Mesoscale Discussion 229

March 18, 2011

The Storm Prediction Center issued this mesoscale discussion at Mar 18, 2011, 2:35 AM CDT. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Mar 18, 2011, 2:35 AM CDT (07:35 UTC)
Expired: Mar 18, 2011, 5:00 AM CDT
In force: 2 hr
Issued by: the Storm Prediction Center

The radar

The Eureka (Bunker Hill) radar (KBHX), 39 km from the middle of the area, began a volume at 07:38 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

Medford/Jackson, OR (KMFR), launched 00:00Z, 7.6 hours before the alert went out and 224 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: 1730 m above ground
0-6 km bulk shear: 15 kt
0-1 km storm-relative helicity: 8 m²/s²
0-3 km storm-relative helicity: 217 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.

856 
ACUS11 KWNS 180735
SWOMCD
SPC MCD 180735 
CAZ000-181000-

MESOSCALE DISCUSSION 0229
NWS STORM PREDICTION CENTER NORMAN OK
0235 AM CDT FRI MAR 18 2011

AREAS AFFECTED...COASTAL NRN CA

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 180735Z - 181000Z

ORGANIZED LINE OF SHOWERS/STORMS ALONG/AHEAD OF THE COLD FRONT WILL
MOVE ONSHORE OVER THE NEXT COUPLE OF HOURS...AND MAY BE CAPABLE OF
LOCAL GUSTS NEAR -- OR SLIGHTLY EXCEEDING -- SEVERE LEVELS.

FRONTAL BAND OF SHOWERS AND EMBEDDED LOW-TOPPED STORMS CONTINUES
APPROACHING THE NRN CA COAST...AND REMAINS FAIRLY WELL-ORGANIZED. 
THOUGH LIGHTNING HAS INCREASED OFFSHORE OVER THE PAST
HOUR...MODIFYING NAM AND RUC MODEL SOUNDINGS FOR
TEMPERATURE/DEWPOINT OBSERVATIONS NEAR THE COAST SUGGESTS
INSTABILITY GENERALLY INSUFFICIENT FOR LIGHTNING.  THIS IS ALSO
CONFIRMED BY OBJECTIVE ANALYSES...REVEALING ONLY OFFSHORE CAPE.  

HOWEVER...WITH THE FRONT MOVING ONSHORE /EXPECTED TO REACH THE COAST
BETWEEN 0830 AND 0900 Z/ AND GIVEN THE ORGANIZED NATURE OF THE
CONVECTION...A FEW STRONGER CONVECTIVE GUSTS MAY BE POSSIBLE LOCALLY
ALONG THE IMMEDIATE COAST...BEFORE CONVECTION WEAKENS INLAND.  ANY
SEVERE POTENTIAL...THOUGH...IS EXPECTED REMAIN LIMITED IN BOTH
COVERAGE AND INTENSITY -- THUS NOT REQUIRING WW ISSUANCE.

..GOSS.. 03/18/2011

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

ATTN...WFO...EKA...

LAT...LON   41652471 41902434 41832401 41292389 41062398 40842398
            40562417 40202416 39522430 39102528 39832517 40192492
            40662496 41102475 41622477 41652471

Nearby

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.