Alert archive / Arizona / Flash Flood Warnings in 1999

Flash Flood Warning 4, NWS Phoenix, AZ

July 18, 1999Gila County, Arizona

NWS Phoenix, AZ issued this flash flood warning at Jul 18, 1999, 4:16 PM MST for Gila County, Arizona. It was in force for 119 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, 1999, 4:16 PM MST (23:16 UTC)
Expired
Jul 18, 1999, 6:15 PM MST
In force
119 min
Issued by
NWS Phoenix, AZ
Area
Whole counties

County Gila County, AZ

The radar

The Flagstaff radar (KFSX), 93 km from the middle of the area, began a volume at 23:16 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

Phoenix, AZ (KPSR), launched 12:00Z, 11.3 hours before the alert went out and 115 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-pSkew-T log-p diagram, Phoenix, AZ at 12:00Z on 1999-07-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 286 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Phoenix, AZ at 12:00Z on 1999-07-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -8 square meters per square second.1939Sfc1 km3 km6 km9 kmRMLM
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
286 J/kg
Mixed-layer CIN
-128 J/kg
Mixed-layer LCL
1758 m above ground
0-6 km bulk shear
10 kt
0-1 km storm-relative helicity
-8 m²/s²
0-3 km storm-relative helicity
-24 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 KPHX 182316 RRA
FFWPHX
AZC007-190115-

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE PHOENIX AZ
416 PM MST SUN JUL 18 1999

THE NATIONAL WEATHER SERVICE IN PHOENIX HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  SOUTH CENTRAL AND EXTREME SOUTHERN GILA COUNTY IN CENTRAL ARIZONA

* UNTIL 615 PM MST

* AT 400 PM MST...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  THUNDERSTORM WITH VERY HEAVY RAIN ALONG STATE HIGHWAY 77 NEAR EL
  CAPITAN CANYON...MOVING NORTHWEST 5 TO 10 MPH.

* THE STORM WAS IN EXTREME SOUTHERN GILA COUNTY AND WAS PRODUCING
  RAINFALL AMOUNTS OF 2 INCHES PER HOUR AS ESTIMATED BY DOPPLER
  RADAR. ROCK SLIDES HAVE BEEN REPORTED BY SPOTTERS ALONG HIGHWAY 77
  NEAR EL CAPITAN CANYON.

DON'T DRIVE ACROSS FLOODED ROADS! MOST FLASH FLOOD DEATHS OCCUR IN
AUTOMOBILES.

RSB


&

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 Phoenix, AZ wrote its last area forecast discussion before this flash flood warning went out at Jul 18, 2:59 PM MST, 1 hour 17 minutes earlier.

Area forecast discussion, Jul 18, 2:59 PM MST, 1 hour 17 minutes before
SOUTHWEST ARIZONA/SOUTHEAST CALIFORNIA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
945 AM MST SUN JUL 18 1999

.SYNOPSIS...
MOISTURE HAS RETURNED TO MOST OF THE REGION IN ONE FORM OR ANOTHER...
WITH SHOWERS AND THUNDERSTORMS BECOMING POSSIBLE MOST ANYWHERE. THE
MOISTURE RETURN CAME ABOUT AS A RESULT OF A WEAK LOW PRESSURE SYSTEM
IN SOUTHEASTERN ARIZONA...MOIST OUTFLOWS FROM THUNDERSTORMS EAST OF
THE REGION LAST EVENING AND THE FLOW ALOFT TURNING MORE SOUTHERLY IN
RESPONSE TO A DISTURBANCE THAT MOVED THROUGH THE LOW PRESSURE TROUGH
ALONG THE WEST COAST. IN ADDITION...A DISTURBANCE MOVING NORTHWARD
OFF THE WEST COAST OF BAJA HAS HELPED BRING MOISTURE NORTHWARD INTO
SOUTHEASTERN CALIFORNIA.

.DISCUSSION...
DEFINITE UPSWING IN CONVECTIVE ACTIVITY AS MOISTURE SURGED BACK NWWD
INTO THE REGION. ISOLATED SHOWERS AND THUNDERSTORMS APPEAR POSSIBLE
IN MOST OF THE CWA NOW...WITH JUST THE RIVER ZONES AND YUMA LEFT OUT
FOR NOW. STORMS ON THE BAJA SPINE SHOULD NOT MOVE FAR ENOUGH NEWD TO
REACH THE YUMA AREA....WHILE THE SERN CA ZONES WILL SEE SOME ACTIVITY
OVER THE HIGHER TERRAIN AREAS. MODELS ARE AT ODDS ABOUT KEEPING THE
MOISTURE OR DRYING THE REGION OUT. OPTING FOR THE WETTER CHOICE...AS
IT SEEMS IT WILL NOT DEVELOP A STRONG ENOUGH SWLY FLOW OVER THE AREA
TO SCOUR THINGS OUT. IN ADDITION...LOOKING OUT FOR VORT MAXIMA MOVING
NEWD IN THE FLOW TO CAUSE SOME PROBLEMS. JUST TOO HARD TO TIME THEM
TO REFINE THE FORECAST. SO...ZWILL USE A FAIRLY BROAD-BRUSHED FORECAST
APPROACH...STAYING A LITTLE MORE CONSERVATIVE THAN THE ETA BUT NOT AS
MUCH AS THE OTHER MODELS.  WILT

In the hours before

Special weather statement, Jul 18, 11:52 AM MST, 4 hours 24 minutes before
AZZ022>024-028-190640-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE PHOENIX AZ
1152 AM MST SUN JUL 18 1999

...THERE WILL BE A CHANCE OF SHOWERS AND THUNDERSTORMS...WITH HEAVY
RAIN POSSIBLE...IN NORTHERN MARICOPA...NORTHWEST PINAL AND SOUTHERN
GILA COUNTIES THIS AFTERNOON AND THIS EVENING...

A LOW PRESSURE SYSTEM OVER SOUTHEASTERN ARIZONA WILL MOVE NORTHEAST
TODAY AND TONIGHT...ENHANCING THE POSSIBILITY OF THUNDERSTORMS WITH
HEAVY RAIN IN THE AFOREMENTIONED AREAS...INCLUDING THE METROPOLITAN
PHOENIX AREA. MOTORISTS AND OTHERS WITH OUTDOOR INTERESTS SHOULD BE
ALERT TO THE POSSIBILITY OF LOCAL FLOODING OF WASHES...HIGHWAY DIPS
AND OTHER NORMALLY DRY AREAS IF THUNDERSTORMS DEVELOP AS FORECAST.

THIS OUTLOOK WILL BE ISSUED ONLY ON DAYS WHEN SOME
FORM OF HAZARDOUS WEATHER IS EXPECTED SOMEWHERE OVER THE PHOENIX
AREA OF WARNING RESPONSIBILITY...WHICH INCLUDES SOUTH-CENTRAL AND
SOUTHWEST ARIZONA AS WELL AS FAR SOUTHEAST CALIFORNIA.

FOR PURPOSES OF THIS OUTLOOK HAZARDOUS WEATHER REFERS TO ANY OF THE
FOLLOWING...LOCALLY HEAVY RAINFALL WHICH RESULTS IN FLOODING AND
RUNNING WASHES...SAND OR DUST STORM WHICH REDUCES VISIBILITY TO ONE
QUARTER MILE OR LESS...DAMAGING WINDS IN EXCESS OF 57 MPH...AND HAIL
AT LEAST THREE QUARTERS OF AN INCH IN DIAMETER.

WHEN HAZARDOUS WEATHER IS IMMINENT OR OCCURRING...THE PHOENIX
NATIONAL WEATHER SERVICE FORECAST OFFICE WILL PROVIDE IMPORTANT LIFE-
SAVING INFORMATION IN THE FORM OF WARNINGS...FOLLOW-UP STATEMENTS...
AND SHORT TERM FORECASTS.

STORM SPOTTER ACTIVATION MAY BE NECESSARY LATER TODAY.

WILT
Special weather statement, Jul 18, 11:52 AM MST, 4 hours 24 minutes before
AZZ022>024-028-190640-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE PHOENIX AZ
1152 AM MST SUN JUL 18 1999

...THERE WILL BE A CHANCE OF SHOWERS AND THUNDERSTORMS...WITH HEAVY
RAIN POSSIBLE...IN NORTHERN MARICOPA...NORTHWEST PINAL AND SOUTHERN
GILA COUNTIES THIS AFTERNOON AND THIS EVENING...

A LOW PRESSURE SYSTEM OVER SOUTHEASTERN ARIZONA WILL MOVE NORTHEAST
TODAY AND TONIGHT...ENHANCING THE POSSIBILITY OF THUNDERSTORMS WITH
HEAVY RAIN IN THE AFOREMENTIONED AREAS...INCLUDING THE METROPOLITAN
PHOENIX AREA. MOTORISTS AND OTHERS WITH OUTDOOR INTERESTS SHOULD BE
ALERT TO THE POSSIBILITY OF LOCAL FLOODING OF WASHES...HIGHWAY DIPS
AND OTHER NORMALLY DRY AREAS IF THUNDERSTORMS DEVELOP AS FORECAST.

THIS OUTLOOK WILL BE ISSUED ONLY ON DAYS WHEN SOME
FORM OF HAZARDOUS WEATHER IS EXPECTED SOMEWHERE OVER THE PHOENIX
AREA OF WARNING RESPONSIBILITY...WHICH INCLUDES SOUTH-CENTRAL AND
SOUTHWEST ARIZONA AS WELL AS FAR SOUTHEAST CALIFORNIA.

FOR PURPOSES OF THIS OUTLOOK HAZARDOUS WEATHER REFERS TO ANY OF THE
FOLLOWING...LOCALLY HEAVY RAINFALL WHICH RESULTS IN FLOODING AND
RUNNING WASHES...SAND OR DUST STORM WHICH REDUCES VISIBILITY TO ONE
QUARTER MILE OR LESS...DAMAGING WINDS IN EXCESS OF 57 MPH...AND HAIL
AT LEAST THREE QUARTERS OF AN INCH IN DIAMETER.

WHEN HAZARDOUS WEATHER IS IMMINENT OR OCCURRING...THE PHOENIX
NATIONAL WEATHER SERVICE FORECAST OFFICE WILL PROVIDE IMPORTANT LIFE-
SAVING INFORMATION IN THE FORM OF WARNINGS...FOLLOW-UP STATEMENTS...
AND SHORT TERM FORECASTS.

STORM SPOTTER ACTIVATION MAY BE NECESSARY LATER TODAY.

WILT

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 18, 4:26 PM MSTSevere Thunderstorm WarningPSRYuma64 min

Nearby

Flash Flood Warnings in Arizona, 1999Every 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.