Alert archive / Oregon / Mesoscale Discussions in 2011

Mesoscale Discussion 103

February 15, 20115 counties in Oregon; Pacific County, Washington

The Storm Prediction Center issued this mesoscale discussion at Feb 15, 2011, 11:39 AM PST for 5 counties in Oregon; Pacific County, Washington. It was in force for 96 min.

The area

The outline as issued.

The facts

Issued: Feb 15, 2011, 11:39 AM PST (19:39 UTC)
Expired: Feb 15, 2011, 1:15 PM PST
In force: 96 min
Issued by: the Storm Prediction Center

Counties Clatsop County, OR, Coos County, OR, Lincoln County, OR, Polk County, OR, Tillamook County, OR, Pacific County, WA

The radar

The Portland,OR radar (KRTX), 146 km from the middle of the area, began a volume at 19:40 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

Salem/Mcnary, OR (KSLE), launched 12:00Z, 7.7 hours before the alert went out and 88 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: 591 m above ground
0-6 km bulk shear: 91 kt
0-1 km storm-relative helicity: 165 m²/s²
0-3 km storm-relative helicity: 171 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.

334 
ACUS11 KWNS 151939
SWOMCD
SPC MCD 151939 
ORZ000-WAZ000-152115-

MESOSCALE DISCUSSION 0103
NWS STORM PREDICTION CENTER NORMAN OK
0139 PM CST TUE FEB 15 2011

AREAS AFFECTED...SWRN WA / ORE COASTS

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 151939Z - 152115Z

TSTMS ARE EXPECTED TO INCREASE IN COVERAGE THIS AFTERNOON ALONG THE
IMMEDIATE COAST WITH SOME RISK FOR ISOLATED SEVERE WEATHER.  A WW IS
NOT ANTICIPATED.

LATEST TRENDS IN LIGHTNING AND REGIONAL RADAR DATA INDICATE A
NOTABLE INCREASE IN TSTM DEVELOPMENT OFF THE ORE COAST SW OF AST. 
INSPECTION OF WATER VAPOR IMAGERY SUGGESTS THAT THIS ACTIVITY IS
OCCURRING WITHIN A ZONE OF DEEP-LAYER FORCING FOR ASCENT ASSOCIATED
WITH SHORT-WAVE TROUGH LIFTING NEWD TOWARD NWRN WA AND VANCOUVER
ISLAND.  BREAKS IN COVER OBSERVED NEAR THE MOUTH OF THE COLUMBIA
RIVER SHOULD ALLOW FOR LOCALLY STRONGER DIABATIC HEATING TO OCCUR
THIS AFTERNOON.  WHEN COUPLED WITH THE DYNAMIC MIDLEVEL COOLING
ATTENDANT TO VORTICITY MAXIMUM...EXPECT FURTHER STEEPENING OF LAPSE
RATES TO OCCUR...SUPPORTING SBCAPE VALUES OF 100-200 J/KG.

ISALLOBARIC RESPONSE TO PRIMARY SURFACE LOW OFF THE WA COAST IN
CONJUNCTION WITH OROGRAPHICALLY BACKED LOW-LEVEL FLOW ALONG THE
COLUMBIA RIVER VALLEY ARE EXPECTED TO MAINTAIN A VERTICALLY VEERING
WIND PROFILE THIS AFTERNOON WITH MORE THAN SUFFICIENT LOW AND
DEEP-LAYER SHEAR FOR UPDRAFT ROTATION.  THE MARGINAL INSTABILITY
WILL REMAIN A LIMITING INGREDIENT FOR A MORE ROBUST SEVERE WEATHER
EPISODE.  HOWEVER...ANY MORE PERSISTENT STORMS WILL BE CAPABLE OF
LOCALLY STRONG WIND GUSTS...SOME SMALL HAIL AND PERHAPS A BRIEF
TORNADO/WATERSPOUT.

..MEAD.. 02/15/2011

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

ATTN...WFO...MFR...SEW...PQR...

LAT...LON   42632429 43252469 44722426 45802429 46622442 47092393
            46462346 45172332 43762361 42912390 42632429

Nearby

Mesoscale Discussions in Oregon, 2011 Mesoscale Discussions in Washington, 2011 Every mesoscale discussion in 2011

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.