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

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000
FXUS64 KFWD 280902
AFDFWD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FORT WORTH TX
402 AM CDT MON JUL 28 2014

.DISCUSSION...

08Z SURFACE ANALYSIS SHOWED A COLD FRONT MOVING SLOWLY SOUTH
ACROSS THE RED RIVER. THE FRONT WAS LOCATED NEAR A LINE FROM
LUBBOCK TO BOWIE TO SHERMAN AT THE TIME OF ANALYSIS. REGIONAL
RADARS SHOWED SCATTERED SHOWERS AND THUNDERSTORMS NORTH OF THE
FRONT...MOVING SOUTH AT 5 TO 10 MPH. 00Z UPPER AIR ANALYSIS SHOWED
THAT UPPER LEVEL RIDGING ONCE AGAIN STRENGTHENED OVER NORTH TEXAS
OVER THE LAST 24 HRS. EARLY MORNING WATER VAPOR SATELLITE IMAGERY
INDICATES THAT THE UPPER LEVEL RIDGE IS LIKELY BREAKING DOWN EARLY
THIS MORNING...AND REORGANIZING WEST OF THE CWA. EXPECT TO SEE 500
MB HEIGHT FALLS OF 3 TO 4 DM ON THE 12Z FWD RAOB THIS MORNING WITH
THE RIDGE WEAKENING AND MOVING WEST OF THE CWA.

TODAY...EXPECT THAT SCATTERED SHOWERS AND THUNDERSTORMS WILL
CONTINUE TO DEVELOP NORTH OF THE SLOW MOVING COLD FRONT THROUGH
THE MID-MORNING HOURS OF THE DAY TODAY. EXPECT THAT THE FRONT WILL
BE LOCATED SOUTH OF THE DFW AREA BY THIS TIME...SO MAINTAINED 30
POPS FOR THIS MORNING FOR LOCATIONS GENERALLY ALONG AND NORTH OF A
LINE FROM CISCO TO ATHENS. THE FRONT IS EXPECTED TO CONTINUE SOUTH
INTO CENTRAL TEXAS FOR THIS AFTERNOON. FROM THE MID-MORNING HRS TO
THE MID-AFTERNOON HRS...THERE WILL PROBABLY BE A LULL IN
THUNDERSTORM ACTIVITY AS THE BEST LIFT FOR ELEVATED THUNDERSTORMS
BECOMES DISRUPTED BY DAYTIME HEATING. THIS IS EXPECTED TO OCCUR AS
HEATING PROMOTES BETTER LOW-LEVEL MIXING...AND DRY AIR ENTRAINS
INTO THE SATURATED LAYER AROUND 800 TO 750 MB WHERE FORECAST
SOUNDINGS INDICATE VERY LITTLE LIFT IS NEEDED FOR AIR TO REACH ITS
LEVEL OF FREE CONVECTION EARLY THIS MORNING. ONCE THE ELEVATED
RESERVOIR OF THUNDERSTORM INITIATION IS INTERRUPTED...NEW
THUNDERSTORM DEVELOPMENT WILL LIKELY HAVE TO WAIT FOR THE PEAK
HEATING HRS OF THE DAY FOR SURFACE BASED AIR PARCELS TO BE HEATED
UP ENOUGH FOR AIR TO BE LIFTED ABOVE THE CAP BY THE WEAK FORCING
ASSOCIATED WITH THE FRONT. SURFACE BASED STORMS APPEAR TO BE MOST
LIKELY ALONG AND JUST NORTH OF THE SURFACE COLD FRONT THIS
AFTERNOON. THE FRONTAL BOUNDARY REPRESENTS A LAYER OF ONLY SHALLOW
COOL AIR...AND ALMOST ALL GUIDANCE INDICATES THAT DEEPER MOISTURE
IS AVAILABLE FOR STORMS NORTH OF THE FRONT...RATHER THAN ALONG OR
SOUTH OF THE FRONT. EITHER WAY...THE SHALLOW FRONTAL INVERSION
WILL LIKELY MIX OUT LEAVING ONLY A WIND-SHIFT LINE DEFINING THE
LEADING EDGE OF THE FRONT DURING THE PEAK HEATING HRS OF THE DAY.
MODELS CONSISTENTLY SHOW THE HIGHEST PWAT VALUES NORTH OF THE
FRONT ACROSS CENTRAL TEXAS THIS AFTERNOON...SO WENT AHEAD AND
BUMPED POPS UP TO 40 PERCENT CENTERED ALONG A LINE FROM COMANCHE
TO WACO TO PALESTINE THIS AFTERNOON.

PWATS ARE FORECAST TO BE IN THE NEIGHBORHOOD OF 2 INCHES...SO
BRIEF HEAVY RAINFALL AND GUSTY OUTFLOW WINDS ARE THE PRIMARY
THUNDERSTORM HAZARDS ASIDE FROM THE LIGHTNING THREAT PRESENT WITH
ANY THUNDERSTORM ACTIVITY.

DESPITE STORMS MORE LIKELY TO OCCUR NORTH OF THE FRONT...AS LONG
AS THE SHALLOW FRONTAL INVERSION MIXES OUT AS EXPECTED...FORECAST
SOUNDINGS STILL ADVERTISE AN INVERTED-V LOW-LEVEL
PROFILE...INDICATIVE OF STORMS CAPABLE OF PRODUCING MICROBURSTS.
SEVERE/DAMAGING WINDS SHOULD NOT BE COMMON DUE TO A SOMEWHAT
MEAGER THETA-E DIFFERENCE WITH HEIGHT IN THE ATMOSPHERE LIMITING
THE STRENGTH OF COLD POOL ACCELERATIONS. REGARDLESS...STEEP LOW
LEVEL LAPSE RATES WILL ALLOW FOR WIND GUSTS IN THE 40-50 MPH
RANGE...WHICH IS STRONG ENOUGH TO CAUSE LIGHT...LOCALIZED DAMAGE.

STORM MOTIONS ARE PROGGED TO BE SLOW THIS AFTERNOON...HOWEVER A
WIDESPREAD FLOODING THREAT IS NOT EXPECTED AS STORMS WILL STILL
PRODUCE OUTFLOW BOUNDARIES THAT SHOULD PROMOTE STORMS TO MOVE AWAY
FROM ANY ONE LOCATION WITH PROPAGATION LIKELY DOMINATING STORM
MOTIONS.

TONIGHT...MODELS ARE FAIRLY CONSISTENT NOW IN ADVERTISING
NORTHEASTERLY FLOW BRINGING COOL AND DRY AIR INTO THE CWA
BEGINNING THIS AFTERNOON...CONTINUING THROUGH THE OVERNIGHT HOURS.
THIS SHOULD CAUSE ANY LINGERING THUNDERSTORM ACTIVITY EAST OF
INTERSTATE 35 TO DIMINISH FAIRLY QUICKLY AFTER SUNSET. MODELS ARE
NOW ALSO CONSISTENTLY SHOWING AN 850 MB THETA-E RIDGE HOLDING UP
OVER WEST CENTRAL TEXAS...AND OVER THE WESTERN PORTION OF THE CWA
TONIGHT INTO TOMORROW. THIS THETA-E RIDGE MAY BECOME ACTIVE AGAIN
OVERNIGHT...WITH A SIMILAR COVERAGE OF STORMS TO WHAT WE ARE
SEEING NORTH OF THE RED RIVER AT THE TIME OF THIS FORECAST
DISCUSSION.

COVERAGE AND PLACEMENT OF STORMS WILL BE DETERMINED BY THE
ORIENTATION OF LOW LEVEL FLOW TO THE WEST OF THIS THETA-E RIDGE.
IF WINDS BECOME SOUTHWESTERLY TO THE WEST OF THIS FEATURE...MORE
STORMS ARE LIKELY DUE TO ENHANCED LOW-LEVEL CONVERGENCE. IF WINDS
REMAIN SOUTHERLY...CONVERGENCE WILL SHUNTED MORE TO THE
WEST...LEAVING THE CWA WITH LOWER THUNDERSTORM CHANCES AND
COVERAGE. JUST MAINTAINED 20-30 POPS OVERNIGHT WEST OF INTERSTATE
35/35W FOR NOW WITHOUT HIGHER CONFIDENCE IN WHICH SCENARIO WILL
PAN OUT. EAST OF INTERSTATE 35 SHOULD BE DRY...ALL GUIDANCE
SUPPORTS THIS...SO LEFT THE FORECAST DRY FOR THESE LOCATIONS.

TUESDAY...MODEL GUIDANCE INDICATES THAT AN 850 MB ANTI-CYCLONE
WILL MOVE SOUTHEAST FROM OKLAHOMA OVER TOWARDS LOUISIANA FROM
TONIGHT INTO TUESDAY AFTERNOON. THIS WILL CAUSE THE TRANSPORT OF
DRY COOL AIR IN FROM THE NORTHEAST TO BE INTERRUPTED AS LOW-LEVEL
FLOW VEERS AROUND TO THE EAST AND EVENTUALLY SOUTHEAST BY TUESDAY
NIGHT. THIS WILL ALLOW THE LOW-LEVEL THETA-E RIDGE TO BUILD SLOWLY
EASTWARD FROM WEST CENTRAL TEXAS BACK OVER THE CWA TUESDAY THROUGH
TUESDAY NIGHT. DURING THE DAY ON TUESDAY...MOST MODEL GUIDANCE
INDICATES THAT THE THETA-E RIDGE WILL REMAIN WEST OF INTERSTATE
35/35W SO WENT AHEAD AND KEPT THE HIGHEST POPS OVER THOSE
LOCATIONS AS SURFACE BASED STORMS ARE MOST LIKELY WITHIN THIS AREA
DURING THE PEAK HEATING HOURS OF THE DAY. THE THETA-E RIDGE IS
EXPECTED TO ADVECT NORTH OVERNIGHT AND BECOME RE-ESTABLISHED OVER
THE NORTHEASTERN CWA BY SUNRISE WEDNESDAY MORNING. OVERNIGHT
THUNDERSTORM ACTIVITY IS MOST LIKELY WITHIN THIS THETA-E
RIDGE...SO TRANSITIONED POPS TO MATCH THE MODEL PLACEMENT OF THIS
FEATURE OVERNIGHT.

THE LOW-LEVEL THETA-E RIDGE IS MENTIONED A LOT HERE BECAUSE IT IS
THE EASIEST WAY TO TRACK OUR BEST PRECIPITATION CHANCES ASSOCIATED
WITH THE FRONT STALLING OUT...BECOMING REORIENTED AND CHANGING IN
CHARACTERISTICS BETWEEN A COLD TO STATIONARY TO WARM FRONT FROM
TODAY THROUGH WEDNESDAY. INSTEAD OF CHANGING THE NAME OF THE
FRONT SEVERAL TIMES...THE THETA-E RIDGE CAN BE USED AS A PROXY
FOR THE BEST PRECIPITATION CHANCES ASSOCIATED WITH THE FRONT AND
IS EASY TO REFER TO AS ONE THING THROUGHOUT THE FORECAST.

BY WEDNESDAY...THE LOW-LEVEL THETA-E RIDGE IS EXPECTED TO REMAIN
STATIONARY ALONG THE RED RIVER...BUT DIPPING SOUTHEAST OVER THE
NORTHEASTERN CWA TOWARDS SHREVEPORT. GUIDANCE CONTINUES TO SHOW
THAT UPPER LEVEL TROUGHING WILL DOMINATE THE EASTERN CONUS BY
WEDNESDAY WITH UPPER LEVEL RIDGING OVER THE SOUTHWESTERN CONUS.
THIS LEAVES THE SOUTH PLAINS IN NORTHWEST FLOW ALOFT. MODELS HAVE
BEEN SHOWING A SHORTWAVE TROUGH IN THIS FLOW REGIME HEADED OVER
THE AREA SOMETIME BETWEEN WEDNESDAY AND THURSDAY. THE CONSENSUS OF
YESTERDAY EVENINGS MODELS NOW INDICATE THAT THIS SHORTWAVE WILL
MOVE OVER THE NORTHERN PORTIONS OF NORTH TEXAS DURING THE DAY ON
WEDNESDAY. THIS FEATURE IS ACTUALLY TRACK-ABLE ON WATER VAPOR
SATELLITE IMAGERY NOW AS WELL...MAKING FOR A HIGHER CONFIDENCE
FORECAST IN GENERAL. THIS SHORTWAVE WAS OVER BAJA CALIFORNIA AT
THE TIME OF THIS DISCUSSION.

WITH THE THETA-E RIDGE/FRONT IN PLACE AS MENTIONED ABOVE...THE
FORCING FOR ASCENT INDUCED BY THE SHORTWAVE TROUGH SHOULD GIVE US
OUR BEST PRECIPITATION CHANCES FOR THIS WEEK. WENT AHEAD WITH 40
TO 60 POPS FOR LOCATIONS ALONG AND NORTHEAST OF A LINE FROM BOWIE
TO MCKINNEY TO EMORY ON WEDNESDAY AND WEDNESDAY NIGHT AS A RESULT.
LOCALLY HEAVY RAINFALL LOOKS MUCH MORE LIKELY FOR THESE AREAS AS
PWATS ARE EXPECTED TO BE IN EXCESS OF 2 INCHES DURING THIS TIME
FRAME...AND A NEARLY STATIONARY THETA-E RIDGE INTERACTING WITH
FORCING SHOULD PROMOTE A GOOD COVERAGE OF STORMS. A FLOOD WATCH IS
NOT EXPECTED AT THIS TIME...BUT WE WILL HAVE TO MONITOR TO SEE IF
MESOSCALE/SMALLER SCALE FORECAST DETAILS DICTATE A MORE
WIDESPREAD FLOODING EVENT IN LATER FORECASTS. FOR NOW IT LOOKS
LIKE THE THREAT OF ANY FLOODING WILL TEND TO BE LOCALIZED IN
NATURE.

THE THETA-E RIDGE/FRONT IS EXPECTED TO SLIDE SOUTH ACROSS NORTH
TEXAS ON THURSDAY...AND KEPT WIDESPREAD 30-50 POPS IN PLACE AS A
RESULT. WITH SO MUCH GOING ON BEFORE THIS FRONT BEGINS TO MOVE
AGAIN ON THURSDAY...WILL NOT GET INTO THE DETAILS OF THIS FORECAST
PERIOD AS WIDESPREAD THUNDERSTORM ACTIVITY OVER THE NORTHEASTERN
CWA WILL PROBABLY CHANGE THINGS QUITE A BIT IN LATER FORECASTS.

PRECIPITATION CHANCES WILL CONTINUE TO DIMINISH BEHIND THE FRONT
ON FRIDAY...WITH MODEL CONSENSUS SHOWING MUCH DRIER CONDITIONS
OVER THE REGION BY SATURDAY. LEFT 20 POPS IN THE FORECAST FOR
FRIDAY...WITH A DRY FORECAST FOR NEXT WEEKEND INTO EARLY NEXT WEEK
AS A RESULT. TEMPERATURES WILL LIKELY BE UNSEASONABLY COOL ACROSS
THE ARE THURSDAY AND FRIDAY...WARMING BACK UP TOWARDS NORMAL BY
EARLY NEXT WEEK WITH DRIER AIR AND MOSTLY SUNNY SKIES IN PLACE.

CAVANAUGH

&&

.AVIATION...
/ISSUED 1150 PM CDT SUN JUL 27 2014/
A COLD FRONT CONTINUES TO SLIDE SOUTH ACROSS THE RED RIVER LATE
THIS EVENING. THE FRONT IS A BIT AHEAD OF SCHEDULE AND SHOULD MOST
LIKELY REACH THE METROPLEX TAF SITES AROUND 12Z AND WACO BY 16Z.
STORMS HAVE BEEN STRUGGLING TO HOLD TOGETHER AS THEY MOVE SOUTH
INTO THE EXTREMELY CAPPED ENVIRONMENT CURRENTLY IN PLACE ACROSS
NORTH TEXAS. SCATTERED SHOWERS AND A FEW STORMS WILL BE POSSIBLE
WELL BEHIND THE FRONT FROM MID MORNING MONDAY THROUGH MID
AFTERNOON AS THE FRONTAL SURFACE DEEPENS. THE HRRR AND TEXAS TECH
WRF SOLUTION AS WELL AS NAM ALL SUPPORT THIS SCENARIO. ANY PRECIP
THAT DOES DEVELOP SHOULD END BEFORE 00Z AS DRIER AIR FINALLY MOVES
INTO THE REGION.

A SOUTH WIND AROUND 10 KNOTS OVERNIGHT WILL TURN TO THE
NORTH/NORTHEAST WITH THE PASSAGE OF THE FRONT AT SPEEDS BETWEEN 8
AND 12 KNOTS.

WE WILL KEEP VFR CONDITIONS THROUGH MONDAY EVENING WITH SCATTERED
TO BROKEN MID LEVEL CLOUDS.

79


&&

.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX  94  75  93  75  93 /  30  30  20  20  20
WACO, TX              99  75  93  73  96 /  30  30  30  10  20
PARIS, TX             90  69  90  70  86 /  40  20  10  10  30
DENTON, TX            91  73  93  73  91 /  40  30  20  20  20
MCKINNEY, TX          92  70  93  72  91 /  40  20  20  20  20
DALLAS, TX            94  75  93  75  93 /  30  30  20  10  20
TERRELL, TX           95  72  93  72  92 /  30  20  20  10  20
CORSICANA, TX         95  73  93  71  94 /  30  30  20  10  20
TEMPLE, TX            97  75  94  72  97 /  30  30  30  10  20
MINERAL WELLS, TX     93  72  92  71  93 /  30  30  30  20  20

&&

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

&&

$$

 /




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