000 FXUS64 KFWD 231737 AAA AFDFWD AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE FORT WORTH TX 1137 AM CST MON NOV 23 2009 .AVIATION... NO AVIATION WEATHER CONCERNS THROUGH THIS EVENING NOW THAT ALL THE DENSE FOG HAS LIFTED. A MOSTLY CLEAR SKY WILL PREVAIL THROUGH THE AFTERNOON WITH A SOUTH WIND AROUND 10 KNOTS. A COLD FRONT WILL MOVE QUICKLY ACROSS THE PLAINS THIS AFTERNOON AND SHOULD REACH NORTH TEXAS LATE THIS EVENING. EXPECT A WIND SHIFT AT THE METROPLEX TAF SITES BETWEEN 6 AND 7Z AND WACO AROUND 08Z. A FEW SHOWERS MAY ACCOMPANY THE FRONT BUT COVERAGE WILL BE TOO LIMITED TO MENTION MORE THAN SHOWERS IN THE VICINITY. THERE COULD ALSO BE SOME BRIEF FOG PRIOR TO THE FRONT AS THE WINDS BECOME LIGHT BUT ANY VISIBILITY RESTRICTIONS SHOULD BE VERY BRIEF. A NORTHWEST WIND WILL PREVAIL BEHIND THE FRONT AT SPEEDS BETWEEN 12 AND 16 KNOTS. && .UPDATE... THE DENSE FOG ADVISORY WILL BE ALLOWED TO EXPIRE AT 11 AM. AS OF 16Z... VISIBILITIES WERE STILL 1/4 MILE OR LESS ACROSS MUCH OF NORTH CENTRAL NORTH TEXAS FROM BOWIE...TO GRANBURY...TO LANCASTER...TO SHERMAN. THE FOG SHOULD CONTINUE TO DISPERSE DURING THE NEXT HOUR SO WE WILL LET THE ADVISORY EXPIRE AT 11 AM. OTHERWISE...HAVE ADJUSTED THE HOURLY TRENDS BUT MADE NO SIGNIFICANT CHANGE TO THE PREVIOUS FORECAST. 58 && .PREV DISCUSSION... /ISSUED 517 AM CST MON NOV 23 2009/ 433 AM TODAY THROUGH TUESDAY...09Z WATER VAPOR IMAGERY INDICATES A STRONG SHORTWAVE TROUGH MOVING SOUTHEAST THROUGH CO EARLY THIS MORNING. THIS IS THE UPPER LEVEL DISTURBANCE THAT WILL MOVE EAST ACRS KS AND OK DURING THE DAY TODAY...SENDING A COLD FRONT SOUTH THROUGH NORTH TX DURING THE OVERNIGHT HRS. SHALLOW MOISTURE REMAINS IN PLACE THROUGH THE FORECAST AREA THIS MORNING...WHERE CLEAR SKIES AND LIGHT WINDS HAVE ONCE AGAIN ALLOWED AREAS OF DENSE FOG TO DEVELOP. WINDS ARE EXPECTED TO PICK UP OUT OF THE SOUTH TODAY AHEAD OF THE UPPER LEVEL DISTURBANCE PUSHING THROUGH THE PLAINS...WHICH SHOULD BRING SOME MEAGER RETURN OF GULF MOISTURE THRU THE AREA AHEAD OF THE COLD FRONT FOR TONIGHT. WITH ONLY AROUND 12 HRS OF GOOD MOISTURE TRANSPORT EXPECTED...THINKING IS THAT GULF MOISTURE WILL REMAIN RELATIVELY SHALLOW OVER MUCH OF NORTH TX. UPPER LEVEL POTENTIAL VORTICITY ANALYSIS INDICATES THAT THE BULK OF THE LARGE SCALE FORCING FOR ASCENT ASSOCIATED WITH THIS UPPER LEVEL DISTURBANCE WILL REMAIN NORTH OF THE RED RIVER...AS HAS BEEN ADVERTISED THE PAST COUPLE OF DAYS OF MODEL RUNS. WITH RELATIVELY SHALLOW MOISTURE IN PLACE AND WITHOUT MUCH IN THE WAY OF LARGE SCALE FORCING FOR ASCENT...THINK THAT RAIN SHOWER ACTIVITY WILL TEND TO REMAIN ALONG AND JUST BEHIND THE COLD FRONT WITH ONLY ISOLATED TO SCATTERED COVERAGE ALONG IT AS IT PUSHES SOUTHEAST TONIGHT. WITH THIS IN MIND...MAINTAINED THE 20 TO 30 PERCENT CHANCE OF PRECIPITATION FOR TONIGHT FROM PREVIOUS FORECAST. THINK THAT RAIN SHOWER ACTIVITY WILL DEVELOP AS THE FRONT MOVES THROUGH...BUT COVERAGE IS EXPECTED TO BE LIMITED AT THIS TIME. BEHIND THE FRONT...MODELS DEPICT A SIGNIFICANT DROP IN LOW LVL MOISTURE AS AIR CURRENTLY OVER THE TX/OK PANHANDLES MOVES INTO NORTH TX. THIS AIRMASS WILL PROBABLY BE MODIFIED SLIGHTLY AS IT MOVES OUR WAY...SO WE MAY NOT SEE THE LOWER 20S DEW POINT VALUES THAT ARE CURRENTLY IN PLACE...BUT DEW POINTS IN THE UPPER 20S TO LOWER 30S LOOK LIKELY AT THIS TIME. TUESDAY NIGHT THROUGH FRIDAY...WITH DRIER AIR IN PLACE...CHANCES OF OVERNIGHT FOG/STRATUS THAT WE HAVE BEEN SEEING THE PAST COUPLE OF DAYS SHOULD BE SMALL. WITH THE DRIER AIR AND EXPECTED CLEAR SKIES WE WILL HAVE A GREATER CHANCE TO SEE MANY LOCATIONS APPROACH OR DIP BELOW THE FREEZING MARK DURING THIS PERIOD...WITH RURAL AND LOW LYING AREAS BEING MOST LIKELY TO SEE NEAR FREEZING TEMPS FOR LOWS. URBAN AREAS WILL MOST LIKELY NOT SEE FREEZING TEMPS DURING THE PERIOD BECAUSE THE AIRMASS IS NOT COLD ENOUGH TO COMBAT THE HEAT ISLAND EFFECT...BUT SOMETHING TO KEEP AN EYE ON IF DAILY HIGHS DO NOT CLIMB AS HIGH AS EXPECTED BEHIND THE COLD FRONT. AS THE INITIAL STRONG SHORTWAVE TROUGH KICKS OFF TO THE NORTHEAST TOWARDS THE GREAT LAKES...ANOTHER POWERFUL TROUGH IS FORECAST TO DIVE SOUTH THRU THE PLAINS WEDNESDAY NIGHT AND THURSDAY BRINGING A REINFORCING SHOT OF COOL...DRY AIR INTO THE FORECAST AREA. THIS SECONDARY FRONT IS ONLY EXPECTED TO KEEP HIGHS A FEW DEGREES LOWER THAN EARLIER IN THE WEEK AS THERE WILL BE NO TIME IN BETWEEN SYSTEMS FOR ANY RETURN OF MOISTURE. ON FRIDAY...UPPER LEVEL RIDGING LOOKS TO SET UP OVER THE GREAT PLAINS AS ANOTHER STRONG SHORTWAVE TROUGH MOVES ONSHORE THE WESTERN CONUS. THIS SHOULD BRING A RETURN OF SOUTHERLY FLOW TO NORTH TX BY FRIDAY AFTERNOON BRINGING A GRADUAL WARM UP HEADED INTO THE WEEKEND. SATURDAY THROUGH MONDAY...MODELS ARE COMING INTO BETTER AGREEMENT THAT WE WILL HAVE SOME SORT OF STRONG TROUGH TO THE WEST OF TX PROMOTING SOUTHWEST FLOW ALOFT OVER MUCH OF THE STATE. MODELS CONTINUE TO DIFFER ON WHEN EXACTLY THIS TROUGH MAY MOVE NORTHEAST OVER THE STATE PROVIDING GOOD FORCING FOR ASCENT AND PRECIPITATION. REGARDLESS...SOUTHWEST FLOW ALOFT SIGNALS A WETTER THAN AVERAGE PATTERN FOR THE FORECAST AREA...SO HAVE GONE AHEAD WITH SLIGHT CHANCE POPS FOR THE ENTIRE AREA SUNDAY THROUGH MONDAY. IT SEEMS MORE LIKELY THAT NORTH TX WILL SEE ANOTHER COLD FRONT PUSH THROUGH EITHER SUNDAY NIGHT OR INTO EARLY NEXT WEEK...BUT AHEAD OF THAT...SOME GOOD MOISTURE RETURN LOOKS LIKELY AT THIS TIME. COULD SEE SOME ELEVATED TSTM ACTIVITY ACRS THE AREA BY SUNDAY AFTERNOON...AND THEN WOULD EXPECT THE BEST PRECIPITATION CHANCES TO OCCUR ALONG AND BEHIND ANY COLD FRONT THAT MOVES THROUGH THE REGION. TOO MUCH UNCERTAINTY TO PIN DOWN A FRONTAL PASSAGE THIS FAR OUT...SO CHOSE TO HIGHLIGHT SOME CHANCE OF PRECIPITATION FOR THE PERIOD IN GENERAL INSTEAD OF TRYING TO PLACE THE FRONT/BETTER PRECIP CHANCES. CAVANAUGH && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 71 50 62 39 64 / 5 20 5 0 0 WACO, TX 73 52 65 39 64 / 5 20 10 0 0 PARIS, TX 69 47 61 38 61 / 5 30 20 0 0 DENTON, TX 71 43 61 35 64 / 10 20 5 0 0 MCKINNEY, TX 70 45 62 36 63 / 5 20 10 0 0 DALLAS, TX 71 51 62 41 64 / 5 20 5 0 0 TERRELL, TX 71 52 64 39 63 / 5 30 10 0 0 CORSICANA, TX 72 52 65 39 64 / 5 30 20 0 0 TEMPLE, TX 73 53 65 39 64 / 5 20 10 0 0 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ /