[MCD] SWOMCD

Tue Jan 16 05:44:12 UTC 2007

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...

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