Area Forecast Discussion
Issued by NWS

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688
FXUS64 KLUB 202346
AFDLUB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LUBBOCK TX
546 PM CST FRI FEB 20 2015

.AVIATION...
CONDITIONAL THREAT EXISTS FOR IFR-MVFR CIGS AFTER 06Z FOLLOWING
COLD FROPA AT ALL THE TERMINALS. CDS MAY HAVE THE BEST CHANCE
FOR A COUPLE HOURS OF IFR CIGS GIVEN STRATUS ALREADY IN NWRN
OK...BUT THESE MAY PROVE TOO FLEETING AND AS SUCH WILL AMEND TAF
IF TRENDS SHOW OTHERWISE. ALSO KEPT SCT LOW CLOUDS AT LBB AND
PVW FOLLOWING FROPA FROM 08Z-09Z. REGARDLESS...DRIER NORTH
WINDS ON SAT SHOULD SERVE TO SCOUR OUT THESE LOW CLOUDS BY
MID-LATE MORNING.

&&

.PREV DISCUSSION... /ISSUED 334 PM CST FRI FEB 20 2015/

SHORT TERM...
A SFC TROUGH DRAPED FROM THE NORTH NORTHWEST TO SOUTHEAST ACROSS
THE CENTRAL PANHANDLES TO ACROSS THE NORTHERN ROLLING PLAINS...HAS
RESULTED IN LIGHT AND VARIABLE SFC WINDS ACROSS THE NORTHERN
ROLLING PLAINS AND BREEZY W-SW WINDS ELSEWHERE /THANKS TO A
TIGHTENED PRESSURE GRADIENT/. AS A RESULT...RELATIVE HUMIDITY
VALUES HAVE PLUMMETED TO 9-25 PERCENT ON THE CAPROCK AND ACROSS
THE LOW ROLLING PLAINS...WITH LOWEST VALUES NOTED ON THE
CAPROCK...THUS CREATING AN ELEVATED FIRE WEATHER DANGER. FOR
ADDITIONAL INFORMATION...PLEASE REFER TO THE FIRE WEATHER
DISCUSSION BELOW. THE DOWNSLOPE SFC WINDS HAVE ALLOWED FOR ABOVE
NORMAL WARMTH...HIGHS IN THE 70S ON THE CAPROCK AND LOW ROLLING
PLAINS...WITH UPPER 50S TO LOWER 60S MORE SO ACROSS THE NORTHERN
ROLLING PLAINS BEHIND THE FRONT. KLBB WAS SITTING AT 79 DEGREES
WHICH IS 3 DEGREES FROM THE RECORD SET IN 1996. THE GRADIENT IS
POISED TO RELAX AOA SUNSET..SETTING US UP WITH LIGHTER W-SW WINDS
ACROSS ALL BUT THE NORTHERN ROLLING PLAINS...WHERE LIGHT AND
VARIABLE WINDS WILL ENSUE INTO TONIGHT.

HOWEVER...CHANGES ARE UNDERWAY AS AN EMBEDDED DISTURBANCE IN THE
NEAR ZONAL FLOW ALOFT RACES EAST ACROSS THE OK PANHANDLE/CENTRAL
PLAINS TONIGHT...AND AID IN DIVING A COLD FRONT ACROSS THE FA. THE
TIMING OF THE FROPA IS AS SUCH: WILL BE AT OUR DOOR STEP/ACROSS THE
SRN TX PANHANDLE AOA MIDNIGHT TONIGHT...WILL IMPACT KLBB AOA 3 AM
AND CLEAR THE CWA AN HOUR SO BEFORE SUNRISE. ATMOSPHERIC LEVELS WILL
BE TOO DRY FOR ANY PRECIP TO DEVELOP ALONG THE COLD FRONT
/PWATS LESS THAN 0.35 INCHES/...THOUGH MODEL SOUNDINGS HINT AT THE
POTENTIAL FOR LOW CLOUDS AND/OR FOG TO DEVELOP. PRESSURE RISES ON
THE ORDER OF 3-8 MB PER 3 HRS SUGGEST N-NE WIND SPEEDS INCREASING TO
15-25 MPH WITH HIGHER GUSTS INITIALLY AFTER THE FRONTAL
PASSAGE...BEFORE SETTLING DOWN TO 10-15 MPH A FEW HOURS AFTER
SUNRISE. OVERNIGHT LOWS IN THE MIDDLE TO UPPER 30S TO MIDDLE 40S
WILL ONLY RECOVER IN THE 50S WITH A FEW 60S FOR HIGHS TOMORROW.
/29

LONG TERM...
SOLUTIONS HAVE TRENDED A BIT COLDER WITH THE AIRMASS ARRIVING
SUNDAY INTO MONDAY. MOISTURE LEVELS STILL APPEAR A BIT MARGINAL
THOUGH THE SHALLOW ARCTIC AIRMASS SHOULD SUFFICE TO GENERATE AT
LEAST LIGHT SNOWFALL OR MAYBE FREEZING DRIZZLE SPREADING NORTH TO
SOUTH SUNDAY. ALOFT...WE CONTINUE TO SEE DECENT AGREEMENT ON
EJECTION OF AN OLD PACIFIC LOW MAINLY LATE SUNDAY AND EARLY MONDAY
WITH INCREASING DYNAMIC LIFT ON TOP OF THE UPSLOPE PATTERN. THE
BIGGEST QUESTIONS REGARD QUALITY AND DEPTH OF MID LEVEL MOISTURE
ARRIVING FROM THE SOUTHWEST...IF THIS WILL SYNCH DECENT ENOUGH
WITH THE LIFT FOR MEANINGFUL SNOW GROWTH ALOFT. ANOTHER TREND HAS
BEEN FOR A BIT MORE SUBSTANTIAL WARM NOSE MAINLY ACROSS SOUTHERN
ZONES DURING THIS PERIOD FROM LATE SUNDAY INTO OR EVEN THROUGH
MONDAY...WITH MODEL SOUNDINGS GIVING A DEPICTION OF SLEET FAVORING
SOUTHERN AND EASTERN ZONES...AND EVEN ENOUGH WARM NOSE EXTREME
SOUTHERN ZONES FOR SOME VALID RISK OF FREEZING RAIN.

FOR NOW...WE HAVE TRENDED CHANCES SLIGHTLY HIGHER BASED ON SLIGHT
CONVERGENCE OF SOLUTIONS BUT NOT YET INTO LIKELY CATEGORY. WE ALSO
ADJUSTED WEATHER TYPES SLIGHTLY AS MENTIONED ABOVE. AN ADVISORY
PERIOD FOR WINTER WEATHER STILL LOOKS PLAUSIBLE THOUGH NOT YET
CONFIDENT ENOUGH FOR HIGHLIGHTS AT THIS TIME.

THE REMAINDER OF THE WEEK DOES NOT LOOK ALL THAT WARM EITHER. WE
STILL EXPECT A TRANSITORY UPPER RIDGE MID-WEEK WHICH SHOULD AT
LEAST ALLOW MODIFICATION OF THE COLD AIR THOUGH IT MAY BE
DIFFICULT TO CLIMB ALL THE WAY BACK TO NORMAL BECAUSE OF THE NORTH
TO NORTHWEST FLOW COMING OUT OF CANADA AND ALL THE COLD AIR
BOTTLED UP ACROSS THE GREAT PLAINS. A NEW FRONT LOOKS TO BE
ENTERING THE AREA PERHAPS AS EARLY AS THURSDAY AND WE HAVE TRENDED
SLIGHTLY COLDER LATER IN THE WEEK. PRECIPITATION CHANCES ALSO
STILL SEEM VALID AS A LARGE-SCALE COLD UPPER TROUGH IS EXPECTED
TO CARVE OUT ACROSS THE INTER-MOUNTAIN WEST AND SOUTHWEST. TIMING
OF INDIVIDUAL WAVES NOT AT ALL CLEAR BUT THE PATTERN WOULD SUGGEST
THIS LIKELY WOULD BE AN ISSUE. SO WE RETAINED A CHANCE FOR MAINLY
LIGHT SNOW LATER IN THE WEEK. /05 RMCQUEEN

FIRE WEATHER...
A NEARBY SFC TROUGH HAS PROMOTED A TIGHTENED PRESSURE GRADIENT
ACROSS THE SOUTH PLAINS AND LOW ROLLING PLAINS LATE THIS
AFTN...RESULTING IN W TO SW WIND SPEEDS OF 15-25 MPH ACROSS THE SAID
AREAS. THESE DOWNSLOPE WINDS HAVE ALLOWED TEMPS TO INCREASE INTO THE
70S THUS CAUSING RELATIVE HUMIDITY VALUES TO FALL INTO THE 9-25
PERCENT RANGE. THE LOWEST HUMIDITIES WERE NOTED ON THE CAPROCK.
THE ABOVE NORMAL WARMTH...HUMIDITIES AT OR BELOW 15 PERCENT AND
BREEZY W TO SW WINDS HAVE RESULTED IN A HIGH FIRE DANGER. IN
FACT...A GRASS FIRE WAS OCCURRING 5 MILES SW OF MULESHOE LATE
THIS AFTN. LATEST PHONE CALLS TO EMERGENCY PERSONNEL STATED THAT
THE FIRE HAS BECOME CONTAINED. A FEW LOCALES ON THE CAPROCK HAVE
TICKED OFF SEVERAL HOURS OF RED FLAG MINUTES...BUT IS NOT
WIDESPREAD ENOUGH FOR THE THE ISSUANCE OF A RED FLAG WARNING.
HOWEVER...A FIRE DANGER STATEMENT IS IN EFFECT FOR MAINLY ON THE
CAPROCK UNTIL 6 PM CST THIS EVENING.

&&

.LUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

93

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