Area Forecast Discussion
Issued by NWS Amarillo, TX

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000
FXUS64 KAMA 221808 AAA
AFDAMA

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE AMARILLO TX
108 PM CDT WED APR 22 2015

.MESOSCALE UPDATE...SEVERE WEATHER THREAT LIKELY MATERIALIZING...

MOTHER NATURE SEEMS TO BE POINTING HER FINGER IN OUR DIRECTION FOR
THIS AFTERNOON. LOW LVL MOISTURE CONVERGENCE SHOULD MAXIMIZE OVER
DEAF SMITH/OLDHAM COUNTIES THIS AFTERNOON BETWEEN A STALLING COLD
FRONT AND ADVANCING DRYLINE. INITIATION SEEMS LIKELY SOMEWHERE WITHIN
A 50 MILE RADIUS OF VEGA, TX BETWEEN 3-6 PM.

IN SPITE OF ONLY MODEST LOW TO MID LEVEL SHEAR INITIALLY...INCREASING
FLOW ABOVE 500MB WILL PROMOTE EFFECTIVE SHEAR VALUES OF UP TO 50 KTS.
WITH ONLY MODEST LOW LEVEL SHEAR VALUES AND NEUTRAL TO SLIGHTLY
INCREASING MID LVL HEIGHTS...WE COULD SEE A SITUATION WHERE THE
FIRST FEW UPDRAFTS GET TOPPLED AS THEY ASCEND INTO THE HIGHER
MOMENTUM AIR. HOWEVER...THINK THAT BY LATE AFTERNOON...THIS WILL BE
OVERCOME BY A COMBINATION OF LOW LVL CONVERGENCE, ADDITIONAL
INSTABILITY, AND INCREASING SHEAR IN THE LOWEST FEW HUNDRED
MILLIBARS.

WITH SOME MIXING OF DRIER PBL AIR EXPECTED...INITIAL CONVECTION
SHOULD BE RELATIVELY HIGH BASED (LCL HEIGHTS OF AROUND 2000M).
HOWEVER...WITH CONTINUED STRONG MOISTURE ADVECTION STORM BASES SHOULD
LOWER, ESPECIALLY IN THE EVENING HOURS.

WITH MLCAPES UPWARD OF 2000 J/KG AND AFOREMENTIONED SHEAR...DAMAGING
HAIL AND STRONG WINDS APPEAR TO BE THE MOST LIKELY THREATS WITH
INITIAL CONVECTION. AS THE EVENT ROLLS ON...LOWERING LCL HEIGHTS
AND THE POTENTIAL FOR HORIZONTAL VORTICITY ADVECTION NEAR THE
IMPRESSIVE BAROCLINIC ZONE (52F IN BEAVER COUNTY, 74F IN HEREFORD AT
17Z) MEAN A TORNADO THREAT COULD DEVELOP. THIS THREAT WOULD BE THE
MOST NOTABLE SOUTH OF A LINE FROM ROUGHLY BORGER TO PAMPA TO
WHEELER.

A SECONDARY AREA OF SHOWERS AND THUNDERSTORMS COULD AFFECT THE NRN TX
PANHANDLE AND OK PANHANDLE THIS EVENING...BUT SEVERE THREATS LOOK
MINIMAL WITH THIS CONVECTION.

WE ARE PREPARING TO RELEASE A SPECIAL 19Z SOUNDING, IF ANYTHING
CHANGES BASED ON THAT OBSERVATIONAL DATA, WE`LL SEND A QUICK UPDATE.

SIMPSON
&&

AVIATION...18Z TAFS

MVFR CONDITIONS CURRENTLY AT KAMA SHOULD LIFT QUICKLY TO VFR. OVER
THE COURSE OF THE PERIOD KAMA WILL SEE DETERIORATING CONDITIONS
THOUGH AND GET AS LOW AS LIFR. WE EXPECT THUNDERSTORMS TO MOVE
THROUGH KAMA BETWEEN 20Z AND 02Z. THESE STORMS WILL BRING VARIABLE
STRONG WINDS WITH GUSTS UP TO 35KTS OR HIGHER AND POSSIBLE TENNIS
BALL SIZE HAIL. AFTER THE STORMS PASS CEILINGS DROP QUICKLY AND FOG
WILL SET IN OVERNIGHT AND STICK AROUND THROUGH THE END OF THE PERIOD.
WINDS WILL BE EASTERLY UNTIL AROUND 16Z WHEN THEY MOVE MORE
SOUTHEASTERLY.

KDHT AND KGUY ARE ALSO CURRENTLY VFR AND WILL SEE DETERIORATING
CONDITIONS OVER THE PERIOD. THUNDERSTORMS ARE POSSIBLE NEAR KDHT AND
KGUY EARLY IN THE PERIOD BEFORE 00Z. AFTER STORMS MOVE AWAY CEILINGS
WILL DROP QUICKLY AND BECOME LIFR AND EVEN POSSIBLE VLIFR AT KDHT.
CLEARING WILL BE SLOW AND PROBABLY NOT UNTIL AFTER 18Z TO GET ABOVE
IFR.

MB
&&

PREV DISCUSSION... /ISSUED 501 AM CDT WED APR 22 2015/

DISCUSSION...
SCATTERED SHOWERS AND THUNDERSTORMS HAVE JUST ABOUT EXITED THE
EASTERN PANHANDLES. ELSEWHERE EARLY THIS MORNING...SHOWERS WITH A FEW
EMBEDDED THUNDERSTORMS ARE POSSIBLE...BUT THE MAIN TIMING FOR CONVECTION
WILL BE THIS AFTERNOON. SOUTHEASTERLY FLOW AT THE SURFACE CONTINUES
TO ADVECT HIGHER DEWPOINTS INTO THE PANHANDLES. SURFACE TROUGH OVER
NEW MEXICO WILL SHIFT EASTWARD AS A COLD FRONT CURRENTLY OVER THE
NORTHEASTERN OKLAHOMA PANHANDLE WILL DRIFT SOUTH THROUGH THE MORNING.
THIS FRONT IS SET TO STALL OUT IN THE CENTRAL/SOUTHERN TEXAS
PANHANDLE...SETTING UP A ZONE OF BOTH SURFACE CONVERGENCE AND
DIFFERENTIAL HEATING. UPPER LEVEL RIDGING WILL CONTINUE TO
BUILD TODAY...AND A WEAK SHORTWAVE COULD CROSS THE AREA DURING PEAK
HEATING THIS AFTERNOON/EARLY EVENING. THESE THINGS...COMBINED WITH
LEFTOVER OUTFLOW BOUNDARIES FROM TONIGHT/S CONVECTION...SHOULD LEAD TO
CONVECTIVE DEVELOPMENT THIS AFTERNOON. THE MAIN AREA OF CONCERN FOR
STRONG TO SEVERE STORMS WILL BE ACROSS THE CENTRAL AND SOUTHERN TEXAS
PANHANDLE...WHERE WARMER TEMPERATURES AND BETTER MOISTURE WILL REMAIN
AHEAD OF THE FRONT. LARGE HAIL AND DAMAGING WINDS WILL BE THE MAIN
THREATS...THOUGH A FEW TORNADOES ARE POSSIBLE AS WELL...MAINLY OVER
THE FAR SOUTHERN TEXAS PANHANDLE. BY THURSDAY...A RENEWED AREA OF
LEE TROUGHING SETS UP AND PUSHES THE CONVECTIVE CHANCES EASTWARD AS
THE FRONTAL BOUNDARY SINKS SOUTH AND AXIS OF CONVERGENCE SHIFTS INTO
THE CENTRAL AND EASTERN PANHANDLES. THE THREAT FOR SEVERE WEATHER
APPEARS LOWER FOR THURSDAY...BUT A FEW STRONG TO MARGINALLY SEVERE
STORMS ARE POSSIBLE.

BY FRIDAY....SOUTHWEST WINDS PICK UP AS LOW PRESSURE TO THE NORTH
STRENGTHENS AND BEGINS MOVING EASTWARD. THE UPPER LEVEL LOW WILL ALSO
CROSS OVER OR JUST NORTH OF THE PANHANDLES AND SHOULD RESULT IN A DRY
FORECAST THROUGH SATURDAY. ON SUNDAY...ANOTHER UPPER LEVEL LOW WILL
APPROACH THE FOUR CORNERS REGION AND BRING THE NEXT CHANCE FOR
THUNDERSTORMS TO THE PANHANDLES AS ANOTHER LEE TROUGH DEVELOPS INTO A
SURFACE LOW AND KEEPS POPS THROUGH MONDAY. DRY NORTHWESTERLY FLOW
SETS UP EARLY NEXT WEEK.

ELSENHEIMER

&&

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

&&

$$

09/14





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