Area Forecast Discussion
Issued by NWS Amarillo, TX

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000
FXUS64 KAMA 221756
AFDAMA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE AMARILLO TX
1256 PM CDT WED OCT 22 2014

.UPDATE...
MAIN SHIELD OF RAIN HAS SHIFTED INTO THE EASTERN PANHANDLES...AND
WILL CONTINUE TO SLOWLY MOVE NORTHEAST THIS AFTERNOON IN TANDEM WITH
ASCENT AHEAD OF UPPER-LEVEL SHORTWAVE TROUGH. ADDITIONAL
ISOLATED/SCATTERED SHOWERS HAVE RECENTLY DEVELOPED JUST WEST OF THE
MAIN SWATH OF RAIN WHERE SOME BREAKS IN THE CLOUDS COMBINED WITH
COOLER TEMPS ALOFT IN THE SHORTWAVE TROUGH AXIS HAVE GENERATED SOME
WEAK INSTABILITY...ALLOWING CONVECTION TO REDEVELOP WITHIN THE
REMNANT MOISTURE PLUME. WEAK INSTABILITY SHOULD PRECLUDE ANY SEVERE
THREAT THIS AFTERNOON.

KB

&&

.AVIATION...
18Z TAFS...IFR CIGS INITIALLY AT KAMA ARE EXPECTED TO LIFT TO MVFR
WITHIN THE NEXT 1-2 HOURS. MVFR CIGS WILL LIKELY LINGER FOR MUCH OF
THE AFTERNOON AT KAMA...BUT SHOULD GIVE WAY TO VFR CONDITIONS BY LATE
AFTERNOON OR EARLY EVENING. VFR CONDITIONS SHOULD HOLD AT KDHT AND
KGUY THIS AFTERNOON...WITH ANY CIGS EXPECTED TO REMAIN ABOVE 3 KFT
AGL. THE MAIN AREA OF RAIN HAS SHIFTED EAST OF ALL TERMINALS...BUT
SOME ISOLATED/WIDELY SCATTERED SHOWERS AND THUNDERSTORMS DEVELOPING
WEST OF THIS COULD CLIP KAMA THIS AFTERNOON. LIGHT WINDS...CLEARING
SKIES...AND LINGERING LOW-LEVEL MOISTURE WILL LIKELY LEAD TO FOG
DEVELOPMENT TONIGHT. STILL TOUGH TO SAY HOW LOW VSBYS WILL DROP...BUT
WILL TAKE THEM INTO THE IFR RANGE FOR NOW.

KB

&&

.PREV DISCUSSION... /ISSUED 329 AM CDT WED OCT 22 2014/

DISCUSSION...

CONCERNS/CHALLENGES FOR THIS FORECAST WILL BE PRIMARILY IN THE NEAR
TERM WITH PRECIPITATION CHANCES AND TEMPERATURES THROUGH TOMORROW
EVENING. NO MAJOR CHANGES WERE NEEDED TO THE PREVIOUS FORECAST.

WV LOOP AND UPPER AIR ANALYSIS SHOWS UPPER LEVEL TROUGH TO OUR WEST
MOVING EASTWARD. THIS WILL BE THE IMPETUS FOR PRECIPITATION TOMORROW
AS IT CROSSES THE PANHANDLES. SHORT TERM MODELS ARE IN FAIR
AGREEMENT WITH SREF ENSEMBLE SPREAD BEING FAIRLY SMALL. EARLY IN THE
DAY LEFT EXIT REGION OF QUICK MOVING UPPER JET STREAK AND WEAK
ISENTROPIC ASCENT IN MOISTENING COLUMN SHOULD SUPPORT SHOWERS MOVING
NORTHEASTWARD ACROSS THE FORECAST AREA THROUGH EARLY AFTERNOON.
PRECIPITATION AMOUNTS WILL BE LIGHT. COMPARISON OF CONVECTION
ALLOWING MODELS SHOWS SOME DIFFERENCES ON THE MESOSCALE WITH
PLACEMENT/MAGNITUDE OF CONVECTION. THE GENERAL THEME IS FOR AN
UPSWING IN CONVECTION ACROSS THE SOUTHEAST PORTION OF THE AREA. THERE
HAS BEEN SOME INCONSISTENCY ON WHERE TO PLACE HIGHER QPF VALUES AND
FELT MORE COMFORTABLE SOMEWHAT BROAD BRUSHING AMOUNTS SOMEWHAT. PWAT
VALUES RISE TO AT LEAST 2SD ABOVE CLIMATOLOGY OVER THE FAR SOUTHEAST
AND SO LOCALIZED NEAR ONE HALF INCH OR GREATER AMOUNTS SEEM POSSIBLE.
MOST OF THE AREA SHOULD SEE AROUND A QUARTER OF AN INCH OR LESS.
UPPER FORCING QUICKLY SHIFTS EAST LATE TOMORROW AND HAVE ADJUSTED
TIMING OF THE END OF PRECIPITATION TO BE SLIGHTLY QUICKER AS
SUBSIDENCE INCREASES CONSIDERABLY DURING THE EVENING. ANOTHER CONCERN
IS FOR PATCHY FOG DEVELOPMENT LATE TONIGHT THROUGH EARLY TOMORROW
MORNING DUE TO LINGERING LOW LEVEL MOISTURE AND LIGHT WINDS. LATER
FORECASTS MAY HIGHLIGHT THE FOG POTENTIAL ONCE IT BECOMES CLEAR WHICH
PORTIONS OF THE PANHANDLE WILL SEE MOST FAVORABLE CONDITIONS FOR FOG
DEVELOPMENT.

MODEL AGREEMENT IS GOOD IN THE LONG TERM SO FELT COMFORTABLE WITH A
CONSENSUS/BLEND APPROACH THROUGH SUNDAY. 590+ DM UPPER LEVEL RIDGING
MOVES SLOWLY EAST ACROSS THE REGION SATURDAY BRINGING MUCH ABOVE
NORMAL TEMPERATURES FOR LATE OCTOBER. HAVE CONTINUED THE UPWARD
TREND IN TEMPERATURES BOTH FRIDAY AND SATURDAY. BY SUNDAY THE RIDGE
MOVES EAST AND A WEAK SHORTWAVE TROUGH MOVES THROUGH FOLLOWED BY A
STRONGER/DEEPER TROUGH ON MONDAY. MEDIUM RANGE GUIDANCE DIVERGES BY
THIS TIME WITH GFS CONTINUING TO BE LESS AMPLIFIED AND MORE
PROGRESSIVE THAN THE ECMWF. UNCERTAINTY IN THE TIMING OF COLD FRONT
AND COOLER AIR MASS LEADS TO A LOW CONFIDENCE FORECAST EARLY NEXT
WEEK. ALSO...THE MORE PROGRESSIVE GFS SOLUTION WOULD NECESSITATE A DRY
FORECAST AS LIMITED MOISTURE TO BEGIN WITH GETS SHIFTED QUICKLY EAST
INTO OKLAHOMA AROUND THE TIME OF PEAK FORCING. LATER FORECASTS MAY
NEED TO INCREASE PRECIPITATION CHANCES LATE MONDAY/TUESDAY IF IS
BECOMES MORE CLEAR THAT THE SLOWER/DEEPER ECMWF SOLUTION IS MOST
VIABLE.

BRB

&&

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

&&

$$

08/15





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