Area Forecast Discussion
Issued by NWS Amarillo, TX

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FXUS64 KAMA 271707 AAA
AFDAMA

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE AMARILLO TX
1207 PM CDT WED AUG 27 2014

.UPDATE...
INCREASED PRECIP CHANCES FOR PARTS OF THE AREA THIS
AFTERNOON...MAINLY TO EXPAND CHANCE/SCATTERED POPS FARTHER EAST
ACROSS MOST OF THE FORECAST AREA. PLUME OF HEALTHY MID/UPPER-LEVEL
MOISTURE WITH A FEED FROM HURRICANE MARIE REMAINS ACROSS THE
AREA...WITH RICH LOW-LEVEL MOISTURE IN PLACE AS WELL /SFC DEWPOINTS
60S TO LOWER 70S/. DESPITE LINGERING CLOUD COVER ACROSS THE
AREA...BELIEVE WE/LL SEE ENOUGH BREAKS TO ALLOW FOR SUFFICIENT
DIURNAL HEATING IN THE PRESENCE OF WEAK BROAD SCALE FORCING AHEAD OF
THE UPPER LOW OVER UT /AND MINIMAL CONVECTIVE INHIBITION/ TO TRIGGER
SCATTERED THUNDERSTORMS THIS AFTERNOON. ALSO LOWERED HIGH TEMPS FOR
THIS AFTERNOON IN AREAS OF THICKER CLOUD COVER.

KB

&&

.PREV DISCUSSION... /ISSUED 635 AM CDT WED AUG 27 2014/

AVIATION...
12Z TAF CYCLE
AN UPPER LOW OVER THE CENTRAL ROCKIES WILL SLOWLY MOVE EAST TODAY AND
TONIGHT. ISOLATED TO SCATTERED CONVECTION CAN BE EXPECTED ALL ACROSS
THE PANHANDLES TODAY AND TONIGHT...HOWEVER CONFIDENCE ON TIMING OF
THE CONVECTION AFFECTING THE THREE TAF SITES VERY LOW.
THEREFORE...WILL FORECAST VCTS OR VCSH RATHER THAN TEMPO GROUPS FOR
THE FIRST 9 HOURS OF THE TAF FORECAST. IFR TO MVFR CEILINGS AND
VISIBILITIES LIKELY IN AND NEAR THE CONVECTION ALONG WITH ERRATIC
WINDS WITH GUSTS UP TO NEAR 40 AND 45 KNOTS POSSIBLE. OTHERWISE...VFR
CONDITIONS THROUGH THE TAF FORECAST PERIOD AT ALL THREE TAF SITES.
WINDS GENERALLY SOUTHEAST TO SOUTH 5 TO 10 KNOTS OR LESS UNTIL
AROUND 15Z TODAY...THEN INCREASING TO 10 TO 20 KNOTS WITH SOME HIGHER
GUSTS POSSIBLE AFTER 15Z TODAY...AND THEN BECOMING MORE SOUTH AND
SOUTHWEST 5 TO 15 KNOTS AFTER 06Z TO 10Z THURSDAY.

SCHNEIDER

PREV DISCUSSION... /ISSUED 459 AM CDT WED AUG 27 2014/

DISCUSSION...
AN ACTIVE WEATHER PATTERN IS EVOLVING OVER THE SOUTHERN HIGH PLAINS
OF WEST TEXAS. THIS AS MOISTURE ALOFT ORIGINATING NEAR HURRICANE
MARIE IN THE EASTERN PACIFIC STREAMS NORTHEASTWARD WITHIN THE
WESTERN PERIPHERY OF THE SUBTROPICAL RIDGE AND IN ADVANCE OF AN
APPROACHING SHORTWAVE TROUGH NOW NEARING THE FOUR CORNERS. CONCERNS
INCLUDE INCREASING RISKS OF FLASH FLOODING...WITH ACTIVITY PEAKING
LATE THURSDAY.

CURRENTLY...REGIONAL RADAR SHOWS MULTIPLE WAVES OF CONVECTION EXTENDING
FROM CENTRAL NEW MEXICO EASTWARD TO THE NORTHEASTERN PANHANDLES. LOCALIZED
RAINFALL RATES THIS MORNING UPWARDS OF 3 TO 4 INCHES/HOUR HAVE BEEN
OBSERVED NEAR BOOKER /LIPSCOMB COUNTY/. A LULL IN CONVECTION IS LIKELY
BY LATE MORNING/MIDDAY...BUT FORCING FOR ASCENT AND ATMOSPHERIC MOISTURE
CONTENT WILL ONLY INCREASE THROUGH THE NEXT 48 HOURS. CONVECTION MAY
REMAIN ISOLATED/WIDELY SCATTERED ENOUGH LATE TODAY TO PRECLUDE A WIDESPREAD
ORGANIZED FLASH FLOOD THREAT...BUT INSTABILITY APPEARS TO INCREASE UPWARDS
OF 1000 J/KG...WHICH MAY SUPPORT A FEW PULSE-TYPE STORMS CAPABLE OF
LOCALIZED/BRIEF DAMAGING WINDS AND HEAVY RAINFALL.

THE MOST LIKELY TIMEFRAME FOR AN ORGANIZED HEAVY RAINFALL THREAT IS
EXPECTED TO OCCUR LATE THURSDAY/EARLY FRIDAY AS THE SHORTWAVE TROUGH
EJECTS OVER THE SOUTHERN PLAINS AND A WEAK FRONTAL BOUNDARY PUSHES
SOUTH ACROSS THE PANHANDLES. SBCAPE VALUES WILL APPROACH 2000 J/KG
AND DEEP LAYER SHEAR WILL INCREASE SUFFICIENTLY TO SUPPORT LOOSELY
ORGANIZED CONVECTION AND WARRANT A THREAT OF A FEW SEVERE STORMS.
MODEL FORECAST SOUNDINGS ADDITIONALLY INDICATE PWAT VALUES IN EXCESS
OF 2 STANDARD DEVIATIONS AS EARLY AS THIS EVENING...BUT VALUES
APPROACHING 2 INCHES OVER THE EASTERN TEXAS PANHANDLE BY THURSDAY
NIGHT. FLASH FLOOD WATCHES MAY BECOME NECESSARY IF SIGNALED TRENDS
FOR MORE WIDESPREAD STORMS/RAINS CONTINUE.

FEW CHANGES TO THE FORECAST/GRIDS FOR THE SATURDAY THROUGH TUESDAY
TIMEFRAME. CONDITIONS APPEAR TO DRY/WARM UP BY THE WEEKEND. MEDIUM
RANGE GUIDANCE STRUGGLES TO REBUILD THE SUBTROPICAL RIDGE THIS FAR
NORTH THROUGH THE REMAINDER OF THE PERIOD...BUT LEE TROUGHING WILL
DEEPEN AND PROMOTE HOT TEMPERATURES BENEATH MODEST NEAR ZONAL FLOW.

LINDLEY

&&

.AMA WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
OK...NONE.

&&

$$

05/08





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