Alert archive / Arizona / Severe Thunderstorm Warnings in 1999

Severe Thunderstorm Warning 90, NWS Tucson, AZ

August 31, 1999Pima County, Arizona

NWS Tucson, AZ issued this severe thunderstorm warning at Aug 31, 1999, 6:30 PM MST for Pima County, Arizona. It was in force for 50 min. 2 reports came from inside the area while it was in force.

The area

The counties it named, with what was reported inside it.

The facts

Issued: Aug 31, 1999, 6:30 PM MST (01:30 UTC)
Expired: Aug 31, 1999, 7:20 PM MST
In force: 50 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 01:33 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.

What was reported inside it

Time	Report	Where	Remark
Aug 31, 6:40 PM MST	Hail 1	Tucson, AZ
Aug 31, 7:05 PM MST	Thunderstorm Wind 55	Tucson, AZ

NCEI Storm Data entries that began inside the alert's area while it was in force. Before 2003 the local storm report archive is thin, so this is the record of what happened rather than what was phoned in.

The nearest sounding before it

Tuscon, AZ (KTUS), launched 00:00Z, 1.5 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: 436 J/kg
Mixed-layer CIN: -84 J/kg
Mixed-layer LCL: 1956 m above ground
0-6 km bulk shear: 6 kt
0-1 km storm-relative helicity: -51 m²/s²
0-3 km storm-relative helicity: -15 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

The text of this product is not in the archive. The NWS text archive before 2002 is incomplete.

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 Aug 31, 3:57 PM MST, 2 hours 33 minutes earlier.

Area forecast discussion, Aug 31, 3:57 PM MST, 2 hours 33 minutes before

SOUTHEAST ARIZONA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
240 PM MST TUE AUG 31 1999

SYNOPSIS...A COUPLE OF UPPER LEVEL WEATHER DISTURBANCES WILL COMBINE
WITH THE DEEP MONSOONAL MOISTURE FOR SCATTERED TO NUMEROUS SHOWERS
AND THUNDERSTORMS TONIGHT. A PACIFIC STORM SYSTEM WILL DROP INTO
CENTRAL CALIFORNIA ON WEDNESDAY AND MOVE INTO THE GREAT BASIN ON
FRIDAY. THIS WILL BEGIN A GRADUAL DRYING TREND THROUGH THE END OF
THE WEEK THAT WILL CONTINUE INTO THE UPCOMING LABOR DAY HOLIDAY.
THUNDERSTORM ACTIVITY WILL BE SCATTERED ON WEDNESDAY DECREASING TO
ISOLATED BY FRIDAY AND GENERALLY BE OVER THE EASTERN MOUNTAINS.

DISCUSSION...HAS BEEN AN ACTIVE AFTERNOON SO FAR ACROSS SOUTHERN
ARIZONA WITH DEEP MONSOONAL MOISTURE (PW VALUES 1.5 TO 2 INCHES) IN
PLACE OVER MUCH THE AREA THIS MORNING. 12Z TUCSON SOUNDING WAS VERY
MOIST AND UNSTABLE WITH PW VALUE JUST OVER 1.5 INCHES...MEAN LAYER
CAPE AROUND 1250 J/KG AND LIFTED INDEX OF -6. LATEST GOES-10 DERIVED
PRODUCTS SHOW THE ABOVE VALUES STILL EXIST FROM TUCSON WEST. 12Z 300
MB PLOT SHOW WEAK DISTURBANCE OVER SW ARIZONA WHICH IS MOVING ACROSS
SOUTHERN ARIZONA TONIGHT. THIS FEATURE LIKELY KICKING OFF BIG STORM
IN PHOENIX AREA THIS AFTERNOON. WATER VAPOR STILL SHOWING AN UPPER
DISTURBANCE AROUND 100 MILES SOUTHEAST NOGALES MOVING SLOWLY NE.
WILL KEEP HIGH SCATTERED TO LIKELY POPS FROM TUCSON EAST WITH ONLY
ISOLATED OUT WEST SINCE THEY HAVE BEEN SLOW TO START AND MAY BE
UNDER SOME NVA WITH PASSAGE OF AFOREMENTIONED DISTURBANCE.

NEXT COUPLE OF DAYS NOT CUT AND DRY AS UPPER LEVEL TROUGH IN THE
PACIFIC NW DIGS INTO CENTRAL CALIFORNIA AND PUTTING MOST OF ARIZONA
UNDER SOUTHWEST FLOW ALOFT. PW VALUES SLOWLY DECREASING FROM WEST TO
EAST AND SHOULD LIMIT ACTIVITY TO THE SCATTERED RANGE ON THURSDAY AND
ISOLATED ON FRIDAY. WILL HAVE TO WATCH IMPULSES FROM THE SOUTH THAT
MAY ADD FUEL TO THE FIRE ON WEDNESDAY. EXTENDED HAS ABOVE MENTIONED
TROUGH MOVING THROUGH THE GREAT BASIN ON FRIDAY AND PUSHING THE DEEPEST
MOISTURE SOUTH AND LIMITING ACTIVITY TO THE EASTERN MOUNTAINS. THIS IS
THE FIRST NAIL IN THE MONSOON COFFIN. GLUECK

.TWC...NONE.

In the hours before

Special weather statement, Aug 31, 12:45 PM MST, 5 hours 45 minutes before

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Special weather statement, Aug 31, 12:45 PM MST, 5 hours 45 minutes before

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
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The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 31, 5:33 PM MST	Severe Thunderstorm Warning	TWC	Pinal	47 min
Aug 31, 7:13 PM MST	Severe Thunderstorm Warning	TWC	Pima	47 min
Aug 31, 7:28 PM MST	Flash Flood Warning	TWC	Pima	92 min

Nearby

Severe Thunderstorm Warnings in Arizona, 1999 Every severe thunderstorm warning in 1999

Sources

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