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000
FXUS64 KAMA 231158 AAA
AFDAMA

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE AMARILLO TX
658 AM CDT THU MAY 23 2013

.AVIATION...
FOR THE 12Z TAFS...A RATHER COMPLICATED AND LOW CONFIDENCE FCST NEXT
24 HOURS. A STATIONARY FRONT IS EXPECTED TO BE DRAPED ACROSS THE SRN
TX PNHDL THIS AFTERNOON. THE GREATEST THREAT FOR TSTMS SHOULD BE
ALONG AND SOUTH OF THE FRONT... AND HAVE INCLUDED VCTS AT KAMA FOR
LATE THIS AFTERNOON INTO THE EVENING HOURS. OMITTED MENTION OF TSTMS
AT KGUY AND KDHT AS THE CHANCE WILL BE LESS ACROSS NRN TX AND OK
PNHDLS. SEVERE STORM THREAT SHOULD ALSO BE HIGHEST IN SRN TX PNHDL
LATE THIS AFTERNOON AND EVENING. LOW CLOUD POTENTIAL WILL ALSO
INCREASE AT ALL TAF SITES LATER TONIGHT AND HAVE INCLUDED MVFR CIGS
AT ALL TERMINAL SITES FOR THIS ISSUANCE. IFR CIGS CERTAINLY A PSBLTY
DEPENDING ON DEPTH OF LOW LEVEL MOISTURE AND PRECIP AMOUNTS...AND
WILL DEFER THAT CONSIDERATION TO LATER SHIFTS.

ANDRADE

&&

.PREV DISCUSSION... /ISSUED 419 AM CDT THU MAY 23 2013/

SHORT TERM...
FOR ONCE FORECAST FOCUS IS ON PRECIPITATION CHANCES FOR NEARLY ALL OF
THE SHORT TERM.

TODAY...NOT MANY CHANGES IN THE EXPECTED PATTERN TODAY. COLD FRONT
HAS NEARLY ENTERED THE OK PANHANDLE. THE EXACT LOCATION WHERE THE
FRONT WILL STALL REMAINS A BIT UNCERTAIN WITH THE LATEST NAM SHOWING
THE FRONT MOVE ALL THE WAY THROUGH THE TX PANHANDLE BY OR JUST AFTER
00Z. FOR NOW THOUGH...WILL CONTINUE WITH THE SOLUTION THAT IT WILL
STALL NEAR DALHART...JUST NORTH OF AMARILLO...AND NEAR
CLARENDON..SINCE THIS HAS HAD THE MOST RUN TO RUN CONSISTENCY.
ANOTHER INGREDIENT THAT WE ARE STILL WAITING ON IS LOW LEVEL
MOISTURE. MODELS CONTINUE TO SHOW DEW POINT TEMPS BY 18Z IN THE MID
60S. HOWEVER...AT THIS HOUR...DEW POINTS RANGE FROM THE MID 30S TO
LOWER 50S ACROSS THE REGION. FEEL RELATIVELY CONFIDENT THAT MOISTURE
ADVECTION WILL OCCUR AS ADVERTISED WITH THE PERSISTENT LOW LEVEL
SOUTHEASTERLY AND EASTERLY FLOW. AND ONE MORE THING WE WILL BE
WATCHING IS THAT A HIGH AMPLITUDE UPPER LEVEL RIDGE REMAINS IN PLACE
OVER THE REGION. MODELS HAVE BEEN CONSISTENT IN SHOWING A SHORT WAVE
TROUGH HELPING TO BREAK DOWN THE RIDGE...AT LEAST IN THE SOUTHERN
HIGH PLAINS...AND PROVIDING THE UPPER LEVEL SUPPORT FOR CONVECTIVE
INITIATION. HAVING SAID ALL THAT...STILL THINK THE INGREDIENTS WILL
COME TOGETHER FOR A SEVERE STORM THREAT BY 21 TO 00Z. AS FOR WHAT
HAZARDS WE ARE CONCERNED WITH:

HAIL AND STRONG WINDS...WITH OUT A DOUBT THIS REMAINS THE BIGGEST
THREAT. EXPECT CAPE VALUES TO BE QUITE LARGE...BY SOME MODELS THERE ARE
ML CAPE VALUES APPROACHING 3000 J/KG. BULK SHEAR VALUES WILL BE MORE
THAN ADEQUATE...GENERALLY 25 TO 35 KT...THOUGH ALONG THE NM/TX STATE
LINE SHEAR VALUES COULD BE OVER 50KT. AS A RESULT...EXPECT PERSISTENT
UPDRAFTS. THE MAIN PERIOD FOR THIS THREAT WILL BE FROM SHORTLY AFTER
THE STORMS DEVELOP...3 OR 4 PM CDT...THROUGH ABOUT 10 PM AS CAPE
VALUES DECREASE AND STORMS BECOME ELEVATED.

FLASH FLOODING...BECOMING MORE CONCERNED WITH THE FLASH FLOOD THREAT
ESPECIALLY IN THE SOUTHERN AND SOUTH EASTERN TEXAS PANHANDLE. AS
MENTIONED IN A PREVIOUS DISCUSSION...ANY STORMS THAT DEVELOP WILL BE
VERY INEFFICIENT RAIN PRODUCERS. HOWEVER...MODEL PRECIPITABLE WATER
VALUES ARE 2 STANDARD DEVIATIONS ABOVE NORMAL. IN ADDITION...MODELS
HAVE BEEN CONSISTENT ON SHOWING STORM MOTIONS OF RIGHT MOVING
SUPERCELLS IN THE SOUTHERN TX PANHANDLE TO BE BETWEEN 0 AND 8KT. ALSO
IF ANY CONVECTIVE COMPLEXES TRAIN ALONG OR BACK BUILD ON THE
FRONT...SOME LOCATIONS COULD SEE LONG DURATION RAINFALL. THESE
FACTORS SHOULD BE ENOUGH TO COUNTERACT THE ISSUE OF INEFFICIENCY. HAVING
SAID ALL THAT HOWEVER...IT SHOULD BE NOTED THAT IF STORMS ARE
PRIMARILY LEFT MOVING SUPERCELLS OR COMPLEXES THAT MOVE WITH THE MEAN
FLOW...STORM MOTIONS SHOULD BE FAST ENOUGH TO GENERALLY MITIGATE THE
FLASH FLOODING CONCERN.

TORNADOES...AS MENTIONED IN A PREVIOUS DISCUSSION THE THREAT PERIOD
FOR THIS WILL BE RATHER BRIEF...AND SHOULD BE PRIMARILY IN THE
VICINITY OF THE FRONT. THE MAIN LIMITING FACTOR FOR THIS THREAT WILL
BE THE LCLS. THE SHORT RANGE MODELS SHOW ONLY A BRIEF
PERIOD...CENTERED AROUND 00Z WHEN THE LCLS WILL BE BELOW 2000 FT AGL.
SO WILL CONTINUE WITH THE PREVIOUS THINKING THAT THE THREAT FOR THIS
SHOULD BE LIMITED TO BETWEEN 5 AND 8 PM CDT.

LATE TONIGHT AND TOMORROW...A LOW LEVEL SOUTHERLY JET SHOULD DEVELOP
BY 06Z TONIGHT...BRINGING NEEDED MOISTURE RETURN. HOWEVER...HIGH
RESOLUTION MODELS SHOW A CONVECTIVE COMPLEX DEVELOPING FURTHER SOUTH.
IF THIS COMPLEX IS PERSISTENT ENOUGH...IT COULD LIMIT THE MOISTURE
RETURN...LIMITING HOW LATE THE CONVECTION WOULD LAST. TOMORROW IS
ALSO RATHER CONDITIONAL. THE MAIN LIMITING FACTOR COULD BE LOW CLOUDS
THAT DEVELOP TONIGHT. DEPENDING ON HOW LONG THESE LOW CLOUDS
PERSIST...THIS COULD LIMIT HEATING...AND THUS CONVECTIVE
INITIATION. HOWEVER...IF STORMS DEVELOP...THERE DOES APPEAR TO BE AT
LEAST SOME SEVERE THREAT.

LONG TERM...
BEYOND FRIDAY...IT LOOKS LIKE THE REGION WILL STAY IN AN UPPER LEVEL
SOUTHWESTERLY FLOW PATTERN...WITH A SERIES OF SHORT WAVE
TROUGHS...AND A PERSISTENT DRY LINE PROVIDING MULTIPLE OPPORTUNITIES
FOR THUNDERSTORMS. HOW LONG THIS PATTERN HOLDS IS DEPENDENT ON HOW
QUICKLY A BROAD UPPER LEVEL TROUGH WILL DIG SOUTHEAST...AND THAT IS
RATHER UNCERTAIN. GIVEN THE AMPLITUDE OF THE RIDGE TO OUR
EAST...FORECAST FAVORS THE SLOWER ECMWF SOLUTION OVER THE GFS. THE
MOST SIGNIFICANT PART OF THIS SOLUTION IS THAT FOR MUCH OF NEXT
WEEK...THE UPPER LEVEL PATTERN WILL BE VERY MERIDIONAL...WHICH SHOULD
MEAN THE DRY LINE ISN/T LIKELY TO MOVE OUT OF THE AREA ANY TIME SOON.
FOR NOW...HAVE INCLUDED POPS IN MONDAY AND TUESDAY AFTERNOON AND
EVENING HOURS. BUT IF THE PATTERN IS AS THE ECMWF SHOWS...POPS MAY
NEED TO BE ADDED FOR WEDNESDAY AND THURSDAY AS WELL.

JOHNSON

FIRE WEATHER...
RELATIVELY HIGH ATMOSPHERIC MOISTURE FOR THE NEXT SEVERAL DAYS WILL
PRECLUDE ANY ELEVATED OR CRITICAL FIRE WEATHER CONCERNS.

JOHNSON

&&

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

&&

$$