Area Forecast Discussion
Issued by NWS Amarillo, TX

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000
FXUS64 KAMA 180347
AFDAMA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE AMARILLO TX
1047 PM CDT SUN MAY 17 2015

.AVIATION...
VFR CONDITIONS EXPECTED FOR THE FIRST 18 HOURS WITH INCREASING LOW
CLOUDS AND CONVECTION POSSIBLE IN THE FINAL 6 HOURS. COLD FRONT
TIMING REMAINS UNCHANGED FROM THE PREVIOUS ISSUANCE...BETWEEN 08Z AND
13Z MONDAY. AFTER 00Z TUESDAY FORECAST CONFIDENCE GREATLY DECREASES.
CONVECTION SHOULD START SOUTHWEST OF THE PANHANDLES AND SPREAD
NORTHEASTWARD WITH TIME. THIS WILL GIVE KAMA AND KDHT BETTER CHANCES
TO BE IMPACTED DURING THIS TAF ISSUANCE. CONFIDENCE IS MODERATE THAT
CONVECTION SHOULD IMPACT THE TERMINALS BETWEEN 03Z AND 12Z TUESDAY.
HAVE STARTED A DECLINING TREND OF CEILING BASES AND VISIBILITIES
GIVEN THERE IS SOME UNCERTAINTY AS TO WHEN CONVECTION WILL IMPACT THE
TERMINALS DIRECTLY.

&&

.PREV DISCUSSION... /ISSUED 604 PM CDT SUN MAY 17 2015/

AVIATION...
VFR CONDITIONS TO PREVAIL FOR THE NEXT 24 HOURS AT ALL TERMINALS. A
COLD FRONT WILL BRING A WIND SHIFT TO EACH TERMINAL BETWEEN 08Z AND
13Z MONDAY. WINDS WILL SLOWLY SHIFT BACK TOWARDS THE EAST BY THE END
OF THIS TAF ISSUANCE.

PREV DISCUSSION... /ISSUED 427 PM CDT SUN MAY 17 2015/

DISCUSSION...

AN ACTIVE PATTERN IS EXPECTED TO CONTINUE THROUGH THE FORECAST
PERIOD. NO SIGNIFICANT CHANCES WERE NEEDED TO THE PREVIOUS FORECAST.

IN THE SHORT TERM A WEAK COLD FRONT WILL MOVE INTO THE NORTHERN
PORTION OF THE AREA DURING THE EARLY MORNING. LITTLE IMPACT IS EXPECTED.
WINDS WILL SHIFT TO THE NORTHEAST AND INCREASE. SLIGHTLY COOLER
TEMPERATURES WILL ARRIVE BEHIND THE FRONT RESULTING IN TEMPERATURES
TOMORROW BEING A FEW DEGREES COOLER OVER THE NORTHERN COUNTIES. THIS
BOUNDARY WILL BECOME DIFFUSE DURING THE DAY AND WINDS WILL VEER
AROUND TO SOUTHEASTERLY AT MOST LOCATIONS AS LEE SURFACE TROUGH
STRENGTHENS IN RESPONSE TO THE NEXT UPPER LEVEL SYSTEM APPROACHING
FROM THE WEST. THIS WILL START THE NORTHWESTWARD MOVEMENT OF LOW
LEVEL MOISTURE CURRENTLY IN CENTRAL AND EASTERN TEXAS. LARGE SCALE
ASCENT AND MOISTURE ADVECTION SHOULD RESULT IN POTENTIAL FOR
WIDESPREAD PRECIPITATION MONDAY NIGHT INTO TUESDAY ACROSS THE AREA.
TRIED TO CONVEY SOME TEMPORAL DETAIL ALTHOUGH UNCERTAINTY STILL
EXISTS. THE STRONGEST PERIOD OF ISENTROPIC LIFT AND SATURATION
THROUGH A DEEP LAYER OCCURS FROM LATE EVENING IN THE SOUTHWEST
THROUGH EARLY MORNING IN THE EAST. THEREAFTER UNRESOLVED DETAILS ON
THE MESOSCALE WILL BE KEY IN HOW THINGS EVOLVED DURING THE DAY
TUESDAY JUST AS WAS THE CASE THIS PAST SATURDAY. NAM IS MORE
AGGRESSIVE WITH DIURNAL DESTABILIZATION IN THE WAKE OF MORNING
CONVECTION AND SHOWS FAVORABLE THERMODYNAMIC PROFILES FOR ADDITIONAL
MORE ROBUST CONVECTION PERHAPS OF A SCATTERED NATURE BY AFTERNOON.
DEEP LAYER SHEAR AROUND 50 KNOTS AND BACKED LOW LEVEL WINDS WILL BE
MORE THAN SUFFICIENT FOR SUSTAINED STORMS AND A SEVERE THUNDERSTORM
POTENTIAL. THE FLOOD THREAT APPEARS LOW SIMILAR TO THE LAST SEVERAL
SYSTEMS. FOR THE 36 HOUR PERIOD WITH THE HIGHEST PRECIPITATION
PROBABILITIES IT APPEARS THAT RAINFALL AMOUNTS WILL GENERALLY RANGE
FROM AN INCH TO AN INCH AND A HALF ACROSS THE AREA.

RETAINED LOW PRECIPITATION PROBABILITIES WEDNESDAY AND THURSDAY
ALTHOUGH THIS PERIOD MAY BE DRIER THAN CURRENTLY INDICATED. NAM AND
ECMWF ARE MORE AGGRESSIVE WITH SOUTHWARD MOVEMENT OF COLD FRONT AND
COOLER/DRIER AIR MASS MOVING INTO THE AREA BEHIND IT COMPARED TO THE
WETTER GFS. WINDS BECOME SOUTHEASTERLY AND STRENGTHEN THURSDAY NIGHT AND
FRIDAY SIGNALING THE APPROACH OF YET ANOTHER SYSTEM. PRECIPITATION
PROBABILITIES ARE HIGHEST IN THE LONG TERM FROM THURSDAY NIGHT THROUGH
SATURDAY MORNING.

BRB

&&

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

&&

$$

14/99




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