343 FXUS64 KLUB 140453 AFDLUB AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LUBBOCK TX 1153 PM CDT SAT APR 13 2013 .AVIATION... LOW LEVEL SOUTHERLY FLOW STILL MAY BE CAPABLE OF PATCHY STRATUS TOWARDS DAYBREAK NEAR KLBB...THOUGH SIGNALS ARE NOT STRONG IN LATEST GUIDANCE. RETAINED A TEMPO GROUP WITH SCATTERED 1000 FOOT LAYER TO INDICATE THAT POSSIBILITY. OTHERWISE...LOW LEVEL FLOW WILL VEER FAIRLY SHARPLY TO THE WEST BY MID MORNING SUNDAY WITH SURFACE TROUGH AND DRY-LINE EDGING MAINLY EAST OF THE AREA. MODEST WESTERLY FLOW ALOFT SHOULD LEAD TO SOLID LOW-END WINDY DAY BOTH TAF SITES WITH VFR CONDITIONS DOMINATING. RMCQUEEN && .PREV DISCUSSION... /ISSUED 909 PM CDT SAT APR 13 2013/ UPDATE... THUNDER CHANCES HAVE ENDED FOR THE EVENING. QUICK UPDATE. RMCQUEEN PREV DISCUSSION... /ISSUED 736 PM CDT SAT APR 13 2013/ UPDATE... HIGH-BASED THUNDER CHANCES WILL REMAIN BEST IN THE ZONE FROM JUST NORTH OF MORTON THROUGH LITTLEFIELD AND OLTON TO KRESS FOR THE NEXT HOUR OR TWO. WE STILL EXPECT ACTIVITY TO DIMINISH AFTER SUNSET. UPDATED FOR SLIGHTLY FURTHER EAST EXPANSION OF THUNDER CHANCES AND FOR BETTER COVERAGE OF GUSTY-WIND PRODUCING THUNDER IN THE FAVORED ZONE INDICATED ABOVE. RMCQUEEN AVIATION... NO SIGNIFICANT CHANGES FROM THE PREVIOUS FORECAST. THUNDER CHANCES THIS EVENING WILL DRIFT NEAR ENOUGH KLBB TO MENTION CUMULONIMBUS AS THE LOW CLOUD TYPE...BUT DO NOT EXPECT TO MOVE THROUGH KLBB. A LOW CLOUD LAYER NEAR IFR/MVFR BOUNDARY IS STILL POSSIBLE NEAR KLBB BRIEFLY NEAR DAYBREAK ON SUNDAY BEFORE THE DRY WESTERLY COMPONENT WINDS SET IN. VFR SHOULD CONTINUE AT KCDS THROUGH THE PERIOD. RMCQUEEN PREV DISCUSSION... /ISSUED 252 PM CDT SAT APR 13 2013/ SHORT TERM... WEST TEXAS WILL REMAIN UNDER BROAD CYCLONIC FLOW OVER THE SHORT TERM AS A STORM SYSTEM DIGS THROUGH THE NORTHWESTERN TIER OF THE NATION AND EMERGES AND STRENGTHENS OVER THE NORTHERN PLAINS SUNDAY. WITHIN THIS FLOW...A TROUGH AXIS WAS APPROACHING WEST TEXAS AND WILL PASS TO THE EAST TONIGHT...THOUGH THE BULK OF THE LARGE-SCALE ASCENT WITH THIS FEATURE WILL EMERGE WELL TO THE SOUTH OF THE FA. EVEN SO...NORTHERN AND WESTERN SECTIONS OF THE CWA WILL SEE THE POSSIBILITY OF ISOLATED CONVECTION LATE THIS AFTERNOON THROUGH EARLY THIS EVENING. LOW-LEVEL MOISTURE IS RATHER LIMITED...WITH DEWPOINTS ONLY IN THE 30S TO LOWER 40S ACROSS THE CAPROCK...BUT STEEP MID-LEVEL LAPSE RATES WERE RESULTING IN AROUND 500 J/KG OF SBCAPE WHILE CIN WAS WEAKENING AND SHOULD BE MINIMAL BY LATE AFTERNOON. THESE FACTORS COMBINED WITH WEAK CONVERGENCE WERE ALREADY RESULTING IN A DEVELOPING CUMULUS FIELD FROM NORTH OF HEREFORD TO WEST OF CLOVIS AS OF 19Z. THE LATEST TTU-WRF...RAP...NAM AND SEVERAL SREF MEMBERS SUGGEST THAT ISOLATED TO WIDELY SCATTERED CONVECTION WILL DEVELOP THROUGH MID TO LATE AFTERNOON AND MOVE EASTWARD. EXPECT ANY ACTIVITY TO QUICKLY WANE THIS EVENING THOUGH THE LATEST RAP AND HRRR SUGGEST THE ACTIVITY COULD HANG ON AND PASS ACROSS MUCH OF THE SOUTH PLAINS THIS EVENING. NOT AS CONVINCED OF THIS AND HAVE MAINTAINED THE ISOLATED THUNDER MENTION GENERALLY ALONG AND WEST OF A MEMPHIS TO LEVELLAND LINE. RATHER WEAK INSTABILITY...FORCING AND DEEP LAYER SHEAR SHOULD LIMIT THE STORM ORGANIZATION AND COVERAGE THOUGH RELATIVELY DRY SUB-CLOUD LAYER /WITH SFC T/TD SPREADS OF 30 TO 40 DEGREES/ COULD SUPPORT LOCALIZED STRONG WIND GUSTS. A STRONG LLJ WILL THEN DEVELOP ACROSS THE CENTRAL PLAINS TONIGHT WITH THE SOUTHERN EXTENT OF IT EXTENDING OVER NORTHWEST TEXAS. THIS JET WILL DRAW BETTER MOISTURE NORTHWARD...WITH MOISTURE ADVECTION MAXIMIZED ACROSS THE SOUTHWEST ZONES WHERE LOW CLOUDS AND FOG COULD DEVELOP. BREEZY AND QUICKLY VEERING WINDS TOWARD MORNING SHOULD LIMIT THE FOG POTENTIAL AND HAVE NOT INCLUDED IN THE GRIDS ATTM. THIS FLOW WILL ALSO PROVIDE A MILD NIGHT...WITH LOWS IN THE UPPER 40S AND LOWER 50S COMMON. A DRYLINE WILL TIGHTEN TONIGHT IN EASTERN NM...BUT THE SFC FLOW WILL QUICKLY VEER WESTERLY EARLY SUNDAY AS THE NORTHERN STORM SYSTEM SHIFTS EASTWARD AND THIS WILL CAUSE THE DRYLINE TO RACE EASTWARD ACROSS THE SOUTH PLAINS SUNDAY MORNING AND CLEAR EAST OF THE FA BY MID-AFTERNOON. GUSTY WESTERLY WINDS SUSTAINED AT 20-25 MPH WILL BE COMMON AND THIS WILL PROPEL HIGHS WELL INTO THE 80S...WITH EVEN A FEW LOWER 90S POSSIBLE OFF THE CAPROCK. THESE WARM...DRY AND GUSTY CONDITIONS WILL ALSO CREATE ELEVATED TO CRITICAL FIRE WEATHER. LONG TERM... MAIN INTEREST CONTINUES TO BE UPPER TROUGH AND FRONTAL PASSAGE MID WEEK AND MODEL INCONSISTENCIES IN HANDLING BOTH FEATURES. 12Z GFS CAME IN ABOUT 18-24 HOURS SLOWER THAN ITS 00Z RUN AND IS NOW SLOWER THAN EITHER THE 00Z OR 12Z RUNS OF THE ECMWF. GOOD CONSISTENCY IN THE ECMWF WILL MAKE IT THE WINNER TODAY...AND GIVEN THAT THE PREVIOUS FCST TRENDED TOWARD IT...FEW CHANGES WILL BE MADE TO THAT PART OF THE FCST. IN GENERAL...COOLING TEMPS WEDNESDAY...THE MAGNITUDE OF WHICH STILL IN DOUBT GIVEN IMPORTANCE OF FRONTAL TIMING ON THAT ELEMENT. SMALL PRECIP CHANCES CONTINUE TO FAVOR THE ROLLING PLAINS WHERE SOME LOW LEVEL MOISTURE MAY BE IN PLACE. EARLY WEEK WILL CONTINUE TO EXPECT A WEAK FRONTAL BOUNDARY IN OR NEAR THE NERN PART OF THE FCST AREA THAT SHOULD RESULT IN SLIGHTLY COOLER TEMPS THERE. LACK OF LOW LEVEL MOISTURE MONDAY SHOULD LIMIT POPS WHILE BETTER MOISTURE RETURN TUESDAY MAY HELP FUEL ISOLATED THUNDER. WEST OF THE BOUNDARY...BREEZY AND WARM WITH POSSIBILITY OF ELEVATED TO CRITICAL FIRE WEATHER CONDITIONS DEVELOPING. LATTER PART OF THE WEEK LOOKS FAIR AND COOL IN POST-FRONTAL AIR MASS AND NWLY FLOW ALOFT. FIRE WEATHER... THE SOUTH PLAINS REGION WILL SEE GOOD TO EXCELLENT RH RECOVERIES TONIGHT AS SOUTHERLY FLOW DRAWS IN IMPROVING AMOUNTS OF MOISTURE. HOWEVER...THIS MOISTURE WILL BE SHUNTED EASTWARD AS A DRYLINE QUICKLY ADVANCES FROM EASTERN NM /EARLY SUNDAY MORNING/ INTO SOUTHWEST OK AND WESTERN NORTH TEXAS BY LATE IN THE DAY. RH VALUES WILL DROP TO 5 TO 10 PERCENT ACROSS THE FA /BEHIND THE DRYLINE/ WHILE TEMPERATURES CLIMB TO 10 TO 15 DEGREES ABOVE AVERAGE. ADDITIONALLY...SOUTHWEST TO WESTERLY WINDS WILL BECOME SUSTAINED AT 15-25 MPH BEHIND THE DRYLINE DURING THE AFTERNOON...RESULTING IN A PERIOD OF ELEVATED TO CRITICAL FIRE WEATHER CONDITIONS. HENCE...HAVE ISSUED A FIRE WEATHER WATCH FOR THE ENTIRE AREA VALID FROM 17-01Z SUNDAY. EXPECT THE STRONGEST WINDS TO BE ON THE CAPROCK WHERE LOW-END CRITICAL CONDITIONS /AT LEAST WITH REGARDS TO THE WINDS/ WILL BE MOST LIKELY TO OCCUR FOR THE REQUIRED 3 HOURS OR MORE. IT IS LESS CERTAIN THAT SPOTS OFF THE CAPROCK WILL OBTAIN MORE THAN SPOTTY/BRIEF CRITICAL CONDITIONS...BUT HAVE DECIDED TO INCLUDE IN THE WATCH AND WILL LET THE OVERNIGHT SHIFT DECIDE IF A FIRE DANGER STATEMENT MAY BE MORE APPROPRIATE. && .PRELIMINARY POINT TEMPS/POPS... FRIONA 44 81 43 80 48 / 20 0 0 0 0 TULIA 49 84 44 82 47 / 30 0 0 0 0 PLAINVIEW 51 85 44 83 50 / 30 0 0 0 0 LEVELLAND 52 85 47 84 49 / 20 0 0 0 0 LUBBOCK 53 87 48 85 52 / 10 0 0 0 0 DENVER CITY 52 85 51 85 51 / 20 0 0 0 0 BROWNFIELD 52 87 49 85 49 / 10 0 0 0 0 CHILDRESS 52 89 48 81 54 / 10 0 0 0 10 SPUR 51 90 50 89 54 / 10 0 0 0 10 ASPERMONT 54 92 53 93 57 / 10 0 0 0 10 && .LUB WATCHES/WARNINGS/ADVISORIES... FIRE WEATHER WATCH FROM SUNDAY AFTERNOON THROUGH SUNDAY EVENING FOR THE FOLLOWING ZONES: TXZ021>044. && $$ 99/99/05