Alert archive / Washington / Mesoscale Discussions in 2009

Mesoscale Discussion 13

January 4, 20094 states

The Storm Prediction Center issued this mesoscale discussion at Jan 4, 2009, 11:04 PM MST for 4 states. It was in force for 4 hr.

The area

The outline as issued.

The facts

Issued: Jan 4, 2009, 11:04 PM MST (06:04 UTC)
Expired: Jan 5, 2009, 3:00 AM MST
In force: 4 hr
Issued by: the Storm Prediction Center

All 39 counties

Ada County, ID, Adams County, ID, Benewah County, ID, Boise County, ID, Bonner County, ID, Clearwater County, ID, Gem County, ID, Idaho County, ID, Kootenai County, ID, Latah County, ID, Lewis County, ID, Nez Perce County, ID, Payette County, ID, Shoshone County, ID, Valley County, ID, Washington County, ID, Mineral County, MT, Union County, OR, Wallowa County, OR, Adams County, WA, Asotin County, WA, Chelan County, WA, Columbia County, WA, Douglas County, WA, Ferry County, WA, Garfield County, WA, King County, WA, Kittitas County, WA, Lincoln County, WA, Okanogan County, WA, Pend Oreille County, WA, Pierce County, WA, Skagit County, WA, Snohomish County, WA, Spokane County, WA, Stevens County, WA, Walla Walla County, WA, Whatcom County, WA, Whitman County, WA

The radar

The Pendleton radar (KPDT), 105 km from the middle of the area, began a volume at 06:03 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 00:00Z, 6.1 hours before the alert went out and 187 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: 1307 m above ground
0-6 km bulk shear: 32 kt
0-1 km storm-relative helicity: 110 m²/s²
0-3 km storm-relative helicity: 302 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 050604
SWOMCD
SPC MCD 050604 
IDZ000-MTZ000-ORZ000-WAZ000-051000-

MESOSCALE DISCUSSION 0013
NWS STORM PREDICTION CENTER NORMAN OK
1204 AM CST MON JAN 05 2009

AREAS AFFECTED...PARTS OF WA...NERN ORE AND W-CENTRAL/NRN ID

CONCERNING...HEAVY SNOW 

VALID 050604Z - 051000Z

HEAVY SNOWFALL RATES OF 1 TO 2 INCHES/HR ARE LIKELY AT TIMES THROUGH
12Z OVER PARTS OF WA...NERN ORE AND AFTER 09Z OVER W-CENTRAL/NRN ID.


06Z REGIONAL RADAR MOSAIC INDICATES PRECIPITATION HAS BEGUN TO
OVERSPREAD MUCH OF ERN WA.  SURFACE OBSERVATIONS WITHIN THE PAST
HOUR AT SEA AND EPH ARE REPORTING HEAVY AND MODERATE SNOW
RESPECTIVELY.  THIS HEAVY SNOW REGIME WILL LIKELY CONTINUE EWD AS
STRONG LOW LEVEL WARM ADVECTION IMPLIED BY 00Z/05 UIL RAOB AND AREA
VWP/S WILL CONTINUE TO PUSH INTO INTERIOR WA/ORE.  DESPITE INITIAL
RELATIVELY DRY LOW LEVELS OVER ERN LOCALES...FORECAST SOUNDINGS
INDICATE TOP-DOWN MOISTENING WILL OCCUR RAPIDLY WITH TIME...LEADING
TO A DEEP /AOA 400MB/ SATURATED COLUMN.  THIS WILL BE FAVORABLY
TIMED WITH STRONG UVV/S OVERSPREADING THE REGION FROM THE W. 
ADDITIONAL LIFT DUE TO OROGRAPHIC CONTRIBUTIONS ON SW FACING SLOPES
SHOULD ACT TO ENHANCE PRECIPITATION RATES FURTHER.  LATEST
DETERMINISTIC/ENSEMBLE QPF SUGGEST OCCASIONAL SNOW RATES OF 1 TO 2
INCHES/HR WILL BE COMMON.  SNOWFALL RATES OVER MUCH OF WA ARE
EXPECTED TO WANE FROM W TO E TOWARDS THE END OF THE PERIOD AND AREAS
WILL PROBABLY BEGIN TO CHANGE RAIN IN WRN AREAS AS TEMPS WARM
TOWARDS 12Z.

..SMITH.. 01/05/2009

...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...PIH...MSO...BOI...OTX...PDT...SEW...PQR...

LAT...LON   46691461 45231395 43541494 43391648 45071788 47551916
            47372044 46112131 46042222 48982261 48912041 48661666
            46691461

Nearby

Mesoscale Discussions in Washington, 2009 Mesoscale Discussions in Idaho, 2009 Mesoscale Discussions in Oregon, 2009 Every mesoscale discussion in 2009

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.