Severe Thunderstorm Warning 22, NWS Tucson, AZ

SOUTHEAST ARIZONA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
930 AM MST SAT JUL 18 1998

SYNOPSIS...HIGH PRESSURE ALOFT OVER SOUTHERN UTAH WILL ALLOW MORE
MOISTURE TO SURGE INTO SOUTHEAST ARIZONA THIS WEEKEND. THUNDERSTORM
ACTIVITY WILL CONTINUE WITH AN INCREASING THREAT OF HEAVY RAIN.

DISCUSSION...RESIDUAL DEBRIS CLOUDS ACROSS SOUTHEAST ARIZONA WILL
DIMINISH QUICKLY THIS MORNING. HIGH PRESSURE ALOFT OVER SOUTHWEST
UTAH STILL REMAINS IN A FAVORABLE POSITION TO ALLOW STORMS TO
DEVELOP OVER THE MOUNTAINS AND MOVE INTO THE LOWER VALLEYS DURING
THE AFTERNOON HOURS.

A FEW THINGS HAVE CHANGED SINCE FRIDAY IN THE ATMOSPHERE...MOST OF
WHICH WERE POINTED OUT BY THE MID SHIFT FORECASTER IN THE PREVIOUS
DISCUSSION AND ARE EVIDENT ON THE 5 AM TUCSON SOUNDING. THE STRONG
MID LEVEL NORTHEAST STEERING WINDS HAVE DIMINISHED. THIS MEANS WE
WILL SEE SLOWER MOVING STORMS.

ANOTHER CONSIDERATION IS A POSSIBLE SURGE OF GULF MOISTURE INTO
SOUTHERN ARIZONA LATER TODAY AS A RESULT OF WIDSPREAD THUNDERSTORM
ACTIVITY IN SOUTHWEST MEXICO YESTERDAY. WILL HAVE TO WAIT AND SEE.
EVEN WITHOUT A RAPID INFLUX OF MOISTURE...SLOWER MOVING STORMS WITH
THE GRADUAL SEEP OF MOISTURE THAT HAS ALREADY OCCURED SHOULD LEAD TO
A GREATER THREAT OF HEAVY RAIN.

THE LAST FEATURE OF INTEREST IS AN INVERTED TROUGH MOVING WESTWARD
ACROSS NEW MEXICO. THIS TROUGH WILL ENTER EASTERN ARIZONA TONIGHT
AND MAY KEEP CONVECTION GOING INTO THE LATE NIGHT TIME DPERIOD.
CURRENT FORECASTS LOOK GOOD. NO UPDATES. TUS 453. OKULSKI

.TWC...NONE.

AZZ019-029>035-190700-
SPECIAL WEATHER STATEMENT...SOUTHEAST ARIZONA CONVECTIVE OUTLOOK
NATIONAL WEATHER SERVICE TUCSON AZ
1245 PM MST SAT JUL 18 1998...THIS PRODUCT IS NOT UPDATED

                        *CONDITIONAL*    *CONDITIONAL*
                AREAL    PROBABILITY   RAIN GREATER THAN   STORM
              COVERAGE    OF SEVERE     1.00       2.00    MOTION

COCHISE          50          30          45         10      W 12
GRAHAM           50          30          45         10      W 12
GREENLEE         50          20          40          5      W 12
TUCSON/ERN PIMA  45          30          40         10      W 12
TOHONO O'ODHAM   45          30          45         10     SW 12
WESTERN PIMA     30          20          25          0     SW 12
SOUTHEAST PINAL  45          30          40         10      W 12
SANTA CRUZ       50          30          40         10      W 12

SYNOPSIS...MOIST AND UNSTABLE. STORMS WILL FORM OVER HIGHER
TERRAIN AND MOVE DOWN INTO VALLEY LOCATIONS. DYNAMICS FROM UPPER
LEVEL DISTURBANCES WILL ENHANCE THUNDERSTORMS THIS AFTERNOON THROUGH
TONIGHT WITH A SLIGHT CHANCE OF SEVERE THUNDERSTORMS ALONG WITH
RAINFALL AMOUNTS AT 1 INCH NOT UNCOMMON. STORMS MAY BE SUSTAINED
INTO THE EARLY MORNING HOURS.

*****************************************************************
KEY...
AREAL COVERAGE - PERCENT OF COUNTY OR AREA THAT WILL EXPERIENCE
                  THUNDERSTORMS
PROB OF SEVERE - THE PROBABILITY THAT ANY ONE OF THE STORMS WILL
                  REACH SEVERE LEVELS (DAMAGING WIND AND/OR
                  LARGE HAIL)
RAIN GRTR THAN - THE PROBABILITY THAT ANY ONE OF THE STORMS WILL
                  PRODUCE RAIN EXCEEDING 1 INCH OR 2 INCHES IN
                  ANY LOCATION
STORM MOTION   - GENERAL DIRECTION TO WHICH THE STORMS WILL
                  LIKELY MOVE AND SPEED IN MPH

NOTE...
VALID TIME IS FROM 12:45 PM TO 12 MIDNIGHT OF THE DAY OF ISSUANCE.
THIS PRODUCT IS NOT TO BE USED IN PLACE OF SEVERE THUNDERSTORM OR
FLASH FLOOD WARNINGS OR WATCHES. THIS PRODUCT IS ONLY USED FOR
OUTLOOK PURPOSES. CORRESPONDING GRAPHICS MAY BE FOUND ON THE NWS
TUCSON INTERNET PAGE AT
HTTP://NIMBO.WRH.NOAA.GOV/TUCSON/SWO/SWO.SHTML
j
END/RJO

AZZ019-029>035-190700-
SPECIAL WEATHER STATEMENT...SOUTHEAST ARIZONA CONVECTIVE OUTLOOK
NATIONAL WEATHER SERVICE TUCSON AZ
1245 PM MST SAT JUL 18 1998...THIS PRODUCT IS NOT UPDATED

                        *CONDITIONAL*    *CONDITIONAL*
                AREAL    PROBABILITY   RAIN GREATER THAN   STORM
              COVERAGE    OF SEVERE     1.00       2.00    MOTION

COCHISE          50          30          45         10      W 12
GRAHAM           50          30          45         10      W 12
GREENLEE         50          20          40          5      W 12
TUCSON/ERN PIMA  45          30          40         10      W 12
TOHONO O'ODHAM   45          30          45         10     SW 12
WESTERN PIMA     30          20          25          0     SW 12
SOUTHEAST PINAL  45          30          40         10      W 12
SANTA CRUZ       50          30          40         10      W 12

SYNOPSIS...MOIST AND UNSTABLE. STORMS WILL FORM OVER HIGHER
TERRAIN AND MOVE DOWN INTO VALLEY LOCATIONS. DYNAMICS FROM UPPER
LEVEL DISTURBANCES WILL ENHANCE THUNDERSTORMS THIS AFTERNOON THROUGH
TONIGHT WITH A SLIGHT CHANCE OF SEVERE THUNDERSTORMS ALONG WITH
RAINFALL AMOUNTS AT 1 INCH NOT UNCOMMON. STORMS MAY BE SUSTAINED
INTO THE EARLY MORNING HOURS.

*****************************************************************
KEY...
AREAL COVERAGE - PERCENT OF COUNTY OR AREA THAT WILL EXPERIENCE
                  THUNDERSTORMS
PROB OF SEVERE - THE PROBABILITY THAT ANY ONE OF THE STORMS WILL
                  REACH SEVERE LEVELS (DAMAGING WIND AND/OR
                  LARGE HAIL)
RAIN GRTR THAN - THE PROBABILITY THAT ANY ONE OF THE STORMS WILL
                  PRODUCE RAIN EXCEEDING 1 INCH OR 2 INCHES IN
                  ANY LOCATION
STORM MOTION   - GENERAL DIRECTION TO WHICH THE STORMS WILL
                  LIKELY MOVE AND SPEED IN MPH

NOTE...
VALID TIME IS FROM 12:45 PM TO 12 MIDNIGHT OF THE DAY OF ISSUANCE.
THIS PRODUCT IS NOT TO BE USED IN PLACE OF SEVERE THUNDERSTORM OR
FLASH FLOOD WARNINGS OR WATCHES. THIS PRODUCT IS ONLY USED FOR
OUTLOOK PURPOSES. CORRESPONDING GRAPHICS MAY BE FOUND ON THE NWS
TUCSON INTERNET PAGE AT
HTTP://NIMBO.WRH.NOAA.GOV/TUCSON/SWO/SWO.SHTML
j
END/RJO