107 FXUS64 KLUB 151148 AFDLUB AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LUBBOCK TX 648 AM CDT SUN SEP 15 2013 .AVIATION... NO RISK OF FOG OR SUB-VFR CIGS THIS MORNING AS DRIER SOUTHERLY FLOW PREVAILS. INSTEAD THERE WILL BE PLENTY OF MID AND UPPER LEVEL CLOUDINESS TODAY INTO TONIGHT. IN ADDITION THERE IS A SLIM CHANCE OF AN ISOLATED SHOWER OR STORM THIS AFTERNOON...WITH CONVECTIVE CHANCES INCREASING TONIGHT AS A WEAK FRONT APPROACHES FROM THE NORTH. EITHER TERMINAL COULD EXPERIENCE A STORM TONIGHT...BUT IT APPEARS THE BETTER CHANCES WILL BE AT KCDS WHERE A PROB30 GROUP WAS INCLUDED FOR LATE THIS EVENING INTO EARLY MONDAY MORNING. OUTSIDE OF ANY THUNDERSTORMS VFR CONDITIONS WILL PREVAIL. && .PREV DISCUSSION... /ISSUED 353 AM CDT SUN SEP 15 2013/ SHORT TERM... THE END OF THE WEEKEND WILL FEATURE ANOTHER WARM MID-SEPTEMBER DAY WITH AT LEAST A LOW CHANCE OF SHOWERS/STORMS TODAY INCREASING INTO TONIGHT. THE SOUTH PLAINS WILL REMAIN UNDER SOUTHWESTERLY MID/UPPER FLOW TODAY AS THE REGION IS POSITIONED BETWEEN A FLAT RIDGE SPANNING MUCH OF TEXAS THROUGH THE DEEP SOUTH AND A SLOWLY EVOLVING COMPLEX WESTERN TROUGH. IN ADDITION...A POTENT SHORTWAVE TROUGH WILL DIVE THROUGH THE GREAT LAKES TODAY HELPING TO DRIVE A FRONT SOUTHWARD THROUGH THE CENTRAL PLAINS. EARLY MORNING WATER VAPOR IMAGERY DOES SHOW A POCKET OF DRIER AIR GETTING CAUGHT UP BETWEEN THE SOUTHEAST RIDGE AND WESTERN TROUGH...AND THIS MODEST DRYING AND THINNING MONSOON PLUME WILL SPREAD OVER NORTHWEST TEXAS TODAY...THOUGH SHALLOWER MOISTURE IS ALSO PROGGED TO MOVE AROUND THE SOUTHWEST PERIPHERY OF THE RIDGE AND INTO THE FA FROM THE SOUTHEAST THIS AFTERNOON. STRONG HEATING AND THE SUBTLE MOISTENING MAY BE ENOUGH TO POP AN ISOLATED SHOWER OR STORM...THOUGH COVERAGE AND DURATION OF THIS ACTIVITY SHOULD BE MINIMAL. STILL...HAVE DECIDED TO CARRY AN ISOLATED THUNDER MENTION WITH 10 PERCENT POPS FOR THIS POSSIBILITY ACROSS MUCH OF THE AREA. TURNING TO THE NORTHWEST...A PREFRONTAL TROUGH MAY FLIRT WITH THE SOUTHWEST PANHANDLE THIS AFTERNOON WELL IN ADVANCE OF THE FRONT /LIKELY IN OR NEAR THE OKLAHOMA PANHANDLE AROUND 00Z/ AND THIS TROUGH COULD PROVIDE ENOUGH OF A FOCUS FOR ISOLATED HIGH-BASED LATE DAY CONVECTION THERE. REGARDLESS IT WILL BE A WARM DAY WITH HIGHS AROUND 5 DEGREES ABOVE AVERAGE. BETTER STORM CHANCES SHOULD DEVELOP THIS EVENING INTO TONIGHT AS A PORTION OF THE WESTERN TROUGH LIFTS OVER THE HIGH PLAINS AND WEAK LARGE SCALE ASCENT GRAZES THE REGION. THE STRONGEST FORCING WILL BE TO OUR NORTH...BUT MAY BE CLOSE ENOUGH TO INSPIRE EXPANDING CONVECTION...LIKELY FAVORING THE NORTHERN AND NORTHWEST ZONES...WITH LOWER CHANCES FARTHER TO THE SOUTH AND EAST. A CONVECTIVELY AIDED FRONTAL BOUNDARY MAY EVEN MAKE A PUSH TOWARD THE NORTHERN ZONES...POTENTIALLY ENHANCING/MAINTAINING STORMS CHANCES THROUGH THE NIGHT...THOUGH THE EXACT POSITION OF THE FRONT IS HIGHLY UNCERTAIN. HENCE...HAVE 30-40 PERCENT POPS ACROSS THE SOUTHERN TEXAS PANHANDLE TAPERING TO AROUND 15 PERCENT ACROSS THE SOUTHERN ZONES TONIGHT. RELATIVELY SLOW STORM MOTION...TRAINING CELLS AND ABOVE NORMAL PWATS COULD SUPPORT LOCALLY HEAVY RAIN...PARTICULARLY IF A LOW-LEVEL FOCUS /BOUNDARY/ CAN MAKE IT INTO THE AREA. LOWS TONIGHT WILL BE ON THE WARM SIDE OF AVERAGE FOR MOST SPOTS GIVEN THE RELATIVELY MOIST ATMOSPHERE AND CONSIDERABLE CLOUDINESS. LONG TERM... WE ARE STILL EXPECTING RAIN CHANCES TO INCREASE ACROSS THE BOARD MONDAY AS WE SHOULD HAVE A DIFFUSE FRONTAL ZONE IN THE AREA...WEAK TROUGHING ALOFT...AND AN INCREASE IN DEEP LAYER MOISTURE. HOWEVER...DYNAMICS OVERALL WILL REMAIN WEAK...AND THERE IS STILL SOME QUESTION REGARDING HOW MUCH TROPICAL MOISTURE WE CAN TAP INTO AS PROGS IN GENERAL SHOW A WEAK SRLY COMPONENT TO THE MID-LVL FLOW...SUGGESTING MUCH OF THE THIS MOISTURE SOURCE MAY REMAIN WELL TO OUR SOUTH. THE ECMWF CONTINUES TO BE THE MOST AGGRESSIVE WITH DEVELOPING THE MOISTURE CHANNEL OVER OUR AREA THROUGH TUESDAY...WITH THE GFS AND NAM DRIER. WITH THIS IN MIND...IT SEEMS PRUDENT TO KEEP OUR POPS IN THE 30 TO 40 PERCENT RANGE FOR THE MOST PART...AND DOWNPLAY THE OVERALL HEAVY RAIN THREAT FOR NOW. FCST PWATS ARE AROUND 1.2 TO 1.4 INCHES AND WILL COMBINE WITH SLOW STORM MOTION TO GIVE AT LEAST A THREAT OF SOME LOCALLY HEAVY DOWNPOURS. THE FRONT SHOULD WASH OUT BY TUESDAY BUT WE SHOULD RETAIN SOME WEAK MID-LVL CYCLONIC CURVATURE AND SUFFICIENT DEEP MOISTURE TO SUPPORT OUR CHANCE POPS IN PLACE THROUGH THE EVENING. BY WED...WHATEVER MOISTURE PLUME WE HAD WILL WANE AND SHIFT EAST AND WE SHOULD DRY OUT TEMPORARILY. BUT ALREADY ON THURSDAY...A SHARP SHORTWAVE SWINGING THROUGH THE NRN PLAINS WILL DRIVE A COLD FRONT SOUTHWARD. THIS FRONT COULD ARRIVE IN OUR NRN COUNTIES AS EARLY AS THURS EVENING. MEANWHILE...THE UPPER RIDGING OVER THE NRN GULF COAST STATES WILL WEAKEN AND SHIFT SE...ALLOWING HIGHER MOISTURE LEVELS TO RETURN TO WEST TEXAS. WHILE THE GFS AND ECMWF DIFFER IN MANY OF THE DETAILS...THEY BOTH SHOW RATHER STRONG QPF SIGNALS LATE THU INTO FRI. AS SUCH WE/VE CONTINUED THE TREND OF INCREASING CLOUD COVER AND POPS IN THIS TIME FRAME AS WELL AS LOWERING TEMPS FOR FRIDAY. SO EVEN IF THE TROPICAL MOISTURE PLUME DOESN/T REALLY PAN OUT MON-TUE IT LOOKS LIKE WE/LL GET ANOTHER CHANCE LATE IN THE WEEK. BY NEXT WEEKEND...ANOTHER TROUGH WILL BE MOVING ACROSS THE WRN STATES AND COULD BRING US ANOTHER CHANCE OF PRECIP SUN INTO EARLY NEXT WEEK. MOS TEMPS ARE VERY FLAT ALL NEXT WEEK - WITH HIGHS MAINLY IN THE 80S. IT LOOKS LIKE WED COULD BE THE WARMEST DAY OF THE PERIOD...AND THEN TEMPS THU INTO FRI WILL DEPEND ON THE TIMING AND STRENGTH OF THE FRONT AND THE COVERAGE OF TSTM ACTIVITY IN IT/S WAKE. && .PRELIMINARY POINT TEMPS/POPS... FRIONA 85 60 80 59 81 / 10 40 40 30 40 TULIA 86 62 83 63 84 / 10 40 40 30 40 PLAINVIEW 87 63 84 62 83 / 10 30 40 30 30 LEVELLAND 88 62 84 61 82 / 10 20 40 20 30 LUBBOCK 89 66 86 65 84 / 10 20 30 20 30 DENVER CITY 87 62 84 62 82 / 10 20 30 20 30 BROWNFIELD 88 64 85 63 83 / 10 20 30 20 30 CHILDRESS 93 69 89 68 88 / 10 30 30 20 30 SPUR 91 66 89 65 86 / 10 20 30 20 30 ASPERMONT 95 68 90 69 89 / 10 10 30 20 30 && .LUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 23/33/23