Area Forecast Discussion
Issued by NWS Amarillo, TX

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421
FXUS64 KAMA 221739 AAB
AFDAMA

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE AMARILLO TX
1239 PM CDT FRI MAY 22 2015

.AVIATION...
IFR AND MVFR CEILINGS EXPECTED TO PREVAIL TODAY AND TONIGHT AS VERY
MOIST LOW-LEVEL FLOW CONTINUES.  EXCEPTION MAY BE KDHT...WHERE
SOUTHWEST LOW-LEVEL WINDS MAY BRING IN SLIGHTLY DRIER FOR A FEW HOURS
THIS AFTERNOON.  NEXT ITEM OF CONCERN WILL BE THUNDERSTORMS LATE
TONIGHT AND SATURDAY MORNING...AS STRONG MID- AND UPPER-LEVEL
DYNAMICS MOVES IN FROM THE SOUTHWEST.  ALL TERMINALS LIKELY TO BE
IMPACTED BY THUNDERSTORMS AFTER 06Z SATURDAY.

COCKRELL

&&

.PREV DISCUSSION... /ISSUED 613 AM CDT FRI MAY 22 2015/

AVIATION...
LOW CLOUDS AND CONVECTION WILL KEEP THE CONFIDENCE LEVEL LOW FOR THIS
TAF ISSUANCE. MOST CONVECTION THIS MORNING  SHOULD SAY AWAY FROM THE
TERMINALS MINUS SOME LIGHT OFF AND ON SHOWERS AT KAMA THROUGH 12Z.
THE MAIN AVIATION CONCERN IN THE SHORT TERM WILL BE THE IFR/LIFR
STRATUS THAT HAS BEEN MOVING INTO THE TERMINALS BEHIND THE SHOWERS.
THIS STATUS DECK SHOULD PERSIST AT THE TERMINALS UNTIL 15Z TO 17Z
BEFORE LIFTING TO MVFR. ENOUGH MIXING COULD ALLOW BRIEF VFR
CONDITIONS DURING THE DAY BUT SIDES WITH MVFR THROUGH THE MAJORITY OF
THE DAYLIGHT HOURS.

THE NEXT ROUND OF CONVECTION AND LOW CLOUDS IS EXPECTED LATE TONIGHT.
THIS CONVECTION WILL DEVELOP ACROSS EASTERN NEW MEXICO AND SPREAD
INTO THE PANHANDLES. AS A RESULT KDHT COULD SEE CONDITIONS DEGRADE
SOONER THAN KAMA AND KGUY. HAVE CONTINUED A LOWERING TREND BY
INTRODUCING IFR CEILINGS INTO PREVAILING AS WELL AS CONVECTION TO ALL
THREE TERMINALS.

PREV DISCUSSION... /ISSUED 458 AM CDT FRI MAY 22 2015/

DISCUSSION...
PRIMARY FOCUS OF THIS FORECAST REMAINS ON THUNDERSTORM CHANCES
THROUGH THE MEMORIAL DAY WEEKEND...AND THE ATTENDANT HEAVY RAIN AND
SEVERE WEATHER POTENTIAL.

THE LATEST ROUND OF RAIN CONTINUES TO MOVE EAST ACROSS THE PANHANDLES
EARLY THIS MORNING...BEING LARGELY FORCED BY A MID/UPPER-LEVEL
LEAD SHORTWAVE TROUGH EJECTING FROM A CLOSED UPPER LOW CURRENTLY
CENTERED ALONG THE SOCAL COAST. THE LOW-LEVEL RESPONSE TO THIS
SHORTWAVE TROUGH TRAVERSING THE AREA CAN BE SEEN IN A 30 KT SOUTHERLY
LLJ...ALONG WHICH LOW-LEVEL MOISTURE ADVECTION AND WAA/ISENTROPIC
LIFT HAS ALSO BEEN AIDING THE OVERNIGHT CONVECTION. MINIMAL
INSTABILITY HAS PRECLUDED ANY STRONG STORMS...BUT ANOTHER GOOD
SOAKING RAIN HAS RESULTED...ADDING MORE MOISTURE TO WHAT HAVE
RECENTLY BECOME QUITE SATURATED SOILS ACROSS MUCH OF THE PANHANDLES.

THIS CURRENT ROUND OF SHOWERS AND THUNDERSTORMS WILL CONTINUE TO
PROGRESS EAST ACROSS THE PANHANDLES THIS MORNING AS THE RESPONSIBLE
SHORTWAVE TROUGH LIFTS NORTHEAST ACROSS THE AREA INTO THE CENTRAL
PLAINS BY MIDDAY. IN WAKE OF THIS SHORTWAVE...SUBSIDENCE AND SUBTLE
HEIGHT RISES WILL BRING A LULL IN PRECIPITATION MUCH OF TODAY AND
THIS EVENING. CAN/T RULE OUT SOME SHOWER/ISOLATED THUNDERSTORM
ACTIVITY IN WAKE OF THIS PRIMARY BATCH OF RAIN...PRIMARILY ACROSS
THE SOUTHEAST HALF OF THE CWA WHERE WEAK ISENTROPIC LIFT LINGERS. BUT
OVERALL...MUCH OF TODAY WILL BRING A BREAK IN THE PRECIP. THE NEXT
ROUND OF THUNDERSTORMS WILL MOVE IN TONIGHT...MAINLY AFTER MIDNIGHT.
FLOW ALOFT WILL BECOME INCREASINGLY DIFFLUENT TONIGHT AHEAD OF THE
UPPER LOW MOVING INTO THE FOUR CORNERS REGION...WITH HEIGHT FALLS
ALSO OVERSPREADING EASTERN NM AND THE WESTERN PANHANDLES. DYNAMIC
FORCING WILL FURTHER INCREASE LATE TONIGHT INTO SATURDAY AS THE
PRIMARY SHORTWAVE EJECTS FROM THE BASE OF THE LOW...IMPINGING ON A
VERY MOIST AND INCREASINGLY UNSTABLE AIRMASS ACROSS THE AREA. A
SOUTHERLY LLJ WILL STRENGTHEN TO 40-50 KTS TONIGHT AHEAD OF THE
APPROACHING UPPER LOW...PROVIDING ROBUST LOW-LEVEL WARM AIR AND
MOISTURE ADVECTION. PWATS ARE PROGGED TO INCREASE TO 1 TO 1.5 INCHES
TONIGHT INTO SATURDAY...OR TO THE 99TH PERCENTILE OF CLIMATOLOGY.
GIVEN THE ANTICIPATED STRONG FORCING AND VERY MOIST AIRMASS...ALONG
WITH ALREADY SATURATED SOILS FROM THE RECENT REPEATED ROUNDS OF
RAIN...HAVE EXPANDED THE FLASH FLOOD WATCH FOR TONIGHT AND SATURDAY
TO COVER ROUGHLY THE SOUTHEAST HALF OF THE COMBINED PANHANDLES. THESE
AREAS HAVE SEEN THE HEAVIEST RAIN OVER THE PAST COUPLE OF WEEKS.

ALONG WITH THE HEAVY RAIN POTENTIAL...THE THREAT FOR SEVERE
CONVECTION WILL INCREASE LATE TONIGHT AS WELL. THE LOW-LEVEL
MOISTENING ALONG WITH STEEPENING LAPSE RATES ALOFT WILL LEAD TO
INCREASING INSTABILITY TONIGHT...WITH CAPES INCREASING TO AROUND 1500
J/KG TO GO ALONG WITH VEERING...DEEPLY-SHEARED WIND PROFILES
/EFFECTIVE BULK SHEAR AROUND 40 KTS/. ONE INTERESTING ASPECT TONIGHT
IS THAT FORECAST SOUNDINGS SHOW THE STRONG LOW-LEVEL WARM AIR AND
MOISTURE ADVECTION LARGELY OFFSETTING NOCTURNAL LOW-LEVEL
COOLING...RESULTING IN MINIMAL BOUNDARY LAYER CONVECTIVE INHIBITION
COMPARED TO WHAT IS OFTEN SEEN OVERNIGHT. THUS...THE POTENTIAL FOR
DAMAGING WINDS AND EVEN AN ISOLATED TORNADO APPEAR HIGHER THAN IS
OFTEN THE CASE WITH LATE NIGHT CONVECTION AS THE STORMS MAY BE MORE
SURFACE BASED GIVEN THE ABSENCE OF A STRONGLY STABLE BOUNDARY LAYER.
LARGE HAIL WILL STILL LIKELY BE THE PRIMARY SEVERE THREAT...BUT CAN/T
RULE OUT THESE OTHER HAZARDS DESPITE THE TIME OF DAY. CONVECTION
WILL CONTINUE TO WORK ITS WAY EAST ACROSS THE PANHANDLES SATURDAY
MORNING. AS HAS OFTEN BEEN THE CASE THIS SPRING...THIS EARLY DAY
CONVECTION WILL MAKE THE DETAILS OF WHAT WILL UNFOLD SATURDAY
AFTERNOON AND EVENING MURKY. PLENTY OF LOW-LEVEL MOISTURE LOOKS TO
STAY IN PLACE AND WITH THE UPPER LOW STILL POSITIONED NEAR THE FOUR
CORNERS...COULD CERTAINLY SEE SOME REDEVELOPMENT OF STORMS LATER IN
THE DAY. HOW WELL THE ATMOSPHERE RECOVERS AND THE DEGREE OF
INSTABILITY PRESENT DURING THE AFTERNOON/EVENING ARE THE MAIN
QUESTIONS AT THIS POINT...BUT SOME SEVERE THREAT IS EXPECTED WITH THE
CENTRAL AND EASTERN PANHANDLES CURRENTLY LOOKING MORE FAVORED FOR
THIS POSSIBLE ADDITIONAL DEVELOPMENT.

AS THE UPPER LOW LIFTS ACROSS THE CENTRAL ROCKIES SATURDAY NIGHT AND
SUNDAY...DRIER AIR IS EXPECTED TO ADVECT INTO THE WESTERN
PANHANDLES...SHIFTING THE BETTER THUNDERSTORM CHANCES TO THE EASTERN
HALF OF THE CWA WHERE MOISTURE/INSTABILITY/DEEP LAYER SHEAR WILL
CONTINUE TO SUPPORT THE POTENTIAL FOR SOME SEVERE STORMS.
THUNDERSTORM CHANCES APPEAR LESS ORGANIZED WITH LIKELY MUCH LESS
STORM COVERAGE BY MEMORIAL DAY. LOW-LEVEL MOISTURE REMAINS IN PLACE
AND SOME WEAKER UPPER FORCING IS STILL EVIDENT DURING THIS TIME...BUT
NOT OF THE MAGNITUDE EXPECTED OVER THE NEXT COUPLE OF DAYS.

LOW PRECIP CHANCES WILL LINGER INTO TUESDAY WITH THE POTENTIAL FOR
WEAK MID-LEVEL SHORTWAVE ENERGY RIPPLING THROUGH THE STILL SOMEWHAT
PERTURBED SOUTHERN STREAM DURING THIS TIME. PROSPECTS FOR MORE
ORGANIZED/WIDESPREAD CONVECTION MAY INCREASE ONCE AGAIN BY MID NEXT
WEEK AS ANOTHER UPPER TROUGH APPROACHES THE REGION. ALL IN ALL...THE
ACTIVE PATTERN LOOKS TO CONTINUE WITH THE BETTER CHANCES FOR MORE
ORGANIZED/WIDESPREAD CONVECTION COMING THROUGH THE WEEKEND AND
POSSIBLY AGAIN MID NEXT WEEK.

KB

&&

.AMA WATCHES/WARNINGS/ADVISORIES...
TX...FLASH FLOOD WATCH FROM LATE TONIGHT THROUGH LATE SATURDAY NIGHT
     FOR THE FOLLOWING ZONES: ARMSTRONG...CARSON...
     COLLINGSWORTH...DEAF SMITH...DONLEY...GRAY...HEMPHILL...
     HUTCHINSON...LIPSCOMB...OCHILTREE...OLDHAM...POTTER...
     RANDALL...ROBERTS...WHEELER.

OK...FLASH FLOOD WATCH FROM LATE TONIGHT THROUGH LATE SATURDAY NIGHT
     FOR THE FOLLOWING ZONES: BEAVER.


&&

$$

03/05





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