000 FXUS64 KSJT 181753 AAC AFDSJT AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE SAN ANGELO TX 1153 AM CST SUN NOV 18 2007 .AVIATION... DENSE FOG AND LOW CLOUDS WERE SLOW TO LIFT THIS MORNING ACROSS OUR SOUTHEASTERN COUNTIES...BUT MIXING EFFECTS ARE NOW QUICKLY BREAKING UP THE FOG AND CLOUDS. WILL SEE GENERALLY CLEAR SKIES THIS AFTERNOON...BUT SOME SCATTERED STRATOCUMULUS POSSIBLE EAST OF A BROWNWOOD TO JUNCTION LINE. AFTER THE INITIAL LOW CLOUD BREAKUP... BASES OF ANY REDEVELOPED CLOUDS WILL BE ABOVE 3 KFT. CLEAR SKIES EXPECTED FOR MUCH OF TONIGHT. WITH ESSENTIALLY THE SAME AIRMASS IN PLACE HOWEVER...THE SETUP FAVORS ANOTHER EPISODE OF FOG AND LOW CLOUDS FOR OUR SOUTHEASTERN COUNTIES...WHERE HIGHER DEWPOINTS AND BOUNDARY LAYER MOISTURE RESIDE. BECAUSE DENSE FOG IS SUCH AN INFREQUENT OCCURRENCE IN WEST-CENTRAL TEXAS...BEING RELATIVELY CONSERVATIVE AT THIS TIME WITH THE VISIBILITY AND CEILING REDUCTION AT THE BRADY AND JUNCTION TAF SITES. CARRYING TEMPORARY IFR CONDITIONS AT THESE SITES 12Z-15Z...BUT LIFR CONDITIONS COULD OCCUR. WINDS WILL BE MOSTLY LIGHT AND VARIABLE THROUGH EARLY MONDAY MORNING. SOUTH WINDS WILL INCREASE TO 8-12 KT BY MIDDAY MONDAY. && .PREV DISCUSSION... /ISSUED 725 AM CST SUN NOV 18 2007/ UPDATE... BASED ON SFC OBSERVATIONS AND LAW ENFORCEMENT REPORTS...ISSUED A DENSE FOG ADVISORY FOR MANY OF THE EASTERN AND SOUTHEASTERN CWA THRU 15Z. AVIATION... IFR CIGS/VIS DUE TO FOG THRU 15Z THIS MORNING AT KSOA...KJCT...AND KBBD...THEN BECOMING MVFR TO VFR BY 15Z AND IMPROVING TO VFR BY 16Z THRU 09Z. INCLUDED IFR CIGS/VIS AT ABI AS ADVECTION FOG IS KNOCKING ON THE DOOR. COULD SEE A REPEAT OF IFR CIGS/VIS AFTER 09Z. BUT NOT CONFIDENT ENUF TO MENTION ATTM. PREV DISCUSSION... /ISSUED 409 AM CST SUN NOV 18 2007/ SHORT TERM... ABOVE NORMAL TEMPERATURES CONTINUE AGAIN TODAY AS A LEE SURFACE TROUGH BEGINS TO DEVELOP ACROSS THE NORTHERN ROCKIES AND A RIDGE OF HIGH PRESSURE OVER THE SOUTHWEST EXPANDS EAST...WITH AFTERNOON MAINLY IN THE LOW 80S WITH ISOLATED UPPER 70S...NEAR RECORD HIGH TEMPERATURES POSSIBLE ACROSS THE CONCHO VALLEY TODAY. LONG TERM... THE WARM AND DRY CONDITIONS WILL CONTINUE THROUGH THE FIRST PART OF THE WORK WEEK WITH A SURFACE LEE TROUGH BRINGING BREEZY CONDITIONS ACROSS WEST CENTRAL TEXAS ON MONDAY AND TUESDAY. A STRONG COLD FRONT IS STILL EXPECTED TO MOVE ACROSS WEST CENTRAL TEXAS ON WEDNESDAY...GFS HAS SLOWED THE FRONT DOWN...HAVE DECIDED TO GO WITH THE MORE PROGRESSIVE FROPA OF ECMWF...AS THE GFS LATELY HAS BEEN TO SLOW WITH FROPA. THE TIMING WILL BE IMPORTANT IN DETERMINING AFTERNOON HIGHS...FOR NOW HAVE GONE ON THE LOW SIDE OF GUIDANCE. THE MEDIUM RANGE MODELS HAVE AN AMPLIFIED UPPER LEVEL PATTERN FOR LATE NEXT WEEK INTO NEXT WEEKEND...WHICH WILL KEEP THE COLD TEMPERATURES AROUND FROM MIDWEEK THROUGH NEXT WEEKEND. TEMPERATURES ARE A CHALLENGE FOR MIDWEEK THROUGH NEXT WEEKEND...AS GFS KEEPS 850 TEMPERATURES IN THE -3 TO -7 RANGE FROM THURSDAY THROUGH SUNDAY...WITH EXTENSIVE CLOUD COVERAGE...CLOUD COVERAGE WILL BE A LIMITING FACTOR IN DETERMINING AFTERNOON HIGHS AND OVERNIGHT LOW SO FOR NOW HAVE FREEZING TEMPERATURES FOR ISOLATED AREAS ON THURSDAY MORNING...EXPECT THE FIRST WIDESPREAD FREEZE THIS SEASON TO OCCUR ON FRIDAY MORNING WITH OVERNIGHT LOWS IN THE UPPER 20S TO LOW 30S...OVERNIGHT LOWS FOR SATURDAY AND SUNDAY WILL BE IN THE LOW TO MID 30S...WITH ISOLATED AREAS OF FREEZING TEMPERATURES FOR SATURDAY AND SUNDAY MORNINGS. BOTH THE GFS AND ECMWF HAVE PRECIPITATION ACROSS WEST CENTRAL TEXAS FOR LATE FRIDAY EVENING INTO SATURDAY...WITH THE ECMWF SHOWING MORE PRECIPITATION AND KEEPS THE PRECIPITATION GOING THROUGH SUNDAY...FOR NOW WILL KEEP 20 POPS ACROSS WEST CENTRAL TEXAS THROUGH SUNDAY MORNING...FOR NOW HAVE PRECIPITATION TYPE AS RAIN BUT IF TEMPERATURES END UP BEING COLDER THAN CURRENTLY FORECASTED SOME TYPE OF WINTRY PRECIP IS NOT OUT OF THE QUESTION FOR SATURDAY AND SUNDAY...WILL HAVE TO MONITOR THE SITUATION. && .PRELIMINARY POINT TEMPS/POPS... ABILENE 80 53 83 61 / 10 10 10 10 SAN ANGELO 82 51 82 59 / 10 10 0 0 JUNCTION 82 51 81 58 / 10 10 10 10 && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$