Winter Weather in Texas, November 16, 2014

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE AMARILLO TX
1106 PM CST SAT NOV 15 2014

.AVIATION...
06Z TAFS...CONDITIONS WILL DETERIORATE OVERNIGHT INTO SUNDAY AS LOW
CLOUDS AND SNOW SPREAD SOUTH/SOUTHEAST. MVFR CIGS CURRENTLY AT KGUY
WILL FILL IN AT KDHT AND KAMA OVER THE NEXT FEW HOURS. CIGS AND VSBYS
WILL FURTHER DROP OVERNIGHT TO LOW MVFR AND IFR LEVELS AS SNOW
SPREADS SOUTHEAST. MOST LIKELY TIMEFRAME FOR SNOW LOOKS TO BE 08-17Z
AT KGUY...08-18Z AT KDHT...AND 11-21Z AT KAMA. VFR CONDITIONS WILL
RETURN FROM NORTH TO SOUTH LATE SUNDAY MORNING INTO SUNDAY AFTERNOON
AS THE SNOW ENDS AND SKIES BEGIN TO CLEAR AS STRONG SUBSIDENCE
OVERSPREADS THE AREA IN WAKE OF THE DEPARTING UPPER-LEVEL TROUGH.
NORTHEAST WINDS WILL BLOW AT 15-20 KTS WITH GUSTS UP TO 30 KTS MUCH
OF THE NIGHT...BEFORE GRADUALLY DIMINISHING FROM NORTH TO SOUTH ON
SUNDAY AS SURFACE HIGH PRESSURE BUILDS IN.

KB

&&

.PREV DISCUSSION... /ISSUED 925 PM CST SAT NOV 15 2014/

UPDATE...
FORECAST FOR THE REST OF TONIGHT AND SUNDAY STILL LOOKS ON TRACK.
MADE SOME TWEAKS TO POPS AND SNOWFALL AMOUNTS...BUT NOTHING REAL
SIGNIFICANT. STILL GENERALLY EXPECTING STORM TOTAL SNOWFALL
ACCUMULATIONS OF 1-3 INCHES...WITH LOCALLY HIGHER AMOUNTS POSSIBLE IN
STRONGER/MORE PERSISTENT MESOSCALE BANDING.

EXPECT SNOW CURRENTLY FALLING OVER CO AND EASTERN KS TO BEGIN TO
MOVE INTO THE WESTERN OK PANHANDLE CLOSER TO MIDNIGHT. SNOW WILL THEN
GRADUALLY EXPAND SOUTH OVERNIGHT AND SUNDAY MORNING...BEFORE TAPERING
OFF FROM NORTH TO SOUTH SUNDAY AFTERNOON. MODEL DIV Q FIELDS CONTINUE
TO SHOW A PERIOD OF NICE SYNOPTIC SCALE LIFT WORKING ACROSS THE AREA
LATE TONIGHT AND SUNDAY AHEAD OF THE MID/UPPER-LEVEL SHORTWAVE
CURRENTLY DROPPING SOUTHEAST INTO UT. IMPOSED ON THIS BROADER REGION
OF ASCENT WILL BE A MESOSCALE BAND OF MID-LEVEL FRONTOGENETIC FORCING
PROGGED TO SLIDE SOUTH ACROSS THE PANHANDLES OVERNIGHT AND SUNDAY. AS
IS ALWAYS THE CASE WITH EVENTS WHERE ENHANCED MESOSCALE BANDING IS
EXPECTED...IT/S DIFFICULT TO IDENTIFY THE AREAS OF POSSIBLE LOCALIZED
HIGHER AMOUNTS. ONE AREA OF CONCERN IS THE SOUTHWEST TX
PANHANDLE...AS SOME MODELS SUCH AS THE NAM/GFS/TTU WRF SHOW SOME
ENHANCED FRONTOGENETIC FORCING DEVELOPING AND SWEEPING ACROSS THIS AREA
DURING LATE MORNING OR EARLY AFTERNOON. HOWEVER...THE ECMWF AND CMC
GEM ON THE OTHER HAND SHOW A GRADUAL WEAKENING OF THE MID-LEVEL
FRONTOGENETIC FORCING AS IT SLIDES SOUTH. DID BUMP UP SNOW AMOUNTS
CLOSER TO 2 INCHES IN THE SOUTHWEST TX PANHANDLE TO ACCOUNT FOR THIS
ENHANCED BANDING POTENTIAL...AS A QUICK BURST OF HIGHER SNOWFALL RATES
WOULD RESULT IF IT DOES INDEED MATERIALIZE. ALSO BUMPED UP AMOUNTS A
LITTLE IN THE WESTERN OK PANHANDLE WHERE IT LOOKS LIKE SOME ENHANCED
BANDING WILL DEVELOP OVERNIGHT. THE SNOW SHOULD END BY LATE
AFTERNOON/EARLY EVENING TOMORROW AS STRONG SUBSIDENCE SWEEPS ACROSS
THE AREA BEHIND THE MID/UPPER-LEVEL SHORTWAVE TROUGH AXIS.

KB

PREV DISCUSSION... /ISSUED 303 PM CST SAT NOV 15 2014/

DISCUSSION...

EARLY THIS AFTERNOON TEMPERATURES HAD WARMED SIGNIFICANTLY ACROSS
THE WESTERN PORTION OF THE FORECAST AREA WHERE WINDS HAVE BECOME
WESTERLY/DOWNSLOPE. BETWEEN DEPARTING SHORTWAVE TROUGH TO THE EAST
AND UPSTREAM SHORTWAVE...SKIES HAVE CLEARED ACROSS THE AREA. WINDS
HAVE ALREADY SHIFTED TO THE NORTH AT OBS IN THE OKLAHOMA PANHANDLE
BEHIND THE COLD FRONT AND TEMPERATURES ARE CONSIDERABLY COOLER
RESULTING IN A FAIRLY WIDE RANGE ACROSS THE FORECAST AREA THIS
AFTERNOON. A SIGNIFICANT COLD SURGE WILL ARRIVE LATER THIS EVENING
AND TONIGHT WITH SUFFICIENT PRESSURE RISES TO ALLOW FOR A PERIOD OF
20-30 MPH NORTHERLY WINDS WITH GUSTS APPROACHING 40 MPH. THE SURFACE
PRESSURE GRADIENT WILL RELAX LATER TONIGHT AND WIND SPEEDS WILL
DECREASE TOWARD MORNING.

CURRENT WATER VAPOR IMAGERY CLEARLY SHOWS AN EAST TO WEST ORIENTED
TROUGH ACROSS NORTHERN PLAINS AND NORTHERN ROCKIES. MODELS ARE ALL
IN REASONABLY GOOD AGREEMENT WITH THE GFS REMAINING THE FASTEST
OVERALL. ONCE THE COLDER AIR ARRIVES LATER TONIGHT THERMAL PROFILES
SEEN IN FORECAST SOUNDINGS ARE SUPPORTIVE OF ALL SNOW ONCE STRONGER
LIFT ARRIVES AND MOISTENING/SATURATION COMMENCES. WARM AIR ADVECTION
MAY BE STRONG ENOUGH FOR WET BULB ZERO PROFILE TO APPROACH FREEZING
IN A SHALLOW LAYER NEAR 700 MB ACROSS THE FAR SOUTHEAST BUT IT LOOKS
TO REMAIN COLD ENOUGH FOR ALL SNOW. WE WILL MONITOR TRENDS FOR
POSSIBLE MENTION OF BRIEF MIX AT THE ONSET IN THE SOUTHEAST. TIMING
OF ALL THIS REMAINS LARGELY UNCHANGED FROM THE PREVIOUS FORECAST AS
DO SNOWFALL AMOUNTS FOR THE MOST PART. THERE ARE A FEW CONCERNS WITH
THIS SYSTEM. 1.) MID LEVEL FRONTOGENESIS IS FAIRLY STRONG AND
MESOSCALE BANDED PRECIPITATION CERTAINLY SEEMS LIKE A POSSIBILITY.
FORTUNATELY THE UPPER LEVEL TROUGH GEOMETRY IS SUCH THAT THE
FRONTOGENESIS BAND MOVES THROUGH RATHER QUICKLY AND EVEN THOUGH
SNOWFALL AMOUNTS MAY BE RELATIVELY HIGH...THIS SHOULD OCCUR FOR ONLY
A SHORT PERIOD. 2.) WHEN LOOKING AT ISENTROPIC SURFACES...THE BEST
MOISTURE AND BEST PRESSURE ADVECTION ARE NOT ALL THAT WELL
ALIGNED...ALBEIT STILL SUFFICIENT TO SUPPORT THE AMOUNTS THAT WE
CURRENTLY HAVE IN THE GRIDS. THESE AMOUNTS ARE SLIGHTLY HIGHER IN
THE NORTHEAST WHERE THE BEST JUXTAPOSITION OF SATURATION AND LIFT
ARE INDICATED IN GUIDANCE. AS WOULD BE EXPECTED...THIS IS WHERE THE
HIGHER QPF AMOUNTS ARE TOO. ISOLATED 3-4 INCH ACCUMULATION SEEM
POSSIBLE IN THIS AREA. HAVE INCREASE SNOWFALL AMOUNTS SLIGHTLY
MAINLY FROM THE FAR EASTERN OKLAHOMA PANHANDLE SOUTHWARD ACROSS THE
EASTERN TEXAS PANHANDLE TO ACCOUNT FOR THIS. FURTHER WEST...LITTLE
CHANGES WERE MADE AND AREAS FROM AMARILLO AND DUMAS WESTWARD WILL
SEE THE LOWEST AMOUNTS.

TEMPERATURES MAY NEED TO BE TRENDED DOWN TOMORROW AFTERNOON WHERE
THE HEAVIEST SNOWFALL COINCIDENT WITH TYPICAL TIME PERIOD OF DIURNAL
UPSWING IN TEMPERATURES...GIVEN EVAPORATIVE COOLING PROCESSES.
ALSO...DEPENDING ON SNOW COVER EARLY MONDAY MORNING AND TIMING OF
CLEARING SKIES...LOWS MAY NEED TO BE ADJUSTED DOWNWARD FURTHER. ALREADY
TRENDED THE LOWS IN THE EASTERN PORTION OF THE AREA DOWN A FEW
DEGREES BELOW A CONSENSUS OF GUIDANCE.

NEXT WEEK A FAIRLY BENIGN WEATHER PATTERN WILL BE IN PLACE WITH
NORTHWESTERLY FLOW GRADUALLY TRANSITIONING TO WEAK UPPER LEVEL
RIDGING BY LATE WEEK. LATE FRIDAY INTO SATURDAY A SHORTWAVE TROUGH
APPROACHES POTENTIALLY BRINGING OUR NEXT CHANCE OF RAIN. TYPICAL
SPREAD AMONG ENSEMBLE AND DETERMINISTIC MEDIUM RANGE MODELS AT THIS
TIME PERIOD LEADS TO UNCERTAINTY AND HAVE SLIGHT CHANCE POPS
CONFINED TO THE FAR SOUTHEAST AT THIS TIME.

BRB

&&

.AMA WATCHES/WARNINGS/ADVISORIES...
TX...WINTER WEATHER ADVISORY UNTIL 6 PM CST SUNDAY FOR THE FOLLOWING
     ZONES: ARMSTRONG...CARSON...COLLINGSWORTH...DALLAM...DEAF
     SMITH...DONLEY...GRAY...HANSFORD...HARTLEY...HEMPHILL...
     HUTCHINSON...LIPSCOMB...MOORE...OCHILTREE...OLDHAM...
     POTTER...RANDALL...ROBERTS...SHERMAN...WHEELER.

OK...WINTER WEATHER ADVISORY UNTIL 6 PM CST SUNDAY FOR THE FOLLOWING
     ZONES: BEAVER...CIMARRON...TEXAS.

&&

08/11

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE AMARILLO TX
900 PM CST SAT NOV 15 2014

OKZ001>003-TXZ001>020-161200-
CIMARRON-TEXAS-BEAVER-DALLAM-SHERMAN-HANSFORD-OCHILTREE-LIPSCOMB-
HARTLEY-MOORE-HUTCHINSON-ROBERTS-HEMPHILL-OLDHAM-POTTER-CARSON-
GRAY-WHEELER-DEAF SMITH-RANDALL-ARMSTRONG-DONLEY-COLLINGSWORTH-
900 PM CST SAT NOV 15 2014

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE TEXAS AND OKLAHOMA
PANHANDLES.

.DAY ONE...TONIGHT.

LIGHT SNOW IS EXPECTED TO DEVELOP ACROSS THE OKLAHOMA AND TEXAS
PANHANDLES TONIGHT. ACCUMULATIONS OF 1 TO 2 INCHES ARE POSSIBLE BY
DAYBREAK ACROSS THE OKLAHOMA PANHANDLE AND EXTREME NORTHERN TEXAS
PANHANDLE. A WINTER WEATHER ADVISORY WILL BE IN EFFECT FOR THE
PANHANDLES BEGINNING AT MIDNIGHT TONIGHT.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY.

LIGHT SNOW WILL CONTINUE TO SPREAD SOUTH ACROSS THE PANHANDLES SUNDAY
MORNING...THEN TAPER OFF FROM NORTH TO SOUTH BY LATE AFTERNOON.
TOTAL SNOWFALL ACCUMULATION OF 1 TO 3 INCHES ARE EXPECTED...WITH
LOCALLY HIGHER AMOUNTS POSSIBLE. A WINTER WEATHER ADVISORY WILL
REMAIN IN EFFECT FOR ALL OF THE PANHANDLES THROUGH 6 PM SUNDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED AT THIS TIME. HOWEVER...THE
NATIONAL WEATHER SERVICE IN AMARILLO WOULD APPRECIATE ANY SNOWFALL
REPORTS.

KB