Alert archive / Montana / Mesoscale Discussions in 2007

Mesoscale Discussion 784

May 13, 2007Sheridan County, Montana

The Storm Prediction Center issued this mesoscale discussion at May 13, 2007, 6:39 PM MDT for Sheridan County, Montana. It was in force for 96 min.

The area

The outline as issued.

The facts

Issued
May 13, 2007, 6:39 PM MDT (00:39 UTC)
Expired
May 13, 2007, 8:15 PM MDT
In force
96 min
Issued by
the Storm Prediction Center

County Sheridan County, MT

The radar

The Glasgow radar (KGGW), 164 km from the middle of the area, began a volume at 00:39 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 00:00Z, 0.7 hours before the alert went out and 162 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, Glasgow Intl Airport, MT at 00:00Z on 2007-05-14Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 179 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, Glasgow Intl Airport, MT at 00:00Z on 2007-05-14The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 127 square meters per square second.193958Sfc1 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
179 J/kg
Mixed-layer CIN
-181 J/kg
Mixed-layer LCL
1243 m above ground
0-6 km bulk shear
49 kt
0-1 km storm-relative helicity
127 m²/s²
0-3 km storm-relative helicity
326 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 
ACUS11 KWNS 140039
SWOMCD
SPC MCD 140039 
NDZ000-MTZ000-140215-

MESOSCALE DISCUSSION 0784
NWS STORM PREDICTION CENTER NORMAN OK
0739 PM CDT SUN MAY 13 2007

AREAS AFFECTED...NE MT...NW ND

CONCERNING...SEVERE THUNDERSTORM WATCH 268...

VALID 140039Z - 140215Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 268
CONTINUES.

AN ADDITIONAL WW IS NOT CURRENTLY ANTICIPATED TO THE NORTHEAST OF WW
268.

NORTH OF STRONGER UPSLOPE FLOW...DESTABILIZATION HAS BEEN WEAKER...
BUT NARROW PRE-FRONTAL THERMAL RIDGE EXTENDING ACROSS EASTERN
MONTANA INTO SOUTHERN SASKATCHEWAN HAS STILL CONTRIBUTED TO MOST
UNSTABLE CAPE OF 500 TO 1000 J/KG ACROSS MUCH OF NORTHEAST MONTANA. 
THIS HAS SUPPORTED VIGOROUS ONGOING CLUSTER OF STORMS ACROSS PARTS
OF DANIELS/ROOSEVELT/SHERIDAN COUNTIES...WHICH HAS MOSTLY BEEN
ENHANCED BY STRONG DEEP LAYER SHEAR ASSOCIATED WITH NORTHEASTERLY
PRE-FRONTAL LOW-LEVEL WINDS BENEATH MODERATELY STRONG 30+ KT
SOUTHWESTERLY 500 MB FLOW.  DAMAGING WIND/HAIL THREAT WITH THIS
SMALL CONVECTIVE SYSTEM MAY CONTINUE INTO AREAS NEAR/NORTH OF
WILLISTON BY 02Z...BUT ACTIVITY IS EXPECTED TO WEAKEN
THEREAFTER...AS IT PROGRESSES EAST OF LOW-LEVEL THERMAL RIDGE AXIS.

..KERR.. 05/14/2007

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

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

48460499 48880442 48740373 48090367 47780432 47910477

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
May 13, 7:13 PM MDTMesoscale DiscussionSPCCarter, Custer, Fallon, Powder River, Rosebud92 min

Nearby

Mesoscale Discussions in Montana, 2007Every mesoscale discussion in 2007

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.