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

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FXUS64 KFWD 210913
AFDFWD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FORT WORTH TX
413 AM CDT TUE APR 21 2015

.DISCUSSION...
AN ACTIVE SPRING SPLIT-FLOW PATTERN IS EXPECTED ACROSS THE
CENTRAL U.S AND PLAINS STATES INTO THE MISSISSIPPI VALLEY THE
LATTER HALF OF THE WEEK. CURRENTLY...AT THE SURFACE COOL HIGH
PRESSURE CONTINUES TO EASE SLOWLY EAST OF NORTH TEXAS. LIGHT
SOUTHEAST WINDS ARE RETURNING...THOUGH THE LOW LEVEL AIRMASS
REMAINS DRY WITH MUCH OF THE AREA IN THE 50S. A SHORTWAVE WAS
MOVING RAPIDLY EAST OVER WESTERN OKLAHOMA WITH SCATTERED LIGHT
SHOWERS AND AN OCCASIONAL EMBEDDED ELEVATED THUNDERSTORM ACROSS
THAT AREA. THIS SHORTWAVE WILL PROGRESS READILY EASTWARD OVER
ARKANSAS AND THE ARKLATEX REGION LATER THIS MORNING. HAVE
INCLUDED LOW TO SLIGHT CHANCE POPS FOR MAINLY AREAS E OF I-35 AND
N OF I-20 FOR THE MORNING HOURS...WITH SLIGHT CHANCES LINGERING
ACROSS THE EASTERN COUNTIES THIS AFTERNOON. I EXPECT MINIMAL
RAINFALL WITH THIS SYSTEM DUE TO THE AFOREMENTIONED DRY LOW
LEVELS. CONFIDENCE REGARDING LINGERING LIFT THIS AFTERNOON AND LOW
RAIN CHANCES IS ALSO VERY LOW...CONSIDERING THE LACK OF ANY
SURFACE BOUNDARY IN THE AREA. OTHERWISE...A PARTLY SUNNY DAY WILL
BE IN STORE WITH MOST AREAS SEEING HIGHS WARM TO BETWEEN 75 AND 80
DEGREES.

LOW LEVEL MOISTURE RETURN WILL BEGIN IN EARNEST TONIGHT INTO
WEDNESDAY...AS BROAD WEEK UPPER LOW NEAR SAN DIEGO DRIFTS
GRADUALLY EAST AND A NOCTURNAL 30-40KT LLJ DEVELOPS OVERNIGHT.
ISOLATED THUNDERSTORMS MAY FORM OFF THE WEST TEXAS DRYLINE AND
MOVE EAST TOWARD OUR FAR WESTERN COUNTIES BY MID EVENING...BUT
AGAIN CONFIDENCE IS LOW ON ACTIVITY SUSTAINING AS IT TRAVERSES
INTO A MORE STABLE AND CAPPED AIRMASS OVER OUR AREA. MORNING
STRATUS SHOULD RETURN NORTHWARD TONIGHT AS WELL AS A SHORTWAVE
EJECTS NORTHEAST OVER NM AND FAR WEST TX LATER WEDNESDAY MORNING
AND DEEPENS THE DRYLINE AND SURFACE LOW ACROSS THAT AREA. TO THE
NORTH...A SURFACE COLD FRONT WILL SLIDE SOUTHWARD INTO CENTRAL
OKLAHOMA DURING THE AFTERNOON HOURS WITH THE DRYLINE MIXING
EASTWARD TOWARDS OUR FAR WESTERN COUNTIES.

THE SHORTWAVE TROUGH WILL LIKELY DAMPEN THE SHORTWAVE RIDGE ALOFT
OVER THE SOUTHERN PLAINS AROUND TIME OF PEAK HEATING. WIDELY
SCATTERED THUNDERSTORMS SHOULD FIRE BY MID AFTERNOON OFF THE
DRYLINE...WHILE MORE NUMEROUS THUNDERSTORMS ARE EXPECTED TO
DEVELOP ALONG THE BOUNDARY ACROSS CENTRAL/SOUTHERN OK DURING THE
AFTERNOON HOURS. WITH NORTH TEXAS IN THE WARM SECTOR AND WITH
HIGHS FORECAST TO CLIMB TOWARDS 75 TO 85 DEGREES...DESTABILIZATION
WILL OCCUR BOTH AT THE SURFACE AND ALOFT WITH COOLING MID LEVEL
TEMPERATURES. THE SET UP WILL BE THERE FOR A SEVERE WEATHER
OUTBREAK WITH DISCRETE SUPERCELLS ALONG THE DRYLINE MOVING INTO
OUR FAR WESTERN COUNTIES AND ALONG THE FRONT ACROSS CENTRAL AND
SOUTHERN OK THROUGH EARLY EVENING. AS WE MOVE INTO THE OVERNIGHT
PERIOD WEDNESDAY NIGHT/EARLY THURSDAY MORNING...WE LOOK FOR
ACTIVITY TO MORPH INTO A SEVERE MCS OR STORM CLUSTER THAT WILL
MOVE SOUTHEAST ACROSS MAINLY THE NORTHEAST THIRD OR MORE OF THE
CWA. DISCRETE ACTIVITY ACROSS THE WEST AND SOUTHWEST COUNTIES WILL
LIKELY WEAKEN OR DISSIPATE...AS THE STRENGTHENING NOCTURNAL LLJ
ENHANCES THE CAPPING INVERSION OVER THESE AREAS WEDNESDAY NIGHT.
SEVERE WEATHER HAZARDS WITH ANY DISCRETE ACTIVITY EARLY IN THE
EVENT AND ACROSS MAINLY OUR WESTERN COUNTIES AND ALONG THE RED
RIVER WILL BE VERY LARGE HAIL...DAMAGING WINDS...FREQUENT
LIGHTNING AND POSSIBLY A TORNADO OR TWO....TRANSITIONING TO MORE
OF A DAMAGING WIND AND HEAVIER RAIN THREAT ACROSS OUR NORTHEAST
COUNTIES WEDNESDAY NIGHT WITH FREQUENT LIGHTNING.

A RESIDUAL OUTFLOW BOUNDARY MAY BE DRAPED MOST LIKELY SOMEWHERE
NEAR THE I-20/1-30 CORRIDORS AND NORTHEAST DFW METROPLEX THURSDAY
MORNING WITH BEST STORM CHANCES OCCURRING NORTHEAST OF THE
BOUNDARY. SOME WEAKENING OF THE MCS ACROSS THE NORTHEAST COUNTIES
WILL OCCUR BY DAYBREAK THURSDAY AND AFTER...AS THE LLJ WEAKENS AND
VEERS AND THE BOUNDARY LAYER STABILIZES. BY THURSDAY
AFTERNOON...THE SOUTHWEST U.S UPPER LOW WILL MOVE EAST OVER THE
AZ/NM BORDER AREA WITH ANOTHER SHORTWAVE DISTURBANCE EJECT OUT OF
THIS FEATURE AND OVER THE TOP OF A FLAT SHORTWAVE RIDGE OVER NORTH
TEXAS. THE COMBINATION OF LARGE-SCALE ASCENT...HEATING...AND
INITIATION ALONG THE DRYLINE OVER THE HILL COUNTRY AND THE
RESIDUAL OUTFLOW BOUNDARY IN THE VICINITY OF I-20 SHOULD RESULT IN
AN INITIATION OF SCATTERED STRONG TO SEVERE STORMS ACROSS MUCH OF
THE AREA ONCE AGAIN THURSDAY AFTERNOON AND EVENING. STRONG
EFFECTIVE 0-6 KM BULK SHEAR AND INSTABILITY WILL BE PRESENT TO
SUSTAIN ACTIVITY EVEN THROUGH THE OVERNIGHT HOURS INTO EARLY
FRIDAY MORNING. WEDNESDAY AND THURSDAY WILL LIKELY BE OUR BIGGEST
SEVERE WEATHER THREAT DAYS AND ALL PARTIES SHOULD PREPARE
ACCORDINGLY.

ON FRIDAY...THE UPPER TROUGH LIFTS QUICKLY NORTHEAST ACROSS THE
CENTRAL HIGH PLAINS WITH A SURFACE LOW FORMING OVER SOUTHEAST CO
FRIDAY MORNING...MOVING EAST ACROSS THE KS/OK BORDER THROUGH THE
DAY AND INTO THE OZARKS FRIDAY NIGHT. THIS WILL PULL A DRYLINE
THROUGH THE AREA DURING THE AFTERNOON AND EARLY EVENING HOURS WITH
STILL A POTENTIAL THREAT FOR STRONG TO SEVERE STORMS ACROSS MAINLY
AREAS E OF I-35...BEFORE A PACIFIC COLD FRONT MOVE THROUGH
OVERNIGHT AND ENDS OUR RAIN CHANCES FOR THE WEEKEND. I DID ADJUST
FOR THESE TRENDS...AS MOST MODEL MOS GUIDANCE SEEMED TOO WET FOR
THE FRIDAY NIGHT AND SATURDAY MORNING PERIOD.

THE WEEKEND SHOULD BE MILD AND PLEASANT AS A RIDGE OF HIGH
PRESSURE BOTH AT THE SURFACE AND ALOFT MAINTAIN OVER THE AREA.
LEFT LOW THUNDERSTORM CHANCES IN FOR NORTH AND EAST AREAS SUNDAY
NIGHT AND NEXT MONDAY AS A SHORTWAVE BREAKS DOWN THE UPPER RIDGE
AND TRANSVERSE ACROSS SOUTHERN OKLAHOMA. SURFACE DEW POINTS SHOULD
BE MAINLY IN THE 50S DURING THIS TIME FRAME...THOUGH SOME LOWER 60
DEW POINTS MAY EASE BACK ACROSS THE SOUTHEAST COUNTIES. AT THIS
TIME...IT DOES NOT APPEAR ANY OF THIS ACTIVITY WOULD BE SEVERE
CONSIDERING THE LOWER LEVEL AIRMASS WILL STILL BE RECOVERING
DURING THIS PERIOD. WE/LL RE-ASSES THE EARLY WEEK POTENTIAL AS WE
GET PAST THE ACTIVE PERIOD WE/RE EXPECTING THE LATTER HALF OF THIS
WEEK.

05

&&

.AVIATION...

FOR THE 06Z TAFS...NO SIGNIFICANT CHANGES WERE MADE FROM THE 00Z
TAFS...SO THE PREVIOUS FORECAST DISCUSSION WAS APPENDED BELOW.

THE CHANCES FOR ELEVATED CONVECTION BUILDING OVER THE DFW AREA
TOMORROW MORNING ARE LOOKING BETTER...SO EXPECT SCATTERED
SHOWERS...AND POSSIBLY SOME THUNDERSTORMS MIXED IN BUILDING OVER
THE AREA BY 15Z TUESDAY MORNING. DID NOT WANT TO GO WITH 7 HOURS
OF THUNDER IN THE TAFS FOR NOW...SO LEFT VCSH IN AND WILL REFINE
TO ADD THUNDER IN A SMALLER TIME INCREMENT BY EARLY TOMORROW
MORNING.

CAVANAUGH

.../PREVIOUS AVIATION DISCUSSION/...
/ISSUED 720 PM CDT MON APR 20 2015/

FOR THE 00Z TAFS...ELEVATED RAIN SHOWERS OR THUNDERSTORMS ON
TUESDAY ARE THE PRIMARY FORECAST CONCERN.

A RELATIVELY DRY LOW-LEVEL AIR MASS IN PLACE ACROSS THE REGION
WILL KEEP CONDITIONS VFR THROUGH TOMORROW MORNING. VFR CONDITIONS
ARE LIKELY TO HOLD THROUGHOUT THE DAY ON TUESDAY AS WELL...HOWEVER
ELEVATED MOISTURE RETURN MAY RESULT IN SOME SCATTERED SHOWERS OR
THUNDERSTORMS DEVELOPING ACROSS THE REGION AFTER 15Z TOMORROW.
MODELS ARE NOT CONSISTENT WITH THE ONSET OR PLACEMENT OF THIS
ELEVATED CONVECTION TOMORROW...HOWEVER MOST MODELS SHOW SOME
ELEVATED PRECIPITATION DEVELOP BY THE LATE MORNING HOURS OF THE
DAY.

FORECAST SOUNDINGS INDICATE SOME SHALLOW CAPE FOR AIR LIFTED FROM
THE 850 MB LEVEL OR ABOUT 1 MILE AGL. CONFIDENCE IN SCATTERED
PRECIPITATION DEVELOPING ON TOP OF THE DFW AREA IS NOT HIGH AT
THIS TIME...SO CHOSE TO HIGHLIGHT THE MOST LIKELY PERIOD FOR
PRECIPITATION WITH A MENTION OF VCSH FROM 15 TO 22Z. MAY HAVE TO
ADD A MENTION OF VCTS OR JUST A COUPLE OF HOURS OF PERSISTENT
THUNDER IF CONFIDENCE INCREASES THAT THIS ELEVATED CONVECTION WILL
DEVELOP RIGHT ON TOP OF THE DFW AREA.

ASIDE FROM THE POTENTIAL FOR ELEVATED SHOWERS AND STORMS NEAR
AIRPORTS TOMORROW...VFR CONDITIONS AND SOUTHERLY FLOW IS EXPECTED
TO PERSIST THROUGHOUT THE DAY.

CAVANAUGH


&&

.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX  75  61  77  66  82 /  20  10  50  40  30
WACO, TX              77  62  81  66  85 /  10  10  30  30  30
PARIS, TX             74  57  76  61  73 /  30  10  60  40  40
DENTON, TX            76  59  77  63  80 /  20  10  40  40  30
MCKINNEY, TX          74  60  76  63  78 /  20  10  50  40  30
DALLAS, TX            76  63  77  66  83 /  20  10  50  40  30
TERRELL, TX           75  61  76  64  80 /  20  10  50  40  30
CORSICANA, TX         76  61  78  67  83 /  20  10  40  30  30
TEMPLE, TX            78  63  80  67  85 /  10  10  30  20  20
MINERAL WELLS, TX     78  61  81  63  82 /  10  10  30  30  30

&&

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

&&

$$

05/15



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