Alert archive / Arizona / Mesoscale Discussions in 2019

Mesoscale Discussion 2001

September 23, 20195 counties in Arizona

The Storm Prediction Center issued this mesoscale discussion at Sep 23, 2019, 7:59 AM MST for 5 counties in Arizona. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Sep 23, 2019, 7:59 AM MST (14:59 UTC)
Expired: Sep 23, 2019, 10:00 AM MST
In force: 2 hr
Issued by: the Storm Prediction Center
Chance of a watch: 80%

Counties La Paz County, AZ, Maricopa County, AZ, Pima County, AZ, Pinal County, AZ, Yuma County, AZ

The radar

The Phoenix radar (KIWA), 123 km from the middle of the area, began a volume at 14:59 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 watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

Severe Thunderstorm Watch 658Sep 23, 9:50 AM MST

The nearest sounding before it

Phoenix, AZ (KPSR), launched 12:00Z, 3.0 hours before the alert went out and 96 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: 843 J/kg
Mixed-layer CIN: -53 J/kg
Mixed-layer LCL: 1085 m above ground
0-6 km bulk shear: 44 kt
0-1 km storm-relative helicity: 65 m²/s²
0-3 km storm-relative helicity: 119 m²/s²
Significant tornado parameter: 0.4
Supercell composite: 2.8

Open this sounding in Storm Lab

The text

As transmitted.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 23, 9:52 AM MST	Severe Thunderstorm Watch	SPC	Gila, La Paz, Maricopa, Mohave, Pinal, Yavapai and 1 more	10 hr
Sep 23, 11:37 AM MST	Mesoscale Discussion	SPC	Gila, La Paz, Maricopa, Pinal, Yavapai	83 min
Sep 23, 3:05 PM MST	Mesoscale Discussion	SPC	Gila, Maricopa, Pinal, Yavapai	115 min

Nearby

Mesoscale Discussions in Arizona, 2019 Every mesoscale discussion in 2019

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.