Severe Thunderstorm Warning 166, NWS Fort Worth, TX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE FORT WORTH TX
945 PM CDT TUE MAY 31 2005

.UPDATE...
HAVE MADE SOME MINOR TWEAKS TO THE GRIDDED FORECAST. UPDATED ZONES
WILL BE ISSUED WITH THE NEW SEVERE THUNDERSTORM WATCH.  #58

&&

.AVIATION...
645 PM CDT TUE MAY 31 2005
A DIFFICULT AVIATION FORECAST THIS EVENING...AND WITH THIS IN
MIND...WILL NOT DEVIATE FAR FROM THE CURRENT FORECAST. SHORT TERM
GUIDANCE FROM THE RUC/NAM/GFS CONTINUES TO SUGGEST MCS DEVELOPMENT
AS CONVECTIVE ACTIVITY CURRENTLY BETWEEN KAMA/KLBB MERGES WITH CELLS
DEVELOPING ACROSS FAR SWRN OKLAHOMA. THE SYSTEM IS PROGGED TO MOVE
SEWD OVERNIGHT AND SHOULD REMAIN TO THE SOUTHWEST OF THE METROPLEX
TAF SITES...WITH KACT HAVING A HIGHER PROBABILITY OF IMPACT.
HOWEVER...DUE TO UNCERTAINTY REMAINING IN THE TRACK OF THE SYSTEM...
WILL MAINTAIN A TEMPO GROUP FOR TSRA AND MVFR CIGS FROM 01/06-10Z
FOR METROPLEX SITES...AND 01/09-13Z FOR KACT. OTHERWISE...VFR CIGS
AND LIGHT/VARIABLE WINDS ARE EXPECTED THROUGHOUT THE FORECAST PERIOD.

65/DD

&&

.DISCUSSION...
A DIFFICULT FORECAST...AS IT USUALLY IS THE CASE WHEN INVOLVING
MESOSCALE CONVECTIVE SYSTEMS.  MODELS ARE IN GOOD AGREEMENT THAT
CONVECTION WILL CONTINUE TO DEVELOP ACROSS THE PANHANDLE LATE THIS
AFTERNOON AND AMALGAMATE INTO A MCS THIS EVENING.  THE MODELS DO
DIFFER SLIGHTLY IN WHERE MCS DEVELOPS AND TRACKS...WITH THE GFS
SLIGHTLY FARTHER NORTH THAN THE NAM (ETA).  CURRENT TRENDS SUGGEST
THE GFS MAY BE CLOSER WITH THE CONVECTIVE INITIATION AND WILL TAKE A
BLEND OF TRACKS FROM THE NAM/GFS FOR THIS FORECAST.  MCS SHOULD FORM
SOMEWHERE BETWEEN LBB-CDS AND TRACK E-SE INITIALLY AS MID LEVEL
WINDS WILL BE THE PRIMARY STEERING MECHANISM DUE TO WEAK LOW LEVEL
FLOW IN PLACE.  SOUTHERLY LOW LEVEL WINDS WILL INCREASE TO THE SW OF
THE CWA AFTER SUNSET AS LOW LEVEL JET FORMS...SO EXPECT MCS TO BEGIN
TO TURN TOWARD THE RIGHT AND HEAD MORE SSE.  THIS PATH WOULD DRAG IT
ACROSS OUR W/SWRN CWA...WITH THE SW CWA AT HIGHEST RISK FOR A BOW
ECHO/DAMAGING WINDS TONIGHT.  30-40KT SEWD PROPAGATION SHOULD KEEP
THREAT OF FLOODING LOW BUT THIS WILL HAVE TO BE WATCHED.  IN
ADDITION...SINCE THE PATH IS NOT SET IN STONE...WE HAVE INCLUDED A
SEVERE RISK WEST OF A GLE-DAL-CRS-CLL LINE IN CASE TRACK IS MORE IN
AGREEMENT WITH THE GFS.  RAINFALL CHANCES/AMOUNTS WILL BE TAPERED
MUCH LOWER TO THE NE DUE TO MORE STABLE AIRMASS/LEAST LIKELY TRACK.

AIRMASS OVER NORTH TEXAS WILL BE SCOURED OUT AND WORKED OVER
TOMORROW IN THE WAKE OF THIS SYSTEM...AND JUST LOW POPS WILL BE
NEEDED.  SHORTWAVE RIDGING THEN BUILDS IN ON THURSDAY SO TEMPS
SHOULD INCREASE...AND VERY UNSTABLE AIRMASS WILL DEVELOP.  WEAK LEAD
SHORTWAVE MAY IGNITE A FEW STORMS IN THE WESTERN COUNTIES THURSDAY
AFTERNOON BUT LACK OF FOCUS/SUBSIDENCE WARRANTS JUST LOW POPS WEST.
CHANCES GRADUALLY INCREASE BY FRIDAY MORNING AS CUTOFF LOW NEAR BAJA
EJECTS ACROSS THE STATE.  HAVE INCREASED POPS FRIDAY DUE TO GOOD
CONTINUITY WITH MODELS REGARDING THIS FEATURE.  TROUGH SETS UP OVER
THE WESTERN US...AND ONLY WEAK IMPULSES THIS WEEKEND ARE EXPECTED...
SO WILL KEEP SOME LOW POPS FOR ISOLATED CONVECTION SATURDAY.  LACK
OF DRYLINE/SURFACE FOCUS SUN-TUE WITH ONLY WEAK SHORTWAVES
IDENTIFIED WARRANTS LEAVING POPS OUT OF THE FORECAST UNTIL LATER
SHIFTS CAN IDENTIFY THE DAYS WITH BEST CHANCES.  OTHERWISE...LEFT
PREVIOUS EXTENDED FORECAST AS IS...WITH WARM/BREEZY/HUMID WX.

TR/92

&&

.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX  66  85  66  90 /  60  20  10  10
WACO, TX              65  86  67  91 /  70  20  10  10
PARIS, TX             66  84  64  88 /  30  30  10  10
DENTON, TX            66  84  66  89 /  60  20  10  10
MCKINNEY, TX          66  85  66  89 /  50  30  10  10
DALLAS, TX            66  85  67  90 /  60  20  10  10
TERRELL, TX           67  85  66  90 /  50  30  10  10
CORSICANA, TX         66  86  66  91 /  60  30  10  10
TEMPLE, TX            64  85  68  92 /  70  30  10  10

&&

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

&&