Area Forecast Discussion
Issued by NWS Amarillo, TX

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000
FXUS64 KAMA 222356 AAA
AFDAMA

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE AMARILLO TX
656 PM CDT MON SEP 22 2014

.AVIATION...
FOR THE 00Z TAFS...VFR CONDITIONS ARE EXPECTED TO START THE
PERIOD...WITH POSSIBLE MVFR CEILINGS DEVELOPING AT KAMA AND KDHT
AFTER 06Z TONIGHT. A FEW LIGHT RAIN SHOWERS NEAR KDHT TONIGHT COULD
BRING BRIEF GUSTY WINDS THIS EVENING. SOUTH WINDS THROUGHOUT THE
PERIOD SHOULD BECOME GUSTY DURING THE DAY TUESDAY.

NF

&&

.PREV DISCUSSION... /ISSUED 411 PM CDT MON SEP 22 2014/

DISCUSSION...
PRECIPITATION CHANCES THE NEXT FEW DAYS POSE THE MAIN FORECAST
CHALLENGE.

A COMPACT UPPER LOW WAS CHURNING EAST ACROSS WY THIS
AFTERNOON...PUTTING A DENT IN THE UPPER RIDGE OVER THE ROCKIES AND
PLAINS. SOME SHOWERS AND ISOLATED THUNDERSTORMS ARE SLOWLY MAKING
THEIR WAY EAST TOWARD THE PANHANDLES OUT OF EASTERN NM WITHIN THE
LINGERING DEEP MOISTURE PLUME. THINK MUCH OF THIS ACTIVITY WILL
DISSIPATE AFTER SUNSET WITH THE LOSS OF DAYTIME HEATING...AS THE
STRONGER FORCING ATTENDANT TO THE AFOREMENTIONED UPPER LOW WILL REMAIN TO
OUR NORTH. HOWEVER SOME WEAK MID/UPPER-LEVEL FORCING ON THE SOUTHERN
FRINGE OF THIS SYSTEM WILL GRAZE THE AREA...WHICH WILL KEEP A SMALL
POSSIBILITY OF A FEW SHOWERS OR STORMS GOING OVERNIGHT. WEAK
INSTABILITY /0-1 KM MLCAPES UP TO AROUND 500 J/KG/ IN THE FAR WESTERN
PANHANDLES WILL PRECLUDE ANY SEVERE WEATHER.

THE UPPER LOW CURRENTLY OVER WY WILL CONTINUE TO OPEN UP AND SLIDE
ACROSS THE DAKOTAS AND NE ON TUESDAY...WITH THE LEE TROUGH SLIDING A
BIT FARTHER EAST IN RESPONSE. WEAK LOW-LEVEL CONVERGENCE ALONG THE
LEE TROUGH IN COMBINATION WITH SOME CONTINUED WEAK FORCING ALOFT ON
THE SOUTHERN END OF THE SHORTWAVE TROUGH MAY TRIGGER SOME ISOLATED
AFTERNOON CONVECTION. IF STORMS DEVELOP...A FEW COULD BE STRONG TO
MARGINALLY SEVERE GIVEN POCKETS OF MLCAPE IN THE 1000-1500 J/KG RANGE
AND DEEP LAYER SHEAR UP TO 20-30 KTS. A LITTLE BETTER THUNDERSTORM
CHANCES WILL DEVELOP OVER THE NORTHEAST PANHANDLES TUESDAY
EVENING/OVERNIGHT AS STRONGER FORCING ATTENDANT TO THE SHORTWAVE
SLIDES ACROSS THE AREA.

THE UPPER RIDGE WILL AMPLIFY OVER THE ROCKIES ON WEDNESDAY DOWNSTREAM
OF A DEEPENING UPPER LOW OVER THE EASTERN PACIFIC. IN RESPONSE...SOME
SHORTWAVE ENERGY FROM THE SHORTWAVE OVER THE UPPER MIDWEST MAY
RETROGRADE SOUTHWEST TOWARD THE PANHANDLES AROUND THE UPPER RIDGE.
AT THE VERY LEAST...IT LOOKS LIKE THERE WILL BE A SHEAR AXIS/WEAKNESS
IN THE RIDGE OVERHEAD. THIS COMBINED WITH A LINGERING LEE SURFACE
TROUGH...AND A LITTLE BETTER INSTABILITY /MLCAPES 1000-2000 J/KG/
WILL SUPPORT WHAT LOOK TO BE A LITTLE BETTER THUNDERSTORM CHANCES
WEDNESDAY. A FEW STORMS COULD BE STRONG TO MARGINALLY SEVERE IN THE
PRESENCE OF THIS INSTABILITY AND DEEP LAYER SHEAR ON THE ORDER OF
20-30 KTS.

UNCERTAINTY INCREASES WITH REGARD TO THE UPPER PATTERN LATE WEEK INTO
EARLY NEXT WEEK. WILL HANG ONTO SOME SMALL THUNDERSTORM CHANCES
THROUGH THURSDAY NIGHT WITH THE SHEAR AXIS OR POTENTIALLY RETROGRADING
SHORTWAVE STILL IN PLAY. THIS ENERGY LOOKS TO WEAKEN ENOUGH BY FRIDAY
AND SATURDAY BENEATH THE BROADER UPPER RIDGE TO KEEP THESE PERIODS
DRY FOR NOW. CONSIDERABLE UNCERTAINTY EXISTS WITH THE EVOLUTION OF
THE WEST COAST UPPER LOW/TROUGH...SPECIFICALLY HOW LONG IT WILL TAKE TO
EVENTUALLY EJECT AND WHETHER IT WILL TRACK MORE NORTHEAST OR EAST
WHEN IT DOES. DEPENDING ON THESE FACTORS...THUNDERSTORM CHANCES COULD
RETURN LATE IN THE WEEKEND INTO EARLY NEXT WEEK.

TEMPERATURES SHOULD REMAIN FAIRLY CONSISTENT THROUGH THE PERIOD WITH
HIGHS GENERALLY IN THE 70S AND 80S AND LOWS IN THE 50S AND 60S.

KB

&&

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

&&

$$

06/14




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