Alert archive / Arizona / Flash Flood Warnings in 1999

Flash Flood Warning 41, NWS Tucson, AZ

August 31, 1999Pima County, Arizona

NWS Tucson, AZ issued this flash flood warning at Aug 31, 1999, 7:28 PM MST for Pima County, Arizona. It was in force for 92 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: Aug 31, 1999, 7:28 PM MST (02:28 UTC)
Expired: Aug 31, 1999, 9:00 PM MST
In force: 92 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 02:27 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 00:00Z, 2.5 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

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

000 
TTAA00 KTUS 010227
FFWTUS
AZC019-010400-

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE TUCSON AZ
728 PM MST TUE AUG 31 1999

THE NATIONAL WEATHER SERVICE IN TUCSON HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  EASTERN PIMA COUNTY IN SOUTHERN ARIZONA
  INCLUDING THE GREATER TUCSON AREA

* UNTIL 900 PM MST

* AT 725 PM MST... RADAR RAINFALL ESTIMATES AND RAIN GAGES INDICATED
  A SEVERE THUNDERSTORM WITH EXTREMELY HEAVY RAIN OVER SOUTHERN
  AND EASTERN TUCSON... MOVING NORTHWEST AT ABOUT 10 MPH.

WIDESPREAD RAINFALL AMOUNTS IN EXCESS OF 1 INCH WITH AREAS OVER 2
INCHES WILL CAUSE FLASH FLOODING...ESPECIALLY IN THE VICINITY OF
WASHES.

MEYER

What forecasters said that day

The local office's own words before this flash flood 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 flash flood warning went out at Aug 31, 3:57 PM MST, 3 hours 31 minutes earlier.

Area forecast discussion, Aug 31, 3:57 PM MST, 3 hours 31 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.

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, 6:30 PM MST	Severe Thunderstorm Warning	TWC	Pima	50 min
Aug 31, 7:13 PM MST	Severe Thunderstorm Warning	TWC	Pima	47 min

Nearby

Flash Flood Warnings in Arizona, 1999 Every flash flood 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.