Winter Storm and Extreme Cold in Texas, February 1 to 4, 2011

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LUBBOCK TX
1121 PM CST MON JAN 31 2011

.UPDATE...
RADAR AND SATELLITE TRENDS SUPPORTING 00Z MODEL RUNS AND EARLIER
THINKING REGARDING DECREASING PRECIP TRENDS THROUGH THE NIGHT.
EVEN AREAS OFF THE CAPROCK ARE BEGINNING TO SEE TRENDS AWAY FROM
THE STRONGER CONVECTION OF ONLY A COUPLE OF HOURS AGO. LOOKS LIKE
WE WILL BE HARD-PRESSED TO RECEIVE 1 TO 2 INCHES ON THE CAPROCK...
ALTHOUGH NWRN ZONES STILL LIKELY TO SEE WIND CHILL WARNING
CRITERIA MET LATE TONIGHT. THAT ALONE WILL BE ENOUGH TO JUSTIFY
KEEPING THE WARNING GOING THERE. AREAS OFF THE CAPROCK STILL HAVE
A THREAT FOR 2 TO LOCALLY 4 INCHES OF SNOW WITH CONVECTIVE
CELLS...ALTHOUGH THAT THREAT WILL DIMINISH THE NEXT FEW HOURS.
WILL KEEP WARNING THERE. FOR LUBBOCK AND POINTS WEST AND SOUTH
WHERE WIND CHILLS LIKELY TO STAY WARMER THAN -15 AND SNOW TOTALS
WILL LABOR TO REACH 1 TO 2 INCHES...WILL DOWNGRADE WARNING TO AN
ADVISORY.

NO OTHER CHANGES ATTM. WEATHER AND POP GRIDS LOOK FINE WITH
WIDESPREAD LIGHT PRECIP. TEMPS AND WINDS APPEAR ON TRACK AS WELL.

&&

.AVIATION...
AS MENTIONED ABOVE TRENDS ARE FOR LESS SNOWFALL TOTALS...BUT COULD
SEE SOME LIGHT SNOW CONTINUE THROUGH THE NIGHT AND PERIODICALLY
THROUGH THE DAY TUESDAY. REGARDLESS...IFR CIGS LIKELY THROUGH THE
NIGHT THEN RISING TO MVFR AFTER SUNRISE.

&&

.PREV DISCUSSION... /ISSUED 951 PM CST MON JAN 31 2011/

UPDATE...
AFTER EXAMINING NEW MODEL RUNS THIS EVENING...WILL KEEP ALL
PRODUCTS AND HEADLINES AS EARLIER. HOWEVER...THERE ARE SOME
CRITICAL TRENDS IN THESE LATEST MODEL RUNS. QPF AND SNOWFALL
AMOUNTS ARE GREATLY DECREASED ON THE CAPROCK WITH HIGHEST AMOUNTS
ACROSS NEW MEXICO AND OFF THE CAPROCK. THE CURRENT LIGHT SNOWFALL
ACTIVITY OVER THE AREA IS DUE TO WEAK FRONTOGENETICAL FORCING
COMBINED WITH THE UPPER LEVEL LIFT AS THE TROUGH APPROACHES THE
AREA. THE UPPER LEVEL LIFT WILL REMAIN STRONG OVERNIGHT THROUGH
TUESDAY MORNING. DOWNGLIDE HAS ALREADY BEGUN TO SPREAD OVER THE
AREA ON THE CAPROCK AND WILL CONTINUE TO DO SO THROUGH THE REST OF
THE EVENING AND EARLY MORNING HOURS. ACROSS THE SOUTHEASTERN
AREAS...MAINLY FROM PADUCAH...DICKENS...TO POST...STRONG
ISENTROPIC LIFT FROM 290-295K WILL CONTINUE THROUGH EARLY TUESDAY
MORNING. ADDITIONALLY...WEAK FRONTOGENETICAL FORCING ACROSS THIS
AREA WILL INCREASE IN INTENSITY IN THE 700-550MB LAYER. STONEWALL
COUNTY HAS ALREADY SEEN SOME THUNDER THIS EVENING WITH ELEVATED
CAPE AROUND 200 J/KG. GIVEN THE NEWER MODEL DATA...AREAS ON THE
CAPROCK MAY BE HARD PRESSED TO REACH WARNING CRITERIA EXCEPT FOR
THE SOUTHWESTERN PANHANDLE WHERE WIND CHILLS WILL BE -10 TO -20F.
THE AREA MOST LIKELY TO RECEIVE HIGHEST QPF TOTALS WILL BE OFF THE
CAPROCK.

PREV DISCUSSION... /ISSUED 345 PM CST MON JAN 31 2011/

SHORT TERM...
CONDITIONS STARTING TO GO DOWNHILL ACROSS THE AREA...WINTER STORM
STILL ON THE WAY FOR THE REGION.

21Z SURFACE ANALYSIS SHOWS THAT THE LEADING EDGE OF THE INITIAL COLD
FRONT BISECTED THE FORECAST AREA FROM WEST TO EAST ROUGHLY ALONG A
CLOVIS TO ASPERMONT LINE AND WAS MOVING SOUTH AT ABOUT 20 MPH.  WIND
SPEEDS BEHIND THE LEADING EDGE HAVE BRIEFLY JUMPED UP INTO THE 15 TO
25 MPH RANGE...BUT OBSERVATIONS OVER THE PANHANDLE SHOW SPEEDS
DECREASING BACK A BIT.  TEMPERATURES TO THE NORTH OF THE FORECAST
AREA HAVE BEEN HOLDING STEADY OR SLOWLY FALLING INTO THE UPPER 20S
AND EXPECT TO SEE THE SECOND STRONGER SURGE OF COLD AIR PUSH INTO
THE REGION AFTER SUNSET.

ALOFT...WV SATELLITE IMAGERY SHOWS THE BASE OF THE TROF STARTING TO
SWING OUT FROM SRN CALIFORNIA ACROSS THE US/MEXICO BORDER REGION
WITH SOME ENHANCEMENT IN VAPOR OVER E AZ/W NM.  NLDN ALSO STARTING
TO SHOW SOME LIGHTNING STRIKES IN THE MOUNTAINOUS REGIONS WHICH MAY
INDICATE SOME STRONGER LIFT THAN MODELS HAD DEPICTED.  LOOKING AT
THE 12Z UPA HAND ANALYSIS AND COMPARING WITH THE CURRENT LOCATION...
THE GFS AND ECMWF PROBABLY HAVE THE CLOSEST FORWARD SPEED TO WHAT IS
SHOWN ON SATELLITE.  NAM AND GEM ARE A BIT FASTER BUT OVERALL...
MODELS ARE IN GOOD AGREEMENT WITH THE PROGRESSION AND TRACK OF THE
INITIAL WAVE FOR TONIGHT INTO TOMORROW.

HOWEVER...BIGGER DIFFERENCES EXISTS WHEN IT COMES TO THE PRECIP/SNOW
FORECASTS BETWEEN THE MODELS.  GENERAL CONSENSUS IS FOR SNOWFALL TO
PICK UP FROM NORTHWEST TO SOUTHEAST ACROSS THE FORECAST AREA
STARTING BETWEEN 6-9 PM OVER THE NORTHWESTERN ZONES AND THEN
SPREADING SOUTHEAST OVER THE REST OF THE FORECAST AREA THROUGH
TONIGHT.  NAM CONTINUES TO INDICATE CONVECTIVE BANDS DEVELOPING WITH
THE MOST FAVORED LOCATION HAVING BEEN THE ROLLING PLAINS FOR THE
PAST SEVERAL RUNS.  GFS CONTINUES TO SHOW TWO AREAS OF ENHANCED
PRECIPITATION...ACROSS THE NORTHWESTERN SOUTH PLAINS AROUND MIDNIGHT
WITH A SECOND AREA ALONG THE EDGE OF THE CAPROCK TOWARDS SUNRISE
TUESDAY.  VARIOUS LOOPS OF CROSS SECTIONS ACROSS THE AREA SHOW THAT
CONDITIONS WILL BE FAVORABLE FOR DENDRITIC SNOW GROWTH...A NEARLY
SATURATED LAYER IN THE -5 TO -15 DEG C SECTION WITH PERIODS OF
MODERATE LIFT AS SHOWN BY OMEGA FIELDS DEVELOP AT VARIOUS TIMES OVER
THE NEXT 24 HOURS AS THE STORM SYSTEM MOVES OVER THE REGION.
SOUNDINGS AND BUFKIT DATA FOR POINTS IN AND AROUND THE FORECAST AREA
SHOW SIMILAR SCENARIO BUT NONE OF THE DATA IS IN GOOD AGREEMENT FOR
WHERE THE MOST FAVORED LOCATION WILL BE FOR ANY OF THE BANDS TO
DEVELOP.  TEMPERATURE PROFILE ALSO SHOWS THAT THE WINDOW FOR SLEET
CONTINUES TO DECREASE AS THE TEMPERATURE IN THE ATMOSPHERIC COLUMN
RAPIDLY COOLS TO BELOW FREEZING.  TIMING OF ONSET OF PRECIPITATION
DOES APPEAR TO BE LATE ENOUGH HOWEVER TO LIMIT THE AMOUNT OF SLEET
THAT SHOULD FALL.  LAST BUT NOT LEAST WILL BE THE COMBINATION OF
EXTREMELY COLD TEMPERATURES AND STRONG WIND SPEEDS.  RESULT WILL BE
WIND CHILL READINGS FALLING FROM -5 TO -25 DEG F AT TIMES ACROSS THE
REGION.  READINGS LIKE THIS WILL RESULT IN FROSTBITE ON EXPOSED SKIN
WITHIN 30 MINUTES.

TO SUMMARIZE ALL THE IMPACTS THAT WILL NEED SOME FORM OF PRODUCT...
AVERAGE SNOWFALL AMOUNTS ACROSS THE REGION ARE EXPECTED TO BE
BETWEEN 1 TO 3 INCHES WHICH IS ADVISORY LEVEL...BUT THE THREAT OF
LOCALIZED 2 TO 6 INCH AMOUNTS WOULD FAVOR A WARNING.  STRONG WINDS
INCREASING TONIGHT AND REMAINING STRONG THROUGH TOMORROW ALSO COULD
RESULT IN WIDESPREAD BLOWING SNOW WHICH COULD REDUCE VISIBILITIES TO
BELOW ONE MILE.  ALSO ADD IN THE LOW WIND CHILL VALUES AND THE
WARNING WARNING ADVISORY WATCH THAT LETTERMAN LOVES TO USE WOULD
BECOME A REALITY. BECAUSE OF THIS WIDE RANGE OF IMPACTS OVER THE NEXT
24 TO 48 HOURS...THE DECISION WAS MADE AFTER COORDINATING WITH
SURROUNDING OFFICES TO LUMP ALL THE IMPACTS INTO A WINTER STORM
WARNING STARTING AT 6 PM TONIGHT THROUGH 6PM TUESDAY /00Z TUE - 00Z
WED.  WILL EVENTUALLY SEE WIND SPEEDS TAPER OFF AS WE HEAD INTO
WEDNESDAY AND THURSDAY WHICH TECHNICALLY WILL NOT MEET OUR
REQUIREMENT FOR DURATION AND STRENGTH OF WINDS...BUT WE WILL BE
CLOSE ENOUGH TO AT LEAST KEEP A WIND CHILL WATCH FOR TUESDAY NIGHT
INTO WEDNESDAY AFTERNOON.

IN REGARDS TO THE GRIDS/FORECAST...GUIDANCE TEMPERATURES CONTINUED
TO COME IN ANOTHER DEGREE OR TWO COLDER COMPARED TO PREVIOUS TEMPS
AND LOWERED MAX AND MINS FOR TOMORROW AFTERNOON AND WEDNESDAY
AFTERNOON A DEGREE OR TWO.  MODEL/MOS WIND GRIDS AGAIN CAME IN UNDER
WHAT SHOULD OCCUR BASED ON THE POST FRONTAL PRESSURE GRADIENT SO
KEPT THE PREVIOUS FORECAST PACKAGE TIMING AND STRENGTH INTACT.  DID
ADJUST POPS DO GO DEFINITE SNOW FOR 06-12Z TUESDAY MORNING OVER THE
REGION AND TWEAKED WEATHER GRIDS TO BETTER REFLECT THE TRANSITION
AND TIMING FOR SLEET ACROSS THE SOUTHERN ZONES.  CLOUDS ALSO APPEAR
TO STAY SOCKED IN OVER THE REGION AND CARRIED CLOUDY CONDITIONS
THROUGH WEDNESDAY AFTERNOON.  ALL IN ALL...PREVIOUS FORECAST SHIFT
DID AN EXCELLENT JOB SETTING THINGS UP FOR OUR GO AT THE FORECAST.

LOTS GOING ON...NOW THE WAITING BEGINS TO SEE IF WE GOT THE FORECAST
RIGHT AND WILL BE CONSIDERED HEROES OR IF WE WILL HAVE TO EAT CROW
WHEN ALL IS SAID AND DONE.

JORDAN

LONG TERM...
THIS LONG TERM FORECAST BEGINS WED EVENING AS SURFACE HIGH
PRESSURE CONTINUES TO MOVE SOUTH ACROSS THE AREA AND EVENTUALLY
EAST. AN ELONGATED UA TROUGH REMAINS IN PLACE ACROSS THE SOUTHERN
ROCKIES WITH A CLOSED LOW FORECAST NEAR THE NM BOOTHEEL BY 12 THU.
WITH THIS SCENARIO EXPECT CONTINUE LIGHT SNOW TO IMPACT PRIMARILY
SW 1/3 OF THE AREA OVERNIGHT WED NIGHT BEFORED TAPERING TO
FLURRIES ON THU. MODELS DO SHOW SOME LARGE SCALE LIFT CROSSING THE
AREA TO SUPPORT THIS THOUGH WITH NEUTRAL OMEGA ON FORECAST
SOUNDINGS DO NOT EXPECT MUCH IN WAY OF ADDITIONAL ACCUMULATIONS.
OPTIMISTICALLY WENT CLOSE TO MODEL GUIDANCE ON THU AS CLOUDS BEGIN
TO CLEAR FROM NORTH TO SOUTH AND WESTERLY FLOW STARTS TO SCOUR THE
ARCTIC AIR IN PLACE. THOUGH WE COULD SEE SOME LOCATIONS STRUGGLE
TO GET BACK INTO THE 20S ESPECIALLY WHERE APPRECIABLE SNOWFALL
REMAINS AND HIGHS ON THU WILL LIKELY NEED ADJUSTING ONCE THAT IS KNOWN.

H8 TEMPS MODIFY FURTHER ON FRI WITH NW SURFACE WINDS DEVELOPING AS
A BROAD SURFACE TROUGH DEVELOPS ACROSS THE CENTRAL PLAINS IN
RESPONSE TO A SHORTWV DROPPING INTO THE REGION. OVERALL BROAD
TROUGHINESS REMAINS IN PLACE ALOFT THROUGH THE WEEKEND ACROSS THE
U.S. WITH A HIGH AMPLITUDE RIDGE STILL TAPPING INTO THE ARCTIC AND
TO SOME EXTENT CROSS POLAR FLOW ACCORDING THE ECMWF. SAT WILL
LIKELY BE THE WARMEST DAY OF THE NEXT 7-10 AS PREFRONTAL WARMING
OCCURS WITH STRONG SW SURFACE WINDS. ARCTIC FROPA IS EXPECTED
HOWEVER TO OCCUR ACROSS THE PNHDLS ON SUN WHICH WILL SIGNAL THE
BEGINNING OF THE NEXT COLD SPELL. CURRENTL MODELS SHOW N/NW FLOW
ALOFT WHICH DOES NOT FAVOR SIGNIFICANT PRECIP BUT WILL LIKELY KEEP
TEMPS BELOW NORMAL FOR A WHILE LONGER. OPTED TO NOT INCLUDE POPS
ATTM ON DAY 7.

&&

.PRELIMINARY POINT TEMPS/POPS...
FRIONA         4  14  -5   9  -4 /  90  50  30  20  20
TULIA          5  13  -2  12  -4 /  90  60  20  20  10
PLAINVIEW      7  16  -1  13  -1 /  90  60  20  20  20
LEVELLAND      9  20   2  15   6 /  90  60  20  20  20
LUBBOCK       10  19   2  15   4 /  90  60  20  20  20
DENVER CITY   11  20   3  16  10 /  90  50  20  20  20
BROWNFIELD    10  20   4  17   9 /  90  60  20  20  20
CHILDRESS     12  16   3  13   5 / 100  70  20  10  10
SPUR          12  20   4  16   7 / 100  70  10  10  20
ASPERMONT     13  16   3  17  11 / 100  70  10  10  10

&&

.LUB WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL 6 PM CST TUESDAY FOR THE FOLLOWING
ZONES: TXZ021>032-036>038-042>044.

WIND CHILL WATCH FROM TUESDAY EVENING THROUGH WEDNESDAY MORNING
FOR THE FOLLOWING ZONES: TXZ021>037-039.

WINTER WEATHER ADVISORY UNTIL 6 PM CST TUESDAY FOR THE FOLLOWING
ZONES: TXZ033>035-039>041.

&&

07/01/07

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE LUBBOCK TX
419 PM CST MON JAN 31 2011

TXZ021>044-012230-
PARMER-CASTRO-SWISHER-BRISCOE-HALL-CHILDRESS-BAILEY-LAMB-HALE-
FLOYD-MOTLEY-COTTLE-COCHRAN-HOCKLEY-LUBBOCK-CROSBY-DICKENS-KING-
YOAKUM-TERRY-LYNN-GARZA-KENT-STONEWALL-
419 PM CST MON JAN 31 2011

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

.DAY ONE...TONIGHT

WINTER WEATHER

THE ARRIVAL OF BITTERLY COLD ARCTIC AIR IS UNDERWAY AS A STORM
SYSTEM IS POISED TO BEGIN IMPACTING THE REGION WITH WINTRY PRECIPITATION.

WINTRY PRECIPITATION WILL BEGIN THIS EVENING OVER THE EXTREME
SOUTHERN PANHANDLE AND THE NORTHERN SOUTH PLAINS...THEN EXPAND
SOUTHWARD OVER ALL OF THE SOUTH PLAINS AND ROLLING PLAINS LATE
TONIGHT. THE PRECIPITATION MAY BEGIN AS RAIN OR SLEET...BUT WILL
TRANSITION TOWARD SNOW AREAWIDE OVERNIGHT. SNOW ACCUMULATIONS ARE
EXPECTED...ESPECIALLY WHERE LOCALLY HEAVIER BANDS OF PRECIPITATION
DEVELOP. WIDESPREAD 1 TO 3 INCH SNOW ACCUMULATIONS ARE LIKELY
OVERNIGHT...WITH ACCUMULATIONS GREATER THAN 4 INCHES IN LOCATIONS
MAINLY ACROSS THE ROLLING PLAINS OR WHERE ANY HEAVY BANDS DEVELOP.

NORTHERLY WINDS MAY APPROACH OR BRIEFLY EXCEED SUSTAINED SPEEDS
OF 30 MPH OVER PARTS OF THE OUTLOOK AREA LATE TONIGHT. THESE WINDS
WILL RESULT IN NEAR WHITE OUT CONDITIONS IN BLOWING SNOW...AND IN
DANGEROUS WIND CHILL VALUES BETWEEN 5 BELOW AND 20 BELOW ZERO.

A WINTER STORM WARNING IS IN EFFECT.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY
SNOW AND BLOWING SNOW WILL RESULT IN HAZARDOUS WEATHER IMPACTS
TUESDAY MORNING. STORM TOTAL ACCUMULATION WILL RANGE FROM 1 TO 5
INCHES ACROSS THE OUTLOOK AREA BEFORE SNOWFALL DECREASES IN
INTENSITY DURING THE LATE MORNING TO MIDDAY HOURS.

DANGEROUS WIND CHILLS WILL OCCUR TUESDAY MORNING...AND AGAIN TUESDAY
NIGHT AND WEDNESDAY MORNING.

ADDITIONAL LIGHT SNOW WILL REMAIN POSSIBLE THROUGH AT LEAST WEDNESDAY
NIGHT...BUT THE PROBABILITY OF ADDITIONAL WIDESPREAD HAZARDOUS
WEATHER IS LOW WEDNESDAY THROUGH SUNDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS AND EMERGENCY FIRST RESPONDER ORGANIZATIONS ARE ASKED TO
RELAY REPORTS OF INCLEMENT WEATHER AND ITS IMPACTS TO THE NATIONAL
WEATHER SERVICE IN LUBBOCK