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

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FXUS64 KFWD 190150 AAB
AFDFWD

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE FORT WORTH TX
750 PM CST THU DEC 18 2014

.UPDATE...
WE CONTINUE MONITORING THE NEXT UPPER LEVEL DISTURBANCE TRACKING
ACROSS WESTERN NEW MEXICO. THIS SYSTEM WAS EXPECTED TO BE OVER
SOUTH-CENTRAL OKLAHOMA BY MIDDAY FRIDAY. A SURFACE FRONT REMAINED
DRAPED SOUTH OF OUR CWA FROM THE HILL COUNTRY INTO THE TEXAS
COASTAL BEND.

HAVE DONE A MINOR UPDATE TO TEMPS AND RAIN CHANCES THIS EVENING.
REGIONAL RADAR SHOWING FIRST SIGNS OF INCREASING WAA AND SHOWER
ACTIVITY EXTENDING FROM THE TEXAS COASTAL BEND TO THE INTERSTATE
10 CORRIDOR. TIME INTERPOLATION BRINGS THIS ACTIVITY TO MAKE IT
POSSIBLY AS FAR NORTH AS GATESVILLE...TO MARLIN...TO COLLEGE
STATES LINE BY MIDNIGHT. HAVE REMOVED EVENING RAIN CHANCES ALONG
AND NORTH OF INTERSTATE 20...WHILE CONFINING LIKELY CHANCES
TO OUR EXTREME SOUTHERN CENTRAL TEXAS COUNTIES. SLIGHT CHANCES
WILL REMAIN AS FAR NORTH AS A COMANCHE TO ATHENS LINE.

OVERNIGHT RAIN CHANCES INTO FRIDAY LOOK ON TRACK AND DID NOT
CHANGE THE FORECAST. BEST CHANCES FOR SHOWERS AND MEASURABLE
RAINFALL WILL BE SOUTH OF INTERSTATE 20 WITHIN BAND OF HIGH 850MB
MOISTURE AND LAYER PRECIPITABLE WATER VALUES PUSHING OVER AN INCH.
AMOUNTS WILL BE MUCH LOWER ACROSS THE NORTH. I ALSO LEFT MENTION
OF ISOLATED THUNDERSTORMS SOUTH OF INTERSTATE 20 WHERE STRONGER
WAA AND MUCAPE VALUES OF A FEW HUNDRED J/KG WILL EXIST.

05/

&&

.AVIATION...
/ISSUED 1238 PM CST THU DEC 18 2014/
/18Z TAFS/

CONCERNS...CEILING/VISIBILITY TRENDS.

WITH WEAK DECEMBER INSOLATION...LIFR CONDITIONS HAVE BEEN SLOW TO
IMPROVE. DESPITE THE CLEARING LINE ADVANCING TO WITHIN 50 MILES OF
THE I-35 CORRIDOR...THE ONSET OF REINFORCING COLD ADVECTION WITHIN
THE BOUNDARY LAYER SHOULD HALT ITS PROGRESS. CEILINGS WILL
CONTINUE TO LIFT THIS AFTERNOON BUT WILL REMAIN IFR.

ANOTHER ROUND OF PRECIPITATION WILL OVERRIDE THE COOL AIR AT THE
SURFACE...ADVANCING FROM SOUTHWEST TO NORTHEAST LATE TONIGHT INTO
FRIDAY MORNING. THE BULK OF THE RAINFALL WILL AFFECT CENTRAL TEXAS
AIRPORTS...BUT FOR ALL TAF SITES...THE PRIMARY IMPACT WILL BE THE
ACCOMPANYING REDUCTIONS TO LIFR CEILINGS/VISIBILITY.

25


&&


.PREV DISCUSSION... /ISSUED 230 PM CST THU DEC 18 2014/

QUITE A DIFFERENCE ACROSS THE REGION TODAY AS FAR AS CLOUDS AND
TEMPS ARE CONCERNED. ABUNDANT SUNSHINE OVER THE WESTERN ZONES HAVE
RESULTED IN TEMPS INTO THE 60S WHEREAS LOW CLOUDS HAVE HUNG IN
TOUGH ACROSS THE REST OF THE REGION ALONG WITH WEAK COLD AIR
ADVECTION RESULTING IN TEMPS STILL IN THE 40S TO LOW 50S.

WATER VAPOR SHOWS A SHORTWAVE TROUGH MOVING ACROSS NORTHERN MEXICO
THIS AFTERNOON WHICH WILL BEGIN TO INCREASE THE LARGE-SCALE LIFT FROM
WEST TO EAST STARTING THIS EVENING. POSITION OF THE 850 FRONT
CONTINUES TO BE APPEAR TO BE THE BEST DISCRIMINATOR AS TO WHERE
THE HEAVIER RAINFALL WILL OCCUR. HIGHER RES MODELS CONSISTENT WITH
KEEPING THIS FEATURE SOUTH OF THE I-20 CORRIDOR...AS A RESULT THAT
IS WHERE THE HIGHER POPS AND HIGHER RAINFALL TOTALS (AROUND ONE-
HALF TO THREE-QUARTERS OF AN INCH) ARE EXPECTED OVERNIGHT AND
MAINLY INTO FRIDAY MORNING. ALSO APPEARS THERE WILL BE ENOUGH
INSTABILITY FOR SOME ELEVATED THUNDERSTORMS OVER THE SOUTHERN
ZONES.

NORTH OF THE 850 MB FRONT...FAIRLY HIGH POPS WILL RESIDE ALONG THE
I-20 CORRIDOR BUT WITH A DRY LAYER EVIDENT ON FORECAST SOUNDINGS
BETWEEN 800-700MB RAINFALL TOTALS WILL BE QUITE A BIT LOWER
(AROUND A TENTH OF AN INCH) AS THE PRECIPITATION WILL HAVE TO
OVERCOME THIS DRY LAYER BEFORE REACHING THE GROUND. FURTHER
NORTH TOWARDS THE RED RIVER...POPS AND ACCOMPANYING RAINFALL
TOTALS WILL BE EVEN LOWER.

LIFT FROM THE UPPER LEVEL SYSTEM WILL DECREASE FROM WEST TO EAST
DURING THE DAY FRIDAY SO MOST OF THE PRECIP WILL END BY AFTERNOON
THOUGH A FEW LIGHT RAIN SHOWERS WILL STILL BE POSSIBLE ACROSS THE
EASTERN ZONES DURING THE EARLY EVENING HOURS.

COOL WEEKEND IN STORE FOR NORTH TEXAS AS CLOUDS WILL REMAIN ACROSS
THE AREA THOUGH NO PRECIP EXPECTED. STILL EXPECTING A COLD FRONT
TO PUSH THROUGH LATE MONDAY AND INTO EARLY TUESDAY. WITH NORTHWEST
FLOW ALOFT...WILL BE DIFFICULT TO GET ENOUGH MOISTURE AND LIFT TO
PRODUCE MUCH IN THE WAY OF RAINFALL THOUGH HAVE KEPT SLIGHT CHANCE
OF POPS OVER THE EASTERN ZONES MONDAY NIGHT AND INTO TUESDAY.

COLDEST AIR WITH THIS SYSTEM WILL STAY TO OUR NORTHEAST SO
GENERALLY EXPECT A COOL DRY PERIOD AS WE HEAD INTO CHRISTMAS.

WILEY



&&



.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX  44  48  39  52  40 /  40  60  10   5   5
WACO, TX              47  52  39  54  39 /  70  70  20   5   5
PARIS, TX             43  48  36  51  36 /  30  50  30  10  10
DENTON, TX            44  48  38  52  38 /  30  50  10   5   5
MCKINNEY, TX          43  48  37  51  38 /  40  60  20   5   5
DALLAS, TX            44  48  39  53  40 /  40  60  20   5   5
TERRELL, TX           45  49  38  53  39 /  50  60  20   5   5
CORSICANA, TX         46  51  39  54  40 /  70  70  20  10   5
TEMPLE, TX            48  52  40  56  39 /  80  70  10   5   5
MINERAL WELLS, TX     44  47  38  52  38 /  40  50  10   5   5

&&

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

&&

$$

14/05





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