Alert archive / Utah / Mesoscale Discussions in 2012

Mesoscale Discussion 1853

September 1, 20124 states

The Storm Prediction Center issued this mesoscale discussion at Sep 1, 2012, 3:02 PM MDT for 4 states. It was in force for 88 min.

The area

The outline as issued.

The facts

Issued: Sep 1, 2012, 3:02 PM MDT (21:02 UTC)
Expired: Sep 1, 2012, 4:30 PM MDT
In force: 88 min
Issued by: the Storm Prediction Center

All 30 counties

Bear Lake County, ID, Cassia County, ID, Franklin County, ID, Oneida County, ID, Twin Falls County, ID, Elko County, NV, White Pine County, NV, Beaver County, UT, Box Elder County, UT, Cache County, UT, Carbon County, UT, Davis County, UT, Duchesne County, UT, Emery County, UT, Juab County, UT, Millard County, UT, Morgan County, UT, Piute County, UT, Rich County, UT, Salt Lake County, UT, Sanpete County, UT, Sevier County, UT, Summit County, UT, Tooele County, UT, Utah County, UT, Wasatch County, UT, Wayne County, UT, Weber County, UT, Lincoln County, WY, Uinta County, WY

The radar

The Salt Lake City radar (KMTX), 108 km from the middle of the area, began a volume at 21:05 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

Salt Lake City I, UT (KSLC), launched 12:00Z, 9.0 hours before the alert went out and 70 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: 158 J/kg
Mixed-layer CIN: -127 J/kg
Mixed-layer LCL: 978 m above ground
0-6 km bulk shear: 44 kt
0-1 km storm-relative helicity: 98 m²/s²
0-3 km storm-relative helicity: 111 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

Open this sounding in Storm Lab

The text

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

584 
ACUS11 KWNS 012102
SWOMCD
SPC MCD 012102 
WYZ000-UTZ000-IDZ000-NVZ000-012230-

MESOSCALE DISCUSSION 1853
NWS STORM PREDICTION CENTER NORMAN OK
0402 PM CDT SAT SEP 01 2012

AREAS AFFECTED...MUCH OF UTAH...NERN NV...SRN ID...FAR SWRN WY

CONCERNING...SEVERE THUNDERSTORM WATCH 604...

VALID 012102Z - 012230Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 604
CONTINUES.

SUMMARY...THE SEVERE THREAT CONTINUES FOR WW 604...WITH SOME THREAT
EXTENDING OUTSIDE OF THE WATCH ACROSS PORTIONS OF NWRN NV INTO SRN
ID. A DIMINISHING TREND FROM SOUTHWEST TO NORTHEAST IS EXPECTED WITH
TIME.

DISCUSSION...2030Z RADAR SHOWS NUMEROUS STRONG/POTENTIALLY SEVERE
THUNDERSTORMS FROM PARTS OF NWRN NV INTO CNTRL AND NRN UT.
CONVECTIVE MODE HAS LARGELY BEEN CELLULAR THUS FAR...WITH SEVERAL
SUPERCELL STRUCTURES NOTED. THE CLUSTER OF STORMS MOVING INTO NWRN
UT FROM NERN NV MAY CONGEAL INTO A LOOSELY ORGANIZED MCS IN THE NEXT
1-2 HOURS...WITH AN INCREASING THREAT OF SEVERE WIND POTENTIALLY
MOVING TOWARD THE SALT LAKE REGION BY 22-23Z. EVEN IF NO UPSCALE
GROWTH OCCURS...SEVERE WIND/HAIL WILL REMAIN POSSIBLE WITH STRONGER
CELLS...AS EFFECTIVE SHEAR OF 35-45 KTS REMAINS SUFFICIENT FOR
ORGANIZED STORM MODES. SOME SEVERE THREAT WILL EXTEND INTO SRN
ID...AS STORMS DEVELOP OR MOVE INTO THE REGION. 

THE STORMS SOUTH OF SALT LAKE MOVING FROM CNTRL INTO NERN UT HAVE
SHOWN SOME WEAKENING AND MAY CONTINUE TO SLOWLY DIMINISH AS THEY
MOVE INTO A SOMEWHAT LESS UNSTABLE ENVIRONMENT. AT THIS TIME...IT
DOES NOT APPEAR THAT A DOWNSTREAM WATCH WILL NE NECESSARY...BUT SOME
THREAT OF ISOLATED SEVERE WIND OR HAIL WILL PERSIST EAST OF THE
WATCH. 

A GENERAL WEAKENING TREND FROM SW TO NE IS LIKELY LATER THIS
AFTERNOON AS DRIER AIR MOVES INTO THE REGION.

..DEAN.. 09/01/2012

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...RIW...GJT...SLC...PIH...VEF...BOI...LKN...

LAT...LON   39811569 41281624 42181564 42551460 42501258 42471131
            42161046 41610986 41240973 40660968 39900974 39110985
            38530996 38241075 38201180 38131332 38281425 38941487
            39811569

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 1, 12:31 PM MDT	Mesoscale Discussion	SPC	White Pine	119 min
Sep 1, 12:59 PM MDT	Severe Thunderstorm Watch	SPC	Beaver, Box Elder, Cache, Carbon, Davis, Duchesne and 14 more	8 hr
Sep 1, 2:31 PM MDT	Mesoscale Discussion	SPC	Kane, San Juan	89 min
Sep 1, 5:49 PM MDT	Mesoscale Discussion	SPC	Beaver, Box Elder, Cache, Carbon, Davis, Duchesne and 14 more	86 min

Nearby

Mesoscale Discussions in Utah, 2012 Mesoscale Discussions in Idaho, 2012 Mesoscale Discussions in Nevada, 2012 Every mesoscale discussion in 2012

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.