Area Forecast Discussion
Issued by NWS Dallas/Fort Worth, TX

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000
FXUS64 KFWD 260958
AFDFWD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FORT WORTH TX
358 AM CST THU FEB 26 2015

.DISCUSSION...

EARLY MORNING WATER VAPOR SATELLITE IMAGERY SHOWED A RELATIVELY
STRONG...BUT FAST MOVING...SHORTWAVE TROUGH OVER EASTERN NEW
MEXICO...MOVING EAST-SOUTHEAST TOWARDS NORTH TEXAS. OUT AHEAD OF
THIS TROUGH...REGIONAL RADARS SHOWED WIDESPREAD LIGHT
PRECIPITATION EXTENDING FROM THE TEXAS/NEW MEXICO BORDER EAST TO
CHILDRESS. LIGHT RADAR RETURNS EXTENDED WELL EAST OF
CHILDRESS...AS FAR EAST AS BOWIE...HOWEVER OBSERVATIONS INDICATED
THAT NO PRECIPITATION WAS REACHING THE GROUND UNDER THESE RETURNS.
ASIDE FROM PRECIPITATION...SURFACE OBSERVATIONS ALSO SHOWED THE
LEADING EDGE OF A FAST-MOVING COLD FRONT MOVING SOUTH TOWARDS THE
INTERSTATE 20/30 CORRIDOR THIS MORNING. AT 3 AM...THE FRONT WAS
ACROSS DENTON BUT NOT YET TO DFW AIRPORT. THIS FRONT REPRESENTS
THE LEADING EDGE OF A COLD CANADIAN AIRMASS THAT WILL BUILD INTO
THE REGION IN THE FRONT`S WAKE.

TODAY...THE COLD FRONT IS EXPECTED TO MOVE SOUTH ACROSS ALL OF
NORTH TEXAS BY 12Z/6AM...AND IS EXPECTED TO PUSH ACROSS THE
CENTRAL TEXAS COUNTIES OF THE CWA BY 8 AM. AS COLD AIR BUILDS IN
BEHIND THE FRONT...THE NEW MEXICO SHORTWAVE TROUGH IS EXPECTED TO
MOVE EAST OVER THE CWA THIS MORNING...SPREADING SOME FAIRLY STRONG
LARGE SCALE FORCING FOR ASCENT OVER NORTH TEXAS. ALL GUIDANCE
INDICATES THAT SOME LIGHT PRECIPITATION WILL FALL ACROSS THE
REGION AS A RESULT. BECAUSE THE LIFT AND ASSOCIATED PRECIPITATION
ARE EXPECTED TO MOVE OVER THE CWA BEHIND THE COLD FRONT...ALL
MODEL GUIDANCE ONCE AGAIN INDICATES THAT WE WILL BE COLD ENOUGH
FOR PRECIPITATION TO FALL AS SNOW. A 245 AM AIRCRAFT SOUNDING FROM
ALLIANCE AIRPORT INDICATED THAT THE ATMOSPHERE WAS ABOVE FREEZING
FROM THE SURFACE TO ABOUT 5000 FEET ABOVE GROUND...WITH NO
SIGNIFICANT INVERSIONS PRESENT. AS A RESULT...IT SEEMS REASONABLE
THAT WE WILL COOL OFF QUICKLY FROM THE SURFACE TO 5000 FEET THIS
MORNING BEHIND THE FRONT...ALLOWING PRECIPITATION TO FALL AS SNOW.

WHILE THE LIFT ASSOCIATED WITH THIS UPPER TROUGH DOES LOOK
IMPRESSIVE...IT IS EXPECTED TO BE FAST MOVING. THE SPEED OF THE
UPPER TROUGH WILL LIKELY PREVENT MUCH IN THE WAY OF MODERATE TO
HEAVY SNOWFALL FROM DEVELOPING BECAUSE A LOT OF THE LIFT WILL BE
USED TO SIMPLY SATURATE THE ATMOSPHERE. SKIES WERE CLEAR OVER MOST
OF NORTH CENTRAL TEXAS OUT AHEAD OF THE FRONT...INDICATING THAT
THE ATMOSPHERE IS NOT SATURATED AT ANY LEVEL BEFORE LIFT ARRIVES.
AIRCRAFT SOUNDINGS FROM 11 PM (THE LAST TIME WATER VAPOR SOUNDINGS
WERE AVAILABLE) INDICATE THAT RELATIVE HUMIDITY VALUES RANGED FROM
30 TO 60 PERCENT FROM THE SURFACE TO 400 MB OVERNIGHT...SO A
DECENT AMOUNT OF LIFT WILL NEED TO TAKE PLACE TO FIRST SATURATE
THE ATMOSPHERE...AND SECOND...GENERATE PRECIPITATION. WITH NO
SIGNIFICANT POSITIVE MOISTURE ADVECTION FEEDING INTO THE REGION
AHEAD OF THE TROUGH...THINK THAT LIGHT SNOW OR FLURRIES WILL BE
THE MOST COMMON PRECIPITATION INTENSITY THIS MORNING.

MODELS DO INDICATE THE POTENTIAL FOR SOME BANDED SNOWFALL
ASSOCIATED WITH FRONTOGENETIC FORCING THIS MORNING. A CROSS
SECTIONAL ANALYSIS OUT AHEAD OF THIS TROUGH REVEALS THAT
FRONTOGENETIC FORCING DOES SET UP FOR A FEW HOURS THIS MORNING IN
BETWEEN WICHITA FALLS AND BRECKENRIDGE. THIS ENHANCED LIFT COULD
GENERATE SOME LOCALLY HIGHER SNOWFALL AMOUNTS ASSUMING THAT A BAND
OF LIGHT SNOW IS ABLE TO ORGANIZE. DUE TO DRY AIR ALREADY IN
PLACE...AND THE FAST MOVING NATURE OF THE UPPER TROUGH...THINK
THAT SNOWFALL AMOUNTS WILL RANGE FROM ABOUT ONE TENTH TO ONE
QUARTER OF AN INCH FROM THE DFW METROPLEX WEST AND NORTHWESTWARD.
IF A SNOW BAND DEVELOPS...IT APPEARS MOST LIKELY TO OCCUR
SOMEWHERE NORTHWEST OF A LINE FROM BRECKENRIDGE TO WEATHERFORD TO
BOWIE. THIS COULD RESULT IN ONE HALF INCH OF SNOWFALL IF THE BAND
DEVELOPS.

DID NOT ISSUE A WINTER WEATHER ADVISORY FOR THIS LIGHT SNOWFALL
THIS MORNING AS ADVERSE IMPACTS ARE EXPECTED TO BE LIMITED TO
NON-EXISTENT. WE WILL CLOSELY MONITOR THE POTENTIAL FOR SNOW
BANDING THIS MORNING...AS THIS COULD RESULT IN SOME QUICK SNOW
ACCUMULATIONS ON BRIDGES AND OVERPASSES WITH TEMPERATURES DROPPING
INTO THE UPPER 20S THIS MORNING BEHIND THE FRONT. ALL LIGHT SNOW
IS EXPECTED TO COME TO AN END AFTER NOON AS SUBSIDENCE SPREADS
OVER THE REGION BEHIND THE UPPER TROUGH.

SUBSIDENCE IS EXPECTED TO LAST FOR ONLY ABOUT 12 TO 18 HOURS FROM
THIS AFTERNOON THROUGH THE OVERNIGHT HOURS AS ANOTHER FAST MOVING
BUT STRONG SHORTWAVE TROUGH APPROACHES THE REGION FROM THE
NORTHWEST. THIS TROUGH WAS CURRENTLY LOCATED OVER EASTERN
OREGON...AND IS EXPECTED TO MOVE OVER NORTH TEXAS FRIDAY MORNING.
WITH A COLD CANADIAN AIRMASS FIRMLY ENTRENCHED OVER THE
REGION...THIS TROUGH WILL INDUCE SOME DEEP LIFT IN THE FORM OF
WARM AIR ADVECTION OVER THE COLD AIR...RESULTING IN ANOTHER
POTENTIAL ROUND FOR LIGHT SNOWFALL ACROSS THE AREA. THE MAIN
DIFFERENCE WITH THIS SECOND TROUGH IS THAT MODERATE LIFT IS
EXPECTED TO BE PRESENT OVER THE CWA FOR A MUCH LONGER PERIOD OF
TIME COMPARED TO TODAY. THE TROUGH IS NOT REALLY STRONGER...WE
SIMPLY WILL HAVE DEEPER COLD AIR IN PLACE WHICH HELPS STEEPEN
ISENTROPIC SURFACES THEREBY ENHANCING LIFT ASSOCIATED WITH WARM
AIR ADVECTION ONCE IT ENSUES.

MORE PERSISTENT LIFT ADDS CONFIDENCE THAT MEASURABLE PRECIPITATION
WILL BE ABLE TO MAKE IT TO THE GROUND ON FRIDAY. THE STRONGEST
LIFT WILL REMAIN TIED TO THE EXACT TRACK OF THE SHORTWAVE TROUGH
AS IT MOVES OVER THE CWA FRIDAY. ITS EXACT TRACK IS STILL NOT
COMPLETELY AGREED UPON IN VARIOUS MODEL FORECASTS...HOWEVER THE
CONSENSUS TAKES THE TROUGH NORTHWEST OF THE DFW AREA. 850 MB
TEMPERATURES ARE EXPECTED TO FALL WELL BELOW FREEZING BEFORE THIS
TROUGH ARRIVES...SO CONFIDENCE IN ANY PRECIPITATION FALLING AS
SNOW IS VERY HIGH ON FRIDAY. ONCE AGAIN...ANY PRECIPITATION
GENERATED ALOFT WILL HAVE TO CONTEND WITH DRY AIR CLOSER TO THE
SURFACE...AND THIS DRY AIR SHOULD REALLY EAT UP A LOT OF POTENTIAL
SNOWFALL AWAY FROM THE STRONGEST FORCING ASSOCIATED WITH THE
TROUGH.

IF YOU`RE NOT IN THE TROUGH`S DIRECT PATH...SNOWFALL TOTALS ARE
EXPECTED TO RANGE FROM A DUSTING/TRACE TO ABOUT ONE HALF INCH ON
FRIDAY. IN THE TROUGH`S PATH...SNOWFALL TOTALS ARE MORE LIKELY TO
CLIMB TO 1 INCH OR SLIGHTLY ABOVE...DEPENDING ON THE POTENTIAL FOR
ANY BANDING/CONVECTION. FOR NOW...HAVE THE HIGHEST SNOWFALL TOTALS
HOLDING NORTHWEST OF THE DFW AREA WITH AN AVERAGE ACCUMULATION OF
1-2 INCHES IN THE FORECAST. FOR MOST OTHER AREAS...HAVE ABOUT ONE
HALF INCH OF SNOW IN THE FORECAST AT THIS TIME. THE PLACEMENT OF
THE HIGHER ACCUMULATION TOTALS WILL DEPEND ON THE EXACT TRACK OF
THE UPPER TROUGH...SO KEEP IN MIND THAT THIS MAY CHANGE IF THE
TRACK IS EXPECTED TO TAKE ON A MUCH DIFFERENT PATH THAN WHAT IS
CURRENTLY FORECAST.

THE UPPER TROUGH IS EXPECTED TO MOVE QUICKLY TO OUR NORTHEAST BY
FRIDAY EVENING AS A LARGE AND POWERFUL UPPER TROUGH BUILDS SOUTH
OVER THE WESTERN CONUS COAST. THIS LARGE TROUGH IS BIG ENOUGH TO
RESULT IN A LARGE SCALE FLOW REGIME CHANGE OVER THE ENTIRE CONUS
THIS WEEKEND. WE WILL TRANSITION FROM HAVING A LARGE UPPER TROUGH
OVER THE CENTRAL CONUS...TO AN UPPER AIR PATTERN DOMINATED BY
SOUTHWEST FLOW ALOFT BY SUNDAY AFTERNOON. THIS BIG PATTERN SHIFT
WILL RESULT IN PERSISTENT LEE SIDE CYCLOGENESIS OVER THE HIGH
PLAINS...AND WILL CAUSE PERSISTENT AND FAIRLY STRONG WARM AIR
ADVECTION TO DEVELOP OVER THE CWA FROM FRIDAY NIGHT THROUGH
SATURDAY NIGHT.

STRONG AND PERSISTENT WARM AIR ADVECTION WILL RESULT IN
LIGHT...BUT PERSISTENT PRECIPITATION TO DEVELOP AND FALL ACROSS
NORTH CENTRAL TEXAS FROM FRIDAY NIGHT THROUGH SATURDAY. WITH AN
ARCTIC AIRMASS INITIALLY IN PLACE...THIS LIGHT PRECIPITATION IS
EXPECTED TO START OF AS VERY LIGHT SNOW FRIDAY EVENING...BUT THEN
QUICKLY TRANSITION TO LIGHT SLEET...THEN FREEZING RAIN...AND
FINALLY OVER TO RAIN THROUGH SATURDAY AFTERNOON. THE TRANSITION
PERIOD FRIDAY NIGHT INTO SATURDAY MORNING POSES THE GREATEST
CONCERN TO THE REGION BECAUSE THIS MAY RESULT IN LIGHT ICE
ACCUMULATIONS FOR LARGE PORTIONS OF NORTH AND CENTRAL TEXAS.

PRECIPITATION IS EXPECTED TO BE LIGHT...BUT SEVERAL HOURS OF
LIGHT SLEET TRANSITIONING OVER TO FREEZING RAIN MAY RESULT IN A
FEW HUNDREDTHS OF AN INCH OF ICE ACCUMULATION ON BRIDGES AND
OVERPASSES. THIS WOULD CERTAINLY MAKE FOR SOME DANGEROUS TRAVEL
ACROSS THE REGION THROUGH SATURDAY MORNING. IF THIS FORECAST HOLDS
THINK THAT WE WILL LIKELY NEED A WINTER WEATHER ADVISORY OR
FREEZING RAIN ADVISORY FOR THIS EVENT. DID NOT ISSUE AN ADVISORY
FOR THIS PERIOD TONIGHT BECAUSE WE HAVE THE POTENTIAL FOR 2 ROUNDS
OF LIGHT SNOWFALL TO GET THROUGH BEFORE THIS LIGHT ICING EVENT
TAKES SHAPE FRIDAY NIGHT AND SATURDAY MORNING.

TEMPERATURES ARE EXPECTED TO WARM ABOVE FREEZING FROM SOUTH TO
NORTH ACROSS THE REGION SATURDAY LATE MORNING OR EARLY AFTERNOON.
LIGHT PRECIPITATION WILL LIKELY PERSIST THROUGHOUT THE DAY...BUT
AS LONG AS IT IS IN LIQUID FORM...IT SHOULD POSE NO ADDITIONAL
THREAT FOR ADVERSE DRIVING CONDITIONS ACROSS THE REGION.

REMAINDER OF THE FORECAST...

SOUTHWEST FLOW ALOFT LOOKS LIKE IT BRINGS AN ELEVATED MIXED LAYER
OVER THE SOUTH PLAINS BY SUNDAY. WHILE WARM AIR ADVECTION WILL
LIKELY PERSIST BELOW THE EML CAP...ANY PRECIPITATION IS EXPECTED
TO BE LIGHT.

THE SOUTHWEST FLOW ALOFT FLOW REGIME IS EXPECTED TO PERSIST FOR
MUCH OF THE WEEK. THIS FAVORS PERSISTENT WARM AIR ADVECTION AND
GULF MOISTURE ADVECTION INTO THE REGION...SO LEFT CHANCE POPS IN
FOR MOST PERIODS NEXT WEEK. IT WILL NOT RAIN EVERYDAY...HOWEVER
EACH DAY CONDITIONS ARE FAVORABLE FOR PRECIPITATION GIVEN ANY
ENHANCEMENT TO LIFT. THOSE ENHANCEMENTS TO LIFT ARE EXPECTED TO
EXIST IN THE FORM OF SHORTWAVE TROUGHS MOVING OVER THE REGION IN
THE SOUTHWEST FLOW ALOFT. BY TUESDAY...MOST MODELS SHOW THAT WE
HAVE ENOUGH MOISTURE IN PLACE FOR THUNDERSTORMS (THE NORMAL NON-
SLEET/SNOW VARIETY)...SO LEFT THUNDER IN THE FORECAST AT THIS
TIME. NO OTHER SIGNIFICANT CHANGES MADE TO THE PREVIOUS FORECAST.

CAVANAUGH


&&

.AVIATION...
/ISSUED 1140 PM CST WED FEB 25 2015/
QUITE A FEW CHALLENGES TO GO ALONG WITH A RELATIVELY QUIET
EVENING. FIRST OFF...THERE ARE AREAS OF LIGHT FOG ACROSS SEVERAL
OBSERVATION SITES TONIGHT...WITH ONLY A HANDFUL OF THEM REPORTING
LESS THAN 5SM VISIBILITY. THE FOG IS A BIT THICKER IN THOSE AREAS
WHICH RECEIVED A BIT MORE SNOW THIS MORNING. LIGHT FOG AT THE
AIRPORTS ARE POSSIBLE...WITH CURRENT THINKING IS THERE WILL NOT BE
MUCH IN THE WAY OF RESTRICTIONS AT THE TAF SITES.

THE NEXT CHALLENGE IS THE HIGH CLOUDS AND COLD FRONT...CURRENTLY
APPROACHING WICHITA FALLS AND ABILENE. THE FRONT WILL MOVE
THROUGH THE METROPLEX SITES BY 08Z...AND WACO BY 10Z. ALONG WITH
THE FRONT WILL BE A FEW LAYERS OF HIGH CLOUDS. MVFR CEILINGS WILL
BE POSSIBLE FOR A FEW HOURS IN THE EARLY MORNING...ALONG WITH A
SMALL POSSIBILITY OF SNOW FLURRIES. HIGH RESOLUTION MODELS ALL
SUGGEST A FEW FLURRIES WEST OF THE TAF SITES...BUT THERE IS A
SMALL POSSIBILITY OF SNOW MAKING IT TO THE EAST.

STRONG WINDS ARE EXPECTED TO LAG BEHIND THE ACTUAL FRONT BY THREE
HOURS OR SO...BUT WINDS WILL INCREASE OUT OF THE NORTH AROUND
16KTS WITH THE OCCASIONAL GUST TO 26KTS. BY LATE AFTERNOON...WINDS
WILL BEGIN TO DIMINISH.

FOX


&&

.AVIATION...
QUITE A FEW CHALLENGES TO GO ALONG WITH A RELATIVELY QUIET
EVENING. FIRST OFF...THERE ARE AREAS OF LIGHT FOG ACROSS SEVERAL
OBSERVATION SITES TONIGHT...WITH ONLY A HANDFUL OF THEM REPORTING
LESS THAN 5SM VISIBILITY. THE FOG IS A BIT THICKER IN THOSE AREAS
WHICH RECEIVED A BIT MORE SNOW THIS MORNING. LIGHT FOG AT THE
AIRPORTS ARE POSSIBLE...WITH CURRENT THINKING IS THERE WILL NOT BE
MUCH IN THE WAY OF RESTRICTIONS AT THE TAF SITES.

THE NEXT CHALLENGE IS THE HIGH CLOUDS AND COLD FRONT...CURRENTLY
APPROACHING WICHITA FALLS AND ABILENE. THE FRONT WILL MOVE
THROUGH THE METROPLEX SITES BY 08Z...AND WACO BY 10Z. ALONG WITH
THE FRONT WILL BE A FEW LAYERS OF HIGH CLOUDS. MVFR CEILINGS WILL
BE POSSIBLE FOR A FEW HOURS IN THE EARLY MORNING...ALONG WITH A
SMALL POSSIBILITY OF SNOW FLURRIES. HIGH RESOLUTION MODELS ALL
SUGGEST A FEW FLURRIES WEST OF THE TAF SITES...BUT THERE IS A
SMALL POSSIBILITY OF SNOW MAKING IT TO THE EAST.

STRONG WINDS ARE EXPECTED TO LAG BEHIND THE ACTUAL FRONT BY THREE
HOURS OR SO...BUT WINDS WILL INCREASE OUT OF THE NORTH AROUND
16KTS WITH THE OCCASIONAL GUST TO 26KTS. BY LATE AFTERNOON...WINDS
WILL BEGIN TO DIMINISH.

FOX


&&

.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX  39  23  30  28  36 /  20   5  40  30  50
WACO, TX              41  26  37  30  41 /  10   5  20  30  50
PARIS, TX             36  21  30  25  35 /   5   5  50  30  30
DENTON, TX            37  21  29  26  35 /  20   5  50  40  50
MCKINNEY, TX          37  21  30  27  35 /  10   5  50  30  50
DALLAS, TX            38  24  31  28  37 /  20   5  40  30  50
TERRELL, TX           38  25  31  29  38 /  10   5  30  30  40
CORSICANA, TX         39  24  36  30  41 /  10   5   5  20  40
TEMPLE, TX            43  26  39  31  42 /   5   5  20  30  50
MINERAL WELLS, TX     37  21  29  26  34 /  40   5  40  40  50

&&

.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$

 /


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