Area Forecast Discussion
Issued by NWS Amarillo, TX

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FXUS64 KAMA 281847
AFDAMA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE AMARILLO TX
147 PM CDT THU APR 28 2016

.SHORT TERM...
LATEST SURFACE ANALYSIS INDICATES A STATIONARY FRONT EXTENDING FROM
EAST-CENTRAL NEW MEXICO TO JUST SOUTH OF OUR FORECAST AREA TO NEAR
THE RED RIVER. WEAK CONVERGENCE IN LAPS STREAMLINE ANALYSIS IS NOTED
ALONG THIS BOUNDARY. EAST-SOUTHEASTERLY FLOW WILL CONTINUE
INCREASING IN RESPONSE TO FALLING PRESSURES TO THE WEST AS THE MAIN
UPPER LEVEL SYSTEM APPROACHES. SHORT TERM MODEL GUIDANCE CONTINUES
TO SUGGEST RAPID LOW-LEVEL MOISTURE RETURN THROUGHOUT THE DAY WITH A
CONSENSUS INDICATING MID 50 DEGREE DEW POINTS REACHING WELL INTO THE
TEXAS PANHANDLE BY LATE AFTERNOON OR EARLY EVENING. SURFACE
OBSERVATIONS SHOW LOW TO MID 50 DEGREE DEW POINTS ALREADY AS FAR
NORTHWEST AS CHILDRESS AND MATADOR. THIS IN COMBINATION WITH SURFACE
HEATING WILL CONTRIBUTE TO WEAK IF NOT MODERATE INSTABILITY BY LATE
AFTERNOON. THE EVOLUTION OF SURFACE PRESSURE PATTERN AND BEHAVIOR OF
THE SURFACE BOUNDARY WILL HAVE IMPLICATIONS ON THE SEVERE
THUNDERSTORM POTENTIAL LATE THIS AFTERNOON AND THROUGH THE EVENING.

DEEP MIXING AND SHARPENING DRYLINE ACROSS THE SOUTHWEST PORTION OF
OUR AREA SEEMS LESS LIKELY THAN EARLIER THOUGHT BASED ON THE LATEST
TRENDS AND THE FIRST ADJUSTMENT TO THE FORECAST WE HAVE MADE IS TO
ADD PRECIPITATION TO THIS PORTION OF THE FORECAST AREA THIS
AFTERNOON. WITHIN THE COVERGENT AND MOISTENING LOW-LEVEL FLOW
ISOLATED/SCATTERED THUNDERSTORMS SHOULD DEVELOP PERHAPS ENHANCED BY A
WEAK SHORTWAVE NOW SEEN IN WATER VAPOR MOVING EASTWARD INTO EASTERN
COLORADO. THIS SHOULD BE COINCIDENT WITH A RELATIVELY NARROW LOW-
LEVEL THETA-E AXIS WHICH IS EXPECTED TO SET UP FROM NEAR OR SOUTH OF
DALHART TO THE AMARILLO AREA AND EXTEND SOUTHEASTWARD JUST AHEAD OF A
SHARPENING DRYLINE JUST SOUTH OF OUR AREA. LARGE HAIL AND DAMAGING
WINDS WOULD BE THE PRIMARY THREAT WITH PERHAPS A BRIEF WINDOW FOR A
TORNADO OR TWO THIS EVENING. TWO CONTRIBUTING FACTORS TO THE TORNADO
THREAT WILL BE 1.) INCREASING LOW LEVEL JET CONTRIBUTING TO
STRENGTHENING 0-1KM BULK SHEAR VALUES OF AROUND 25 KNOTS (THERE IS
QUITE A SPREAD IN 850 MB SPEEDS AND RESULTANT LOW LEVEL SHEAR VALUES
IN THE SHORT TERM GUIDANCE) AND 2.) CONTINUED MOISTENING RESULTING IN
LCL HEIGHTS OF AROUND 1KM...POSSIBLY LOWER.

WE WILL PROVIDE AN UPDATED DISCUSSION FOCUSING ON SEVERE POTENTIAL
LATER THIS AFTERNOON ONCE FURTHER ANALYSIS IS COMPLETED AND AS WE
CONTINUE TO MONITOR TRENDS. A SPECIAL 21Z SOUNDING IS BEING
CONSIDERED. WE ARE PARTICULARLY INTERESTED IN THE EVOLUTION OF THE
LOW LEVEL WIND FIELDS LATER TODAY AND MAY BE ABLE TO CAPTURE THE
BEGINNING OF THIS SUFFICIENTLY WITH THE 00Z SOUNDING. SO AN EARLIER
SOUNDING MAY BE OF LITTLE VALUE.

CONVECTION SHOULD EXPAND IN COVERAGE LATER TONIGHT AS ISENTROPIC
ASCENT OCCURS ATOP THE AFOREMENTIONED BOUNDARY STRENGTHENS WITH THE
APPROACH OF THE CLOSED LOW NOW OVER ARIZONA. ASCENT IS STRONGEST AND
CONDENSATION PRESSURE DEFICIT VALUES ARE LOWEST IN THE NORTHWEST
LATE THIS EVENING AND EARLY TONIGHT SO THIS IS WHERE WE HAVE PLACED
THE HIGHEST PROBABILITIES. ELEVATED INSTABILITY APPEARS SUFFICIENT
FOR AT LEAST MARGINALLY SEVERE HAIL LATE INTO THE NIGHT. ANY SURFACE
BASED STORMS AND WIND/TORNADO RISK SHOULD BE FURTHER SOUTH NEAR THE
BOUNDARY AND BEFORE DECOUPLING INCREASES SUBSTANTIALLY LATE THIS
EVENING OR EARLY TONIGHT. AFTER WHICH THE PRIMARY THREAT WILL BE
HAIL.

THE LONG TERM PORTION OF THE DISCUSSION WILL BE SENT LATER THIS
AFTERNOON.

BRB

&&

.PREV DISCUSSION... /ISSUED 1234 PM CDT THU APR 28 2016/

AVIATION... /FOR THE 18Z TAFS/
VFR CONDITIONS ARE EXPECTED TO PREVAIL THIS AFTERNOON AND LIKELY
THROUGH MOST OF THE EVENING. MOIST EASTERLY FLOW MAY RESULT IN MVFR
TO IFR STRATUS AT ALL LOCATIONS LATE THIS EVENING AND ESPECIALLY BY
LATER TONIGHT. ISOLATED TO SCATTERED THUNDERSTORMS WILL FORM LATE THIS
AFTERNOON AND COULD IMPACT KAMA. SHOWERS AND STORMS ARE EXPECTED TO
EXPAND IN COVERAGE LATER THIS EVENING AND OVERNIGHT. HIGHEST
PROBABILITIES ARE NORTHEAST OF DALHART AND AMARILLO THIS EVENING AND
TONIGHT...SO FOR NOW ONLY PREVAILED THUNDER AT GUYMON. EXPECT
AMENDMENTS TO NARROW WINDOW FOR HIGHEST CHANCES OF THUNDERSTORMS
IMPACTING TERMINALS. OTHERWISE EAST TO EAST-SOUTHEAST WINDS WILL
PREVAIL UNTIL THE SURFACE LOW NEARS TOWARD THE END OF THE TAF PERIOD.
WINDS WILL LESSEN THEN AND EVENTUALLY BECOME SOUTHWESTERLY...MOST
LIKELY BEYOND THE TAF PERIOD.

BRB

PREV DISCUSSION... /ISSUED 507 AM CDT THU APR 28 2016/

SURFACE LOW OVER EASTERN NEW MEXICO THIS MORNING WITH A DRYLINE
EXTENDING SOUTH OF THE SURFACE LOW INTO FAR WEST TEXAS. A WARM FRONT
EXTENDS SOUTH AND EAST OF THE SURFACE LOW INTO NORTH TEXAS SOUTH OF
THE RED RIVER. THE WARM FRONT IS EXPECTED TO LIFT NORTH AND EAST
TODAY INTO THE SOUTHERN TEXAS PANHANDLE WHILE THE SURFACE LOW AND
DRYLINE PUSH SLOWLY EAST JUST WEST AND SOUTH OF THE FORECAST AREA.
LOW LEVEL MOISTURE IS EXPECTED TO SURGE NORTH AND WEST INTO THE
EASTERN AND SOUTHERN TEXAS PANHANDLE BY THIS AFTERNOON AND EVENING
WITH SURFACE DEW POINTS REACHING INTO THE UPPER 40S TO LOW 50S BY 00Z
FRIDAY ACROSS THE SOUTHEASTERN TEXAS PANHANDLE. THE ATMOSPHERE WILL
QUICKLY DESTABILIZE BY 00Z FRIDAY WITH 0-3 KM SRH OF 296 M2/S2 AND
BRN SHEAR OF 96-99 M2/S2. SURFACE-6 KM SHEAR OF 60-65 KNOTS AND
700-500 MB LAPSE RATES OF 18 DEGREES CELSIUS. SEVERE THREAT LIKELY
AFTER 21Z TODAY...BUT WILL PUSH BACK TIMING OF CONVECTIVE DEVELOPMENT
IN THE GRIDS TO BETWEEN 18Z TODAY AND 00Z FRIDAY. CLOSED UPPER LOW
TRACKING EAST OUT OF SOUTHERN CALIFORNIA TODAY WILL APPROACH THE FOUR
CORNERS REGION BY 00Z FRIDAY AND THEN ACROSS THE CENTRAL AND SOUTHERN
ROCKIES TONIGHT AND FRIDAY. CONVECTION WILL SPREAD ACROSS ALL OF THE
PANHANDLES BY TONIGHT THROUGH FRIDAY AND THEN WILL END FROM WEST TO
EAST BY 06Z SATURDAY. A COLD FRONT EXPECTED BY LATE FRIDAY OR FRIDAY
NIGHT.

ANOTHER ROUND OF CONVECTION WILL MOVE INTO THE WESTERN PANHANDLES
FROM EASTERN NEW MEXICO SATURDAY AFTERNOON...AND THEN SPREADING
EASTWARD ACROSS ALL OF THE FORECAST AREA SATURDAY NIGHT AND SUNDAY
INTO MONDAY AS THE CLOSED UPPER LOW APPROACHES THE PANHANDLES. DRIER
CONDITIONS EXPECTED BY MONDAY NIGHT THROUGH THE MIDDLE AND END OF
NEXT WEEK AS AN UPPER RIDGE BUILDS IN FROM THE WEST. NEXT OPPORTUNITY
FOR CONVECTION MAY COME BY LATE FRIDAY INTO NEXT WEEKEND AS ANOTHER
CLOSED UPPER LOW TRACKS TO NEAR THE FOUR CORNERS REGION AND THEN INTO
THE CENTRAL ROCKIES. NEAR OR SLIGHTLY ABOVE NORMAL CONDITIONS TODAY
THROUGH FRIDAY...AND THEN BELOW NORMAL TEMPS THIS WEEKEND THROUGH
MOST OF NEXT WEEK. ANOTHER REINFORCING SURGE OF MUCH COOLER AIR
EXPECTED SATURDAY NIGHT AND THEN BY LATE MONDAY OR MONDAY NIGHT.

SCHNEIDER

&&

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

&&

$$

17/16



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