Alert archive / Arizona / Severe Thunderstorm Warnings in 2009

Severe Thunderstorm Warning 33, NWS Tucson, AZ

July 20, 2009Pima County, Arizona

NWS Tucson, AZ issued this severe thunderstorm warning at Jul 20, 2009, 4:25 PM MST for Pima County, Arizona. It was in force for 65 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Jul 20, 2009, 4:25 PM MST (23:25 UTC)
Expired
Jul 20, 2009, 5:30 PM MST
In force
65 min
Issued by
NWS Tucson, AZ
Area
Storm-based polygon

County Pima County, AZ

The radar

The Tucson radar (KEMX), 64 km from the middle of the area, began a volume at 23:27 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.

Did it verify

Not verified. The Iowa Environmental Mesonet's Cow found no qualifying storm report inside this severe thunderstorm warning while it was in force. That is not proof nothing happened: reports are thin where few people live.

Cow counts a report within 15 km of the polygon while the warning was in force: a tornado for a tornado warning; hail of 1 inch or more, a gust of 58 mph or more or wind damage for a severe thunderstorm warning; a flash flood report for a flash flood warning.

The nearest sounding before it

Tuscon, AZ (KTUS), launched 12:00Z, 11.4 hours before the alert went out and 30 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, Tuscon, AZ at 12:00Z on 2009-07-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Tuscon, AZ at 12:00Z on 2009-07-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 39 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
2 J/kg
Mixed-layer CIN
-353 J/kg
Mixed-layer LCL
2950 m above ground
0-6 km bulk shear
15 kt
0-1 km storm-relative helicity
39 m²/s²
0-3 km storm-relative helicity
43 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 
WUUS55 KTWC 202325
SVRTWC
AZC019-210030-
/O.NEW.KTWC.SV.W.0033.090720T2325Z-090721T0030Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE TUCSON AZ
425 PM MST MON JUL 20 2009

THE NATIONAL WEATHER SERVICE IN TUCSON HAS ISSUED A

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

* UNTIL 530 PM MST

* AT 424 PM MST...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM CAPABLE OF PRODUCING DAMAGING WINDS IN EXCESS
  OF 60 MPH.  THIS STORM WAS LOCATED NEAR THREE POINTS...OR 22 MILES
  NORTHWEST OF GREEN VALLEY...AND MOVING SOUTHEAST AT 15 MPH.

* OTHER LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO RYAN
  FIELD.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

EXPECT DAMAGING WINDS IN EXCESS OF 60 MPH...LARGE HAIL...FREQUENT
LIGHTNING...AND HEAVY RAIN WITH THIS STORM.

&&

LAT...LON 3232 11119 3229 11114 3227 11110 3207 11107
      3190 11124 3207 11145 3223 11136
TIME...MOT...LOC 2325Z 294DEG 15KT 3207 11127

$$

CS
3 follow-up statements
000 
WWUS55 KTWC 202347
SVSTWC

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE TUCSON AZ
447 PM MST MON JUL 20 2009

AZC019-210030-
/O.CON.KTWC.SV.W.0033.000000T0000Z-090721T0030Z/
PIMA AZ-
447 PM MST MON JUL 20 2009

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 530 PM MST
FOR CENTRAL PIMA COUNTY...

AT 446 PM MST...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO 
INDICATE A CLUSTER OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING 
DAMAGING WINDS IN EXCESS OF 60 MPH.  THESE STORMS WERE LOCATED ALONG 
A LINE EXTENDING FROM SAGUARO NATIONAL PARK WEST TO THREE POINTS.

LAT...LON 3232 11119 3229 11114 3227 11110 3207 11107
      3190 11124 3207 11145 3223 11136
TIME...MOT...LOC 2346Z 294DEG 15KT 3223 11116 3204 11121
          3202 11133

$$

CS
000 
WWUS55 KTWC 210009
SVSTWC

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE TUCSON AZ
509 PM MST MON JUL 20 2009

AZC019-210030-
/O.CON.KTWC.SV.W.0033.000000T0000Z-090721T0030Z/
PIMA AZ-
509 PM MST MON JUL 20 2009

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 530 PM MST
FOR CENTRAL PIMA COUNTY...

AT 509 PM MST...A SEVERE THUNDERSTORM WAS REPORTED CAPABLE OF
PRODUCING DAMAGING WINDS IN EXCESS OF 60 MPH.  THIS STORM WAS LOCATED
NEAR RYAN FIELD...OR 14 MILES SOUTHWEST OF TUCSON...MOVING SOUTHEAST
AT 20 MPH.

THE SEVERE THUNDERSTORM WILL OTHERWISE REMAIN OVER MAINLY RURAL AREAS
OF THE INDICATED COUNTY.

LAT...LON 3232 11119 3229 11114 3227 11110 3207 11107
      3190 11124 3207 11145 3223 11136
TIME...MOT...LOC 0009Z 315DEG 18KT 3214 11116

$$

CS
000 
WWUS55 KTWC 210028
SVSTWC

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE TUCSON AZ
528 PM MST MON JUL 20 2009

AZC019-210038-
/O.EXP.KTWC.SV.W.0033.000000T0000Z-090721T0030Z/
PIMA AZ-
528 PM MST MON JUL 20 2009

...THE SEVERE THUNDERSTORM WARNING FOR CENTRAL PIMA COUNTY WILL
EXPIRE AT 530 PM MST...

LAT...LON 3232 11119 3229 11114 3227 11110 3207 11107
      3190 11124 3207 11145 3223 11136
TIME...MOT...LOC 0028Z 315DEG 18KT 3207 11108

$$

CS

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 20, 1:06 PM MST, 3 hours 19 minutes earlier.

Area forecast discussion, Jul 20, 1:06 PM MST, 3 hours 19 minutes before
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
110 PM MST MON JULY 20 2009

.SYNOPSIS...STRONG HIGH PRESSURE ALOFT WILL BRING HOT CONDITIONS TO
SOUTHEAST ARIZONA THROUGH AT LEAST THE MIDDLE OF THE WEEK. MOISTURE
WILL ALSO BE SUFFICIENT FOR THE DAILY CYCLE OF SCATTERED MAINLY
AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS.

&&

.DISCUSSION...SOME CLOUDS ARE BEGINNING TO FORM OVER THE MOUNTAIN
TOPS AND HIGHER ELEVATIONS OF SOUTHEAST ARIZONA...THOUGH SCATTERED
SHOWER AND THUNDERSTORM ACTIVITY STILL LOOKING TO HOLD OFF. LOOKING
OUTSIDE THE CWA...ACTIVITY HAS STARTED IN EARNEST ALONG THE RIM.
GIVEN WEAK FLOW SEEN IN THE 12Z SOUNDING...NOT CONFIDENT THAT MUCH
OF THAT WILL MAKE ITS WAY DOWN HERE. WILL LIKELY NEED TO WAIT FOR
HOMEGROWN STORMS. STARTING TO SEE JUST A SMALL HANDFUL OF THOSE AT
THE TIME OF THIS WRITING...MAINLY ALONG THE INTERNATIONAL BORDER AND
ONE ISOLATED CELL OVER CENTRAL PIMA COUNTY. DEWPOINTS HAVE FALLEN TO
THE UPPER 40S AND THAT DRYING WILL HELP IN THE FORMATION OF GUSTY
WINDS/DOWNBURSTS FROM ANY STORMS THAT MAY DEVELOP TODAY.

NOT MUCH CHANGE IN THINKING WITH REGARDS TO FORECAST...SO FOR
DETAILS...PLEASE SEE PREV DISCUSSION SECTION BELOW.

&&

.AVIATION...EXPECT ISOLATED TO SCATTERED TSRA/SHRA THE REST OF THIS
AFTERNOON AND EVENING. THE STRONGEST TSRA WILL BE ACCOMPANIED WITH
WIND GUSTS OF 40-45 KTS. OTHERWISE...SCATTERED TO OCCASIONALLY
BROKEN CUMULOFORM CLOUDS WITH BASES 11-13K FT AGL INTO THIS EVENING.
TSRA/ SHRA TO DECREASE IN COVERAGE AFTER 04Z AND ANY CONVECTIVE
CLOUD DEBRIS TO DISSIPATE DURING THE NIGHT. SURFACE WINDS WLY/NWLY
5-15 KTS THRU 06Z THEN SLY/SELY 5-15 KTS LATE TONIGHT AND INTO
TUESDAY MORNING. AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...ISOLATED TO SCATTERED THUNDERSTORMS WILL OCCUR THIS
WEEK...WITH THE BULK OF ACTIVITY DURING THE AFTERNOON AND EARLY
NIGHTTIME HOURS. GENERALLY LIGHT DIURNALLY DRIVEN SURFACE WINDS
EXCEPT STRONG AND ERRATIC WINDS NEAR THE STRONGEST THUNDERSTORMS.
ABOVE NORMAL DAYTIME TEMPERATURES TO OCCUR THIS WEEK.

&&

.PREV DISCUSSION...SOME DEBRIS CLOUDINESS TO START THE
MORNING...WHICH LOOKS MORE IMPRESSIVE ON SATELLITE THAN IT DOES OUT
THE WINDOW. TRENDS HAVE IT THINNING...SO THAT IS NOT EXPECTED TO
INTERFERE WITH DEVELOPMENT TODAY. MORE ON THAT LATER. DEWPOINTS AT
AREA ASOS STATIONS WERE MOSTLY IN THE MID 50S...WITH THE EXCEPTION
OF KDUG JUST SHY OF 50. TAKING A LOOK AT THE 12Z SOUNDING...A LITTLE
MORE WET BUT SLIGHTLY MORE STABLE THAN 24 HOURS AGO WITH BETTER
DIRECTIONAL SHEER...THOUGH STILL FAIRLY WEAK FLOW. ALSO OF NOTE ON
THE SATELLITE...ALREADY GETTING SOME ACTIVITY SOUTH OF THE
BORDER...WAY SOUTH...AS WELL AS SOME LINGERING ACTIVITY SOUTHEAST OF
PRESCOTT.

TAKING WHAT IS ALREADY HAPPENING INTO ACCOUNT...12Z NAM SHOWS A
COUPLE OF DISTURBANCES THAT WILL IMPACT SE AZ TODAY...ONE OVER
SOUTHERN NV AT THIS TIME MOVING INTO NORTHERN AZ...THE OTHER PUSHING
INTO SE AZ FROM THE SOUTH. SHOULD THIS HOLD...AND THE AFOREMENTIONED
ACTIVITY HINTS STRONGLY IN FAVOR OF THIS...SHOULD SEE A SIMILAR DAY
TODAY AS WHAT WAS SEEN YESTERDAY...WITH ACTIVITY FLARING UP BOTH ON
THE RIM AND ALONG THE INTERNATIONAL BORDER...EACH SPREADING INTO SE
AZ. WITH THE WEAK FLOW...NOT EXPECTING ANY STORMS THAT DEVELOP TO
MOVE ALL THAT FAST. MORE MOISTURE AT THE SURFACE...SHOULD IT
HOLD...MAY HELP MITIGATE A WIND THREAT FROM STORMS THAT
DEVELOP...BUT GIVEN THAT THERE IS NOT MUCH DIFFERENCE IN CONDITIONS
VERSUS 24 HOURS AGO...DO NOT FEEL COMFORTABLE RULING THAT OUT AT
THIS TIME.

MOVING OUT OF THE VERY SHORT TERM...THE HIGH WOBBLES WESTWARD AND
THIS WOBBLING WILL MAKE TUES AND WEDS LOOK SIMILAR TO TODAY
ACCORDING TO THE MODELS. MOVING BEYOND MID WEEK...MID TO LONG RANGE
MODELS SHOW THE RIDGE INTENSIFYING WITH THE HIGH CENTER NORTH OF THE
FOUR CORNERS. THIS WOULD TAKE IT OUT OF THE PRIME REAL ESTATE FOR
BRINGING MOISTURE INTO SE AZ WHICH WOULD VALIDATE THE INHERITED LOW
RANGE MONSOON POPS. WILL WAIT AND SEE WHAT THE 12Z RUN OFFERS...BUT
CAN SEE NO REASON TO ARGUE.

ONE LAST THING TO MENTION...WITH THE RIDGE REMAINING IN PLACE...AND
EVEN INTENSIFYING...AFTERNOON HIGH TEMPERATURES ARE EXPECTED TO
REMAIN ABOVE CLIMATOLOGICAL NORMALS AND SHOW LITTLE VARIANCE FROM
DAY TO DAY. THIS WOULD KEEP THE TUCSON METRO OVER THE CENTURY MARK
FOR THE ENTIRE FORECAST PERIOD...PUSHING THE WESTERN DESERTS TO
CLOSER TO 110 AND EASTERN VALLEYS TO THE UPPER 90S.

INHERITED FORECAST APPEARS TO BE ON TRACK. EXPECT TO MAKE SOME
SLIGHT TWEAKS TO TAKE INTO ACCOUNT CURRENT OBS AND NEWEST MODEL
DATA...BUT OTHERWISE NO SIGNIFICANT CHANGES EXPECTED.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...NONE.

WEATHER.GOV/TUCSON
Hazardous weather outlook, Jul 20, 8:57 AM MST, 7 hours 28 minutes before
HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TUCSON AZ
857 AM MST MON JUL 20 2009

AZZ019-030-034-035-211200-
NORTHERN GREENLEE COUNTY-UPPER GILA RIVER VALLEY-
SANTA CRUZ COUNTY-COCHISE COUNTY-
857 AM MST MON JUL 20 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHEAST
ARIZONA.

.DAY ONE...TODAY AND TONIGHT

ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED TO
DEVELOP THIS AFTERNOON AND CONTINUE INTO THIS EVENING. THE
STRONGEST STORMS MAY PRODUCE BRIEF HEAVY RAIN AND WIND GUSTS UP TO
45 MPH. THE BULK OF THE ACTIVITY IS FORECAST TO END BY AROUND
MIDNIGHT TONIGHT.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

THE DAILY CYCLE OF ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS
IS EXPECTED TO CONTINUE THROUGH SUNDAY...WITH ACTIVITY EXPECTED TO
DEVELOP DURING THE AFTERNOON AND CONTINUE INTO THE EVENING HOURS.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

AZZ029-031>033-211200-
SOUTHEAST PINAL COUNTY-WESTERN PIMA COUNTY-TOHONO OODHAM NATION-
TUCSON METRO/MARANA/GREEN VALLEY-
857 AM MST MON JUL 20 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTH CENTRAL
ARIZONA AND SOUTHEAST ARIZONA.

.DAY ONE...TODAY AND TONIGHT

ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED TO
DEVELOP ACROSS THE AREA THIS AFTERNOON INTO THIS EVENING. THE
STRONGEST STORMS MAY PRODUCE BRIEF PERIODS OF HEAVY RAIN...WIND
GUSTS UP TO 45 MPH AND REDUCED VISIBILITIES DUE TO BLOWING DUST.
THE MAJORITY OF ACTIVITY IS EXPECTED TO END BY MIDNIGHT TONIGHT.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

THE DAILY CYCLE OF ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS
IS EXPECTED TO CONTINUE THROUGH WEDNESDAY BEFORE BECOMING MORE
ISOLATED FOR THE REMAINDER OF THE WEEK. ACTIVITY IS EXPECTED TO
DEVELOP DURING THE AFTERNOON AND CONTINUE INTO THE EVENING HOURS.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

WEATHER.GOV/TUCSON

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 19, 5:23 PM MSTSevere Thunderstorm WarningTWCPima52 min
Jul 19, 6:06 PM MSTSevere Thunderstorm WarningTWCPima39 min
Jul 19, 6:24 PM MSTFlash Flood WarningTWCPima111 min

Nearby

Severe Thunderstorm Warnings in Arizona, 2009Every severe thunderstorm warning in 2009

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.