Alert archive / Texas / Mesoscale Discussions in 2012

Mesoscale Discussion 9

January 9, 201214 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Jan 9, 2012, 6:51 AM CST for 14 counties in Texas. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued: Jan 9, 2012, 6:51 AM CST (12:51 UTC)
Expired: Jan 9, 2012, 11:45 AM CST
In force: 5 hr
Issued by: the Storm Prediction Center

Counties Andrews County, TX, Borden County, TX, Crane County, TX, Dawson County, TX, Ector County, TX, Garza County, TX, Glasscock County, TX, Howard County, TX, Martin County, TX, Midland County, TX, Pecos County, TX, Reagan County, TX, Scurry County, TX, Upton County, TX

The radar

The Midland/Odessa radar (KMAF), 19 km from the middle of the area, began a volume at 12:52 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

Midland Regional, TX (KMAF), launched 12:00Z, 0.9 hours before the alert went out and 20 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: 2 J/kg
Mixed-layer CIN: 0 J/kg
Mixed-layer LCL: 521 m above ground
0-6 km bulk shear: 51 kt
0-1 km storm-relative helicity: 123 m²/s²
0-3 km storm-relative helicity: 80 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

438 
ACUS11 KWNS 091251
SWOMCD
SPC MCD 091251 
TXZ000-091745-

MESOSCALE DISCUSSION 0009
NWS STORM PREDICTION CENTER NORMAN OK
0651 AM CST MON JAN 09 2012

AREAS AFFECTED...PORTIONS W TX.

CONCERNING...HEAVY SNOW 

VALID 091251Z - 091745Z

RAIN-SNOW TRANSITION HAS BEGUN OVER LOWER PECOS REGION GENERALLY
FROM INK-FST.  PRIND RATES WILL INCREASE TO 1-2 INCHES/HOUR IN
INCREASINGLY WELL-ORGANIZED PRECIP BAND INITIALLY EXTENDING FROM WRN
PECOS COUNTY NWD OVER WINKLER COUNTY.  EMBEDDED TSTMS WILL OFFER
LOCALIZED/BRIEF RATES ABOVE 2 INCHES/HOUR.

SNOW AREA SHOULD PIVOT CYCLONICALLY IN KEEPING WITH EWD SHIFT OF
MID-UPPER LOW...WHILE EXPANDING IN COVERAGE BENEATH ELEVATED MOIST
CONVEYOR.  THIS WILL OCCUR AS STRONGEST DEEP-LAYER ASCENT WITHIN
OPTIMAL DENDRITIC-GROWTH LAYER MOVES ACROSS REGION.  EXPECT INCREASE
IN SNOW RATES OVER MAF AREA AND NWD/NEWD TOWARD PORTIONS
GARZA/LYNN/TERRY COUNTIES...WHILE HEAVY SNOW AREA SNOW
EXPANDS/SHIFTS EWD ACROSS PORTIONS PECOS/CROCKETT/REAGAN/
GLASSCOCK/HOWARD COUNTIES THROUGH 16Z.  SFC TEMPS WILL CONTINUE TO
DECREASE THROUGH MID-LOW 30S F FROM W-E...FROM COMBINATION OF
BOUNDARY-LAYER CAA...WEAK WET-BULB COOLING...AND COLUMNAR DYNAMIC
COOLING.  MEANWHILE RELATIVE WARM LAYER BETWEEN 700-800 MB WILL
CONTINUE TO COOL...WHILE RH INCREASES WITHIN DENDRITIC GROWTH COLUMN
AS WELL.  THESE PROCESSES WILL FOSTER RAIN-SNOW CHANGEOVER IN ERN
PARTS OF DISCUSSION AREA...AND MAINTAIN SNOW AS DOMINANT
WINTER-PRECIP PHASE.  OBSERVED 12Z MAF SOUNDING AND MODIFIED RUC
FCST SOUNDINGS INDICATE THIS TREND...AS WELL AS SUFFICIENTLY STEEP
MIDLEVEL LAPSE RATES TO SUPPORT MUCAPE 100-300 J/KG ROOTED NEAR 700
MB AND EXTENDING INTO ICING LAYERS SUITABLE FOR LTG GENERATION. 
THEREFORE OCNL THUNDERSNOW IS EXPECTED OVER MORE OF AREA...WITH LTG
ALREADY DETECTED BETWEEN MAF-FST.

..EDWARDS.. 01/09/2012

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

ATTN...WFO...SJT...LUB...MAF...

LAT...LON   30490278 30930310 31790306 32550272 33030231 33160177
            33270107 32860077 32030119 31450130 30970160 30560229
            30490278

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jan 9, 1:29 AM CST	Mesoscale Discussion	SPC	Aransas, Austin, Bee, Brazoria, Calhoun, Chambers and 23 more	3 hr
Jan 9, 5:59 AM CST	Mesoscale Discussion	SPC	Atascosa, Austin, Bandera, Bastrop, Bexar, Blanco and 43 more	3 hr
Jan 9, 9:33 AM CST	Mesoscale Discussion	SPC	Brazoria, Chambers, Fort Bend, Galveston, Hardin, Harris and 9 more	117 min

Nearby

Mesoscale Discussions in Texas, 2012 Every 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.