Alert archive / Montana / Special Weather Statements in 2017

Special Weather Statement, NWS Great Falls, MT

February 10, 2017Lewis and Clark County, Montana

NWS Great Falls, MT issued this special weather statement at Feb 10, 2017, 7:21 AM MST for Lewis and Clark County, Montana. It was in force for 114 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Feb 10, 2017, 7:21 AM MST (14:21 UTC)
Expired: Feb 10, 2017, 9:15 AM MST
In force: 114 min
Issued by: NWS Great Falls, MT

County Lewis and Clark County, MT

The radar

The Great Falls radar (KTFX), 85 km from the middle of the area, began a volume at 14:22 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

Great_falls, MT (KTFX), launched 12:00Z, 2.4 hours before the alert went out and 133 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1462 m above ground
0-6 km bulk shear: 79 kt
0-1 km storm-relative helicity: 37 m²/s²
0-3 km storm-relative helicity: 52 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

748 
WWUS85 KTFX 101421
SPSTFX

Special Weather Statement
National Weather Service Great Falls MT
721 AM MST FRI FEB 10 2017

MTZ014-101615-
Central and Southern Lewis and Clark-
721 AM MST FRI FEB 10 2017

...BLACK ICE WILL AFFECT CENTRAL AND SOUTHERN LEWIS AND CLARK 
COUNTY...

At 7:18 AM, MT DOT and an NWS meteorologist reported black ice along 
roadways in the Helena area and along Rogers Pass. Moderating 
temperatures should allow this black ice to melt by mid-morning. 

Locations impacted include...
Helena, Lincoln, East Helena, Wolf Creek, York, Rimini, Spring Meadow
Lake State Park, Austin, Bean Lake, Bowmans Corner, Marysville,
Craig, Canyon Creek and Black Sandy State Park.

This includes the following highways...
 Interstate 15 between mile markers 190 and 239.
 Highway 200 between mile markers 66 and 113.
 Highway 12 between mile markers 28 and 54.
 Highway 287 between mile markers 2 and 24.

LAT...LON 4733 11206 4720 11205 4712 11189 4713 11179
      4692 11179 4691 11163 4684 11164 4679 11149
      4674 11164 4657 11164 4657 11202 4642 11231
      4665 11231 4670 11253 4684 11254 4684 11275
      4689 11280 4717 11279 4717 11304 4733 11306
TIME...MOT...LOC 1418Z 240DEG 49KT 4700 11223 

$$

KJ

The office that day

Everything else NWS Great Falls, MT issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Feb 9, 7:35 PM MST	Areal Flood Advisory	TFX	Beaverhead, Broadwater, Gallatin, Jefferson, Judith Basin, Lewis and Clark and 2 more	15 hr
Feb 9, 10:57 PM MST	Areal Flood Advisory	TFX	Cascade, Glacier, Lewis and Clark, Pondera, Teton, Toole	12 hr
Feb 10, 9:33 AM MST	Special Weather Statement	TFX	Lewis and Clark	3 hr

Nearby

Special Weather Statements in Montana, 2017 Every special weather statement in 2017

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.