Area Forecast Discussion
Issued by NWS Amarillo, TX

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FXUS64 KAMA 271533
AFDAMA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE AMARILLO TX
1033 AM CDT WED MAY 27 2015

.UPDATE...

UPDATED HOURLY GRIDS TO MATCH TRENDS FOR THE DAY. THE REMAINDER OF
THE FORECAST LOOKS ON TRACK.

&&

.PREV DISCUSSION... /ISSUED 622 AM CDT WED MAY 27 2015/

AVIATION...
LOW CLOUDS IN THE IFR RANGE MAY MAKE IT TO THE AMA TAF SITE...SO HAVE
INSERTED A TEMPO GROUP THERE. THINKING RIGHT NOW IS THAT THE LOW
CLOUDS WILL NOT MAKE IT TO DHT OR GUY. SOUTHERLY WINDS WILL PICK INTO
THE 14 TO 17 KNOT RANGE BY EARLY THIS AFTERNOON...THEN THEY SHOULD
BACK SOME AND DECREASE DURING THE EVENING. THUNDERSTORMS WILL ALSO BE
POSSIBLE WITH THE GREATER CHANCES NEAR DHT AND GUY LATE THIS
AFTERNOON. HAVE NOT MENTIONED THEM IN THE TAFS AT THIS TIME AS
COVERAGE SHOULD BE PRETTY SCATTERED.

PREV DISCUSSION... /ISSUED 432 AM CDT WED MAY 27 2015/

DISCUSSION...

CHALLENGING FORECAST AHEAD WITH REGARDS TO TIMING OF PERIODS OF
HIGHEST PRECIPITATION CHANCES THROUGH THE END OF THE WEEK. EARLY
THIS MORNING CONVECTION WAS ONGOING IN A SMALL CLUSTER FROM THE
CENTRAL OKLAHOMA PANHANDLE NORTHWARD INTO EXTREME SOUTHWEST KANSAS.
OTHER ISOLATED/SCATTERED SHOWERS AND STORMS WERE MOVING EASTWARD
ACROSS NEW MEXICO. PRIMARY DRIVING FORCE FOR GREATER COVERAGE OF
CONVECTION THIS AFTERNOON ASIDE FROM DIABATIC
HEATING/DESTABILIZATION WILL BE A WEAK SHORTWAVE SEEN IN WATER VAPOR
NOW OVER SOUTH CENTRAL COLORADO. THIS IS THE MOST APPARENT OF A
SERIES OF WAVES EMBEDDED WITHIN RELATIVELY WEAK WESTERLY FLOW.
STORMS THAT OCCUR THIS AFTERNOON WILL BE IN AT LEAST A MODERATELY
UNSTABLE ENVIRONMENT WITH DEEP LAYER SHEAR AROUND 30-35 KNOTS
FAVORING STORM ORGANIZATION. ALL MODES OF SEVERE WEATHER ARE
POSSIBLE WITH HAIL BEING THE MOST COMMON TYPE. ROUGHLY THE NORTHEAST
HALF IS MOST FAVORED FOR DEVELOPMENT.

A MORE IMPACTFUL UPPER LEVEL FEATURE IN THE FORM OF A COMPACT CLOSED
LOW NOW OFF THE SOUTHERN CALIFORNIA COAST WILL MOVE TOWARD THE AREA
THROUGH TOMORROW. BY TOMORROW NIGHT MODELS ARE IN DECENT AGREEMENT
THAT THIS FEATURE WILL BECOME MORE OPEN AND PHASE SOMEWHAT WITH
NORTHERN STREAM SHORTWAVE. NET RESULT WILL BE MEAN HEIGHT FALLS AND
INCREASING LARGE SCALE ASCENT NECESSITATING HIGHER PRECIPITATION
PROBABILITIES LATE WEDNESDAY NIGHT INTO THURSDAY. WITH ANOMALOUS
MOISTURE STREAMING NORTHWARD LOCALLY HEAVY RAINFALL WILL BE
POSSIBLE...ESPECIALLY ACROSS THE SOUTHERN PORTION OF THE AREA FROM
ROUGHLY MID/LATE MORNING THURSDAY INTO THE AFTERNOON. DURING THIS
TIME SPATIAL AND TEMPORAL DETAILS BECOME INCREASINGLY BLURRY GIVEN
THE INHERENT NATURE OF DIFFICULT TO RESOLVE SMALL WAVES AND LARGER
SYNOPTIC SCALE DISCREPANCIES THAT EMERGE IN THE MODELS.
ADDITIONALLY...SMALLER SCALE DETAILS THAT ARE INFLUENCED BY THE
DEVELOPMENT OF CONVECTION INCLUDING BOUNDARY LAYER MOISTURE AND
MESOSCALE BOUNDARY FORCING WILL BE A FACTOR. ALL OF THIS WILL BE
RESOLVED BETTER WITH TIME. FOR NOW HAVE RELEGATED HIGHER
PRECIPITATION PROBABILITIES IN THE LIKELY CATEGORY TO THE SOUTHERN
PORTION OF THE AREA EARLY THURSDAY AND EXPANDED/INCREASED THIS
ACROSS ROUGHLY THE SOUTHEASTERN ONE THIRD OF THE TEXAS PANHANDLE
DURING THE AFTERNOON.

MODELS SHOW ONE MORE DISTINCT SHORTWAVE IN BROAD TROUGH THAT MAY LEAD
TO INCREASED PRECIPITATION PROBABILITIES FRIDAY EVENING AND FRIDAY
NIGHT FOLLOWED BY THE PASSAGE OF A COLD FRONT AND COOLER/DRIER
CONDITIONS FOR THE WEEKEND. MEDIUM RANGE GUIDANCE SHOWS A MORE
AMPLIFIED PATTERN EVOLVING EARLY NEXT WEEK WITH AT LEAST A BRIEF
PERIOD OF UPPER RIDGING AND WARMER TEMPERATURES. INTRODUCTION OF
ISOLATED-SCATTERED CONVECTION INTO THE FORECAST MAY BE NEEDED BY
TUESDAY IN LATER FORECAST ISSUENCES AS THE PATTERN DEAMPLIFIES AND A
TROUGH EVOLVES IN THE WEST. MEAN CROSS MOUNTAIN FLOW MAY BECOME
ESTABLISHED WITH A DEEPENING LEE SURFACE TROUGH AND SHARPENING
DRYLINE.

BRB

&&

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

&&

$$

16/18




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