Dense Fog in Texas, December 8 to 9, 2007

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LUBBOCK TX
347 PM CST SAT DEC 8 2007

.SHORT TERM...
VERY IMPRESSIVE TEMPERATURE GRADIENT EXISTS OVER THE CWA THIS AFTN
DUE TO SHALLOW COLD AIRMASS...WITH READINGS VARYING FM NEAR 70 OVER
THE FAR SOUTHWEST CWA TO THE MID AND UPR 30S OFF THE CAPROCK. AT 20Z
THE COLD FRONT HAD ALREADY BEGUN MOVING BACK WEST AS NOTED BY TTU
MESONET STATIONS AT SUNDOWN AND SEAGRAVES...AS SFC PRESSURES DROP
OVER SOUTHEAST NEW MEXICO. DURING THE EVENING...THE FRONT WILL
CONTINUE MOVING FARTHER INTO NEW MEXICO AS THE COLD AIR SLOWLY
DEEPENS. EXPECT LOW CLOUDS AND AREAS OF FOG TO SPREAD BACK WEST IN
WAKE OF THE BOUNDARY. AT THIS TIME...DO NOT PLAN ON ISSUING A FOG
ADVISORY BUT VSBYS MAY DROP TO LESS THAN ONE MILE AT TIMES FOR AREAS
ALONG AND WEST OF INTERSTATE 27/HIGHWAY 87.

BY 06Z...WARM AIR ADVECTION/ISENTROPIC LIFT WILL BEGIN TO INCREASE
OVER THE AREA AS WEAK PIECES OF ENERGY EJECT THROUGH THE SOUTHERN
PLAINS FROM THE POWERFUL UPPER TROUGH OVER THE DESERT SOUTHWEST.
SHOULD SEE AREAS OF LIGHT RAIN OR DRIZZLE DEVELOP WITH THE BEST
CHANCES OVER THE NORTHERN AND EASTERN CWA. AS TEMPS SLOWLY DROP TO
FREEZING OR SLIGHTLY BELOW ACRS THAT REGION...THE PRECIP WILL CHANGE
TO FREEZING DRIZZLE/FREEZING RAIN. THIS LOOKS MAINLY TO OCCUR NORTH
OF A LINE FROM NEAR MULESHOE TO ABERNATHY TO GUTHRIE. AT THIS
TIME...DO NOT FORESEE ANY ADVISORIES AS AMOUNTS SHOULD REMAIN VERY
LIGHT AND SHORT DURATION OF FREEZING PRECIP.

FOR SUNDAY...WE EXPECT A LULL IN THE PRECIP DURING THE AFTN AS
THE BULK OF LIFT SHIFTS EAST. OTHERWISE...MOSTLY CLOUDY SKIES AND
CHILLY CONDITIONS WILL PERSIST WITH SHALLOW COLD AIRMASS IN PLACE.
MOST OF THE REGION WILL REMAIN IN THE 30S EXCEPT FOR 40S ACRS THE
SOUTHWEST CORNER WHICH MAY SEE A FEW PEEKS OF SUNSHINE DURG THE
AFTN.

.LONG TERM...
THE POTENTIAL FOR A SIGNIFICANT WINTER STORM WITH ACCUMULATING ICE
EXISTS OVER THE SOUTH/CENTRAL U.S. MONDAY. IT APPEARS OUR AREA WILL
BE NEAR THE SOUTHWESTERN PERIPHERY OF THE THREAT AREA. A WINTER
STORM WATCH IS BEING POSTED.

ANALYSES INDICATE TWO CORES OF ARCTIC AIR TO OUR NORTH...ONE OVER
B.C. AND THE OTHER OVER NORTH DAKOTA/MINNESOTA...WHERE TEMPERATURES
WERE DOWN TO -27 DEGREES F THIS MORNING. THE PERIPHERY OF SAID AIR
MASS IS ALREADY BISECTING WEST TEXAS...AS DISCUSSED ABOVE. VAPOR
IMAGERY/UAA DEPICT A DEEP AND VERY COMPLEX WESTERN U.S. TROUGH.

THE ARCTIC HIGH NOW OVER THE PLAINS WILL SETTLE SOUTHWARD THROUGH
SUNDAY NIGHT...WHEN IT/S SOUTHWARD PUSH WILL BE ENFORCED BENEATH
SHORTWAVE RIDGING IN ADVANCE OF SAID UPPER AIR TROUGH. HOWEVER...AS
HEIGHT/PRESSURE FALLS INCREASE OUT WEST...A PRONOUNCED WAA/
ISENTROPIC UPGLIDE REGIME WILL BECOME ESTABLISHED OVER OUR REGION
LATE SUNDAY NIGHT/EARLY MONDAY. AIDED BY INCREASINGLY DIFFLUENT
FLOW...POSSIBLE JET DYNAMICS...AND AN INFLUX OF ELEVATED SUBTROPICAL
MOISTURE...THE DEPTH OF FORCING/ASCENT AND SATURATION WILL INCREASE
MONDAY SUFFICIENTLY FOR LIGHT TO MODERATE RAINFALL INTO THE SHALLOW
ARCTIC AIRMASS. FORECAST SOUNDINGS INDICATE A CLASSIC FREEZING RAIN/
ICE PROFILE WITH A WELL-DEFINED MID LEVEL WARM NOSE 9 DEGREES C
CENTERED AT THE 800MB LEVEL. HPC QPF GRAPHICS SUGGEST 1 TO 2 INCHES
OF STORM TOTAL PRECIPITATION IN THE FA. THIS COULD EASILY RESULT IN AN
ICE STORM WITH MORE THAN ONE QUARTER OF AN INCH ACCUMULATIONS WITHIN
THE CWA. BROAD/WIDESPREAD NATURE OF THE FORCING MAKES PIN POINTING
AREAS OF BETTER PRECIP POTENTIAL IMPOSSIBLE AT THIS POINT...BUT THE
ENTIRE AREA APPEARS UNDER SUFFICIENT THREAT TO WARRANT A WINTER
STORM WATCH.

IT IS NOTEWORTHY THAT THE GFS SOLUTION WARMS THE LOW LEVEL THERMAL
PROFILE DURING THE DAY MONDAY TO ABOVE FREEZING WITHIN THE STRONG
WAA REGIME. GIVEN SHALLOW/COLD NATURE OF THE ARCTIC AIR AND KNOWN
MODEL BIASES...WE HAVE TRENDED TOWARD THE COLDER WRF-NAM WHICH
MAINTAINS SUBFREEZING TEMPERATURES. ALTHOUGH SOME TRANSITION TO
DRIZZLE OR SLIGHTLY WARMER SURFACE TEMPS MAY TEMPER ACCUMULATIONS OR
TRANSITION TO UNFROZEN CONDITIONS OVER PARTS OF THE FA LATE MONDAY.
PRECIPITATION SHOULD GRADUALLY DIMINISH LATE MONDAY NIGHT/EARLY
TUESDAY FROM WEST TO EAST AS DOWNGLIDE/DRY SLOT BEGIN TO OVERSPREAD
THE REGION.

VERY FEW CHANGES WERE MADE TO THE FORECAST/GRIDS FOR WEDNESDAY AND
BEYOND. STILL EXPECT THAT LIGHT PRECIPITATION...WINTRY AT TIMES...
WILL BE POSSIBLE AT MID WEEK...AS THE MEAN SYNOPTIC SCALE TROUGH
AXIS TRANSLATES EAST OVER THE AREA. TEMPERATURES WILL REMAIN BELOW
SEASONAL AVERAGES WITH THE THEN MODIFIED SURFACE HIGH MAINTAINING AT
LEAST SOME INFLUENCE ON THE REGION/S WEATHER.

&&

.AVIATION...
IFR TO LIFR CIGS WILL PERSIST AT KLBB AND KCDS THROUGHOUT THE NIGHT
WITH VSBYS GRADUALLY LOWERING TO BTWN 1-3 MILES. SOME LIGHT DRIZZLE
OR RAIN IS POSSIBLE MAINLY AFT 06Z...POSSIBLY CHANGING TO FREEZING
PRECIP AT KCDS FM 09-15Z.

&&

.PRELIMINARY POINT TEMPS/POPS...
FRIONA        29  35  21  27  21 /  30  30  40  70  30
TULIA         27  33  21  26  22 /  30  30  40  70  60
PLAINVIEW     29  35  23  26  25 /  30  30  40  70  60
LEVELLAND     32  42  23  29  28 /  20  20  60  70  50
LUBBOCK       31  39  24  27  27 /  20  20  50  70  70
DENVER CITY   34  49  27  30  29 /  20  20  60  70  40
BROWNFIELD    33  44  27  30  30 /  20  20  60  70  60
CHILDRESS     29  34  25  27  26 /  30  30  50  70  70
SPUR          31  36  27  28  28 /  30  30  60  70  70
ASPERMONT     33  39  27  30  29 /  30  30  60  60  70

&&

.LUB WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM LATE SUNDAY NIGHT THROUGH LATE MONDAY
NIGHT FOR THE FOLLOWING ZONES: TXZ021>044.

&&

21/20/21

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE LUBBOCK TX
348 PM CST SAT DEC 8 2007

TXZ021>044-092200-
PARMER-CASTRO-SWISHER-BRISCOE-HALL-CHILDRESS-BAILEY-LAMB-HALE-
FLOYD-MOTLEY-COTTLE-COCHRAN-HOCKLEY-LUBBOCK-CROSBY-DICKENS-KING-
YOAKUM-TERRY-LYNN-GARZA-KENT-STONEWALL-
348 PM CST SAT DEC 8 2007

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE EXTREME SOUTHERN TEXAS
PANHANDLE...SOUTH PLAINS AND ROLLING PLAINS.

.DAY ONE...THIS AFTERNOON AND TONIGHT

NON PRECIPITATION

FOG MAY BECOME LOCALLY DENSE OVER PORTIONS OF THE OUTLOOK AREA
OVERNIGHT...ESPECIALLY FOR AREAS ALONG AND WEST OF THE INTERSTATE
27/HIGHWAY 87 CORRIDOR.

IN ADDITION...LIGHT FREEZING DRIZZLE MAY RESULT IN A LIGHT ICE
GLAZE ON ELEVATED OBJECTS OVER THE EXTREME SOUTHERN PANHANDLE OR
THE NORTHERN SOUTH PLAINS BY MORNING. HOWEVER...PARTICULARLY
HAZARDOUS ICING CONDITIONS ARE NOT ANTICIPATED.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

THE PROBABILITIES OF FREEZING RAIN AND FREEZING DRIZZLE...POSSIBLY
MIXED WITH SLEET...WILL INCREASE LATE SUNDAY NIGHT THROUGH MONDAY.
THE POTENTIAL EXISTS FOR A SIGNIFICANT WINTER STORM WITH ICE
ACCUMULATIONS DURING THE DAY ON MONDAY. ICE ACCUMULATIONS
TOTALING ONE QUARTER OF AN INCH OR MORE WILL BE POSSIBLE. A
WINTER STORM WATCH IS IN EFFECT.

ALTHOUGH THE HEAVIEST WINTER PRECIPITATION WILL LIKELY END LATE
MONDAY NIGHT OR EARLY TUESDAY...LIGHT WINTRY PRECIPITATION WILL
REMAIN POSSIBLE THROUGH MID WEEK.

.SPOTTER INFORMATION STATEMENT...

STORM SPOTTER ACTIVATION WILL NOT BE REQUIRED. HOWEVER...LOCAL
OFFICIALS WITH PUBLIC SAFETY AND DECISION MAKING RESPONSIBILITIES
SHOULD PREPARE NOW FOR IMPACTS FROM A POTENTIALLY SIGNIFICANT
WINTER STORM...INCLUDING THE POSSIBILITY OF ICE ACCUMULATIONS.