGES AT THE SAME LEVELS...AND PW VALUES IN
THE 1.5 RANGE WILL LEAD TO THUNDERSTORMS MAINLY NEAR THE MOUNTAINS
THROUGH 4 PM. ALREADY SEEN LOCALLY HEAVY RAIN WITH EARLIER MOUNTAIN
STORMS. CELLS WHICH MAKE IT INTO THE VALLEYS THIS EVENING WILL ALSO
PRODUCE LOCALLY HEAVY RAIN. THE ONLY POSSIBLE SYNOPTIC SCALE TRIGGER
IS UPPER LEVEL SPEED DIVERGENCE...HOWEVER WE GET INTO THE FAVORABLE
JET QUADRANT ACCORDING TO THE 12Z ETA BETWEEN 5 PM AND 11 PM LOCAL
TIME. ALL THINGS CONSIDERED...THE AREAL COVERAGE WILL BE MORE
EXTENSIVE THAN THE DOWN DAY YESTERDAY.

WATER VAPOR IMAGERY DOES NOT SHOW A SIGNIFICANT EASTERLY WAVE ON THE
HORIZON FOR THE NEXT FEW DAYS. THE 500 MB HIGH CENTER RETROGRADES
FROM TEXAS TO NEAR THE FOUR CORNERS REGION BY EARLY NEXT WEEK AS THE
PERSISTENT WEST COAST UPPER TROUGH FINALLY FILLS. EXPECT THE
MONSOON MOISTURE BOUNDARY TO EXPAND INTO WESTERN ARIZONA DURING THE
EXTENDED FORECAST PERIOD.

OKULSKI

.TWC...NONE.

AZZ019-029>035-190700-

SOUTHEAST ARIZONA HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TUCSON AZ
1145 AM MST WED JUL 18 2001

.SYNOPSIS...DEEP MONSOONAL MOISTURE REMAINS OVER SOUTHEAST ARIZONA
WITH DRY AIR OVER THE WESTERN PORTION OF THE STATE. WINDS ALOFT ARE
LIGHT SO STORMS THAT FORM WILL PRODUCE LOCALLY HEAVY RAIN. UPPER
LEVEL CONDITIONS ARE NEUTRAL SO ORGANIZED COMPLEXES ARE NOT EXPECTED
AND THUNDERSTORMS WILL PROBABLY NOT SPREAD TOO FAR WEST.

.DISCUSSION...STORMS ALREADY FORMING THIS MORNING OVER
MOUNTAINS...BUT IT WILL PROBABLY BE MID AFTERNOON BEFORE VALLEYS ARE
READY FOR STORMS. UNLIKE YESTERDAY...TEMPS SHOULD SUPPORT VALLEY
STORMS. QUESTION IS HOW FAR WILL DRY AIR IN WESTERN DESERTS SHIFT
EASTWARD...AND THINK THAT WILL BE LIMITING FACTOR INTO HOW FAR WEST
THE STORMS MOVE. THIS SEEMS LIKE A DAY WHERE TUCSON VALLEY WOULD BE
FAVORABLE FOR HAVING STORMS MOVE INTO THE VALLEY...SINCE WINDS ALOFT
ARE OUT OF THE SOUTHWEST AND ANVILS WILL STAY AWAY FROM THE VALLEYS
AND NOT AFFECT SOLAR HEATING. WITH TEMPS ALREADY NEAR 90 AT 11 AM WE
SHOULD BE ABLE TO REACH CONVECTIVE TEMPERATURE. WEST AND UPSLOPE
WINDS THIS AFTERNOON SHOULD HOLD STORMS BACK AWAY FROM THE METRO
AREA FOR A WHILE BUT WOULD EXPECT THEM TO WORK WEST AND NORTHWEST
INTO HIGHER ENERGY.

ALSO SLIGHTLY COLDER ALOFT TODAY...BUT CANT FIND ANY SIGNIFICANT
FEATURES ALOFT THAT WOULD HELP ORGANIZE CONVECTION. STILL HAVE TO
RESPECT THE 14C 850 MB DEW POINT...SO WILL KEEP FLASH FLOOD...SEVERE
THREAT HIGHER AND ESPECIALLY AROUND TUCSON AREA WHERE LOCAL
CONVERGENCE WILL ASSIST STORM DEVELOPMENT.

STORM MOTION WILL BE NORTH AT 5 TO 10 MPH...BUILDING WESTWARD DURING
THE AFTERNOON.

HOLBROOK