AP-TX--AMA-TX W Area Forecast Discussion, TX

000

FXUS64 KAMA 151106

AFDAMA

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE AMARILLO TX

606 AM CDT WED JUL 15 2015

.AVIATION... /FOR THE 12Z TAFS/

CONFIDIENCE WAS HIGH ENOUGH FOR INCLUSION OF THUNDERSTORMS IN THE TAF

THIS EVENING ONLY AT KGUY. LATER TAFS WILL REVISE THE TIME RANGE

WHEN THUNDERSTORMS ARE MOST LIKELY AND MAY NEED TO INCLUDE THEM AT

KDHT ALSO. UNCERTAINTIES WITH THE EXACT POSITION OF LEE TROUGH AS

WELL AS ANY OUTFLOW BOUNDARIES FROM THUNDERSTORMS WILL HAVE

IMPLICATIONS FOR THE WIND FORECAST. ADJUSTMENTS TO WINDS MAY BE

NEEDED LATER TODAY BASED ON RADAR AND OBSERVATION TRENDS. WINDS

SHOULD GENERALLY BE SOUTHERLY AT ALL SITES WITH THE HIGHEST SPEEDS UP

TO 15 KNOTS THIS AFTERNOON AND EVENING.

BRB

&&

.PREV DISCUSSION... /ISSUED 412 AM CDT WED JUL 15 2015/

DISCUSSION...

THE MAIN CHALLENGE FOR THIS FORECAST IS HANDLING SPACE AND TIME

DETAILS OF PRECIPITATION OVER THE NEXT FEW DAYS. EARLY THIS MORNING

WATER VAPOR SHOWED A MID-UPPER HIGH CENTERED OVER NORTH CENTRAL

TEXAS WITH PLUME OF DEEP MOISTURE CONTINUING TO MOVE NORTHWARD ON

ITS WESTERN PERIPHERY. DEEP MOISTURE WAS MORE EXTENSIVE OVER ROUGHLY

THE NORTHWEST HALF OF THE PANHANDLE REGION WHERE CONVECTION THE

PREVIOUS EVENING WAS MOST EXTENSIVE. A SLIGHT UPTICK IN CONVECTIVE

COVERAGE WAS NOTED ON RADAR AFTER MIDNIGHT AS LOW LEVEL JET

STRENGTHENED BUT THE BEST NORTH TO SOUTH 850 MB TEMPERATURE GRADIENT

WAS CONFINED TO WEST KANSAS AND THUS MORE EXTENSIVE ASCENT AND

CONVECTIVE DEVELOPMENT OCCURRED THERE. ISOLATED TO SCATTERED

SHOWERS AND STORMS SHOULD LINGER INTO THE EARLY MORNING HOURS ACROSS

MAINLY NORTH CENTRAL AND NORTHEASTERN PARTS OF THE FORECAST AREA.

THE LARGE SCALE PATTERN DOES NOT CHANGE MUCH TODAY. THE UPPER HIGH

WILL DRIFT SLIGHTLY FURTHER EAST BUT MID LEVEL HEIGHT TRENDS ARE

NEUTRAL INTO THE NIGHT. MODELS ARE IN AGREEMENT IN A WEAK SHORTWAVE

APPROACHING THE NORTHWEST PORTION OF THE AREA LATE IN THE DAY AND

WEAK ASCENT ASSOCIATED WITH THIS FEATURE WILL INTERACT WITH AN

ATMOSPHERE THAT HAS CHANGED LITTLE THERMODYNAMICALLY OVER THE PAST

COUPLE DAYS. THIS WARRANTS A CHANCE OF SHOWERS AND THUNDERSTORMS FOR

ROUGHLY THE NORTHWEST HALF OF THE AREA TAPERING TO SLIGHT CHANCE

FURTHER EAST. DEEP LAYER SHEAR AND INSTABILITY WILL GENERALLY BE

WEAK SO SEVERE THUNDERSTORMS ARE UNLIKELY. A SIMILAR SCENARIO AS

LAST NIGHT MAY PLAY OUT AGAIN TONIGHT WITH RESIDUAL CONVECTION

PROBABLY INCREASINGLY SLIGHTLY LATER IN THE NIGHT AS LOW LEVEL JET

STRENGTHENS ACROSS A WEAK TEMPERATURE GRADIENT IN A FAIRLY MOIST

ENVIRONMENT.

LOW PROBABILITIES (NEAR CLIMO) OF PRECIPITATION WERE KEPT FOR MUCH

OF THE AREA THROUGH FRIDAY EVENING AS SMALL DIFFICULT TO RESOLVE

WAVES TRAVERSE THE NORTHWESTERN EDGE OF THE RIDGE. STARTING SATURDAY

MEDIUM RANGE MODELS BEGIN TO DIVERGE AND SIGNIFICANT DIFFERENCES

EMERGE BY EARLY NEXT WEEK. THE GFS IS MORE SUPPRESSED WITH MEAN

RIDGING AND HAS A RELATIVELY SIGNIFICANT SHORTWAVE TROUGH

APPROACHING BY TUESDAY. MEANWHILE THE ECWMF SHIFTS THE RIDGE

WESTWARD AND IS MUCH WEAKER AND LESS AMPLIFIED WITH THE

AFOREMENTIONED SHORTWAVE. THIS WOULD KEEP THE AREA WHICH WOULD

SUGGEST A DRIER PATTERN. EVEN THE ENSEMBLE MEAN FROM BOTH MODELS IS

QUITE DIFFERENT WITH THEIR DEPICTIONS OF THE LARGE SCALE PATTERN. A

CONSENSUS WAS USED WITH A SLIGHT DOWNWARD ADJUSTMENT OF PROBABILITIES

A LITTLE CLOSER TO CLIMATOLOGY UNTIL MODELS COME INTO BETTER

AGREEMENT. LOCALLY HEAVY RAINFALL MAY OCCUR ESPECIALLY EARLY NEXT

WEEK AS MOISTURE BECOMES MORE ANOMALOUS (PWATS AROUND OR ABOVE 1.5

INCHES) BUT PROBABLY WILL NOT BE WIDESPREAD OR PROLONGED ENOUGH FOR

SIGNIFICANT FLOODING CONCERNS. THE ABOVE MENTIONED UNCERTAINTIES ALSO

HAVE IMPLICATIONS FOR TEMPERATURES WITH POTENTIALLY COOLER WEATHER IF

THE RIDGE IS WEAKER AND TRANSIENT SYSTEMS HAVE MORE OF AN INFLUENCE

ON OUR REGION. A BLEND OF MEDIUM RANGE GUIDANCE WAS USED FOR NOW.

BRB

&&

.AMA WATCHES/WARNINGS/ADVISORIES...

TX...NONE.

OK...NONE.

&&

$$

17

Delivered by Weather Underground Inc. Wed Jul 15 2015 7:06AM EDT