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

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FXUS64 KFWD 301214 AAA
AFDFWD

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE FORT WORTH TX
714 AM CDT THU OCT 30 2014

.AVIATION...
/12Z TAFS/

CONCERNS...STORM POTENTIAL...WIND SHIFT.

CLOUD COVER...
OLD FRONTAL BOUNDARY IS DISCERNIBLE BY A NORTH-SOUTH ORIENTED
MOISTURE DISCONTINUITY. FLOW WITHIN A MILE OF THE SURFACE IS
GENERALLY PARALLEL TO THIS BOUNDARY...WHICH WILL PREVENT THE MVFR
STRATUS OVER THE HILL COUNTRY FROM REACHING WACO. HOWEVER...
VEERING FLOW IN ADVANCE OF ANOTHER COLD FRONT WILL ALLOW THE
DEEPER MOISTURE TO REACH THE I-35 CORRIDOR THIS AFTERNOON. THIS
WILL MEAN SOME VFR CEILINGS LATE THIS AFTERNOON INTO THE EARLY
EVENING...DURING THE HANDFUL OF HOURS PRECEDING FROPA. SKIES
SHOULD RAPIDLY CLEAR AFTER THE FRONTAL PASSAGE.

STORM POTENTIAL...
MOISTURE RECOVERY IN ADVANCE OF THE APPROACHING COLD FRONT MAY BE
SUFFICIENT FOR THE DEVELOPMENT OF SHOWERS AND THUNDERSTORMS LATE
THIS AFTERNOON IN VICINITY OF THE METROPLEX. THERE IS CONSIDERABLE
DISPARITY AMONG SHORT RANGE GUIDANCE IN TERMS OF INTENSITY AND
AREAL COVERAGE...BUT WITH MOST SOLUTIONS IN GENERAL AGREEMENT WITH
THE FRONTAL TIMING...CONFIDENCE IS HIGH IN WINDOW FOR POTENTIAL
IMPACTS...EVEN IF PROBABILITY OF PRECIPITATION IS LOW. HAVE
INTRODUCED VCSH...BUT AVIATION INTERESTS SHOULD BE AWARE OF THE
POTENTIAL FOR THUNDERSTORMS LATE AFTERNOON THROUGH THE EVENING.

WIND SHIFT...
SURFACE WINDS WILL STEADILY VEER TODAY FROM SOUTHEAST TO
SOUTHWEST. SPEEDS WILL BE PRIMARILY UNDER 10KTS. UNLESS CONVECTION
IS MORE WIDESPREAD THAN THE CURRENT FORECAST...THE EVENTUAL
VEERING TO THE NORTH WILL BE DURING THE EVENING HOURS.

25

&&


.PREV DISCUSSION... /ISSUED 419 AM CDT THU OCT 30 2014/
OUR FIRST WEATHER CONCERN WILL BE WITH THE NORTHERN PLAINS COLD
FRONT SURGING SOUTH INTO THE SOUTHERN PLAINS THIS AFTERNOON...AS
A NORTHWEST FLOW SHORTWAVE MOVES QUICKLY SOUTHEAST. A SURFACE LOW
OVER EASTERN SOUTH DAKOTA WILL MOVE INTO CENTRAL MISSOURI BY
MIDDAY. THE COLD FRONT CROSS THE RED RIVER BY LATE AFTERNOON...THEN
THROUGH THE REMAINDER OF NORTH AND CENTRAL TEXAS TONIGHT. MODELS
CONTINUE TO SHOW MOISTURE INCREASING AHEAD OF THE FRONT...PARTICULARLY
ACROSS THE SOUTHWEST HALF OF OUR COUNTY WARNING AREA THROUGH THE
DAY WITH PWAT VALUES APPROACHING 1.15-1.3 INCHES. HIGH RESOLUTION
MODELS ARE SIGNALING HIGHER RAIN CHANCES THAN IN PREVIOUS RUNS
FROM THE DFW METRO SOUTHWEST INTO THE NORTHERN HILL COUNTRY. THE
GFS AND HRRR ARE THE DRIEST SOLUTIONS AND KEEP CONVECTIVE ACTIVITY
ISOLATED...WHILE THE ECMWF/VARIOUS WRF MODELS INDICATE SCATTERED
COVERAGE...WHILE THE SREF/NAM12 MODELS THE WETTEST. ALL THESE
VARIABLE SOLUTIONS CREATED QUITE A QUANDARY FOR FORECASTING RAIN
CHANCES LATER TODAY AND HOW MUCH TO RAMP THEM UP.

AFTER COLLABORATING WITH SEVERAL NEIGHBORING OFFICES...THE DECISION
AGREED UPON WAS TO RAISE POPS...BUT STAY CONSERVATIVE AND LEAN
TOWARD THE MIDDLE OF THE ROAD ECMWF/WRF PROJECTIONS. MOISTURE DOES
INCREASE...BUT IS NOT OVERLY RICH WITH BEST VALUES ACROSS OUR
SOUTHWEST COUNTIES. THE GENERAL FEELING WAS THAT THERE WOULD BE
ENOUGH FORCING TRAILING FROM THE SHORTWAVE MOVING THROUGH THE
OZARKS AND INTO THE LOWER MISSISSIPPI VALLEY TONIGHT IN ADDITION
TO THE SURFACE FORCING ALONG THE COLD FRONT TO RAISE AREAS SOUTH
OF I-20 AND WEST OF I-35 INTO THE CHANCE CATEGORY. INSTABILITY BOTH
SURFACE AND ALOFT APPEARS MARGINAL...BUT STRONG NORTHWEST BULK
SHEAR ON THE ORDER OF 40 KTS MAY LEND TO A STRONG STORM OR TWO
FROM LATE AFTERNOON INTO THIS EVENING. HOWEVER...THE MAJORITY OF
CONVECTIVE ACTIVITY SHOULD REMAIN OF THE GENERAL VARIETY.

COOL AND BRISK CONDITIONS ARE EXPECTED BEHIND THE COLD FRONT BY
FRIDAY MORNING. THE ORIGIN OF THIS NEXT AIRMASS IS OUT OF NORTH-
CENTRAL CANADA WHERE TEMPERATURES ARE PRETTY CHILLY. HIGHS ARE
ONLY EXPECTED TO BE IN THE 60S NORTH TO THE LOWER 70S ACROSS
CENTRAL TEXAS FRIDAY WITH BRISK NORTH WINDS. THE GUSTY WINDS WILL
SETTLE DOWN DURING THE EVENING HOURS FRIDAY FOR TRICK OR TREATERS
OR THOSE HEADING TO AREA HIGH SCHOOL FOOTBALL GAMES. NEVERTHELESS...
TEMPERATURES BY NIGHTFALL WILL BE IN THE 50S AND WILL FALL READILY
INTO THE MID- UPPER 40S BY LATE EVENING ACROSS MOST AREAS...SO
BRINGING A LIGHT COAT OR JACKET IS HIGHLY RECOMMENDED FOR ANY
OUTDOOR ACTIVITIES FRIDAY EVENING. THE WINDS WILL BECOME LIGHT
NORTHEAST BY SATURDAY MORNING WITH POSSIBLE FROST ON THE PUMPKINS
ACROSS RURAL AREAS NORTH OF I-20...AS LOW TEMPERATURES FALL WELL
INTO THE 30S. ANY EXTENT OF FROST WILL REALLY DEPEND ON ANY NEAR-
SURFACE MOISTURE THAT MAY BE PRESENT. MIGHT NOT BE A BAD IDEA TO
PROTECT SENSITIVE OUTDOOR PLANTS AND VEGETATION FRIDAY NIGHT/SATURDAY
MORNING AND MAKE SURE OUTDOOR PETS ARE PREPARED FOR THIS ROUND OF
COLDER AIR. A SURFACE HIGH SETTLES ACROSS THE OZARKS DURING THE
DAY SATURDAY WITH HIGHS WARMING ONLY INTO THE 60S...DESPITE
SOUTHEAST WINDS RETURNING AND ABUNDANT SUNSHINE. LEE SURFACE
CYCLOGENESIS OVER THE HIGH PLAINS ALONG WITH AN UPPER RIDGE SETTLING
OVER THE AREA SATURDAY NIGHT INTO SUNDAY WILL RESULT IN BREEZY
SOUTH WINDS AND TEMPERATURES SLOWLY MODERATING BACK UP TO NEAR 70
DEGREES FOR HIGHS SUNDAY.

THE LONGWAVE UPPER TROUGH CURRENTLY ENTERING THE U.S. WEST COAST
WILL BE OUR NEXT SYSTEM OF INTEREST FOR THE EARLY HALF OF NEXT
WEEK. THIS SYSTEM WILL TRACK EAST OVER THE ROCKIES OVER THE
WEEKEND AND BEGIN AFFECTING THE WESTERN HIGH PLAINS BY MONDAY.
WE EXPECT MONDAY TO BE MOSTLY DRY AS THE INCREASING SOUTHWEST
FLOW ALOFT WILL LIKELY ENHANCE THE CAPPING INVERSION OVER MUCH OF
THE AREA WITH PLENTY OF STRATUS UNDERNEATH THE INVERSION. MODELS
NOW HAVE THIS SYSTEM MORE OF AN OPEN AND DEEP WAVE THIS RUN VERSUS
BEING CUT OFF ON RUNS 24 HOURS AGO. THOUGH MOVEMENT WILL BE SLOW...
WE DO EXPECT THE SYSTEM TO EJECT OVER THE AREA TUESDAY INTO TUESDAY
NIGHT...AS MID LEVEL TROPICAL MOISTURE GETS PICKED UP FROM AN OLD
PACIFIC TROPICAL SYSTEM. WE PLAN TO CARRY HIGH RAIN CHANCES
TUESDAY AND TUESDAY NIGHT...AS THE SURFACE COLD FRONT MOVES INTO
THE AREA.

BY WEDNESDAY AND BEYOND...THE ECMWF AND GFS BEGIN TO WIDELY DIVERGE
ON HOW THE SOUTHERN PIECE OF ENERGY ALOFT IS HANDLED. THE GFS
REMAINS PROGRESSIVE THE SYSTEM AND COLD FRONT...WHILE THE ECMWF
CUTS IT OFF AND DROPS IT EVEN FURTHER SOUTH OVER NORTHERN MEXICO
BY WEDNESDAY WITH THE FRONT STALLING ACROSS THE AREA. THE ECMWF
SOLUTION WOULD KEEP THE AREA WET INTO THE LATE WEEK PERIOD...BUT THE
GFS DRIES THINGS OUT. FOR NOW...WILL GO WITH LOWER POPS THAN
GUIDANCE AND AWAIT LATER MODEL RUNS TO BETTER RESOLVE THINGS.

05/

&&


.SYNOPSIS...
QUIET WEATHER WAS OCCURRING ACROSS THE REGION THIS MORNING...AS
A SURFACE RIDGE OF HIGH PRESSURE EXTENDED FROM THE GREAT LAKES
SOUTHWEST INTO TEXAS. A COLD FRONT WAS PROGRESSING SOUTH ACROSS
THE HIGH PLAINS OF THE DAKOTAS AND EASTERN MONTANA WITH A SURFACE
TROUGH EXTENDING FROM EASTERN SOUTH DAKOTA SOUTH INTO SOUTHEAST
COLORADO AND NORTHEAST NEW MEXICO. A SHORTWAVE WAS SEEN ON WATER
VAPOR SATELLITE IMAGERY MOVING SOUTHEAST ACROSS THE UPPER MIDWEST
AND NORTHERN PLAINS THIS MORNING...WHILE ANOTHER STRONG UPPER
SYSTEM WAS APPROACHING THE U.S. WEST COAST.

&&


.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX  80  53  66  40  62 /  30  20   0   0   0
WACO, TX              79  53  70  40  64 /   5  30   0   0   0
PARIS, TX             73  46  63  34  59 /  10  10   0   0   0
DENTON, TX            78  48  65  36  61 /  30  10   0   0   0
MCKINNEY, TX          76  50  65  34  61 /  30  10   0   0   0
DALLAS, TX            79  55  67  40  62 /  20  20   0   0   0
TERRELL, TX           77  52  67  38  62 /  10  20   0   0   0
CORSICANA, TX         77  54  69  40  62 /   5  20   0   0   0
TEMPLE, TX            78  54  71  41  64 /   5  40   0   0   0
MINERAL WELLS, TX     80  48  67  36  63 /  30  20   0   0   0

&&

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

&&

$$

25/05





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