Alert archive / Idaho / Mesoscale Discussions in 2008

Mesoscale Discussion 2413

December 6, 20089 counties in Idaho; 8 counties in Montana; Pend Oreille County, Spokane County, Washington

The Storm Prediction Center issued this mesoscale discussion at Dec 6, 2008, 4:20 AM PST for 9 counties in Idaho; 8 counties in Montana; Pend Oreille County, Spokane County, Washington. It was in force for 4 hr.

The area

The outline as issued.

The facts

Issued: Dec 6, 2008, 4:20 AM PST (12:20 UTC)
Expired: Dec 6, 2008, 8:15 AM PST
In force: 4 hr
Issued by: the Storm Prediction Center

Counties Benewah County, ID, Bonner County, ID, Boundary County, ID, Clearwater County, ID, Idaho County, ID, Kootenai County, ID, Latah County, ID, Lewis County, ID, Shoshone County, ID, Flathead County, MT, Granite County, MT, Lake County, MT, Lincoln County, MT, Mineral County, MT, Missoula County, MT, Ravalli County, MT, Sanders County, MT, Pend Oreille County, WA, Spokane County, WA

The radar

The Missoula radar (KMSX), 88 km from the middle of the area, began a volume at 12:23 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

Spokane, WA (KOTX), launched 12:00Z, 0.3 hours before the alert went out and 114 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: 1508 m above ground
0-6 km bulk shear: 62 kt
0-1 km storm-relative helicity: 317 m²/s²
0-3 km storm-relative helicity: 410 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 061221
SWOMCD
SPC MCD 061220 
MTZ000-IDZ000-WAZ000-061615-

MESOSCALE DISCUSSION 2413
NWS STORM PREDICTION CENTER NORMAN OK
0620 AM CST SAT DEC 06 2008

AREAS AFFECTED...NERN WA/NRN ID/PARTS OF WRN MT

CONCERNING...FREEZING RAIN 

VALID 061220Z - 061615Z

LIGHT FREEZING RAIN...APPROACHING AND/OR LOCALLY EXCEEDING 0.05
INCH/3 HOURS...WILL DECREASE ACROSS NERN WA IN THE NEXT 1-2
HOURS...BUT PERSIST THROUGH THE MORNING IN THE VALLEYS OF NRN ID
INTO PARTS OF W/NWRN MT WHERE SURFACE TEMPERATURES ARE AOB 32 F.

WATER VAPOR IMAGERY/MODEL GUIDANCE SUGGESTED A MID LEVEL SPEED MAX
/80 KT/ WAS CURRENTLY TOPPING THE RIDGE OVER THE NRN ROCKIES. 
ASCENT WITHIN THE ENTRANCE REGION OF THIS FEATURE COMBINED WITH
PACIFIC MOISTURE HAS RESULTED IN PERIODS OF MAINLY LIGHT FREEZING
RAIN OVER ERN WA INTO WRN MT DURING THE OVERNIGHT HOURS.  THE AREA
OF ASCENT IS FORECAST TO SPREAD ACROSS WRN/CENTRAL MT THIS MORNING
INTO THE AFTERNOON...AND THUS MAINTAIN THE POTENTIAL FOR ADDITIONAL
PRECIPITATION ACROSS NRN ID AND W/NWRN MT THROUGH 18Z.  FORECAST
SOUNDINGS SUGGEST THE LOW LEVEL THERMODYNAMIC STRATIFICATION WILL
SUPPORT THE POTENTIAL FOR ADDITIONAL FREEZING RAIN...ESPECIALLY IN
THE VALLEYS WHERE SURFACE TEMPERATURES ARE AOB 32 F.

FORECAST SOUNDINGS ALSO INDICATED A W-E DRYING TREND IN THE LOW-MID
LEVELS AS THE STRONGER FORCING FOR ASCENT SPREADS ESEWD.  THIS WOULD
SUGGEST THAT ANY FREEZING PRECIPITATION SHOULD END BY 12-14Z ACROSS
ERN WA AND AFTER 18Z ACROSS WRN MT.  THE LAST TWO RUNS OF THE SREF
/21Z AND 03Z/ SUPPORT THIS SCENARIO OF FREEZING PRECIPITATION ENDING
IN ERN WA AFTER 12Z AND ACROSS WRN MT AFTER 18Z.

..PETERS.. 12/06/2008

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

...NOTICE...
SPC WINTER WEATHER MESOSCALE DISCUSSIONS WILL BE ISSUED ON A
SCHEDULED BASIS FROM DECEMBER 1 THROUGH FEBRUARY 28...FOUR
TIMES A DAY...AROUND 00 UTC...06 UTC...12 UTC...AND 18 UTC
FOR SIGNIFICANT SHORT RANGE WINTER WEATHER EVENTS.

ATTN...WFO...TFX...MSO...BOI...OTX...

LAT...LON   49031404 47001331 45821316 44901403 45421554 46641701
            47651780 48791729 49031404

Nearby

Mesoscale Discussions in Idaho, 2008 Mesoscale Discussions in Montana, 2008 Mesoscale Discussions in Washington, 2008 Every mesoscale discussion in 2008

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.