Area Forecast Discussion
Issued by NWS Amarillo, TX

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000
FXUS64 KAMA 181039 AAA
AFDAMA

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE AMARILLO TX
539 AM CDT MON AUG 18 2014

.AVIATION...
AN OUTFLOW BOUNDARY WILL CONTINUE TO PUSH SOUTHWEST ACROSS THE
NORTHEAST TEXAS PANHANDLE AND THE WESTERN OKLAHOMA PANHANDLE. DO NOT
THINK THAT THIS BOUNDARY WILL MAKE IT TO DHT...SO SOUTHERLY WINDS
WILL PREVAIL THERE TODAY. EAST WINDS AT GUY WILL VEER AROUND TO THE
SOUTHEAST BEHIND THIS BOUNDARY BY MID DAY. AMA WILL HAVE SOUTHERLY
WINDS WHICH WILL GET GUSTY AT TIMES THIS AFTERNOON. WINDS WILL REMAIN
SOUTHERLY TONIGHT...BUT WILL BE AROUND 10 KNOTS OR LESS. SKIES WILL
REMAIN VFR.

&&

.PREV DISCUSSION... /ISSUED 436 AM CDT MON AUG 18 2014/

DISCUSSION...
TODAY-TONIGHT: A SHORTWAVE TROUGH PASSING TO OUR NORTHWEST AND A WEAK
COLD FRONT TRIGGERED SHOWERS AND THUNDERSTORMS ACROSS WESTERN AND
CENTRAL KANSAS EARLIER THIS MORNING. OUTFLOW ASSOCIATED WITH THIS
CONVECTION HAS CAUSED SHOWERS AND STORMS TO FORM ACROSS SOUTHWEST
KANSAS AND EVEN THE OKLAHOMA PANHANDLE. THESE SHOWERS AND STORMS ARE
EXPECTED TO DISSIPATE AND/OR PUSH INTO NORTHWEST OKLAHOMA BY SUNRISE.

FOR THIS AFTERNOON, 850 MB TEMPERATURES ARE FORECAST TO BE 1 TO 1.5 C
WARMER THAN YESTERDAY, SO HIGH TEMPERATURES SHOULD AVERAGE ABOUT 1 TO 3
DEGREES WARMER THAN YESTERDAY. THIS SHOULD PUT MOST PLACES IN THE MID
90S TO LOWER 100S. A FEW HIGH-BASED CUMULUS WILL DEVELOP AGAIN THIS
AFTERNOON, AND A FEW OF THESE COULD DEVELOP INTO ISOLATED
THUNDERSTORMS BETWEEN 3 PM AND 10 PM. THE HIGHEST CHANCES OF ANY
STORMS WILL LIKELY BE NORTH OF A DALHART TO LIPSCOMB LINE WITH THE
MOST LIKELY AREA TO BE NORTHWEST OF A DALHART TO ELKHART LINE. NO
SEVERE STORMS ARE EXPECTED AS MIXED LAYER CAPE VALUES WILL ONLY
INCREASE UP TO 1000 J/KG AND DEEP LAYER SHEAR WILL REMAIN VERY WEAK.
NONETHELESS, IT WON`T TAKE MUCH OF A CORE TO PRODUCE GUSTY WINDS UP
TO 50 MPH AS THE STORMS COLLAPSE DUE TO THE DRY SUB-CLOUD LAYER.
OVERNIGHT LOWS WILL DROP INTO THE LOWER 60S TO NEAR 70.

TUESDAY-TUESDAY NIGHT: IT`S HARD TO GET EXCITED ABOUT THUNDERSTORM
CHANCES WITH THE INFLUENCE OF THE UPPER RIDGE TO OUR SOUTHEAST AND
WARM MID-LEVEL TEMPERATURES. DESPITE THIS, WE MAY SEE A FEW SHOWERS
AND STORMS STRAY INTO THE NORTHWEST PANHANDLES DURING THE LATE
AFTERNOON AND EARLY EVENING, BUT CONFIDENCE OF OCCURRENCE IS NOT VERY
HIGH AS THE STEERING FLOW WILL BE LESS THAN 10 KT. WE MAY ALSO HAVE
TO WATCH THE FAR SOUTHEAST TEXAS PANHANDLE FOR AN ISOLATED SHOWER OR
STORM MOVING INTO THAT AREA DURING THE LATE AFTERNOON. MODEL GUIDANCE
IS SHOWING A WEAKNESS ALONG THE WESTERN PERIPHERY OF THE UPPER RIDGE,
LIKELY SOME SEMBLANCE OF A SHEAR AXIS. MOST OF THE CONVECTION WILL
STAY TO OUR SOUTH AND EAST, BUT IT`S SOMETHING TO WATCH. HIGHS WILL
TOP OUT IN THE LOWER 90S TO NEAR 100 AS UPPER HEIGHTS FALL AND 850 MB
TEMPERATURES COOL SLIGHTLY. ALTHOUGH IT SEEMS LIKE THE WIND ALWAYS
BLOWS AROUND HERE, IT WILL BE NOTICEABLE DURING THE AFTERNOON AS DEEP
SOUTHWESTERLY FLOW WILL PROMOTE A DEEPENING LEE SIDE SURFACE TROUGH.
EXPECT SOUTHERLY WINDS BETWEEN 15 AND 25 MPH WITH GUSTS UP TO 30 MPH.
THE SOUTHERLY WINDS WILL DIMINISH AFTER SUNSET, BUT THEY WILL STILL
REMAIN IN THE 10 TO 15 MPH RANGE OVERNIGHT, WHICH WILL KEEP LOW
TEMPERATURES A FEW DEGREES WARMER.

WEDNESDAY-FRIDAY NIGHT: THESE DAYS WILL BE A RINSE AND NEAR REPEAT
OF TUESDAY`S WEATHER EXCEPT FOR SLIGHTLY WARMER HIGH TEMPERATURES.
SOME LATE AFTERNOON AND EVENING STORMS COULD MOVE INTO THE FAR
WESTERN PANHANDLES EACH DAY, MAINLY WEST OF A LIBERAL TO HEREFORD
LINE, BUT THE VAST MAJORITY OF LOCATIONS WILL REMAIN HIGH AND DRY. A
MARGINALLY SEVERE STORM (THE PRIMARY HAZARD WILL BE WIND) OR TWO
CAN`T BE RULED OUT DURING THIS PERIOD, BUT BUOYANCY AND SHEAR WILL
REMAIN WEAK AND UNSUPPORTIVE OF ORGANIZED CONVECTION.

SATURDAY-SUNDAY NIGHT: THERE ARE STILL SOME DETAILS TO BE IRONED OUT,
BUT MODELS GENERALLY SHOW A BROAD UPPER RIDGE LOCATED OVER THE
SOUTHEAST U.S. AND AN UPPER TROUGH OVER THE PACIFIC NORTHWEST. THE
PANHANDLES WILL BE SANDWICHED BETWEEN THESE FEATURES. ANOTHER FEATURE
THAT MODELS ARE STRUGGLING TO HANDLE IS A CLOSED UPPER LOW THAT IS
FORECAST TO BECOME CUT-OFF ACROSS SOUTHERN CALIFORNIA. THE GFS
REMAINS FASTER WITH ITS EJECTION THAN THE ECMWF, BUT GIVEN THAT IT
WILL BE DISPLACED WELL AWAY FROM THE WESTERLIES, THE SLOWER ECMWF
SEEMS MORE PLAUSIBLE. THEREFORE, WE KEPT POPS OUT OF THE FORECAST FOR
SATURDAY. MORE UNCERTAINTY LURKS FOR SUNDAY AS THE ECMWF SHOWS A
COLD FRONT MOVING INTO THE AREA. IF THIS OCCURS, WE`LL BE LOOKING AT
INCREASED RAIN CHANCES SUNDAY AFTERNOON, BUT FORECAST CONFIDENCE
CONTINUES TO REMAIN LOW.

JACKSON

FIRE WEATHER...
RELATIVE HUMIDITIES ARE EXPECTED TO FALL BELOW 20 PERCENT ACROSS
PORTIONS OF THE PANHANDLES TODAY AND TUESDAY. 20-FOOT SOUTHERLY WINDS
BETWEEN 10 AND 20 MPH ARE EXPECTED BOTH DAYS, PARTICULARLY ON TUESDAY.
HOWEVER, NO ELEVATED OR CRITICAL FIRE WEATHER CONDITIONS ARE EXPECTED
DUE TO UNSUPPORTIVE FUELS. SOUTHERLY 20-FOOT WINDS WILL REMAIN
BETWEEN 10 AND 20 MPH WEDNESDAY THROUGH SATURDAY, BUT RELATIVE
HUMIDITIES ARE EXPECTED TO REMAIN ABOVE 20 PERCENT DURING THIS
PERIOD. THEREFORE, NO ELEVATED OR CRITICAL FIRE WEATHER CONDITIONS
ARE EXPECTED.

&&

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

&&

$$

15/13




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