Alert archive / Utah / Mesoscale Discussions in 2011
Mesoscale Discussion 503
The Storm Prediction Center issued this mesoscale discussion at Apr 21, 2011, 1:08 PM MDT for 4 counties in Idaho; 11 counties in Utah. It was in force for 97 min.
The area
The outline as issued.
The facts
- Issued
- Apr 21, 2011, 1:08 PM MDT (19:08 UTC)
- Expired
- Apr 21, 2011, 2:45 PM MDT
- In force
- 97 min
- Issued by
- the Storm Prediction Center
Counties Bannock County, ID, Bear Lake County, ID, Franklin County, ID, Oneida County, ID, Cache County, UT, Davis County, UT, Juab County, UT, Morgan County, UT, Rich County, UT, Salt Lake County, UT, Sanpete County, UT, Summit County, UT, Utah County, UT, Wasatch County, UT, Weber County, UT
The radar
The Salt Lake City radar (KMTX), 77 km from the middle of the area, began a volume at 19:08 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, 7.1 hours before the alert went out and 9 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.
- Mixed-layer CAPE
- 411 J/kg
- Mixed-layer CIN
- -62 J/kg
- Mixed-layer LCL
- 1122 m above ground
- 0-6 km bulk shear
- 60 kt
- 0-1 km storm-relative helicity
- 87 m²/s²
- 0-3 km storm-relative helicity
- 138 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- -1.2
The text
As transmitted, in the capitals the NWS used until 2016.
707
ACUS11 KWNS 211908
SWOMCD
SPC MCD 211908
UTZ000-WYZ000-IDZ000-212045-
MESOSCALE DISCUSSION 0503
NWS STORM PREDICTION CENTER NORMAN OK
0208 PM CDT THU APR 21 2011
AREAS AFFECTED...CNTRL-NRN UT...SE ID AND FAR SW WY
CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY
VALID 211908Z - 212045Z
A MARGINAL SEVERE THREAT WILL CONTINUE ACROSS NRN UT AND SE ID WHERE
HAIL AND LOCALLY SEVERE WIND GUSTS MAY ACCOMPANY THE STRONGER CELLS.
THE THREAT MAY AFFECT SW WY LATER THIS AFTERNOON. DUE TO THE
ISOLATED NATURE OF THE THREAT...WW ISSUANCE IS NOT ANTICIPATED.
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW AN UPPER-LEVEL TROUGH OVER
THE PACIFIC NW EXTENDING SWD ACROSS THE INTERMOUNTAIN WEST. SEVERAL
VORTICITY MAXIMA ARE LOCATED JUST AHEAD OF THE TROUGH FROM SE ID SWD
INTO NRN AND CNTRL NV. STRONG LARGE-SCALE ASCENT IS LOCATED AHEAD OF
THESE FEATURES WHICH ALONG WITH SFC HEATING IS SUPPORTING THE
DEVELOPMENT OF A LINE OF THUNDERSTORMS EXTENDING SWD FROM NEAR
POCATELLO SWD TO ERN PARTS OF THE GREAT SALT LAKE. THIS LINE SHOULD
CONTINUE TO BE SUSTAINED THIS AFTERNOON...MOVING ACROSS THE I-15
CORRIDOR INTO THE NRN PART OF THE SALT LAKE CITY AREA WHERE SBCAPE
VALUES ARE ESTIMATED IN THE 1000 TO 1200 J/KG RANGE. THE INSTABILITY
COMBINED WITH STRONG DEEP LAYER SHEAR AND STEEP MID-LEVEL LAPSE
RATES AROUND 9.0 C/KM SHOULD RESULT IN A HAIL THREAT WITH THE MORE
INTENSE CORES. IN ADDITION...A THREAT FOR ISOLATED DAMAGING WIND
GUSTS WILL CONTINUE WITH THE LINE AS THE LINE PROGRESSES EWD OVER
THE NEXT FEW HOURS.
..BROYLES.. 04/21/2011
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...RIW...SLC...PIH...
LAT...LON 39301138 40241087 40991058 42231078 42651127 42881211
42841275 42181308 41131294 39761299 38751269 38661220
38931163 39301138SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 21, 4:52 PM MDT | Mesoscale Discussion | SPC | Uintah | 53 min |
Nearby
Mesoscale Discussions in Utah, 2011Mesoscale Discussions in Idaho, 2011Every mesoscale discussion in 2011
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.