Alert archive / Minnesota / Mesoscale Discussions in 2016

Mesoscale Discussion 1817

November 18, 201619 counties in Minnesota

The Storm Prediction Center issued this mesoscale discussion at Nov 18, 2016, 6:14 AM CST for 19 counties in Minnesota. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued: Nov 18, 2016, 6:14 AM CST (12:14 UTC)
Expired: Nov 18, 2016, 11:15 AM CST
In force: 5 hr
Issued by: the Storm Prediction Center

Counties Aitkin County, MN, Becker County, MN, Big Stone County, MN, Cass County, MN, Crow Wing County, MN, Douglas County, MN, Grant County, MN, Hubbard County, MN, Itasca County, MN, Morrison County, MN, Otter Tail County, MN, Pope County, MN, Saint Louis County, MN, Stevens County, MN, Swift County, MN, Todd County, MN, Traverse County, MN, Wadena County, MN, Wilkin County, MN

The radar

The Duluth radar (KDLH), 167 km from the middle of the area, began a volume at 12:16 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

International Fa, MN (KINL), launched 12:00Z, 0.2 hours before the alert went out and 218 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: 668 m above ground
0-6 km bulk shear: 70 kt
0-1 km storm-relative helicity: 128 m²/s²
0-3 km storm-relative helicity: 267 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

188 
ACUS11 KWNS 181215
SWOMCD
SPC MCD 181214 
MNZ000-SDZ000-NDZ000-181715-

MESOSCALE DISCUSSION 1817
NWS STORM PREDICTION CENTER NORMAN OK
0614 AM CST FRI NOV 18 2016

AREAS AFFECTED...CENTRAL AND NORTHERN MN

CONCERNING...HEAVY SNOW 

VALID 181214Z - 181715Z

SUMMARY...SNOWFALL RATES WILL INCREASE TO 1-2 INCHES PER HOUR ACROSS
CENTRAL AND NORTHERN PORTIONS OF MINNESOTA THROUGH LATE MORNING.
REDUCTIONS IN VISIBILITY AND NEAR-BLIZZARD CONDITIONS ARE POSSIBLE.

DISCUSSION...A LOW-LEVEL CYCLONE CONTINUES TO DEEPEN WHILE ADVANCING
NEWD INTO NORTHERN IA AND SOUTHERN MN THIS MORNING WHERE SURFACE
PRESSURE FALLS ON THE ORDER OF 1-2 MB PER 2 HOURS WERE OBSERVED AT
12Z. RECENT RADAR TRENDS INDICATE AN INCREASE IN PRECIPITATION HAS
OCCURRED OVER THE PAST 2 HOURS...PRIMARILY AS SNOWFALL NORTH OF 46N.
SLIGHTLY WARMER TEMPERATURES ARE PRESENT ACROSS CENTRAL MN...BUT NLY
SURFACE WINDS SHOULD GRADUALLY ADVECT SUB-FREEZING TEMPERATURES
SOUTHWARD AND SUPPORT A CHANGEOVER TO SNOW THROUGH 14-15Z.  

STRENGTHENING LOW-LEVEL WINDS AND BACKING WINDS E OF THE CYCLONE
WILL RESULT IN INCREASED FRONTOGENETIC FORCING FOR ASCENT FOCUSED N
OF THE CYCLONE ACROSS CNTRL/NRN MN....WHILE A BROADER PLUME OF
ASCENT ASSOCIATED WITH THE MIDLEVEL SHORTWAVE TROUGH CONTINUES TO
SPREAD NEWD. MODEL FORECAST SOUNDINGS ALSO SUGGEST A DEEPENING OF AN
ISOTHERMAL LAYER NEAR 2 KM AGL WILL OCCUR. THIS WILL CORRESPOND WITH
AN INCREASE IN SNOWFALL RATES...WITH WIDESPREAD 1 INCH PER HOUR TO
LOCALLY 2 INCHES PER HOUR POSSIBLE. A TIGHTENING SURFACE PRESSURE
GRADIENT WILL ALSO RESULT IN SUSTAINED WIND SPEEDS OF 20-30 MPH AND
COULD FAVOR REDUCTIONS IN VISIBILITY WITH LOCALIZED BLIZZARD
CONDITIONS POSSIBLE.

..ROGERS.. 11/18/2016

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

ATTN...WFO...DLH...MPX...FGF...ABR...

LAT...LON   47289230 46699318 45459506 45139621 45489666 46289656
            47289589 47749435 47879327 47799257 47289230

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Nov 18, 2:42 AM CST	Mesoscale Discussion	SPC	Lac qui Parle, Lincoln	4 hr
Nov 18, 11:22 AM CST	Mesoscale Discussion	SPC	Aitkin, Benton, Carlton, Cass, Chippewa, Crow Wing and 19 more	5 hr

Nearby

Mesoscale Discussions in Minnesota, 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.