Alert archive / California / Mesoscale Discussions in 2012

Mesoscale Discussion 2127

November 29, 2012Del Norte County, Humboldt County, California

The Storm Prediction Center issued this mesoscale discussion at Nov 29, 2012, 4:19 AM PST for Del Norte County, Humboldt County, California. It was in force for 86 min.

The area

The outline as issued.

The facts

Issued
Nov 29, 2012, 4:19 AM PST (12:19 UTC)
Expired
Nov 29, 2012, 5:45 AM PST
In force
86 min
Issued by
the Storm Prediction Center
Chance of a watch
5%

Counties Del Norte County, CA, Humboldt County, CA

The radar

The Eureka (Bunker Hill) radar (KBHX), 50 km from the middle of the area, began a volume at 12:19 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 12:00Z, 0.3 hours before the alert went out and 197 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, Medford/Jackson, OR at 12:00Z on 2012-11-29Temperature 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, Medford/Jackson, OR at 12:00Z on 2012-11-29The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 219 square meters per square second.1939587897117136Sfc1 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
1805 m above ground
0-6 km bulk shear
67 kt
0-1 km storm-relative helicity
219 m²/s²
0-3 km storm-relative helicity
489 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.

458 
ACUS11 KWNS 291219
SWOMCD
SPC MCD 291219 
CAZ000-ORZ000-291345-

MESOSCALE DISCUSSION 2127
NWS STORM PREDICTION CENTER NORMAN OK
0619 AM CST THU NOV 29 2012

AREAS AFFECTED...COASTAL AREAS OF FAR NORTHERN CA

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 291219Z - 291345Z

PROBABILITY OF WATCH ISSUANCE...5 PERCENT

SUMMARY...CONVECTIVELY ENHANCED WIND GUSTS ASSOCIATED WITH
LOW-TOPPED TSTMS MAY OCCUR EARLY THIS MORNING IN COASTAL AREAS OF
FAR NORTHERN CA. NO CONVECTIVE WATCH IS EXPECTED.

DISCUSSION...EARLY THIS MORNING...IR SATELLITE/RADAR IMAGERY SHOW A
MULTI-SEGMENTED LOW-TOPPED CONVECTIVE LINE STEADILY NEARING THE
COAST OF NORTHERN CA...ROUGHLY 25-45 MILES WEST OF THE COAST AS OF
1215Z. IN SPITE OF VERY MINIMAL INSTABILITY...ESTIMATED TO BE LESS
THAN 100 J/KG OF SBCAPE...THE LOW-TOPPED CONVECTIVE LINE IS
WELL-ORGANIZED WITH A SHARP REFLECTIVITY GRADIENT AND EMBEDDED SMALL
BOWING STRUCTURES. ESPECIALLY GIVEN THAT SOME EMBEDDED UPDRAFTS ARE
STOUT ENOUGH TO PRODUCE LIGHTNING /PER RECENT TRENDS/...CONVECTIVELY
ENHANCED WIND GUSTS MAY OCCUR GIVEN THE VERY STRONG WIND PROFILES IN
ASSOCIATION WITH THE APPROACHING CONVECTIVE LINE. WSR-88D VWP DATA
FROM EUREKA/KBHX IS INDICATIVE OF 60+ KT SOUTH-SOUTHWESTERLY WINDS
WITHIN THE LOWEST 2-3 KM.

..GUYER/HART.. 11/29/2012

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

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

LAT...LON   41072502 41922464 42112385 41662356 41032346 40112344
            39602405 39972497 41072502

Nearby

Mesoscale Discussions in California, 2012Every mesoscale discussion in 2012

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.