Area Forecast Discussion
Issued by NWS Amarillo, TX

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS64 KAMA 280356
AFDAMA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE AMARILLO TX
1056 PM CDT WED APR 27 2016

.AVIATION...
VFR CONDITIONS EXPECTED TO CONTINUE THROUGH THIS TAF CYCLE. THE MAIN
AVIATION CONCERNS WILL BE WITH THE POSSIBILITY OF LOW LEVEL WIND
SHEAR...GUSTY WINDS...AND CONVECTION. LIGHT WINDS OVERNIGHT WITH AN
INCREASING LOW LEVEL JET NEAR THE KAMA TERMINAL COULD LEAD TO A
WINDOW OF LOW LEVEL WIND SHEAR UNTIL WINDS INCREASE AROUND DAYBREAK.
KDHT WILL BE ON THE PERIPHERY OF THE UPPER JET SO LOW LEVEL WIND
SHEAR CONCERNS ARE TO LOW TO MENTION IN PREVAILING.

WINDS WILL COME UP TOMORROW AROUND DAYBREAK AND WILL STAY UP THROUGH
THE DAYLIGHT HOURS. THE HIGHEST GUSTS LOOK TO TOP OUT AROUND 30KT
FROM A EAST-SOUTHEAST. TOMORROW EVENING WILL SEE THE CHANCE FOR
CONVECTION NEAR THE TERMINALS. THERE REMAINS SOME UNCERTAINTY ON THE
TIMING FOR KAMA AND KDHT BUT CONFIDENCE OF OCCURRENCE IS HIGH ENOUGH
TO INSERT VICINITY WORDING FOR KGUY.

&&

.PREV DISCUSSION... /ISSUED 358 PM CDT WED APR 27 2016/

DISCUSSION...
THE CLOSED MID-UPPER LOW CONTINUES MOVING TO THE NORTHEAST WHILE WEAK
RIDGING BUILDS IN OVER OUR REGION. THIS WILL ALLOW FOR MOSTLY CLEAR
SKIES AND CALMER WINDS UNTIL ANOTHER UPPER LEVEL LOW APPROACHES FROM
THE WEST AND BRINGS MID TO UPPER LEVEL CLOUDS OVERNIGHT.

SURFACE PRESSURES WILL FALL TO OUR WEST TOMORROW IN RESPONSE TO THE
APPROACHING UPPER LOW...AND WINDS WILL STRENGTHEN FROM THE SOUTHEAST.
MODELS HAVE STRUGGLED WITH KEY SURFACE FEATURES SUCH AS THE PLACEMENT
AND STRENGTH OF FRONT THAT WILL MOVE THROUGH TONIGHT...AND RESULTANT
SURFACE WINDS IN ITS WAKE...AND ALSO THE MAGNITUDE OF MOISTURE
RETURN. THE NAM REMAINS THE MOST AGGRESSIVE WITH LOW LEVEL MOISTURE
RETURN ALTHOUGH THE 12Z GFS HAS TRENDED TOWARD THE NAM WITH STRONGER
6 HOUR SURFACE PRESSURE FALLS OF 8-10 MB ACROSS NORTHEAST NEW MEXICO
AND THE WESTERN PORTION OF OUR AREA. 12Z GFS HAS A LOW-LEVEL THETA-E
AXIS EXTENDING NORTHWEST INTO OUR AREA SIMILAR TO THE NAM NOW ALBEIT
SLIGHTLY SOUTH OF WHERE THE NAM SHOWS. THE MAIN CONTRIBUTER IS
AGGRESSIVE RETURN ON SOUTHEASTERLY WINDS OF 55-60 DEGREE DEW POINTS
THROUGH THE AFTERNOON AND ESPECIALLY BY EVENING. LOW LEVEL MOISTENING
AND AFTERNOON HEATING CONTRIBUTE TO MODERATE INSTABILITY IN THE NAM
BY AFTERNOON WHICH MAY BE OVERDONE. DEW POINTS IN THE NAM SEEM
EXAGGERATED AND OUR GRIDS CURRENTLY REPRESENT A COMPROMISE BETWEEN
THE MORE TEMPERED GFS/ECMWF AND THE NAM. THIS SEEMS TO BE A MORE
REALISTIC FORECAST AND WOULD STILL CONTRIBUTE TO DECENT INSTABILITY
DURING THE AFTERNOON. MOST OF THE CAMS INCLUDING SPC CAM ENSEMBLE
SUPPORTS THIS CONCEPT AND GENERATES ISO/SCT CONVECTION ACROSS MAINLY
THE EASTERN PANHANDLES BY 21Z. IF THUNDERSTORMS FORM THEY COULD BE
SEVERE. LOW LEVEL DIRECTIONAL SHEAR AND INCREASING DEEP/EFFECTIVE
SHEAR WOULD SUPPORT ORGANIZED STORMS AND SUPERCELL POTENTIAL WITH
PRIMARILY A LARGE HAIL AND DAMAGING WIND THREAT. A TORNADO OR TWO
WOULD BE POSSIBLE ESPECIALLY WITH AS MUCH MOISTURE AS THE NAM DEPICTS
(LCL HEIGHTS AROUND 1KM). A MORE SIGNIFICANT THREAT WOULD BE LIMITED
BY FAIRLY WEAK SPEED SHEAR IN THE LOW LEVELS.

THE AFOREMENTIONED SURFACE FRONT SHOULD BECOME DIFFUSE BY THEN. THE
06Z RUN OF THE GFS WAS MUCH MORE PRONOUNCED WITH THIS FEATURE AND
FURTHER SOUTH RESTRICTING MOISTURE RETURN INTO THE PANHANDLES AS WAS
PREVIOUSLY MENTIONED ABOVE. IN ALL MODELS SOME SEMBLANCE OF THIS
BOUNDARY REMAINS IN THE FORM OF A NORTHWARD MOVING WARM FRONT ON THE
NORTHERN EDGE OF THE LOW-LEVEL THETA-E AXIS. PLACEMENT OF THIS
FEATURE WILL BE CRITICAL FOR SPATIAL DETAILS ON CONVECTION THAT MAY
FORM LATE TOMORROW AFTERNOON...AND WHERE THE MOST WIDESPREAD
CONVECTION OCCURS OVERNIGHT. CURRENT THINKING IS THE THREAT TOMORROW
AFTERNOON WILL BE LATE AND STILL QUITE CONDITIONAL. WEAK FORCING FROM
APPROACHING UPPER LOW WILL BE PRESENT AND PROBABLY SUFFICIENT FOR AT
LEAST ISOLATED LATE DAY CONVECTION IF MOISTURE AND INSTABILITY
INCREASE ENOUGH BUT BETTER CHANCES WILL EXIST OVERNIGHT. CURRENT
THINKING IS THAT DURING THE EVENING CONVECTION WILL INCREASE MARKEDLY
AS ISENTROPIC ASCENT AND SATURATION OCCURS ON 300-305K SURFACES.
MODELS AGREE ON THE MAGNITUDE OF ISENTROPIC ASCENT SUPPORTING HIGH
PRECIPITATION PROBABILITIES BUT SPATIAL DETAILS REMAIN UNCERTAIN
BASED ON THE POSITION OF THE WARM FRONT. THE HIGHEST PROBABILITIES
WERE PLACED ACROSS THE NORTHERN TEXAS PANHANDLE AND THE OKLAHOMA
PANHANDLE TOMORROW NIGHT THROUGH EARLY FRIDAY AND TAPERED TO CHANCE
PROBABILITIES IN THE SOUTHWEST SINCE THAT PORTION OF THE AREA IS MOST
LIKELY TO BE SOUTH OF THE WARM FRONT. GLANCING AT THE 18Z NAM
SUGGESTS THE MORE WIDESPREAD THREAT MAY BE FURTHER NORTH INTO KANSAS.

FORECAST SOUNDINGS SUGGEST ELEVATED INSTABILITY WILL BE PRESENT ABOVE
AN INCREASINGLY STABLE BOUNDARY LAYER. 1000-1500 J/KG MUCAPE NORTH OF
THE WARM FRONT AND INCREASING DEEP LAYER SHEAR (40-50 KNOTS) AS MID-
LEVEL SPEED MAX MOVES OVER THE REGION WOULD SUPPORT A MARGINALLY
SEVERE HAIL THREAT WITH THUNDERSTORMS OVERNIGHT.

THERE IS SOME UNCERTAINTY IN HOW LONG CONVECTIVE CHANCES WILL LAST ON
FRIDAY AS THE MODELS APPEAR TO BE A LITTLE AGGRESSIVE WITH MIXING
THE DRYLINE EAST ACROSS THE SOUTHERN PANHANDLES. MUCH LOWER
PROBABILITIES OF THUNDERSTORMS THIS WEEKEND...UNTIL BETTER CHANCES
RETURN EARLY NEXT WEEK WITH THE ARRIVAL OF THE NEXT SYSTEM. MONDAYS
HIGH TEMPERATURES WERE LOWERED DUE TO EXPECTED PRECIPITATION AND
CLOUD COVER. MODELS DISAGREE ON THE PATTERNS LEADING INTO THE MID
WEEK TIME FRAME...AND THEREFORE UNCERTAINTY IS HIGH.

FIRE WEATHER...
NEITHER ELEVATED NOR CRITICAL FIRE WEATHER CONDITIONS ARE EXPECTED
FOR THE OKLAHOMA AND TEXAS PANHANDLES TONIGHT. ON THURSDAY...BREEZY WINDS
AND LOWER RELATIVE HUMIDITY VALUES NEAR OR BELOW 20 PERCENT COULD
LEAD TO ELEVATED FIRE WEATHER IN THE SOUTHWESTERN PORTIONS OF THE
TEXAS PANHANDLE. NO ELEVATED OR CRITICAL FIRE WEATHER CONDITIONS ARE
EXPECTED ON FRIDAY.

PRELIMINARY POINT TEMPS/POPS...
AMARILLO TX                45  79  51  73  41 /   0  10  60  20  10
BEAVER OK                  41  70  50  59  41 /   0  10  80  70  40
BOISE CITY OK              39  66  46  53  36 /   0  10  80  60  20
BORGER TX                  47  77  54  70  41 /   0  20  60  40  10
BOYS RANCH TX              46  81  49  70  40 /   0  10  30  20  10
CANYON TX                  44  81  50  74  41 /   0  10  50  20  10
CLARENDON TX               47  80  56  78  45 /   0  20  70  40  10
DALHART TX                 42  75  49  63  37 /   0  10  40  30  20
GUYMON OK                  42  70  50  57  38 /   0  20  80  60  30
HEREFORD TX                44  82  49  73  41 /   0  10  40  10   5
LIPSCOMB TX                43  72  55  70  42 /   0  20  80  70  40
PAMPA TX                   46  76  53  74  42 /   0  20  70  40  20
SHAMROCK TX                47  78  58  81  46 /   0  20  70  60  30
WELLINGTON TX              49  82  60  84  48 /   0  20  70  50  30

&&

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

&&

$$

14/3


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.