Alert archive / Washington / Mesoscale Discussions in 2004

Mesoscale Discussion 484

April 27, 2004King County, Washington

The Storm Prediction Center issued this mesoscale discussion at Apr 27, 2004, 4:22 PM PDT for King County, Washington. It was in force for 113 min.

The area

The outline as issued.

The facts

Issued
Apr 27, 2004, 4:22 PM PDT (23:22 UTC)
Expired
Apr 27, 2004, 6:15 PM PDT
In force
113 min
Issued by
the Storm Prediction Center

County King County, WA

The radar

The Seattle radar (KATX), 99 km from the middle of the area, began a volume at 23:25 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

Quillayute State, WA (KUIL), launched 12:00Z, 11.4 hours before the alert went out and 206 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, Quillayute State, WA at 12:00Z on 2004-04-27Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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, Quillayute State, WA at 12:00Z on 2004-04-27The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 0 square meters per square second.1939Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1526 m above ground
0-6 km bulk shear
0 kt
0-1 km storm-relative helicity
0 m²/s²
0-3 km storm-relative helicity
0 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.

282 
ACUS11 KWNS 272322
SWOMCD
SPC MCD 272322 
WAZ000-280115-

MESOSCALE DISCUSSION 0484
NWS STORM PREDICTION CENTER NORMAN OK
0622 PM CDT TUE APR 27 2004

AREAS AFFECTED...WRN WA

CONCERNING...SEVERE THUNDERSTORM POTENTIAL 

VALID 272322Z - 280115Z

ISOLATED TSTMS DEVELOPING ALONG PSCZ AND AHEAD OF STRONG COLD FRONT
COULD POSE A THREAT OF DAMAGING WINDS AND SMALL HAIL OVER THE NEXT
COUPLE OF HOURS.

RADAR COMPOSITE IMAGERY WAS INDICATING A BACKBUILDING SEGMENT OF
LINEAR CONVECTION INCREASING ALONG STRONG PUGET SOUND CONVERGENCE
ZONE ACROSS NRN KING COUNTY. POTENT UPPER TROUGH WILL CONTINUE TO
AID DEEP ASCENT ACROSS THE REGION THROUGH EVENING WITH STRONG
MESOSCALE FORCING RESULTING IN LOW-TOPPED TSTMS IN WEAKLY UNSTABLE
ENVIRONMENT. AS MID LEVEL TEMPERATURES AND FREEZING LEVEL FALL
RAPIDLY WITHIN THE MID LEVEL TROUGH...A FEW OF THE STORMS COULD
PRODUCE SMALL HAIL. IN ADDITION...ALREADY STRONG GRADIENT WINDS MAY 
BE LOCALLY ENHANCED BY BOTH TOPOGRAPHY AND CONVECTIVE OVERTURNING
RESULTING IN A FEW STRONGER...PERHAPS DAMAGING...WIND GUSTS.

..CARBIN.. 04/27/2004

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

ATTN...WFO...PDT...SEW...

47172127 47082184 47022274 47412267 47742231 47792166
47842125

Nearby

Mesoscale Discussions in Washington, 2004Every mesoscale discussion in 2004

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.