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

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FXUS64 KFWD 261156 AAA
AFDFWD

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE FORT WORTH TX
656 AM CDT TUE MAY 26 2015

.AVIATION...
/12Z TAFS/

CONCERNS...IFR CIGS/VSBY EARLY...PM THUNDERSTORM POTENTIAL.

A RAIN-COOLED NOCTURNAL BOUNDARY LAYER EASILY SATURATED DURING THE
PREDAWN HOURS. ON THE WESTERN PERIPHERY OF AN EXITING CLOUD
SHIELD...ENHANCED RADIATIONAL COOLING RESULTED IN SOME PATCHY FOG.
BUT AS A 30-40KT LLJ LIFTED OVER THE SHALLOW SURFACE LAYER...IFR
CEILINGS ALSO DEVELOPED. THE CEILINGS ARRESTED THE COOLING...AND
AS SOUTHERLY SURFACE WINDS GENTLY WARMED THE SURFACE...RH VALUES
FELL BELOW 100 PERCENT...AND VISIBILITIES STEADILY IMPROVED.
HOWEVER...THE SUPERSATURATION WILL CONTINUE WITHIN THE CLOUD
DECK...AND PATCHY DRIZZLE WILL LINGER UNTIL THE LATE MAY SUN WARMS
THE SURFACE LAYER. THIS INSOLATION WILL LIFT IFR CEILINGS INTO THE
MVFR CATEGORY BY MID-MORNING. VFR CONDITIONS WILL PREVAIL THIS
AFTERNOON...BUT A WARM LAYER AT 850MB MAY MAINTAIN VFR CEILINGS.

A DRYLINE WILL INVADE WESTERN NORTH TEXAS THIS AFTERNOON.
THUNDERSTORMS ARE EXPECTED TO DEVELOP ALONG THE BOUNDARY AND MOVE
EASTWARD INTO THE I-35 CORRIDOR DURING THE LATE AFTERNOON OR EARLY
EVENING HOURS. WITH TREMENDOUS INSTABILITY...THIS ACTIVITY WILL
MAINTAIN ITS INTENSITY AFTER DARK...AND MAY POSE A SEVERE WEATHER
THREAT TO TAF SITES. THE ACTIVITY WILL EVENTUALLY WEAKEN IN
INTENSITY AS IT MOVES EAST OF THE I-35 CORRIDOR LATE THIS
EVENING.

25

&&

.PREV DISCUSSION... /ISSUED 346 AM CDT TUE MAY 26 2015/
AN UNSETTLED WEATHER PATTERN WILL CONTINUE THROUGH THE REMAINDER
OF THE WEEK AND INTO THE WEEKEND...AS LARGE-SCALE TROUGHING ALOFT
CONTINUES ACROSS THE WESTERN CONUS. THE COMPLEX OF SEVERE STORMS
THAT AFFECTED THE AREA YESTERDAY AFTERNOON AND EVENING HAS NOW
MOVED AWAY FROM THE AREA AND INTO THE UPPER TEXAS COAST AND LOWER
MISSISSIPPI VALLEY EARLY THIS MORNING. IN THE WAKE OF THIS LARGE
SCALE MCS...CLEARING WAS OCCURRING ACROSS WESTERN NORTH TEXAS.
WHEREVER SOUTHERLY WIND SPEEDS DROP OFF ACROSS THIS AREA...PATCHY
DENSE FOG WILL CONTINUE TO FORM DUE TO SATURATED SOIL AND
RADIATIONAL COOLING TAKING PLACE. WE WILL HAVE THE PATCHY DENSE
FOG ADVERTISED FOR AREAS ALONG AND WEST OF I-35/35W WITH THE
CLEARING LINE REACHING THIS CORRIDOR BY SUNRISE. THE FEELING IS
CURRENTLY A DENSE FOG ADVISORY WILL NOT BE NEEDED AS MOST AREAS
SHOULD CONTINUE TO SEE SOUTH WINDS NEAR 10 MPH THIS MORNING.

THE NEXT SHORTWAVE DISTURBANCE CURRENTLY MOVING OVER NEW MEXICO
WILL ARRIVE DURING PRIME HEATING TODAY. A SURFACE DRYLINE
CURRENTLY NEAR THE NM/TX BORDER WILL MOVE EAST WITH THE SHORTWAVE
DISTURBANCE TODAY. VERY HIGH INSTABILITY VALUES IN EXCESS OF 4000
J/KG SBCAPE AND MID LEVEL LAPSE RATES IN EXCESS OF 7 DEG/C ARE
EXPECTED OUT AHEAD OF THE SURFACE DRYLINE WITH DEEP-LAYER WESTERLY
BULK SHEAR VALUES APPROACHING 40-45 KTS. HIGH RESOLUTION MODELS
ALL AGREE ON AT LEAST INITIATING ISOLATED TO SCATTERED STORMS ON
THE DRYLINE BY MID-LATE AFTERNOON. SUBSIDENCE FROM THIS MORNING/S
LINEAR MCS SHOULD HAVE SHUNTED EAST BY THIS TIME WITH DISCRETE
SUPERCELL THUNDERSTORMS EXPECTED AT LEAST INTO THE EARLY EVENING
HOURS WITH GREATEST COVERAGE EXPECTED TO BE NORTH OF I-20 AND WEST
OF I-35/35W. THIS ACTIVITY SHOULD MOVE EAST-SOUTHEAST LATER
TONIGHT WITH THE MEAN STEERING FLOW INTO COUNTIES DOWNSTREAM.
STORM COVERAGE WILL LIKELY DIMINISH OVERNIGHT TONIGHT AS
CONVECTION MOVES INTO AN AREA OF WEAKER LOW LEVEL SOUTHERLY FLOW
AND THE SHORTWAVE RESPONSIBLE FOR THE LIFT MOVES EAST OUT OF THE
AREA. ALL MODES OF SEVERE WEATHER WILL BE POSSIBLE...INCLUDING
TORNADOES THROUGH MID EVENING. AFTERWARD...WE EXPECT DAMAGING
WINDS...HAIL...AND LOCALIZED HEAVY RAINFALL TO BE THE MAIN
THREATS. WE WILL NOT RE-ISSUE A NEW FLASH FLOOD WATCH AT THIS
TIME...AS THE SMALL-SCALE MESOSCALE SYSTEM SHOULD MOVE
PROGRESSIVELY ENOUGH TO KEEP WIDESPREAD FLOODING FROM OCCURRING.

A BRIEF LULL IN CONVECTIVE ACTIVITY IS EXPECTED WEDNESDAY INTO
MUCH OF WEDNESDAY EVENING...AS SMALL-SCALE RIDGING ALOFT AND
ASSOCIATED SUBSIDENCE TAKE HOLD. AN ISOLATED THUNDERSTORM CANNOT
BE RULED OUT THROUGH HEATING OF THE MOIST AIRMASS...HOWEVER
SUSTAINED STRONG TO SEVERE CONVECTION IS NOT EXPECTED. WEAK
SHORTWAVE ENERGY OVER OKLAHOMA WILL PRODUCE LATE DAY STORMS NORTH
OF THE RED RIVER VALLEY WEDNESDAY EVENING. A COUPLE OF HIGH RES
MODELS WANT TO PRODUCE ENOUGH OF A COLD POOL TO MOVE ANY STORMS
INTO OUR FAR NW COUNTIES BEFORE DAYBREAK THURSDAY MORNING.
CONFIDENCE IS NOT HIGH AND MANY MESOSCALE FACTORS ARE UNCERTAIN.
NEVERTHELESS...WE WILL ADVERTISE SLIGHTLY HIGHER POPS UP ACROSS
THE NORTHWEST WEDNESDAY NIGHT.

BY THURSDAY...ANOTHER SHARP SHORTWAVE DISTURBANCE WILL ROTATE
EAST WITHIN THE BASE OF THE LARGER SCALE WESTERN CONUS TROUGH
ACROSS THE 4 CORNERS AND TOWARD THE SOUTHERN PLAINS LATER THURSDAY
INTO FRIDAY IN A NEGATIVE-TILTED FASHION. THE BULK OF THE
STRONGEST LIFT WILL BE NORTH OF I-20 AND NORTHWARD INTO THE
CENTRAL PLAINS. AS SUCH...WILL HAVE HIGHEST RAIN CHANCES ACROSS
THE NORTH AND LESSER TO THE SOUTH. THE ENVIRONMENTAL SET UP FOR
THE LATE WEEK ACTIVITY REMAINS UNCERTAIN FOR THE POTENTIAL FOR
SEVERE WEATHER...HOWEVER THERE IS HIGHER CONFIDENCE THAT POCKETS
OF HEAVY RAIN COULD OCCUR TO THE NORTHERN HALF OF THE CWA WHERE
ONGOING RIVER FLOODING AND SATURATED SOILS CONTINUES TO EXIST.
FUTURE WATCHES FOR FLASH FLOODING LOOK PROBABLE AND WE WILL RE-
EVALUATE THE NEED AS THE WEEK PROGRESSES. TEMPERATURES WILL
CONTINUE TO REMAIN NEAR OR BELOW SEASONAL NORMALS DEPENDING ON
COVERAGE OF SHOWERS AND THUNDERSTORMS.

THE LARGE-SCALE WESTERN CONUS UPPER TROUGH DOES APPEAR TO BEGIN
SHIFTING EASTWARD ACROSS THE PLAINS OVER THE WEEKEND WITH A COLD
FRONT ARRIVING LATE IN THE WEEKEND. LOW RAIN CHANCES WILL BE HELD
DURING THIS PERIOD BEFORE LARGE-SCALE UPPER RIDGING APPEARS TO
FINALLY SHUT THE SPIGOT OFF EARLY NEXT WEEK/THE FIRST WEEK OF
JUNE. WE CAN ONLY HOPE THIS IS THE CASE AFTER WEEKS OF SEVERE
WEATHER...HEAVY RAINS...FLASH FLOODING AND RIVER FLOODING.

05/

&&



.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX  86  69  86  71  85 /  20  30  30  20  30
WACO, TX              85  71  86  71  86 /  20  20  20  20  30
PARIS, TX             81  67  85  69  83 /  20  40  30  20  30
DENTON, TX            85  68  86  70  84 /  20  40  30  20  30
MCKINNEY, TX          83  68  86  70  84 /  20  40  30  20  30
DALLAS, TX            85  70  87  71  85 /  20  30  30  20  30
TERRELL, TX           84  70  88  70  85 /  20  30  30  20  30
CORSICANA, TX         84  72  86  71  84 /  20  20  20  20  30
TEMPLE, TX            86  70  88  71  85 /  20  20  20  20  30
MINERAL WELLS, TX     87  69  86  69  84 /  20  30  20  20  30

&&

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

&&

$$

25/05


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