972 FXUS64 KLIX 130119 AFDLIX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW ORLEANS LA 819 PM CDT SUN OCT 12 2014 .00Z SOUNDING DISCUSSION... ROUTINE FLIGHT TERMINATED OVER EASTERN HANCOCK COUNTY MISSISSIPPI JUST SOUTH OF THE LITTLE BILOXI WILDLIFE REFUGE SOUTHWEST OF SAUCIER. FLIGHT TERMINATED AT AN ALTITUDE OF 111K FEET OR 21 MILES. AIRMASS HAS CONTINUED TO MOISTEN WITH A PRECIPITABLE WATER VALUE OF 1.94 INCHES. THIS IS ABOUT 167 PERCENT OF NORMAL FOR OCTOBER. LIFTED INDEX OF -5 AND CAPE AROUND 2000 J/KG. MID-LEVEL LAPSE RATES AROUND 6C/KM. FREEZING LEVEL AT 14.7K FEET AND -20C AT 25.2K FEET. SOUTHEAST WINDS AT THE SURFACE BECOME SOUTHWEST BY ABOUT 700 MB AND REMAINED SOUTHWEST TO WEST THROUGH 100 MB. MAX WIND WAS WESTERLY AT 65 KNOTS NEAR 200 MB. 35 && .PREV DISCUSSION... /ISSUED 337 PM CDT SUN OCT 12 2014/ DISCUSSION... THE MAIN FORECAST CONCERN IS THE POTENTIAL FOR SEVERE WEATHER MONDAY AFTERNOON AND MONDAY NIGHT. THE UPPER AIR PATTERN ACROSS THE CONUS WILL AMPLIFY SIGNIFICANTLY EARLY IN THE FORECAST PERIOD AS AN UPPER TROUGH MOVING OUT OF THE NORTHERN AND CENTRAL ROCKIES AND INTO THE PLAINS LATE TODAY AND TONIGHT DEEPENS AND TAKES ON MORE A NEUTRAL TILT AS IT MOVES ACROSS THE SOUTHERN PLAINS MONDAY AND THE LOWER AND MID MISSISSIPPI VALLEY MONDAY NIGHT. THE MAIN THREAT FOR SEVERE WEATHER FOR THE LOCAL FORECAST AREA WILL OCCUR FROM MID AND LATE AFTERNOON MONDAY THROUGH MONDAY EVENING AND POSSIBLY INTO EARLY TUESDAY MORNING. INITIALLY...MODEL FORECAST SOUNDINGS INDICATE THAT CAPPING MAY LIMIT CONVECTIVE ACTIVITY ACROSS THE FORECAST AREA DURING THE FIRST HALF OF THE DAY MONDAY. HOWEVER AS LARGE SCALE ASCENT INCREASES WITH THE APPROACH OF THE UPPER TROUGH...THIS CAP WILL BE OVERCOME WITH DISCREET SCATTERED CELLS LIKELY TO DEVELOP IN THE AFTERNOON AHEAD OF THE EXPECTED MAIN SQUALL LINE. STRONG DIVERGENCE ALOFT IS FORECAST OVER THE REGION LATE IN THE DAY MONDAY AND THROUGH THE EVENING HOURS IN ASSOCIATION THE RIGHT REAR QUADRANT OF A STRONG UPPER JET ON ON THE EAST SIDE OF THE TROUGH. DURING THE EVENING HOURS MONDAY...SOUTHWESTERLY MID LEVEL FLOW OF 50 TO 70 KNOTS WILL TRANSLATE ACROSS THE AREA WITH 85H FLOW AROUND 40 KNOTS. INCREASING SOUTHERLY LOW LEVEL WINDS WILL YIELD SURFACE DEW POINTS IN THE LOW TO MID 70S AHEAD OF THE SYSTEM. FAIRLY STRONG SHEAR AND INSTABILITY IS FORECAST TO BE PRESENT DURING THE EVENT. THE BEST HELICITY VALUES WILL BE IN THE LATE AFTERNOON. THUS THE BEST CHANCE OF SEEING ANY ISOLATED TORNADOES WILL BE IN THE AFTERNOON AND EARLY EVENING HOURS MONDAY WITH ANY DISCREET THUNDERSTORMS THAT DEVELOP AHEAD OF THE SQUALL LINE. THE SQUALL LINE ITSELF WILL LIKELY MOVE THROUGH FORECAST AREA FROM WEST TO EAST FROM THE VERY LATE AFTERNOON HOURS MONDAY THROUGH THE EVENING BEFORE EXITING THE FAR EASTERN SECTIONS OF THE FORECAST AREA AND THE COASTAL WATERS EARLY TUESDAY MORNING. THE MAIN THREAT WITH THE SQUALL LINE WILL BE DAMAGING WINDS ALTHOUGH AN ISOLATED TORNADO CAN NOT BE RULED OUT. COOLER AND MUCH DRIER CONDITIONS WILL FILTER INTO THE REGION IN THE WAKE OF THE COLD FRONT TUESDAY. PLEASANT MORE FALL LIKE CONDITIONS WILL THEN PREVAIL THROUGH THE REMAINDER OF THE WEEK. UPPER LEVEL RIDGING WILL ATTEMPT TO NOSE INTO THE WESTERN AND CENTRAL GULF COAST REGION FROM THE WEST FOR THE LAST HALF OF THE WORK WEEK WITH TEMPERATURES MODERATING SOMEWHAT. A WEAK COLD FRONT WILL ATTEMPT TO MAKE ITS WAY SOUTH IN THE GULF COAST STATES SATURDAY...BUT WILL LIKELY STALL OUT NORTH OF THE LOCAL AREA. 11 AVIATION... EXPECT SCATTERED CONVECTION TO CONTINUE THROUGH THE AFTERNOON AND EVENING HOURS. OTHERWISE...EXPECT VFR CONDITIONS TO PREVAIL. A LOW STRATUS DECK IS EXPECTED DEVELOP LATER ON TONIGHT. WILL HAVE TO WATCH FOR SOME MVFR CONDITIONS OVERNIGHT INTO MONDAY MORNING. HAVE NO ADDED MENTION OF THUNDERSTORMS IN TAFS AS THE BULK OF THE PRECIPITATION SHOULD FALL AFTER THE VALID TAF PERIOD. 13/MH MARINE... SOUTHERLY FLOW WILL INCREASE ACROSS THE COASTAL WATERS THROUGH MONDAY IN ADVANCE OF A STRONG COLD FRONT THAT WILL TRAVERSE THE COASTAL WATERS MONDAY NIGHT AND EARLY TUESDAY. A SQUALL LINE IS EXPECTED TO ACCOMPANY THE FRONTAL PASSAGE. EXERCISE CAUTION CRITERIA WINDS WILL LIKELY BE OBSERVED ACROSS MUCH OF THE COASTAL WATERS MONDAY AHEAD OF THE COLD FRONT. IN THE WAKE OF THE FRONT...OFFSHORE WINDS WILL FLIRT WITH SMALL CRAFT CONDITIONS LATE MONDAY NIGHT AND TUESDAY. WINDS WILL DIMINISH TUESDAY NIGHT INTO WEDNESDAY AS HIGH PRESSURE SETTLES ACROSS THE COASTAL WATERS. 11 DECISION SUPPORT... DSS CODE...ORANGE. DEPLOYED...NONE. ACTIVATION...NONE. ACTIVITIES...SLURRY SUPPORT. MONITORING SEVERE WEATHER THREAT FOR MONDAY AFTERNOON AND MONDAY NIGHT. SLIGHT RISK FOR SEVERE WEATHER MONDAY AND MONDAY NIGHT. DECISION SUPPORT SERVICES (DSS) CODE LEGEND GREEN = NO WEATHER IMPACTS THAT REQUIRE ACTION BLUE = LONG FUSED WATCH/WARNING/ADVISORY IN EFFECT OR HIGH VISIBILITY EVENT YELLOW = HEIGHTENED IMPACTS WITH SHORT FUSED WATCH/WARNING/ADVISORY ISSUANCES; RADAR SUPPORT ORANGE = HIGH IMPACTS - SLIGHT TO MODERATE RISK SEVERE; NEARBY TROPICAL EVENTS; HAZMAT OR OTHER LARGE EPISODES RED = FULL ENGAGEMENT FOR MODERATE TO HIGH RISK SVR AND/OR DIRECT TROPICAL THREATS; EVENTS OF NATIONAL SIGNIFICANCE. && .PRELIMINARY POINT TEMPS/POPS... MCB 69 86 57 75 / 20 70 80 10 BTR 70 87 58 76 / 20 80 80 10 ASD 69 86 62 76 / 20 60 80 10 MSY 72 87 63 76 / 20 60 80 10 GPT 71 86 65 76 / 20 60 80 20 PQL 69 86 64 77 / 20 60 80 20 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...NONE. GM...NONE. MS...NONE. GM...NONE. && $$