Severe Thunderstorm Warning 222, NWS Fort Worth, TX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FORT WORTH TX
109 PM CDT TUE MAY 19 2015

.AVIATION...
CONCERNS...SCATTERED SHOWERS/THUNDERSTORMS. MVFR REDEVELOPING
AFTER 06Z...GOING DOWN TO IFR BY 10Z WEDNESDAY.

SCATTERED SHOWERS AND A FEW THUNDERSTORMS HAD ALREADY DEVELOPED
ACROSS NORTH AND CENTRAL TEXAS AS OF 1730Z. HAVE PLACED A TEMPO
TSRA FOR THE 19-24Z PERIOD IN THE METROPLEX AND WACO. EXPECT MVFR
CEILINGS TO SPREAD BACK NORTH OVERNIGHT TONIGHT. CEILINGS SHOULD
LOWER TO IFR BY 10Z. SCATTERED SHOWERS AND THUNDERSTORMS WILL
ONCE AGAIN BE POSSIBLE LATE TONIGHT INTO WEDNESDAY MORNING...FOR
NOW HAVE PLACED VSCH STARTING AT 10Z.

58

&&

.UPDATE...
A SHORTWAVE WILL CONTINUE TRANSITING THE EASTERN TEXAS PANHANDLE
AND WESTERN OKLAHOMA TODAY. LATEST MESOSCALE GUIDANCE SUGGESTS THE
BULK OF THE ASSOCIATED PRECIPITATION WILL REMAIN NORTHWEST OF OUR
CWA...CLOSER TO A RETREATING SURFACE BOUNDARY. THIS WOULD APPEAR
TO SIGNIFICANTLY REDUCE THE FLOOD THREAT WITHIN THE FLASH FLOOD
WATCH TODAY...PARTICULARLY ACROSS THE SOUTHERN HALF WHERE THE
PRECIP-INDUCED MCV APPROACHING FROM SAN ANGELO IS NOW FAR LESS
DEFINED. HOWEVER...THE LACK OF MORNING ACTIVITY WILL HELP TO
SUFFICIENTLY DESTABILIZE THE ATMOSPHERE THIS AFTERNOON. THE SUNNY
SKIES HEADING FOR THE SOUTHWESTERN ZONES WILL LIKELY FILL IN WITH
DENSE CUMULUS...BUT EVEN WITH EXTENSIVE CLOUD COVER...MLCAPE
VALUES ARE ALREADY APPROACHING 2000J/KG. DEW POINTS WILL REMAIN
NEAR 70F...WHICH COULD PUSH MLCAPE VALUES OVER 3000J/KG IN
SOUTHERN ZONES. EVEN WITH NO SURFACE FOCUS FOR INITIATION...THIS
INSTABILITY WILL BE UNCAPPED AND SHOULD RESULT IN DISORGANIZED
CONVECTION...NOT UNLIKE MONDAY AFTERNOON. MINIMAL STORM MOTION
WILL POSE A FLOODING THREAT...PARTICULARLY WHERE SIGNIFICANT
RAINFALL HAS OCCURRED IN RECENT DAYS. IN ADDITION...PRECIP-LOADING
IN A LOW-SHEAR ENVIRONMENT WILL RENEW A THREAT OF DAMAGING
DOWNBURST WINDS. CELLS WILL BE MORE PROGRESSIVE IN NORTHWEST
ZONES...BUT EXTRAORDINARY PW VALUES WILL ASSURE PRECIPITATION
EFFICIENCY THAT COULD RESULT IN FLASH FLOODING.

MIDDAY UPDATE REDUCED POPS IN MANY AREAS...DUE TO THE LACK OF
CONFIDENCE IN OVERALL COVERAGE AND STORM MOTION...BUT THE FLOOD
THREAT REMAINS...EVEN IN AREAS OUTSIDE OF THE ONGOING FLASH FLOOD
WATCH. POPS WERE RAISED IN SOUTHEAST ZONES WHERE INSTABILITY
SHOULD BE SUFFICIENT FOR 40- TO 50-PERCENT COVERAGE.

25

&&

.PREV DISCUSSION... /ISSUED 347 AM CDT TUE MAY 19 2015/
A COMPLEX OF SHOWERS AND THUNDERSTORMS CONTINUES TO PRODUCE HEAVY
RAINFALL OVER THE CONCHO VALLEY AND BIG COUNTRY THIS MORNING.
LATEST RADAR TRENDS INDICATE SOME MESO-SCALE CIRCULATION IN THE
COMPLEX WHICH SHOULD CONTINUE TO SPAWN ADDITIONAL CONVECTION
THROUGH THE MORNING. SOME OF THESE SHOWERS AND THUNDERSTORMS
SHOULD REACH THE WESTERN ZONES OF NORTH TEXAS THIS MORNING AND
PRODUCE SOME HEAVY RAINFALL. THEREFORE...WE WILL ISSUE A FLASH
FLOOD WATCH ALONG AND WEST OF A LINE FROM LAMPASAS TO WEATHERFORD
TO BOWIE FOR TODAY. ADDITIONAL RAINFALL BETWEEN 1 AND 2 INCHES
WITH SOME LOCALLY HIGHER AMOUNTS ARE POSSIBLE.

WE EXPECT SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS TO
DEVELOP ACROSS THE ENTIRE REGION THIS AFTERNOON WITH THE BEST
COVERAGE OF STORMS ACROSS THE NORTHWEST ZONES IN THE VICINITY OF A
STALLED COLD FRONT. STORMS THAT DEVELOP THIS AFTERNOON WILL BE
PRIMARILY HEAVY RAIN PRODUCERS BUT ALSO HAVE A POTENTIAL TO BECOME
MARGINALLY SEVERE WITH HAIL AND DOWNBURST WINDS.

THE COLD FRONT IS PROGGED TO LIFT TO NEAR THE RED RIVER TONIGHT
IN RESPONSE TO ANOTHER DEVELOPING LOW PRESSURE SYSTEM IN THE WEST.
THE FRONT SHOULD BECOME THE FOCUS FOR SHOWERS AND THUNDERSTORMS
TONIGHT ESPECIALLY DURING THE EVENING WHEN A SHORTWAVE ROTATES
ACROSS THE REGION. WE WILL NEED TO MONITOR THE MOVEMENT OF THE
FRONT DURING THE DAY TODAY FOR A POSSIBLE EXTENSION/EXPANSION OF
THE FLASH FLOOD WATCH.

THE SHORTWAVE WILL MOVE TO THE NORTHEAST OVERNIGHT TONIGHT
THROUGH WEDNESDAY MORNING AND SHOULD BRING A BRIEF PERIOD OF LARGE
SCALE SUBSIDENCE AND DECREASING PRECIPITATION CHANCES.
HOWEVER...THIS WILL ONLY BE TEMPORARY AS LARGE SCALE LIFT INCREASE
ACROSS THE REGION WEDNESDAY AFTERNOON/NIGHT IN RESPONSE TO AN
APPROACHING UPPER LOW FROM THE WEST AND THE RETURN OF THE COLD
FRONT.

THE COLD FRONT IS FORECAST TO STALL OVER NORTH TEXAS WEDNESDAY
NIGHT AND THURSDAY. ALTHOUGH THE FRONT WILL CONTINUE TO BE A
SOURCE OF LIFT...SOME LARGE SCALE SUBSIDENCE UNDERNEATH A BUILDING
UPPER LEVEL RIDGE SHOULD LIMIT CONVECTION SOMEWHAT.

WE WILL CONTINUE TO CARRY CHANCE TO LIKELY POPS THURSDAY NIGHT
THROUGH MONDAY DUE TO NUMEROUS DISTURBANCES MOVING THROUGH
SOUTHWEST FLOW ALOFT. IT APPEARS THAT THE BEST POTENTIAL FOR
WIDESPREAD HEAVY RAINFALL WILL BE SUNDAY/SUNDAY NIGHT WHEN LARGE
SCALE FORCING WILL BE THE STRONGEST.

79

&&

.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX  84  71  82  66  75 /  40  60  50  50  30
WACO, TX              83  70  85  66  81 /  40  30  20  50  30
PARIS, TX             81  69  80  64  75 /  30  50  50  50  30
DENTON, TX            82  70  81  59  71 /  40  60  50  50  30
MCKINNEY, TX          81  70  82  62  75 /  30  60  50  50  30
DALLAS, TX            84  71  83  67  77 /  40  60  50  50  30
TERRELL, TX           84  71  83  64  78 /  40  40  40  50  30
CORSICANA, TX         85  69  84  68  79 /  40  30  30  50  30
TEMPLE, TX            84  70  84  68  82 /  40  20  20  50  30
MINERAL WELLS, TX     82  68  83  62  72 /  50  50  50  50  30

&&

.FWD WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH UNTIL 7 PM CDT THIS EVENING FOR TXZ091-100>102-
115>117-129>132-141>143-156.

&&

58/25

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE FORT WORTH TX
348 AM CDT TUE MAY 19 2015

TXZ091>095-100>107-115>123-129>135-141>148-156>162-174-175-200900-
MONTAGUE-COOKE-GRAYSON-FANNIN-LAMAR-YOUNG-JACK-WISE-DENTON-COLLIN-
HUNT-DELTA-HOPKINS-STEPHENS-PALO PINTO-PARKER-TARRANT-DALLAS-
ROCKWALL-KAUFMAN-VAN ZANDT-RAINS-EASTLAND-ERATH-HOOD-SOMERVELL-
JOHNSON-ELLIS-HENDERSON-COMANCHE-MILLS-HAMILTON-BOSQUE-HILL-NAVARRO-
FREESTONE-ANDERSON-LAMPASAS-CORYELL-BELL-MCLENNAN-FALLS-LIMESTONE-
LEON-MILAM-ROBERTSON-
348 AM CDT TUE MAY 19 2015

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH CENTRAL TEXAS.

.DAY ONE...TODAY AND TONIGHT.
SHOWERS AND THUNDERSTORMS ARE LIKELY ACROSS THE WESTERN THIRD OF
NORTH TEXAS TODAY...WITH A CHANCE OF SHOWERS AND THUNDERSTORMS
ACROSS THE REST OF THE REGION. A FEW STORMS COULD BRIEFLY REACH
STRONG TO SEVERE LIMITS WITH HAIL...DAMAGING WINDS...AND FREQUENT
LIGHTING.

LOCALLY HEAVY RAINFALL ON TOP OF SATURATED SOILS MAY POSE A
FLOODING PROBLEM...ESPECIALLY ALONG AND WEST OF A LINE FROM BOWIE
TO GLEN ROSE TO LAMPASAS WHERE RAINFALL TOTALS OF ONE TO TWO
INCHES ARE POSSIBLE.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY.
A CHANCE OF THUNDERSTORMS WILL CONTINUE ACROSS ALL OF NORTH TEXAS
WEDNESDAY THROUGH MONDAY. ISOLATED AREAS OF SEVERE WEATHER WILL
BE POSSIBLE EACH DAY...ALONG WITH A POTENTIAL FOR LOCALIZED HEAVY
RAIN AND FLOODING.

SEVERE WEATHER CHANCES WILL INCREASE THIS COMING WEEKEND...THOUGH
MANY UNCERTAINTIES EXIST ON OVERALL THREATS AND SYSTEM EVOLUTION
AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.