935
FXUS64 KAMA 181958
AFDAMA
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE AMARILLO TX
258 PM CDT TUE JUN 18 2019
SHORT TERM...THIS AFTERNOON THROUGH TOMORROW
SYNOPSIS: UPPER LEVEL TROUGHING IS NOTED ACROSS THE CENTRAL CONUS. A
LEADING SHORTWAVE IS NOW SHIFTING EAST/NORTHEAST ACROSS THE CENTRAL
PLAINS, WITH A SECOND MORE SUBTLE SHORTWAVE IN NORTHERN NM. ISOLATED
TO SCATTERED THUNDERSTORMS ARE EXPECTED LATE THIS AFTERNOON INTO THE
EVENING HOURS IN CONJUNCTION WITH THE UPPER LEVEL SHORTWAVE AND A
COLD FRONT. THERE IS A CAP, BUT IT IS NOT AS STRONG AS PREVIOUSLY
THOUGHT BASED ON THE 19Z KAMA SPECIAL SOUNDING. ANY STORMS THAT DO
DEVELOP COULD BECOME SEVERE WITH LARGE HAIL AND STRONG WINDS BEING
THE MAIN THREAT. AN ISOLATED TORNADO CAN'T BE RULE OUT THIS EVENING
MAINLY IN THE EASTERN TEXAS PANHANDLE. STORM SHOULD BE ENDING AFTER
THE FRONT MOVES THROUGH TONIGHT. THERE IS A CHANCE OF SOME VERY
ISOLATED DIURNALLY DRIVEN STORMS WEDNESDAY AFTERNOON, WITH STORMS
MOVING OFF THE HIGHER TERRAIN AND PERHAPS ALONG A WEAK AREA OVER
CONVERGENCE NEAR THE CAPROCK. A FEW OF THESE STORMS COULD BECOME
BRIEFLY SEVERE WITH HAIL AND WIND, WITH A DIMINISHING THREAT INTO
THE EARLY EVENING. THE FOLLOWING DISCUSSION WILL FOCUS ON TODAY AND
TONIGHT:
CONVECTIVE INITIATION (CI): CONVECTION HAS ALREADY INITIATED NEAR
RATON NM NEAR A PRE-FRONTAL TROUGH THAT IS CURRENTLY DRAPED ACROSS
SOUTHEAST CO DOWN INTO THE WESTERN OKLAHOMA PANHANDLE AND BACK UP
INTO SOUTHERN KS. A CUMULUS FIELD IS ALSO BECOMING MORE EVIDENT JUST
SOUTH OF THE PRE-FRONTAL TROUGH NEAR KDHT TO KDUX AND WILL NEED TO
BE MONITORED FOR ADDITIONAL INITIATION IN THE NEXT 1-2 HOURS. THE
CAP IS A CONCERN IN THE PANHANDLES AND MAY LIMIT CONVECTIVE
INITIATION AND SUSTAINMENT, ESPECIALLY ACROSS THE SOUTHERN TEXAS
PANHANDLE. THE 19Z SPECIAL SOUNDING SHOWED 51 J/KG MLCIN WHICH MAY
LIMIT COVERAGE, BUT A FEW STORMS SHOULD BE ABLE TO DEVELOP IN THE
PANHANDLES, OR AT LEAST PERSIST AS THEY MOVE INTO THE AREA FROM OUR
WEST. ANOTHER AREA OF ATTEMPTED CI IS ALONG A LOW LEVEL THETA-E
GRADIENT THAT IS SLOWLY SHIFTING NORTH NEAR PLAINVIEW TO CHILDRESS,
AND HAS AN AREA OF TCU NEAR FLOYDATA AS OF 19Z. THE CAP MAY BE TOO
STRONG FOR DEVELOPMENT IN THIS AREA BASED ON THE CONVECTIVE TRENDS.
THE SUBTLE SHORTWAVE TROUGH IS NOTED IN THE MID LEVEL WATER VAPOR
IMAGERY NOW MOVING INTO NORTH CENTRAL NM, AND THIS MAY RESULT IN
ADDITIONAL CONVECTIVE DEVELOPMENT ACROSS THE NORTHERN ZONES IN THE
EVENING. THESE STORMS ARE EXPECTED TO MOVE EAST TO SOUTHEAST AT 10
TO 25 MPH. ANOTHER ROUND OF STORMS MAY DEVELOP OVERNIGHT AS THE MAIN
COLD FRONT MOVES SOUTH AND GENERATES ELEVATED CONVECTION IN THE
EASTERN TEXAS PANHANDLE NEAR THE BETTER THETA-E AXIS.
PRE-STORM ENVIRONMENT: A BAND OF MODERATE 500MB WESTERLIES IS NOTED
ACROSS THE NORTHERN ZONES WHICH SUPPORTS 25 TO 35 KNOTS OF EFFECTIVE
BULK SHEAR. FURTHER SOUTH, MID LEVEL WINDS ARE WEAKER AND SURFACE
WINDS ARE STILL VEERED TO THE SOUTHWEST, RESULTING IN LOWER
EFFECTIVE SHEAR VALUES OF AROUND 20 KNOTS. THESE MAY INCREASE SOME
THIS EVENING AS THE LOW LEVEL JET INCREASES. PLENTY OF INSOLATION
ACROSS THE PANHANDLES SUPPORTS A THERMODYNAMIC ENVIRONMENT AROUND
1500 - 2000 J/KG MLCAPE. TEMPERATURES SHOULD COME UP ANOTHER FEW
DEGREES WHICH WILL INCREASE MLCAPE, WITH SOME 2500 TO 3000 J/KG
POSSIBLE. STEEP LAPSE RATES ARE ALSO NOTED IN THE LOW AND MID LEVELS
WITH EML THAT ALSO COULD KEEP CAPPING CONCERNS. HOWEVER, SHORT
TERM MODELS CONTINUE TO SUGGEST THAT THE CAP WILL WEAKEN ENOUGH FOR
STORMS TO SURVIVE. LOW LEVEL MOISTURE IS CHARACTERIZED WITH A SUBTLE
MOISTURE GRADIENT OF MID 50S DEW POINTS IN THE NORTHEASTERN NM
PLAINS TO LOW 60S DEW POINTS IN THE EASTERN HALF OF THE PANHANDLES.
THIS MOISTURE IS FAIRLY SHALLOW SO LCL HEIGHTS ARE STILL MODERATE
HIGH, AROUND 1500 TO 2000 M. THESE MAY DROP SOME THIS EVENING AIDED
BY SOME ADDITIONAL MOISTURE ADVECTION WITH THE LOW LEVEL JET.
CONVECTIVE MODE AND SEVERITY: GIVEN PLENTIFUL INSTABILITY AND
MODERATE SHEAR IN THE NORTHERN ZONES, A FEW DISCRETE STORMS CAPABLE
OF SUPERCELL STRUCTURES WILL BE POSSIBLE. THESE STORMS MAY LOOSE
THEIR SUPERCELL CHARACTERISTICS IF THEY MOVE SOUTHWARD OUT OF THE
BETTER SHEAR, HOWEVER SOME BACKING OF THE LOW LEVEL WINDS THIS
EVENING AND THE INCREASE IN LLJ COULD OFFSET THIS SOME. UPSCALE
GROWTH WILL LIKELY BE THE RESULT OF THE STRENGTHENING LLJ AND BETTER
LIFT WITH THE SHORTWAVE. OVERALL, THE DISCRETE STORMS WILL POSE THE
MAIN HAIL THREAT. CERTAINLY CAN'T RULE OUT SOME GOLF BALL TO TENNIS
BALL SIZE HAIL WITH THE STRONGEST DISCRETE STORMS. WINDS WILL BECOME
MORE OF A THREAT IF STORMS CAN GROW UPSCALE WITH DCAPE AS HIGH AS
1400 J/KG IN THE TEXAS PANHANDLE. THE TORNADO THREAT IS LOW DUE TO
LACK OF BETTER LOW LEVEL SHEAR AND HIGH LCL HEIGHTS, HOWEVER IF
SURFACE WINDS CAN BACK ENOUGH THIS EVENING, AN ISOLATED TORNADO
THREAT CAN'T BE RULED OUT.
WARD
LONG TERM
UPPER LEVEL FLOW WILL TRANSITION FROM NORTHWEST TO ZONAL ON THURSDAY
AND THEN IT WILL BECOME MORE SOUTHWEST BY FRIDAY AS AN UPPER LEVEL
TROUGH MOVES THROUGH THE NORTHWEST U.S. THURSDAY AND FRIDAY ARE
EXPECTED TO BE DRY WITH TEMPERATURES ABOVE NORMAL AS SOUTHWEST
SURFACE WINDS INCREASE.
SHOWERS AND THUNDERSTORMS MAY RETURN TO THE NORTHERN AND EASTERN CWA
SATURDAY NIGHT THROUGH SUNDAY AS A COLD FRONT MOVES INTO THE REGION
AND STALLS. SEVERAL UPPER LEVEL SHORT WAVE TROUGHS WILL MOVE
THROUGH THE SOUTHWEST FLOW ALOFT WHICH WILL HELP TRIGGER THE SHOWERS
AND STORMS.
THE UPPER LEVEL TROUGH THEN SWINGS THROUGH THE HIGH PLAINS BY MONDAY
WHICH SHOULD TAKE THE RAIN WITH IT.
THE RAIN AND COLD FRONT WILL HELP TO DROP TEMPERATURES BACK DOWN TO
NEAR NORMAL FOR THE WEEKEND AND THEN TEMPERATURES WILL WARM AGAIN ON
MONDAY.
PRELIMINARY POINT TEMPS/POPS
AMARILLO TX 59 85 60 95 66 / 30 10 10 0 0
BEAVER OK 59 82 60 93 67 / 40 10 10 5 5
BOISE CITY OK 53 79 56 90 60 / 30 20 10 0 5
BORGER TX 60 86 62 96 68 / 30 20 10 0 0
BOYS RANCH TX 58 85 59 96 65 / 20 10 10 0 5
CANYON TX 59 88 59 96 65 / 20 10 10 0 0
CLARENDON TX 62 86 62 93 69 / 20 20 10 0 5
DALHART TX 54 81 56 92 60 / 20 20 10 0 5
GUYMON OK 56 81 58 92 64 / 40 10 10 0 5
HEREFORD TX 59 89 60 97 65 / 20 10 10 0 0
LIPSCOMB TX 61 83 62 94 69 / 40 10 10 0 5
PAMPA TX 60 83 61 93 67 / 30 20 10 0 0
SHAMROCK TX 64 87 62 94 70 / 30 20 10 0 5
WELLINGTON TX 65 89 64 95 71 / 30 20 10 0 5
AMA WATCHES/WARNINGS/ADVISORIES
TX...NONE.
OK...NONE.
7/15
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