Severe Thunderstorm Warning 64, NWS Tucson, AZ

SOUTHEAST ARIZONA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
230 PM MST THU AUG 7 2003

.SYNOPSIS...AN INCREASE IN LOW LEVEL MOISTURE MAINLY ACROSS CENTRAL
AND WESTERN SECTIONS WILL PROVIDE AN INCREASED CHANCE OF SHOWERS AND
THUNDERSTORMS THIS AFTERNOON INTO TONIGHT. HIGH PRESSURE CENTERED
OVER NORTHERN NEW MEXICO WILL MAINTAIN A MORE FAVORABLE POSITION FOR
THUNDERSTORM DEVELOPMENT INTO THE WEEKEND. A TROUGH OF LOW PRESSURE
OVER THE PACIFIC NORTHWEST WILL BRING DRIER AIR TO SOUTHEAST ARIZONA
EARLY NEXT WEEK.

.DISCUSSION...SOUTHEAST ARIZONA BEGINNING TO SEE THUNDERSTORMS
DEVELOP ACROSS THE EASTERN MOUNTAINS THIS AFTERNOON. AMAZING HOW
CONDITIONS CAN CHANGE IN JUST 24 HOURS DURING THE MONSOON SEASON. IT
DOES NOT TAKE MUCH...IT CAN BE FAIRLY DRY IN THE LOW LEVELS ONE DAY
AND THEN THE NEXT MORNING AN MCS IN NORTHERN SONORA CAN BE STRONG
ENOUGH TO PUSH A SURGE OF MOISTURE BACK INTO THE DESERTS FROM TUCSON
WEST. IN FACT...SFC DEW POINTS HAVE JUMPED INTO THE LOWER TO MID 60S
IN THE SANTA CRUZ COUNTY AND THE WESTERN DESERTS OF CENTRAL AND
WESTERN PIMA COUNTY.

THE CURRENT WATER VAPOR IMAGERY INDICATED A DIFFLUENT AREA IN THE
MID TO UPPER LEVELS WHICH THE MODELS DID NOT INITIALIZE VERY WELL.
IN ADDITION...THE DRIER AIR LOCATED IN SRN NM AND FAR WRN TX WILL
PUSH WEST TODAY ALONG THE SRN PERIPHERY OF THE HIGH AND INTO SE AZ
BY 00Z THIS AFTERNOON. BOTH OF THESE FEATURES WILL AID CONVECTIVE
DEVELOPMENT. THE SHEAR PROFILE IS PROGGED TO INCREASE LATER THIS
AFTERNOON AND EVENING. THIS NEEDS TO HAPPEN FOR ANY OF THESE STORMS
TO PUSH OFF OF THE MOUNTAINS AND GET BETTER ORGANIZED. WILL HAVE TO
WAIT AND SEE. OTHERWISE...WILL ONLY SEE PULSE TYPE CELLS OVER HIGHER
TERRAIN. THINKING IS THAT THE FLOW WILL PICK UP. THEREFORE...LOOK
FOR STORMS TO DEVELOP ACROSS THE ERN MOUNTAINS THIS AFTERNOON AND
PUSH WEST TO NORTHWEST ACROSS THE REST OF THE CWA INTO THE EVENING
HOURS.

WILL SEE SCATTERED AFTERNOON AND EVENING THUNDERSTORM COVERAGE FRI
AND INTO THE WEEKEND AS THE UPPER HIGH MOVES TO A MORE FAVORABLE
POSITION...RESULTING IN A MORE ACTIVE SOUTHEASTERLY FLOW PATTERN.
OTHERWISE...THE MEDIUM RANGE MODELS CONTINUE TO STRENGTHEN THE UPPER
LOW OVER THE PACIFIC NW. THIS SHUNTS THE MEAN RIDGE BACK INTO NE
SONORA/NW CHIHUAHUA AND TURNS OUR FLOW BACK TO THE SW. OUR DAY
EXTENDED ZONES CAPTURE THE NEAR SHUTDOWN VERY WELL.

.TWC...NONE.

AZZ019-029>035-081400-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TUCSON AZ
1130 AM MST THU AUG 7 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST ARIZONA

.DAY ONE...TODAY

SYNOPSIS...AN INCREASE IN LOW LEVEL MOISTURE MAINLY ACROSS CENTRAL
AND WESTERN SECTIONS WILL PROVIDE AN INCREASED CHANCE OF SHOWERS AND
THUNDERSTORMS THIS AFTERNOON INTO TONIGHT. HIGH PRESSURE CENTERED
OVER NORTHERN NEW MEXICO WILL MAINTAIN A MORE FAVORABLE POSITION FOR
THUNDERSTORM DEVELOPMENT INTO THE WEEKEND. A TROUGH OF LOW PRESSURE
OVER THE PACIFIC NORTHWEST WILL BRING DRIER AIR TO SOUTHEAST ARIZONA
EARLY NEXT WEEK.

DISCUSSION...AN INCREASE IN LOW LEVEL MOISTURE OCCURRED FROM TUS
VICINITY WWD LAST NIGHT IN RESPONSE TO AN MCS ACROSS NRN SONORA.
DEWPOINTS AT 1800Z WERE IN THE UPPER 50S-MID 60S F FROM TUS TO
NOGALES AND WWD TO SE CA. MEANWHILE A DRIER LOW-LEVEL ENVIRONMENT
EXISTED ACROSS SW NM AND EXTREME SE AZ. DEWPOINTS ACROSS SW NM AT
1800Z WERE IN THE 40S F WHILE IN THE MID 50S F AT DOUGLAS. THE KYUX
WSR-88D VAD WIND PROFILE DEPICTED A 4-5 KFT SURGE WED NIGHT WITH THE
LOW LEVEL FLOW HAVING WEAKENED CONSIDERABLY BY LATE MORNING. KEMX
WSR-88D DETECTED NO PRECIPITATION ECHOES AS OF 1800Z.

WATER VAPOR SATELLITE IMAGERY DEPICTED THE ELY WAVE THAT ASSISTED
WITH THE MCS DEVELOPMENT WAS MOVING WWD ACROSS THE CENTRAL GULF OF
CA AT LATE MORNING. AN AREA OF DIFLUENT FLOW ALOFT IN COMBINATION
WITH SOMEWHAT DRIER AIR FROM SW NM ENCROACHING UPON ERN LOCALES MAY
AID CONVECTIVE DEVELOPMENT THIS AFTERNOON. THE SHEAR PROFILE SHOULD
INCREASE DURING THE AFTERNOON AS THE UPPER HIGH SHIFTS EWD AND MID-
LEVEL FLOW INCREASES. THE MAIN THREAT OF SEVERE WEATHER ACROSS ERN
SECTIONS THIS AFTERNOON AND EVENING WILL BE DUE TO STRONG WIND. THE
BEST CHANCE OF SEVERE WEATHER EVENTS OCCURRING THOUGH WILL BE FROM
TUS VICINITY WWD WHERE DEEPER MOISTURE RESIDES. THE MAIN THREAT FOR
HEAVY RAINFALL WILL ALSO EXIST FROM TUS VICINITY WWD ALTHOUGH THIS
AFTERNOON AND EVENING CAN BE CHARATERIZED AS AN AVERAGE MONSOON DAY.
THUS PRECIPITATION AMOUNTS GREATER THAN ONE INCH WILL BE NEAR
CLIMATOLOGICAL NORMALS FROM TUS VICINITY WWD. ANY THUNDERSTORMS THAT
DO DEVELOP SHOULD MOVE TOWARD THE WEST AROUND 10 MPH.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

SEASONAL SCATTERED THUNDERSTORM ACTIVITY WILL CONTINUE THROUGH THE
WEEKEND. THIS WILL RETURN THE AREA INTO THE NORMAL THREAT OF HEAVY
RAIN AND STRONG WINDS. A DRIER REGIME IS EXPECTED TUE-WED AS A LOW
PRESSURE TROUGH ENCROACHES UPON THE PACIFIC NORTHWEST.

.SPOTTER INFORMATION STATEMENT...

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