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

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113
FXUS64 KFWD 261706 AAB
AFDFWD

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE FORT WORTH TX
1206 PM CDT TUE APR 26 2016

.UPDATE...
OVERALL THE DETAILS AND THREATS CONCERNING TODAY AND TONIGHT`S
SEVERE WEATHER EVENT HAVE NOT CHANGED. THE LATEST DAY 1 SPC
OUTLOOK HAS UPGRADED A LARGE PART OF THE REGION TO A MODERATE RISK
CATEGORY WHICH IS DUE TO AN INCREASED THREAT FOR LARGE HAIL AND
DAMAGING WINDS. THERE ALSO REMAINS A THREAT FOR TORNADOES...IN
PARTICULAR WITH THE INITIAL STORMS THAT DEVELOP THIS AFTERNOON AND
EVENING. IN ABOUT 30 MINUTES WE WILL BE LAUNCHING A SPECIAL 18Z
SOUNDING THAT WILL HELP US ASSESS THE CAP STRENGTH.

THERE ARE SOME CHALLENGES WITH THE EVOLUTION OF STORMS THIS
EVENING BUT SEVERE STORMS ARE EXPECTED TO DEVELOP AROUND 3-4 PM
NEAR A WICHITA FALLS TO ABILENE LINE. OUR CONFIDENCE IN THE
LOCATION OF STORM DEVELOPMENT IS MODERATE AND COULD OCCUR ON
EITHER SIDE OF THIS LINE. BY THAT TIME...THE CAP WILL HAVE
WEAKENED AND/OR ERODED WITH SUFFICIENT LIFT OVERSPREADING A VERY
UNSTABLE ENVIRONMENT. THE INITIAL STORMS WILL BE SUPERCELLULAR
WITH A THREAT FOR LARGE HAIL...DAMAGING WINDS...AND TORNADOES.
THESE STORMS MAY MERGE INTO A LINE LATER AS THEY MOVE EAST AND/OR
ANOTHER LINE OF STORMS MAY FORM ALONG THE DRYLINE/PACIFIC FRONT AS
IS MOVES EAST A FEW HOURS LATER. BOWING SEGMENTS WITHIN THE LINE
WILL RESULT IN A POTENTIAL FOR VERY STRONG DAMAGING WINDS AND
ISOLATED TORNADOES. IF THERE ARE TWO ROUNDS OF STORMS...WE DO NOT
EXPECT THERE TO BE MUCH TIME SPREAD BETWEEN THE TWO ROUNDS.

FOR THE UPDATE...ADJUSTED POPS AND QPF BACK WEST A LITTLE BIT THIS
AFTERNOON AND EVENING TO ACCOUNT FOR A SLOWER TIMING OF THE
STORMS. THE STORMS WILL LIKELY BE REACHING AT LEAST THE NORTHERN
PORTIONS OF THE INTERSTATE 35 CORRIDOR BETWEEN 10 PM - 1 AM AND
THE LINE WILL CONTINUE MOVING EAST OVERNIGHT. OVERNIGHT...THE HI-
RES MODELS INDICATE THE LINE WILL REMAIN PROGRESSIVE THROUGH THE
REGION BUT IF IT SLOWS DOWN....THE THREAT FOR LOCALIZED FLOODING
WILL INCREASE.

JLDUNN

&&

.AVIATION...
/ISSUED 658 AM CDT TUE APR 26 2016/
CONCERNS...POTENTIAL FOR STRONG TO SEVERE STORMS THIS EVENING.

EXPECT MVFR CEILINGS TO PREVAIL ACROSS THE TAF SITES THROUGH MID
AFTERNOON WITH AN IMPROVEMENT TO VFR AFTER 21Z. A DRYLINE IS
EXPECTED TO EXTEND EAST OF A KF05 /VERNON/ TO KJCT /JUNCTION/ LINE
BY 00Z. SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP ALONG THE
DRY LINE AND INITIALLY MOVE NORTHEAST. THESE STORMS SHOULD FORM
INTO A SQUALL LINE AND MOVE EAST TOWARD THE I-35 CORRIDOR LATE
EVENING. THUS HAVE PLACED A TEMPO TSRA BETWEEN 02Z AND 05Z. SOME
ISOLATED STORMS COULD FORM OUT AHEAD OF THIS LINE...SO HAVE PLACE
VCTS STARTING AT 00Z. SOUTH WINDS 15 TO 25 KNOTS WILL PREVAIL
THROUGH THIS EVENING...THESE STORMS WILL BECOME SOUTH SOUTHWEST
BEHIND THE STORMS...AND BECOME WEST BY 15Z WEDNESDAY.

58


&&



.PREV DISCUSSION... /ISSUED 341 AM CDT TUE APR 26 2016/
THE LAST WEEK OF APRIL THROUGH THE FIRST FEW DAYS OF MAY ARE
SHAPING UP TO BE AN ACTIVE PERIOD AS A SERIES OF UPPER LEVEL
STORM SYSTEMS MOVE ACROSS THE COUNTRY. THIS MORNING/S SATELLITE
DATA INDICATES THAT THE FIRST SYSTEM SLATED TO AFFECT THE NORTH
AND CENTRAL TEXAS IS AN UPPER LOW CURRENTLY SITUATED OVER THE FOUR
CORNERS REGION. A DISTINCT VORTICITY LOBE CAN BE SEEN ROTATING
AROUND THE SOUTHWEST QUADRANT OF THE UPPER LOW OVER ARIZONA. THIS
FEATURE WILL CONTINUE AROUND THE BASE OF THE SYSTEM ACROSS NEW
MEXICO THIS MORNING AND THEN INTO NORTHWEST TEXAS THIS
AFTERNOON...FORCING THE UPPER LOW TO EJECT NORTHEASTWARD THROUGH
THE PLAINS TONIGHT.

THE RESULTING NEGATIVELY TILTED APPEARANCE TAKEN ON BY THE UPPER
LEVEL SYSTEM IS GENERALLY CONDUCIVE FOR THE DEVELOPMENT OF STRONG
TO SEVERE THUNDERSTORMS...PARTICULARLY IN THE SPRING WHEN OTHER
PARAMETERS ASSOCIATED WITH CONVECTION ARE MORE LIKELY TO BECOME
FAVORABLE. ONE SUCH PARAMETER WILL BE LOW LEVEL
CONVERGENCE...WHICH IN THIS CASE WILL BE ENHANCED AS A DRYLINE IS
NUDGED EASTWARD INTO WESTERN COUNTIES OF NORTH AND CENTRAL TEXAS.
ANOTHER WILL BE INSTABILITY...WHICH IS FORECAST TO BE IN GREAT
SUPPLY AS CAPE CLIMBS TO NEAR 4000 J/KG IN THE VICINITY OF THE
DRYLINE THIS AFTERNOON. SHEAR WILL BE MORE THAN SUFFICIENT FOR
THE DEVELOPMENT OF ROTATING CELLS CAPABLE OF MAINTAINING STRONG
UPDRAFTS...WHICH MEANS THAT LARGE HAIL WILL BE OUR MOST LIKELY
SEVERE THREAT. DAMAGING DOWNBURST WINDS WILL ALSO BE A GOOD
POSSIBILITY WITH ANY STORMS WHICH BECOMES SEVERE. LOW LEVEL SHEAR
DOES NOT LOOK PARTICULARLY GREAT FOR AN OUTBREAK OF
TORNADOES...BUT WHEN COMBINED WITH SUCH GOOD INSTABILITY WILL BE
ENOUGH FOR A FEW TORNADOES TO OCCUR.

THE HIGHEST PROBABILITIES FOR SEVERE THUNDERSTORM DEVELOPMENT
WILL BE EARLY ON IN THE DEVELOPMENT OF STORMS...OR DURING THE 4 TO
10 PM TIME-FRAME WHEN DISCRETE CELLS ARE MORE LIKELY TO OCCUR.
LOCATION SHOULD INITIALLY BE WEST OF THE INTERSTATE 35/35W
CORRIDOR NEAR THE DRY-LINE. UPSCALE DEVELOPMENT INTO A LINEAR
CONVECTIVE MODE IS LIKELY LATE THIS EVENING AND OVERNIGHT AS
STORMS SHIFT EAST ACROSS THE I-35 CORRIDOR AND CONTINUE ACROSS THE
EASTERN HALF OF THE REGION. BRIEF HEAVY RAIN AND LOCALIZED
FLOODING WILL BE ANOTHER POSSIBLE THREAT OVERNIGHT...ESPECIALLY IF
ANY STORMS ARE ABLE TO TRAIN OVER THE SAME AREAS. ACTIVITY IS
EXPECTED TO END FROM WEST TO EAST DURING THE MORNING HOURS ON
WEDNESDAY.

THE NEXT ROUND OF STORMS WILL OCCUR LATE THURSDAY AS ANOTHER UPPER
LOW DEEPENS OVER THE FOUR-CORNERS REGION BEFORE LIFTING NORTHEAST
THROUGH THE PLAINS. IT LOOKS LIKE TWO MAIN PIECES OF ENERGY WILL
BE ASSOCIATED WITH THIS SYSTEM...ONE OF WHICH WILL GENERATE THE
THURSDAY NIGHT STORMS...AND THE NEXT WHICH WILL GENERATE A SECOND
ROUND OF CONVECTION FRIDAY NIGHT INTO EARLY SATURDAY. THE
CONVECTIVE PARAMETERS DO NOT LOOK QUITE AS FAVORABLE AS THEY DO
WITH THIS EVENINGS/S SYSTEM,...BUT STILL LOOK SUFFICIENT FOR SOME
SEVERE WEATHER BOTH THURSDAY NIGHT AND FRIDAY NIGHT. SATURATED
SOILS FROM THE EARLY-WEEK STORMS WILL ALSO INCREASE THE
LIKELIHOOD OF LOCALIZED FLOODING.

THERE SHOULD BE A BREAK IN THE ACTIVITY LATE SATURDAY AND SUNDAY
AS THE SYSTEM HEADS FOR THE GREAT LAKES. ON MONDAY...A SHORTWAVE
TROUGH WILL PROPAGATE EAST ALONG THE RED RIVER REGION...GENERATING
YET ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS. AT THIS TIME...THE
GFS INDICATES THAT THIS WILL BE A MONDAY DAYTIME EVENT...WHILE THE
ECMWF IS ABOUT 12 HOURS SLOWER...INDICATING A MONDAY NIGHT EVENT.
WE WILL SHOW POPS FOR BOTH TIME PERIODS AND REFINE AS MODELS COME
INTO BETTER AGREEMENT. EITHER WAY...THERE LOOKS TO BE A BREAK IN
THE ACTIVE WEATHER FOR THE REST OF NEXT WEEK AS TROUGHING DEEPENS
IN THE EASTERN CONUS AND AN UPPER RIDGE DEVELOPS ACROSS THE
PLAINS.

30



&&


.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH    84  64  86  63  85 /  20  80  10   5  10
WACO                83  63  86  62  85 /  20  70  20  10  10
PARIS               82  65  81  60  83 /  20  70  30  10   5
DENTON              83  60  84  59  85 /  30  80  10   5  10
MCKINNEY            82  62  83  59  84 /  20  80  20  10  10
DALLAS              84  64  86  63  86 /  20  80  20  10  10
TERRELL             82  65  84  62  85 /  20  70  20  10  10
CORSICANA           84  66  85  64  85 /  20  70  30  10  10
TEMPLE              83  64  86  63  84 /  20  60  20  10  20
MINERAL WELLS       86  58  85  58  85 /  40  80   5   5  10

&&

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

$$

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