Mesoscale Discussion 71

Issued

Jan 15, 2007, 11:46 PM CST (05:46 UTC)

Expired

Jan 16, 2007, 4:15 AM CST

In force

4 hr

Issued by

the Storm Prediction Center

The Austin/San Antonio radar (KEWX), 46 km from the middle of the area, began a volume at 05:45 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.

000 
ACUS11 KWNS 160546
SWOMCD
SPC MCD 160546 
TXZ000-161015-

MESOSCALE DISCUSSION 0071
NWS STORM PREDICTION CENTER NORMAN OK
1146 PM CST MON JAN 15 2007

AREAS AFFECTED...SOUTH CENTRAL TX/TX HILL COUNTRY INTO SOUTHEAST TX

CONCERNING...WINTER MIXED PRECIPITATION 

VALID 160546Z - 161015Z

FREEZING RAIN/PERHAPS SOME SLEET IS LIKELY TO PERSIST OVERNIGHT
ACROSS MUCH OF SOUTH CENTRAL TX/THE TX HILL COUNTRY INTO SOUTHEAST
TX...INCLUDING A CORRIDOR FROM SAN ANTONIO/AUSTIN TO COLLEGE STATION
AND LUFKIN. LIQUID EQUIVALENTS UP TO 0.05-0.10 IN/HR WILL CONTRIBUTE
TO ADDITIONAL ICE GLAZE AND HAZARDOUS TRAVEL CONDITIONS.

AS COLD ARCTIC AIR BECOMES PROGRESSIVELY ENTRENCHED ACROSS SOUTH
TX...SURFACE WET BULB ZERO C LINE AT 05Z IS ANALYZED FROM NEAR THE
UVALDE-HONDO-SAN ANTONIO CORRIDOR...TO NEAR VICTORIA AND THE
NORTHWEST HOUSTON METRO WITH EASTERN EXTENT. COINCIDENT WITH DEEP
PACIFIC MOISTURE PLUME AND ALIGNED WITH LOW TO MID LEVEL BAROCLINIC
ZONE/FRONTOGENETICAL FORCING...VOLUMETRIC RADAR DATA AND SURFACE
OBSERVATIONS HAVE SHOWN A PERSISTENT BELT OF PRECIPITATION STREAMING
NORTHEASTWARD THIS EVENING OUT OF MEXICO INTO SOUTH
CENTRAL/SOUTHEAST TX.

ALTHOUGH SOMEWHAT LIMITED BY DRY AIR IN THE LOW LEVELS PER SURFACE
OBSERVATIONS AND RECENT ACARS DATA FROM NEAR SAN ANTONIO...LIGHT
FREEZING RAIN/ICE GLAZE HAS BEEN COMMON THIS EVENING ACROSS SOUTH
CENTRAL/SOUTHEAST TX. PER MODEL SOUNDINGS AND THE AFOREMENTIONED
ACARS DATA...FREEZING RAIN SHOULD REMAIN PREDOMINANT OVERNIGHT VIA A
WARM/MELTING LAYER /5-7 DEG C/ ABOVE A SHALLOW SUB-FREEZING LAYER IN
THE LOWEST 1 KM. LIQUID EQUIVALENTS AROUND 0.05 IN/HR HAVE BECOME
MORE COMMON OVER THE PAST HOUR OR TWO PER RECENT OBSERVATIONS AROUND
SAN ANTONIO /KSAT AND KSSF/...SUGGESTING THAT THE DRY LOW LEVELS
HAVE BECOME SATURATED SIMILAR TO FORECAST TRENDS REFLECTED IN 00Z
NAM SOUNDINGS. 00Z NAM/WRM-NMM 4KM GUIDANCE SUGGESTS THIS GENERAL
SOUTHWEST-NORTHEAST BAND OF AT LEAST LIGHT MIXED PRECIPITATION
SHOULD PERSIST THROUGH THE OVERNIGHT...WITH SOME INCREASE/NORTHWARD
SPREAD SUGGESTED OVERNIGHT ACROSS THE HILL COUNTRY...INCLUDING THE
JUNCTION/KERRVILLE TX VICINITIES. PREDOMINANT FREEZING RAIN WITH
LIQUID EQUIVALENTS UP TO 0.10 IN/HR WILL CONTRIBUTE TO FURTHER ICE
GLAZE OVERNIGHT.

..GUYER.. 01/16/2007

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

...NOTICE...
SPC WINTER WEATHER MESOSCALE DISCUSSIONS WILL BE ISSUED ON A
SCHEDULED BASIS FROM DECEMBER 1 THROUGH FEBRUARY 28...FOUR
TIMES A DAY...AROUND 00 UTC...06 UTC...12 UTC...AND 18 UTC
FOR SIGNIFICANT SHORT RANGE WINTER WEATHER EVENTS.

ATTN...WFO...SHV...HGX...FWD...EWX...SJT...

29100042 29690085 30430016 30579750 31609481 30559490
28979807 28849902

Mesoscale Discussions in Texas, 2007Every mesoscale discussion in 2007

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.