527 FXUS64 KSHV 260942 AFDSHV AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SHREVEPORT LA 442 AM CDT FRI JUL 26 2013 .DISCUSSION... MCS OVER CNTRL OK IS SLOWLY MAKING STEADY PROGRESS ESE THIS MORNING...AHEAD OF THE PARENT SHORTWAVE OVER ECNTRL KS/WRN OK. THE STRONGEST STORMS HAVE ACTUALLY SHIFTED FARTHER S TOWARDS A CONVERGENCE ZONE AHEAD OF A WEAK DEVELOPING SFC LOW JUST W OF SPS...WHERE MODERATE INSTABILITY EXISTS NEAR AND N OF THE LOW. THUS...THE LEADING EDGE OF THE SHRA HAVE ACTUALLY ERODED SLIGHTLY AS IT ENCOUNTERS SLIGHTLY DRIER AIR ALOFT OVER EXTREME N TX/SE OK...BUT THIS AIR MASS SHOULD QUICKLY SATURATE LATER THIS MORNING AS THE CONVECTION REMAINS WIDESPREAD AND EVENTUALLY SPREADS FARTHER SE AHEAD OF THE SHORTWAVE. THE SHORT TERM PROGS MAINTAIN A 20-30KT SWRLY LLJ AHEAD OF A SECONDARY SFC LOW THAT WILL DEVELOP ALONG A WEAK SFC FRONT THIS MORNING OVER NRN OK...WHICH SHOULD KEEP STORM ORGANIZATION INTACT AS THE SHORTWAVE ENTERS ERN OK/WRN AR THIS AFTERNOON. SEEING A CONSIDERABLE AMOUNT OF CONVECTION DEBRIS SPREAD DOWNWIND OF THIS CONVECTION THIS MORNING...WHICH SHOULD KEEP MAX TEMPS TODAY A LITTLE COOLER THAN IN RECENT DAYS...ESPECIALLY OVER NE TX/SW AR. HOWEVER...THIS WILL BE KEY AS TO THE EXTENT OF INSTABILITY THAT DEVELOPS THIS AFTERNOON...WITH THE NAM HINTING TO AT LEAST MODERATE INSTABILITY DEVELOPING MAINLY ALONG/S OF THE I-20 CORRIDOR IN TIME AS DEEP LAYER SHEAR INCREASES TO 30-40KTS ALONG THE SHORTWAVE AXIS. SHOULD THIS INDEED OCCUR...COULD SEE AN ENHANCED THREAT FOR SVR CONVECTION WHERE ANY ASSOCIATED OUTFLOW BNDRYS FROM THIS CONVECTION INTERACT THE MORE UNSTABLE AREAS. FOR NOW...WILL HIGHLIGHT THIS THREAT IN THE HWO GIVEN THE UNCERTAINTIES. DID TAPER POPS BACK SLIGHTLY TODAY...MAINTAINING CATEGORICAL/LIKELY POPS FOR NE TX/SE OK/SW AR...WITH CHANCE POPS FARTHER SE ACROSS E TX/NW LA. COULD SEE AN INTERESTING EVENING UNFOLD AS THE NAM IS MORE BULLISH IN DEVELOPING A STRONGER SFC LOW ALONG THE ATTENDANT SFC FRONT OVER SW AR...SLIDING IT ESE INTO NCNTRL LA AFTER 06Z. IT ALSO ENHANCES SFC AND 850MB MOISTURE CONVERGENCE AS WELL...AT A TIME WHERE DEEP LAYER SHEAR IS MAXIMIZED AND ALLOWED TO WORK WITH THE BEST INSTABILITY FARTHER TO THE SE ACROSS SCNTRL AR/NCNTRL LA ALONG THE LEADING EDGE OF THE SHORTWAVE. STEEP MID LEVEL LAPSE RATES ALSO ADVECT E THIS EVENING AS WELL...WHICH COULD RESULT IN A BKN LINE OF CONVECTION /SOME OF WHICH MAY BE STRONG/...AND ENHANCING A HEAVY RAINFALL THREAT AS THEY SLIDE ESE ACROSS N LA. HAVE PLACED HEAVY RAINFALL WORDING ACROSS THESE AREAS CLOSER TO THE ENSEMBLE GUIDANCE ENVELOPE...WITH THIS THREAT DIMINISHING BY 12Z SATURDAY AS THE SHORTWAVE EXITS TO THE SE INTO THE GULF STATES. THE PROGS HAVE SPED UP THE DEPARTURE OF THE CONVECTION SLIGHTLY FROM RECENT RUNS...AND HAVE FOLLOWED SUITE WITH POPS...DIMINISHING POPS TO SLIGHT CHANCE IN THE AFTERNOON OVER DEEP E TX/SRN SECTIONS OF NCNTRL LA WHERE THE 850MB TROUGH WILL BE SLOWER TO SHIFT S. THE FRONT ITSELF LOOKS TO DRIFT S TO NEAR THE I-10 CORRIDOR OR S LA BEFORE GOING STATIONARY...WITH THE 850MB TROUGH HANGING UP IN THE VC OF CNTRL LA/LOWER TOLEDO BEND COUNTRY. HAVE CONTINUED MENTION OF SLIGHT CHANCE POPS SATURDAY NIGHT ACROSS THE SRN ZONES...BUT THESE BNDRYS SHOULD LIFT N AND WASH OUT SUNDAY AS 850-700MB RIDGING BUILDS E OVER THE AREA. DRY NW FLOW ALOFT BENEATH THE DEVELOPING GREAT LAKES CLOSED LOW WILL CONTINUE THROUGH THE LATTER HALF OF THE WEEKEND...WITH THE DESERT SW RIDGE BEGINNING TO FLATTEN LATE SATURDAY...ALLOWING FOR SHORTWAVE PERTURBATIONS TO SLIDE ESE ACROSS OK AND THE OZARKS LATE SUNDAY/MONDAY BEHIND THE CLOSED LOW AS IT BEGINS TO DRIFT E. THE PROGS MAINTAIN THIS SHORTWAVE ENERGY JUST N OF THE REGION MONDAY...ALTHOUGH ISOLATED CONVECTION CAN/T BE RULED OUT OVER SE OK/NRN SECTIONS OF SW AR MONDAY BEFORE THIS DISTURBANCE EXITS. AFTERWARDS...THE FLAT RIDGING WILL EXPAND E TO THE LOWER MS VALLEY TUESDAY...PERSISTING THROUGH THE END OF THE WEEK. THUS...MAX TEMPS SHOULD CLIMB BACK INTO THE MID AND UPPER 90S AREAWIDE...WITH ANY ISOLATED CONVECTION HARD TO COME BY GIVEN THE INFLUENCE OF THE RIDGE. HOWEVER...SHOULD THE NRN OR ERN SECTIONS OF THIS RIDGE BUCKLE BY MID TO LATE WEEK...SLIGHT CHANCE POPS MAY BE NEEDED FOR THE NRN AND ERN ZONES GIVEN THE STRONG HEATING AND AVAILABLE MOISTURE IN PLACE. PRELIMS TO FOLLOW BELOW... 15 && .AVIATION... VFR CONDITIONS AREAWIDE THIS OVERNIGHT..WITH ONLY CIRRUS CLOUDS ABUNDANT IN UPPER LVLS...THAT ARRIVED IN DEEP NW FLOW ALOFT FROM MCS OVER CENTRAL OK AND UPPER RED RIVER VALLEY. VFR CIGS TO INCREASE AS THIS SYSTEM ADVANCES TO THE SE TOWARDS THE REGION. KTXK TERMINAL WILL BE FIRST TO SEE CONVECTION...BTWN 12-15Z THIS MORNING. OUTFLOW BOUNDARIES AND COOLING ALOFT WILL SET UP FOR SCT AFTN TSTMS MOST OF AREA WITH DAYTIME HEATING AND COLD FRONT SLOWLY MOVG TO NEAR THE I-20 AIRPORT TERMINAL LOCATIONS. DRY AIR IN LOW LVLS WILL CONTRIBUTE TO ENHANCEMENT OF STG DOWNDRAFT WINDS NEAR STORMS. MOIST GROUND AND SECONDARY FRONTAL BOUNDARY ARRIVING AFTER 27/06Z...MAY BRING SOME MVFR CIGS AND POSSIBLE PATCHY FOG...WITH VFR SKC SEEN LATER IN WEEKEND WITH PASSAGE OF SECONDARY FRONT. /VII/ && .PRELIMINARY POINT TEMPS/POPS... SHV 93 71 90 70 94 / 40 60 20 10 0 MLU 94 70 88 68 92 / 20 70 40 10 0 DEQ 81 66 88 65 91 / 80 50 0 0 0 TXK 84 69 88 67 91 / 70 60 10 0 0 ELD 89 69 88 66 92 / 50 70 20 0 0 TYR 93 72 91 72 93 / 40 50 10 10 0 GGG 93 71 91 70 94 / 40 50 10 10 0 LFK 96 73 93 74 95 / 20 50 20 20 10 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...NONE. LA...NONE. OK...NONE. TX...NONE. && $$ 15/07