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

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000
FXUS64 KFWD 172153
AFDFWD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FORT WORTH TX
353 PM CST WED DEC 17 2014

.DISCUSSION...
AFTER A SOMEWHAT SLOW START...THE RAIN SHIELD HAS STEADILY
EXPANDED IN COVERAGE THIS AFTERNOON AND ADVANCED INTO THE I-35
CORRIDOR AS OF 3 PM. THE SHEARED UPPER LEVEL SHORTWAVE TROUGH
OVER NM/FAR WEST TEXAS THAT IS LARGELY RESPONSIBLE FOR THIS RAIN
ACTIVITY SHOULD SHIFT EASTWARD INTO OK BY LATE TONIGHT...PUSHING
MOST OF THE RAIN OUT OF NORTH TEXAS AFTER 06Z. INSTABILITY HAS
BEEN SUFFICIENT TO PRODUCE SOME PEA TO DIME-SIZED HAIL WITH SOME
OF THE CELLS IN TARRANT AND SOUTHERN DENTON COUNTIES...AND SOME
ADDITIONAL THUNDER AND SMALL HAIL IS POSSIBLE THROUGH EARLY
EVENING. THE GREAT BULK OF THE AREA...HOWEVER...SHOULD EXPERIENCE
JUST RAIN.

NORTH TEXAS SHOULD SEE A BREAK FROM ANY PRECIPITATION
THURSDAY...BUT THEN ANOTHER...LARGER AND MORE PRONOUNCED UPPER TROUGH
SHOULD BUILD INTO THE THE SOUTHERN PLAINS LATE THURSDAY NIGHT INTO
FRIDAY. THIS NEXT SYSTEM SHOULD INDUCE SURFACE CYCLOGENESIS OVER
SE TEXAS EARLY FRIDAY...WITH A LARGE SHIELD OF RAIN EVOLVING OVER
EASTERN AND SOUTHERN TEXAS. THE BIG QUESTION IS HOW FAR
NORTH...AND IN WHAT AMOUNTS...THIS RAIN WILL EXPAND INTO OUR AREA FRIDAY.
OUR THINKING...BASED ON CURRENT MODEL SOUNDINGS...IS THAT A
SUBSTANTIAL AMOUNT OF DRY AIR WILL PERSIST ON THE NORTHERN
PERIPHERY OF THIS SYSTEM...AND THIS SHOULD LIMIT AMOUNTS ALONG AND
NORTH OF INTERSTATE 20 TO LESS THAN ONE QUARTER INCH...IF THAT
MUCH. QPFS FARTHER TO THE SOUTH...WHERE MOISTURE AND LIFT WILL BE
RICHER...SHOULD BE MORE GENEROUS - PERHAPS ON THE ORDER OF AN INCH
OR SO.

MOST OF THE MOISTURE SHOULD LIFT EAST OF THE AREA BY
SATURDAY...AND WITH ZONAL TO NORTHWESTERLY UPPER FLOW PERSISTING
FROM THAT POINT ONWARD...THE FORECAST INTO MID-WEEK SHOULD BE
MOSTLY DRY. DID INCLUDE A SMALL POP FOR AREAS GENERALLY EAST OF
I-35 FOR LATE MONDAY INTO TUESDAY...AS A COLD FRONT MOVES INTO THE
AREA...AND ANOTHER VIGOROUS TROUGH BUILDS INTO THE ARKLATEX REGION.

BRADSHAW

&&

.AVIATION...
/ISSUED 1209 PM CST WED DEC 17 2014/
A VERY TRICKY 18 UTC TAF CYCLE LATE THIS MORNING FOR THE METROPLEX
AND WACO TAF SITES. THE MAIN CONCERNS/IMPACTS WILL BE THE
THREAT FOR PRECIPITATION/THUNDER AS WELL AS THE POTENTIAL FOR IFR
CIGS/VISBY THIS EVENING THROUGH THE OVERNIGHT HOURS.

FOR THE METROPLEX TAF SITES...REGIONAL RADARS THIS MORNING
REVEALED SCATTERED SHOWERS ALONG AND NORTH OF THE INTERSTATE 20 CORRIDOR.
THE 12 UTC FWD RAOB AND RECENT AMDAR DATA REVEALED A VERY DRY
LAYER OF AIR PERSISTED AROUND THE 3-5 KFT AGL. TRENDS IN VAD WINDS
FROM THE KFWS WSR-88D INDICATED THAT VIRGA BELOW THE SUB-CLOUD
REGION WAS AIDING IN GRADUAL SATURATION OF THE AFORMENTIONED LAYER.
THIS TREND IS EXPECTED TO CONTINUE THROUGH THE AFTERNOON HOURS.
GUIDANCE FROM THE RAP/NAM HAS DONE A DECENT JOB IN HANDLING THIS
TOP-DOWN MOISTENING PROCESSES AND THUS THIS FORECAST LEANS
SOMEWHAT HEAVIER ON THE OUTPUT FROM THESE MODELS. HI-RES MODEL
GUIDANCE CONTINUES TO INDICATE THAT MORE WIDESPREAD PRECIPITATION
WILL BE POSSIBLE THIS AFTERNOON. THE INSTABILITY AXIS AS NOTED BY THE
RAP MESOANALYSIS SUGGESTS SOME POTENTIAL FOR THUNDER AND AS A
RESULT...HAVE INCLUDED VCTS AT THE METROPLEX TAF SITES FOR SEVERAL
HOURS THIS AFTERNOON. AS GREATER FORCING ARRIVES...MORE WIDESPREAD
PRECIPITATION SHOULD DEVELOP...AND A CONTINUED MOISTENING OF THE
LOW LEVELS SHOULD ENSUE. THIS MOISTENING WILL RESULT IN CIGS AND
VISBY DETERIORATING QUICKLY LATE THIS AFTERNOON AND INTO THE
EVENING HOURS. IFR CIGS AND VISBY ARE EXPECTED ACROSS THE
METROPLEX TAF SITES AROUND 0200 UTC. THE ONSET OF THE
DETERIORATING CIGS/VISBY WILL BE MOST LIKELY BE TIED TO AREAS OF
LIGHT RAIN/DRIZZLE DEVELOPING THIS EVENING AND THROUGH MIDNIGHT.
THERE IS THE POTENTIAL FOR LIFR CIGS/VISBY...BUT THERE REMAINS
SOME UNCERTAINTY IN THIS AND AS A RESULT...WILL DEFER TO LATER
SHIFTS. VISBY SHOULD IMPROVE AROUND MIDNIGHT WITH CONTINUED IFR CIGS
EXPECTED TO PERSIST THROUGH THURSDAY MORNING.

FOR THE WACO TAF SITE...MVFR CIGS JUST TO THE SOUTH OF THE TAF
SITE SHOULD SLOWLY LIFT NORTHWARD AS LOW LEVEL WARM/MOIST AIR
ADVECTION OVERSPREADS THE REGION. UNLIKE AREAS TO THE
NORTH...PRECIPITATION HAS BEEN SLIGHTLY SLOWER TO BREAKOUT
HERE THIS AM AND THUS A SLIGHTLY DEEPER LAYER OF DRIER AIR ALOFT
REMAINS. PRECIPITATION SHOULD GRADUALLY INCREASE AS THE LARGER
SCALE FORCING GRAZES CENTRAL TEXAS. AREAS OF LIGHT PRECIPITATION
SHOULD DEVELOP TOWARDS THE MID TO LATE AFTERNOON HOUR. AREAS OF
LIGHT RAIN AND DRIZZLE WILL SUPPORT IFR CIGS THROUGH TONIGHT AND
INTO THE EARLY PORTION OF THURSDAY. THEREAFTER...CIGS SHOULD
IMPROVE TO MVFR.

15-BAIN/92-TR


&&

.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX  41  61  47  51  38 /  60   5  40  50  20
WACO, TX              44  62  49  54  39 /  60  10  70  70  10
PARIS, TX             38  51  43  48  38 /  90  10  30  50  30
DENTON, TX            40  59  44  49  36 /  60   5  30  40  20
MCKINNEY, TX          40  57  44  50  37 /  60  10  40  40  20
DALLAS, TX            41  60  47  51  40 /  60   5  40  50  20
TERRELL, TX           42  58  47  50  39 /  80   5  50  50  20
CORSICANA, TX         45  63  49  52  41 /  80  10  70  70  20
TEMPLE, TX            45  64  50  55  40 /  50  10  80  80  10
MINERAL WELLS, TX     41  60  44  51  35 /  50   5  40  40  10

&&

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

&&

$$

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