Alert archive / Arizona / Severe Thunderstorm Warnings in 1998

Severe Thunderstorm Warning 25, NWS Tucson, AZ

July 18, 1998Pima County, Arizona

NWS Tucson, AZ issued this severe thunderstorm warning at Jul 18, 1998, 3:25 PM MST for Pima County, Arizona. It was in force for 45 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Jul 18, 1998, 3:25 PM MST (22:25 UTC)
Expired: Jul 18, 1998, 4:10 PM MST
In force: 45 min
Issued by: NWS Tucson, AZ
Area: Whole counties

County Pima County, AZ

The radar

The Tucson radar (KEMX), 112 km from the middle of the area, began a volume at 22:20 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Tuscon, AZ (KTUS), launched 12:00Z, 10.4 hours before the alert went out and 84 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 87 J/kg
Mixed-layer CIN: -338 J/kg
Mixed-layer LCL: 2567 m above ground
0-6 km bulk shear: 20 kt
0-1 km storm-relative helicity: 11 m²/s²
0-3 km storm-relative helicity: -2 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

131 
WUUS1 KTUS 182226 RRA
SVRTUS
AZC019-182310-

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE TUCSON AZ
325 PM MST SAT JUL 18 1998

THE NATIONAL WEATHER SERVICE IN TUCSON HAS EXTENDED A

* SEVERE THUNDERSTORM WARNING FOR...
  SOUTH CENTRAL PIMA COUNTY IN SOUTHERN ARIZONA

* UNTIL 410 PM MST

* AT 322 PM MST... DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM 15
  MILES SOUTH OF SELLS OR 7 MILES NORTHWEST OF SAN MIGUEL MOVING
  WEST SOUTHWEST AT 10 MPH.

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Tucson, AZ wrote its last area forecast discussion before this severe thunderstorm warning went out at Jul 18, 2:00 PM MST, 1 hour 25 minutes earlier.

Area forecast discussion, Jul 18, 2:00 PM MST, 1 hour 25 minutes before

SOUTHEAST ARIZONA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
200 PM MST SAT JUL 18 1998

SYNOPSIS...WEATHER DISTURBANCES IN AN EASTERLY FLOW ALOFT WILL
ENHANCE THUNDERSTORM ACTIVITY THROUGH TONIGHT. HIGH PRESSURE ALOFT
OVER FAR NORTHERN ARIZONA THROUGH ALLOW MONSOONAL MOISTURE TO
PERSIST THROUGH THE MIDDLE OF NEXT WEEK.

DISCUSSION...A WEAK EMBEDDED DISTURBANCE IN THE EASTERLY FLOW ALOFT
WAS TRIGGERING AFTERNOON THUNDERSTORMS FROM CENTRAL PIMA COUNTY TO
THE NEW MEXICO BORDER. STORMS WERE MOVING MUCH SLOWER THAN FRIDAY
AND IN A WESTERLY DIRECTION. THE SLOWER MOVEMENT WAS ALLOWING STORMS
TO PRODUCE HEAVIER RAIN AND SLIGHTLY WEAKER DOWNBURST WINDS.
DUE TO THE DYNAMICS WITH THE ABOVE MENTIONED DISTURBANCE...SOME
STORMS WILL BE BECOME SEVERE.

A STRONGER UPSTREAM EASTERLY WAVE CURRENTLY OVER NEW MEXICO WILL
MOVE INTO EASTERN ARIZONA TONIGHT AND KEEP CONVECTION GOING PAST
MIDNIGHT. SUNDAY MAY BE A "DOWN" DAY OR AT LEAST A SLOWR STARTER IF
THERE IS A LOT DEBRIS CLOUDS DUE TO TONIGHTS CONVECTION.

HIGH PRESSURE ALOFT REMAINS OVER FAR NORTHERN ARIZONA THROUGH MID
WEEK FOR MORE MONSOONAL CONVECTIVE ACTIVITY. TUS 4343. OKULSKI

.TWC...NONE.

In the hours before

Special weather statement, Jul 18, 12:45 PM MST, 2 hours 40 minutes before

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

Special weather statement, Jul 18, 12:45 PM MST, 2 hours 40 minutes before

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

The office that day

Everything else NWS Tucson, AZ issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 17, 5:41 PM MST	Severe Thunderstorm Warning	TWC	Pima	49 min
Jul 17, 6:25 PM MST	Severe Thunderstorm Warning	TWC	Pima	60 min
Jul 17, 7:25 PM MST	Severe Thunderstorm Warning	TWC	Pima	45 min
Jul 17, 7:33 PM MST	Severe Thunderstorm Warning	TWC	Greenlee	47 min
Jul 17, 8:09 PM MST	Severe Thunderstorm Warning	TWC	Pima	61 min
Jul 17, 8:17 PM MST	Severe Thunderstorm Warning	TWC	Graham	48 min
Jul 17, 11:14 PM MST	Severe Thunderstorm Warning	TWC	Pinal	46 min
Jul 18, 12:15 AM MST	Severe Thunderstorm Warning	TWC	Pima	90 min
Jul 18, 1:44 AM MST	Severe Thunderstorm Warning	TWC	Pima	46 min
Jul 18, 1:37 PM MST	Severe Thunderstorm Warning	TWC	Santa Cruz	48 min
Jul 18, 2:08 PM MST	Severe Thunderstorm Warning	TWC	Pima, Santa Cruz	62 min
Jul 18, 2:44 PM MST	Severe Thunderstorm Warning	TWC	Pima	46 min

Nearby

Severe Thunderstorm Warnings in Arizona, 1998 Every severe thunderstorm warning in 1998

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.