559 
FXUS64 KFWD 141108 AAA
AFDFWD

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE FORT WORTH TX
608 AM CDT MON MAY 14 2012

.AVIATION...
/12Z TAFS/

VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD. INCREASING HIGH
CLOUD COVER IS EXPECTED ACROSS NORTH TEXAS TODAY AS AN UPPER
DISTURBANCE MOVES ACROSS THE WESTERN PART OF THE STATE. WEAK
ASCENT WITH THIS FEATURE WILL OVERSPREAD NORTH TEXAS WHICH WILL
LIKELY RESULT IN AT LEAST ISOLATED SHOWERS AND POSSIBLY A
THUNDERSTORM THROUGH LATE EVENING. AT THIS TIME WILL LEAVE PRECIP
OUT OF ALL TAF SITES AND AMEND IF NECESSARY. LIGHT NORTH WINDS AND
BKN/OVC120 CIGS CAN BE EXPECTED THROUGH THE PERIOD.

DUNN 

&&

.PREV DISCUSSION... /ISSUED 428 AM CDT MON MAY 14 2012/

00Z UPPER AIR ANALYSIS CONTINUED TO DEPICT A BROAD UPPER LEVEL
TROUGH EXTENDING FROM THE CONUS ROCKIES TO THE EAST COAST AT THE
H500 LEVEL. EARLY MORNING WATER VAPOR IMAGERY INDICATED TWO
SHORTWAVE TROUGHS NEAR THE PLAINS WITHIN THIS LARGE TROUGH AXIS.
THE STRONGEST OF THE TWO TROUGHS WAS IN PLACE OVER THE NM/AZ
BORDER AS OF 08Z AND THE SECOND WAS IN PLACE OVER NORTHERN KS.
H250 ANALYSIS INDICATED GOOD DIFFLUENCE OF THE FLOW ALOFT
DOWNSTREAM OF THE AZ/NM TROUGH...AND THIS COMBINED WITH SOME WEAK
LARGE SCALE FORCING INDUCED BY THE TROUGH MOVING EAST SEEMS TO BE
THE PRIMARY FORCING MECHANISMS FOR ELEVATED RAIN SHOWERS
DEVELOPING IN THE SOUTHERN TX PANHANDLE EARLY THIS MORNING.
REGIONAL RADARS ALSO INDICATED A DECAYING COMPLEX OF STORMS JUST
TO THE NORTHWEST OF DEL RIO...MOVING SOUTHEAST.

TODAY THROUGH TUESDAY...THE BROAD TROUGH OVER THE EASTERN UNITED
STATES IS EXPECTED TO SHIFT SOUTHEAST AS UPPER LEVEL RIDGING
NUDGES EAST OVER THE ROCKIES. THIS WILL SEND THE NM/AZ AND
NORTHERN KS SHORTWAVE TROUGHS SOUTHEAST TODAY AND TONIGHT. THE
BEST LARGE SCALE FORCING FOR ASCENT WITH THESE TROUGHS ACTUALLY
LOOKS AS THOUGH IT WILL SPLIT AROUND THE CWA WITH ONE TROUGH
MOVING WELL OFF TO THE SOUTH AND THE OTHER PROGGED TO MOVE JUST
NORTHEAST OF NORTH TX. REGARDLESS...PERSISTENT BUT WEAK LARGE
SCALE FORCING IS EXPECTED TO EXIST OVER THE ENTIRE FORECAST AREA
THIS AFTERNOON AND THIS EVENING AS THE AREA OF BEST DIFFLUENT FLOW
ALOFT LOOKS TO MOVE DIRECTLY OVER NORTH TX DURING THIS PERIOD.

WHILE FORCING IS EXPECTED TO BE WEAK...FORECAST SOUNDINGS INDICATE
THAT THE TROPOSPHERE WILL BE LARGELY UNCAPPED AND THEREFORE
RESPONSIVE TO WEAK/PERSISTENT FORCING FOR ASCENT THIS AFTERNOON
AND EVENING. MEAGER MID LEVEL LAPSE RATES AND ONLY SLIGHTLY ABOVE
NORMAL PWAT VALUES WILL CONTRIBUTE TO VERY LOW CAPE VALUES OVER
MOST OF NORTH TX THROUGH THIS EVENING. FORECAST MIXED AND SURFACE
BASED CAPE VALUES ARE EXPECTED TO REMAIN BELOW 250 J/KG...BUT
BECAUSE FORECAST SOUNDINGS EXHIBIT LITTLE TO NO CAP OVER THE
AREA...THIS SHOULD BE SUFFICIENT FOR THE DEVELOPMENT OF ISOLATED
THUNDERSTORM ACTIVITY ACROSS THE FORECAST AREA THIS AFTERNOON.
KEPT POPS BROAD BRUSHED AND AT 20 PERCENT DUE TO THE EXPECTATIONS
FOR ISOLATED COVERAGE AND BECAUSE THERE IS NO OBVIOUS SURFACE
FEATURE TO FOCUS CONVECTION OVER THE NEXT 24 HRS. FOR THIS MORNING
HAVE A MENTION OF ISOLATED RAIN SHOWERS WEST OF INTERSTATE 35 TO
ACCOUNT FOR THE ELEVATED RAIN SHOWER ACTIVITY DEVELOPING IN THE
SOUTHERN TX PANHANDLE. THE DECAYING COMPLEX OF STORMS NEAR DEL RIO
SHOULD NOT HAVE ANY IMPACT ON PRECIPITATION CHANCES ACROSS THE CWA
TODAY.

THE NORTHERN KS TROUGH IS EXPECTED TO REMAIN JUST NORTH OF THE RED
RIVER LATE TONIGHT INTO TUESDAY MORNING. THE PRESENCE OF THIS
TROUGH WILL DELAY THE ONSET OF STRONGER FORCING FOR SUBSIDENCE
ASSOCIATED WITH THE SOUTHWARD MOVING BROAD TROUGH AXIS ON TUESDAY.
AS A RESULT MAINTAINED LOW/20 POPS ACROSS THE SOUTHERN PORTIONS OF
THE CWA THROUGH TUESDAY AFTERNOON. SUBSIDENCE IS EXPECTED TO MOVE
SOUTHEAST OVER NORTH TX LATE TUESDAY AFTERNOON BRINGING AN END TO
ANY LINGERING PRECIPITATION ACROSS THE CWA.

WEDNESDAY THROUGH FRIDAY...A WELL-DEFINED CLOSED LOW WAS OBSERVED
JUST OFF THE COAST OF NORTHERN CA ON EARLY MORNING WATER VAPOR
IMAGERY. THIS FEATURE IS EXPECTED TO MOVE SLOWLY EAST DURING THE
PERIOD WHILE SIGNIFICANTLY WEAKENING. GUIDANCE IS CONFIDENT THAT
THIS FEATURE WILL CAUSE UPPER LEVEL RIDGING TO SLIDE EAST OVER THE
PLAINS DURING THE PERIOD. GUIDANCE CONTINUES TO STRUGGLE WITH THE
EXACT PLACEMENT AND TIMING OF THIS FEATURE OVER THE PLAINS
THURSDAY NIGHT OR FRIDAY. BOTH THE GFS AND ECMWF INDICATE THAT
THIS FEATURE WILL BECOME A WEAK OPEN WAVE BY THE TIME IT REACHES
THE PLAINS BUT THEY CONTINUE TO STRUGGLE WITH ITS EVOLUTION AS IT
MOVES OVER THE CONUS ROCKIES. 

THE GFS IS A BIT FASTER WITH THE PROGRESS OF THIS WAVE...AND KEEPS
IT WELL NORTH OF TX ACTUALLY MOVING IT OVER EASTERN NE THURSDAY
NIGHT. THE ECMWF OFFERS UP A MORE NEBULOUS SOLUTION WHERE IT SEEMS
TO SPLIT THE LOW INTO TWO PIECES OF ENERGY...ONE THAT MOVES OVER
EASTERN NE SIMILAR TO THE GFS...BUT WITH THE SOUTHERN PIECE OF
ENERGY DIGGING SOUTH OVER NORTH TX BY FRIDAY MORNING. EVEN IF THE
ECMWF PANS OUT...THE FORCING FOR ASCENT IS EXPECTED TO BE TOO WEAK
TO BRING ANY SIGNIFICANT PRECIPITATION CHANCES TO THE
CWA...HOWEVER IT COULD HAVE AN IMPACT ON TEMPERATURES BY BRINGING
PARTLY TO MOSTLY CLOUDY SKIES OVER NORTH TX ON FRIDAY. AT THIS
TIME SIDED WITH THE GFS AND WENT AHEAD WITH A PERSISTENT WARM UP
DURING THE PERIOD UNDER MOSTLY SUNNY/CLEAR SKIES.

EXTENDED...THERE IS GOOD CONSENSUS AMONGST GUIDANCE MEMBERS THAT
UPPER LEVEL RIDGING WILL HOLD IN PLACE OVER NORTH TX FOR
SATURDAY...HOWEVER MODELS ARE STRUGGLING TO HANDLE THE EVOLUTION
OF A STRONG TROUGH THAT LOOKS TO MOVE OVER THE WESTERN CONUS COAST
BY FRIDAY MORNING. THE ECMWF INDICATES THAT SOME PART OF THIS
TROUGH WILL MOVE SOUTH OVER NORTH TX BY SUNDAY WHILE THE GFS
INDICATES THAT THE UPPER RIDGE WILL DEFLECT MOST OF THIS ENERGY TO
THE NORTH OF THE REGION. AT THIS TIME THINK THAT THE UPPER RIDGE
IS MORE LIKELY TO HOLD IN PLACE AS BOTH THE GFS AND ECMWF RE-
ESTABLISH STRONG UPPER RIDGING OVER THE CONUS ROCKIES BY EARLY NEXT
WEEK. THIS WOULD BRING NORTH-NORTHWEST FLOW ALOFT OVER THE
SOUTHERN PLAINS FOR EARLY NEXT WEEK WHICH WOULD LIKELY ALLOW A
COLD OR PACIFIC FRONT TO MOVE INTO THE CWA AND BRING A CHANCE OF
PRECIPITATION FOR NORTH TX. WENT AHEAD AND MIRRORED THE FORECAST
BASED ON THIS THINKING AT THIS TIME AND MAINTAINED A DRY FORECAST
THROUGH THE WEEKEND BUT ADDED 20 POPS OVER THE AREA FOR MONDAY AND
MONDAY NIGHT.

CAVANAUGH
 
&&

.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX  81  62  83  61  85 /  20  20  10   5   5 
WACO, TX              82  60  82  58  86 /  20  20  20  10   5 
PARIS, TX             80  58  81  57  83 /  20  20  10   5   5 
DENTON, TX            80  58  82  57  85 /  20  20   5   5   5 
MCKINNEY, TX          81  59  82  57  85 /  20  20  10   5   5 
DALLAS, TX            82  63  83  62  85 /  20  20  10   5   5 
TERRELL, TX           81  60  82  58  85 /  20  20  10   5   5 
CORSICANA, TX         82  62  81  60  84 /  20  20  20  10   5 
TEMPLE, TX            81  61  80  58  85 /  20  30  20  10   5 
MINERAL WELLS, TX     80  57  82  55  86 /  20  20   5   5   5 

&&

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

&&

$$