Alert archive / Montana / Mesoscale Discussions in 2016

Mesoscale Discussion 1449

July 30, 20165 counties in Montana

The Storm Prediction Center issued this mesoscale discussion at Jul 30, 2016, 4:50 PM MDT for 5 counties in Montana. It was in force for 115 min.

The area

The outline as issued.

The facts

Issued: Jul 30, 2016, 4:50 PM MDT (22:50 UTC)
Expired: Jul 30, 2016, 6:45 PM MDT
In force: 115 min
Issued by: the Storm Prediction Center
Chance of a watch: 5%

Counties Daniels County, MT, Garfield County, MT, McCone County, MT, Phillips County, MT, Valley County, MT

The radar

The Glasgow radar (KGGW), 16 km from the middle of the area, began a volume at 22:50 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

Glasgow Intl Airport, MT (KGGW), launched 12:00Z, 10.8 hours before the alert went out and 18 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: 22 J/kg
Mixed-layer CIN: -179 J/kg
Mixed-layer LCL: 1760 m above ground
0-6 km bulk shear: 36 kt
0-1 km storm-relative helicity: 74 m²/s²
0-3 km storm-relative helicity: 149 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

866 
ACUS11 KWNS 302251
SWOMCD
SPC MCD 302250 
MTZ000-310045-

MESOSCALE DISCUSSION 1449
NWS STORM PREDICTION CENTER NORMAN OK
0550 PM CDT SAT JUL 30 2016

AREAS AFFECTED...PORTIONS OF NERN MT

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 302250Z - 310045Z

PROBABILITY OF WATCH ISSUANCE...5 PERCENT

SUMMARY...A VERY ISOLATED LARGE HAIL AND DAMAGING-WIND THREAT MAY
OCCUR OVER THE NEXT SEVERAL HOURS. DUE TO THE ISOLATED NATURE OF THE
THREAT...WW ISSUANCE IS NOT EXPECTED.

DISCUSSION...WEAK SFC CONVERGENCE ALONG A BOUNDARY AND THE GLANCING
INFLUENCE OF A SHORTWAVE TROUGH OVER WRN SK HAVE FOSTERED ISOLATED
CONVECTIVE DEVELOPMENT ACROSS PORTIONS OF NERN MT INTO S-CNTRL SK.
CURRENT RADAR TRENDS SHOW SOME POTENTIAL FOR ACTIVITY IN S-CNTRL SK
TO CROSS THE INTERNATIONAL BORDER THROUGH 2330Z AND POSE A VERY
ISOLATED LARGE HAIL/DAMAGING-WIND RISK ACROSS PARTS OF NERN MT.
THUNDERSTORMS ORIGINATING IN NERN MT HAVE THUS FAR STRUGGLED TO
INTENSIFY...PROBABLY DUE TO WEAK LOW-LEVEL CONVERGENCE AND GREATER
DISTANCE FROM THE SHORTWAVE TROUGH IN SK. THE VWP FROM KGGW DOES
SHOW A VEERING LOW-LEVEL WIND PROFILE...ALTHOUGH MAGNITUDES REMAIN
RELATIVELY WEAK. WITH SOME ENHANCEMENT TO THE MID-LEVEL FLOW ALOFT
ASSOCIATED WITH THE SHORTWAVE TROUGH OVER SK...SUPERCELL STRUCTURES
WILL BE POSSIBLE. SUFFICIENT LOW-LEVEL MOISTURE REMAINS CONFINED TO
A RELATIVELY NARROW NW-SE CORRIDOR ACROSS PARTS OF NERN MT PER
LATEST SFC OBSERVATIONS AND 22Z RAP MESOANALYSIS. DUE TO THE
ISOLATED FORECAST COVERAGE OF CONVECTION AND THE NARROW
SPATIAL/TEMPORAL WINDOW FOR A SEVERE THREAT...WW ISSUANCE IS NOT
EXPECTED.

..GLEASON/EDWARDS.. 07/30/2016

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

ATTN...WFO...GGW...

LAT...LON   49050700 49050543 47910555 46880562 46880695 46860823
            49040820 49050700

Nearby

Mesoscale Discussions in Montana, 2016 Every mesoscale discussion in 2016

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.