Alert archive

Mesoscale Discussion 145

February 25, 2011

The Storm Prediction Center issued this mesoscale discussion at Feb 25, 2011, 11:53 PM CST. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued
Feb 25, 2011, 11:53 PM CST (05:53 UTC)
Expired
Feb 26, 2011, 6:00 AM CST
In force
6 hr
Issued by
the Storm Prediction Center

The radar

The Santa Ana Mts radar (KSOX), 85 km from the middle of the area, began a volume at 05:55 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

San Diego, CA (KNKX), launched 00:00Z, 5.9 hours before the alert went out and 112 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, San Diego, CA at 00:00Z on 2011-02-26Temperature 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, San Diego, CA at 00:00Z on 2011-02-26The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -40 square meters per square second.1939587897Sfc1 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
1246 m above ground
0-6 km bulk shear
57 kt
0-1 km storm-relative helicity
-40 m²/s²
0-3 km storm-relative helicity
75 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.

139 
ACUS11 KWNS 260553
SWOMCD
SPC MCD 260553 
CAZ000-261200-

MESOSCALE DISCUSSION 0145
NWS STORM PREDICTION CENTER NORMAN OK
1153 PM CST FRI FEB 25 2011

AREAS AFFECTED...SWRN CA MOUNTAINS

CONCERNING...HEAVY SNOW 

VALID 260553Z - 261200Z

SNOW WILL SPREAD SWD ACROSS THE MOUNTAINS OF SWRN CA OVERNIGHT
TONIGHT INTO SATURDAY MORNING WITH RATES OF 2 INCHES PER HOUR
ANTICIPATED. SNOW LEVELS ARE EXPECTED TO FALL TOWARD LOWER
ELEVATIONS DURING THE MORNING HOURS ON SATURDAY.

VIGOROUS ASCENT IN ASSOCIATION WITH DEEP-LAYER LOW PRESSURE DROPPING
S-SEWD NEAR THE WRN CA COAST WILL CAUSE PRECIPITATION TO SHIFT SWD
ACROSS THE SWRN CA MOUNTAINS OVERNIGHT TONIGHT INTO SATURDAY
MORNING. AS STRONG LOW/MID-LEVEL W-SWLY FLOW /AOA 70 KT AT 500 MB
PER RUC ANALYSIS/ IMPINGES ON THE MOUNTAINS OF SWRN CALIFORNIA...AND
COMBINES WITH A PLUME OF DEEP-LAYER MOISTURE CHARACTERIZED BY PWAT
VALUES OF 0.50 TO 0.75 INCH...PRECIPITATION RATES WILL INTENSIFY
TONIGHT. WHILE MOST OF THE SNOW WILL INITIALLY BE CONFINED TO THE
HIGHER MOUNTAIN ELEVATIONS...SNOW LEVELS WILL LOWER TOWARD LOWER
ELEVATIONS SATURDAY MORNING WITH THE APPROACH OF THE LOW AND COLDER
TEMPERATURES ALOFT. THE STRONG UPSLOPE FLOW AND DEEP-LAYER FORCING
WILL FAVOR SNOWFALL RATES OF 2 INCHES PER HOUR ACROSS THE DISCUSSION
AREA. THE SNOW IS FORECAST TO PERSIST INTO SATURDAY MORNING PER THE
03Z RUN OF THE EXPERIMENTAL HRRR.

..COHEN.. 02/26/2011

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

ATTN...WFO...PSR...VEF...SGX...LOX...

LAT...LON   32751641 32841659 33131670 33301687 33441695 33581682
            33871688 34091701 34211726 34241768 34181797 34411804
            34471732 34311666 34211633 34121612 33991605 33921618
            33981645 33961656 33841656 33731643 33601629 33451631
            33351639 32841629 32751641

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.