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000
FXUS64 KAMA 130439 AAB
AFDAMA

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE AMARILLO TX
1139 PM CDT SUN MAY 12 2013

.AVIATION...
FOR THE 06Z TAFS...HIGH CONFIDENCE THAT VFR CONDITIONS WILL CONTINUE
THROUGH THE TAF PERIOD WITH ONLY FEW TO SCT HIGH CIRRUS CLOUDS. THERE
IS A SMALL RISK OF LOW LEVEL WIND SHEAR AT KAMA THROUGH 12Z. BASED ON
DATA FROM THE SODAR NEAR HRX...A LOW LEVEL SOUTHERLY JET HAS
DEVELOPED ABOUT 500 TO 700 FT AGL...WITH A MAX WIND SPEED AROUND
40KT. THIS LOW LEVEL JET SHOULD CONTINUE OVER THE SOUTHERN TX
PANHANDLE ONLY THROUGH THE OVERNIGHT HOURS...WEAKENING WITH MIXING
NEAR SUNRISE. SINCE WINDS AT KAMA SHOULD STAY NEAR 10KT...SHEAR
VALUES WILL BE JUST BELOW THRESHOLDS...SO WILL NOT MENTION IN THE
TAFS FOR NOW BUT WILL CONTINUE TO MONITOR. A LOW LEVEL TROUGH WILL
KEEP THE JET STREAK SOUTH OF KDHT AND KGUY.

JOHNSON
&&

.PREV DISCUSSION... /ISSUED 625 PM CDT SUN MAY 12 2013/

AVIATION...
FOR THE 00Z TAFS...THERE IS HIGH CONFIDENCE THAT VFR CONDITIONS WILL
CONTINUE THROUGH THE TAF PERIOD. WHAT FEW SHRA ARE OUT THERE NOW
SHOULD DISSIPATE BY 00Z OR SHORTLY THEREAFTER. THUS...HAVE NOT
INCLUDED ANY MENTION IN THE TAFS. COULD SEE A FEW WIND
SHIFTS...ESPECIALLY AT KGUY WHICH SHOULD SEE VRB WINDS THROUGH
OVERNIGHT HOURS UNTIL THE WINDS BECOME SOUTHWESTERLY TOWARDS SUNRISE.

JOHNSON

PREV DISCUSSION... /ISSUED 332 PM CDT SUN MAY 12 2013/

DISCUSSION...
AFTERNOON WATER VAPOR SATELLITE IMAGERY AND UPPER AIR ANALYSIS SHOWS
A CUTOFF UPPER LOW OVER WESTERN MEXICO. THIS LOW WILL MAKE LITTLE
PROGRESS TO THE EAST OVER THE NEXT 24-36 HOURS AND IN FACT WILL
RETROGRADE A LITTLE MONDAY. AN UPPER-LEVEL RIDGE OVER THE GREAT
BASIN WILL SLIDE OVER THE SOUTHERN PLAINS MONDAY...LEADING TO WARMER
TEMPS AND THE CONTINUATION OF DRY WX. A SURFACE TROUGH NEAR THE
NORTHWESTERN PORTION OF THE PANHANDLES WILL SHIFT FURTHER TO THE
SOUTH THIS EVENING. HIGH-RES MODELS AND SOME OF THE NWP MODELS
INDICATE ISOLATED SHOWERS AND THUNDERSTORMS FORMING NEAR THIS
TROUGH AND SLIDING SOUTHWARD DURING THE EVENING. LATEST DOPPLER
RADAR REFLECTIVITY SHOWS ISOLATED SHOWERS ALONG AND NORTH OF A
HOOKER TO STRATFORD TO DALHART LINE. HOWEVER THESE SHOWERS
ARE STRUGGLING TO MAINTAIN THEIR STRENGTH AS THEY MOVE TO THE
SOUTH...GIVEN THE DRY AIR AT THE SURFACE. SINCE COVERAGE OF ANY
STORMS WILL BE VERY ISOLATED HAVE OPTED TO MAINTAIN A DRY FORECAST
TONIGHT AND LET THE INCOMING SHIFT COVER THIS WITH SHORT TERM
FORECASTS. IF ANY STORMS DO DEVELOP THIS EVENING...EXPECT THEM TO BE
HIGH BASED...OR VIRGA SHOWERS...AS FORECAST SOUNDINGS INDICATE
INVERTED-V PROFILES. CERTAINLY NOT EXPECTING SEVERE WEATHER ALTHOUGH
GUSTY WINDS AND HAIL ARE POSSIBLE PER SPC SWODY1. ANY STORMS SHOULD
QUICKLY DIE AFTER SUNSET DUE TO THE LOSS OF DIURNAL HEATING.

THE UPPER LOW WILL FINALLY EJECT TO THE NORTHEAST AND MOVE ACROSS
WEST TX TUESDAY. AHEAD OF THIS SYSTEM...CYCLOGENESIS WILL TAKE PLACE
OVER THE LEE OF THE ROCKIES...PROMOTING BREEZY SOUTHWEST LOW-LEVEL
FLOW. LOW-LEVEL MOISTURE WILL BE SLOW TO RETURN GIVEN THE
DOWNSLOPING EFFECTS AND WITH THE BULK OF THE UPPER LIFT ASSOCIATED
WITH THIS SYSTEM STAYING TO OUR SOUTH...HAVE KEPT A DRY FORECAST
GOING. A WEAK COLD FRONT WILL PUSH INTO THE AREA WEDNESDAY BUT ONLY
A REFLECTION IN THE WIND FIELD IS EXPECTED TO ACCOMPANY THIS FRONTAL
PASSAGE. IN FACT THE PANHANDLES WILL REMAIN IN ITS TYPICAL POSITION
OF BEING IN BETWEEN TWO AREAS OF PRECIP WITH STORMS IN OK AND
CONVECTION OVER THE HIGHER TERRAIN TO THE NORTHWEST.
THE NAM/SREF DO SPREAD SOME QPF ACROSS OUR AREA...KEYING IN ON THE
CONVECTION MOVING OFF THE HIGHER TERRAIN ON NORTHWEST FLOW ALOFT.
BUT GIVEN THAT THE MAJORITY OF THE NWP MODELS DO NOT SHOW THIS
SOLUTION WILL KEEP THE FORECAST DRY.

HAVE NOT MADE TOO MANY CHANGES TO THE REMAINDER OF THE EXTENDED
PERIOD WITH AN UPPER-LEVEL RIDGE OVER THE REGION AND SOUTHWEST FLOW
ALOFT. A DRYLINE IS EXPECTED TO MIX EAST OF THE AREA ALTHOUGH THE
LOCATION /IE IF THIS DRYLINE WILL PUSH ALL THE WAY INTO WESTERN OK/
IS UNCERTAIN. SO THE FORECAST REMAINS DRY AS CONFIDENCE IN ANY
STORM DEVELOPMENT OVER THE EASTERN ZONES IS FAR TOO LOW TO MENTION.
RISING HEIGHTS ASSOCIATED WITH THIS RIDGE WILL LEAD TO WARMER
TEMPS...WITH UPPER 80S TO LOWER 90S BY THE END OF THE WEEK.

CLK

FIRE WEATHER...
MINIMUM RELATIVE HUMIDITY VALUES ARE EXPECTED TO BE BETWEEN 10 TO 15
PERCENT ACROSS THE TX/OK PANHANDLES MONDAY. DESPITE THESE LOW
RELATIVE HUMIDITY VALUES...20 FOOT WINDS ARE EXPECTED TO BE UNDER
15 MPH AND THEREFORE SHOULD PRECLUDE ELEVATED AND CRITICAL FIRE
WEATHER CONDITIONS. ELEVATED FIRE WEATHER CONDITIONS ARE POSSIBLE
TUESDAY OVER THE WESTERN AND CENTRAL TX/OK PANHANDLES DUE TO BREEZY
SOUTHWEST 20 FOOT WINDS AND RELATIVE HUMIDITY VALUES FALLING ONCE
AGAIN TO BETWEEN 10 TO 15 PERCENT /RELATIVE HUMIDITY VALUES ABOVE 20
PERCENT ACROSS THE EASTERN PANHANDLES WILL PRECLUDE ELEVATED FIRE
WEATHER CONDITIONS IN THIS AREA/. NEITHER ELEVATED OR CRITICAL FIRE
WEATHER CONDITIONS ARE EXPECTED BEYOND TUESDAY DESPITE MINIMUM
RELATIVE HUMIDITY VALUES FALLING BELOW 20 PERCENT MOST DAYS SINCE 20
FOOT WINDS ARE EXPECTED TO STAY BELOW 20 MPH. THE CHANCE FOR
WETTING RAINS IS PRETTY SLIM THROUGH THE PERIOD.

CLK

&&

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

&&

$$

16/02