RSS FeedsIssued by NWS Paducah, KY
000 FXUS63 KPAH 242114 AFDPAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PADUCAH KY 314 PM CST TUE NOV 24 2009 .SHORT TERM... /TONIGHT THROUGH FRIDAY/ FOR TONIGHT...THE INSTABILITY THAT BROUGHT ISOLATED THUNDERSTORM ACTIVITY TO PART OF THE WFO PAH FORECAST AREA WILL HAVE SHIFTED NORTHWARD CLOSER TO THE UPPER LOW...AS THE LOSS OF DIURNAL HEATING IMPACTS SURFACE/NEAR SURFACE BASED PARCELS. THE RUC/NAM-WRF APPEARS TO BE DOING FAIRLY WELL WITH THE SPACE/TIME ASPECTS OF THE CONVECTIVE LINE CURRENTLY MOVING THROUGH THE QUAD STATE REGION...SO WAS RELIED ON SLIGHTLY MORE WITH THE TRAILING EDGE OF POP/WEATHER CHANCES TONIGHT. FOR WEDNESDAY AND WEDNESDAY NIGHT...THE CURRENT DETERMINISTIC /WITH THE POSSIBLE EXCEPTION OF THE GFS/ MODEL GUIDANCE...AS WELL AS THE SHORT RANGE /SREF/ AND MEDIUM RANGE /GFS...ECMWF/ ENSEMBLES ARE GENERALLY CONSISTENT IN KEEPING SMALL CHANCES FOR PRECIPITATION LIMITED TO SOUTHEAST ILLINOIS...SOUTHWEST INDIANA AND THE PENNYRILE REGION OF WEST KENTUCKY FOR THANKSGIVING DAY AND EVENING. PRECIPITATION TYPE...FOR THE MOST PART WILL BE JUST LIGHT RAIN. THE BEST CHANCE FOR SEEING ANY MIXED /RAIN OR SNOW/ POTENTIAL WILL LIKELY BE LIMITED PART OF SOUTHEAST ILLINOIS AND SOUTHWEST INDIANA IN THE 5-9 AM CST TIME FRAME...THEN AGAIN LATE THURSDAY EVENING NORTH OF THE INTERSTATE 64 CORRIDOR NEAR THE WABASH RIVER. WIND GUSTS ACROSS THIS AREA WILL ALSO BE EXPECTED TO EASILY RANGE IN THE 20 TO 30 MPH...REDUCING WIND CHILLS DOWN TO THE FREEZING MARK. GIVEN THE HIGH TRAFFIC VOLUME AND WELL BELOW ADVISORY THRESHOLD WEATHER FOR THANKSGIVING DAY...I WILL ENHANCE THE HAZARDOUS WEATHER OUTLOOK TO ACCOUNT FOR THE MARGINALLY INCLEMENT WEATHER ELEMENTS. FOR MAX/MIN TEMPERATURES...DEWPOINTS AND WINDS...LEANED CLOSER TO THE NAM-WRF FOR THIS PERIOD. .LONG TERM... /FRIDAY NIGHT THROUGH TUESDAY/ THE FRIDAY NIGHT THROUGH TUESDAY PERIOD LOOKS SIMILAR TO WHAT WE SAW YESTERDAY. HOWEVER...THE DETAILS ARE GOING TO BE TRICKY...AND HAVE A SIGNIFICANT IMPACT ON OUR WEATHER...ESPECIALLY EARLY NEXT WEEK. SATURDAY SHOULD BE THE PICK DAY OF THE WEEKEND...WITH AN UPPER RIDGE OVER OR JUST EAST OF THE QUAD STATE...AND SOUTHERLY RETURN FLOW ALREADY UNDERWAY. THE GULF IS ALREADY OPEN...SO A MORE SIGNIFICANT MOISTURE RETURN WILL BE POSSIBLE. BY SUNDAY...THE ECMWF AND GFS DEVELOP A TROUGH ALOFT FROM THE SOUTHERN ROCKIES/DESERT SOUTHWEST THROUGH THE NORTHERN PLAINS. THIS WILL LEAD TO SOUTHWEST FLOW ALOFT...AND PLENTY OF LOW-LEVEL FLOW COMING FROM THE GULF. CLOUDS WILL BE ON THE INCREASE SATURDAY INTO SUNDAY...AND THE PROBABILITY OF RAIN/SHOWERS WILL BE ON THE INCREASE FROM SOUTHWEST TO NORTHEAST THROUGH THE AREA SATURDAY NIGHT INTO SUNDAY. HEADING INTO NEXT WEEK...AS THE TROUGH ALOFT EVOLVES AND MOVES EAST...AND THE MODELS HAVE INTERMITTENTLY TRIED TO CREATE A CLOSED LOW OUT OF THE BASE OF THAT TROUGH. MOST RECENTLY THE 00Z ECMWF AND THE 06Z GFS DEVELOPED A CLOSED LOW...BUT THE LOCATION AND TIMING OF THE LOW WERE CONSIDERABLY DIFFERENT WHICH LEADS TO SIGNIFICANT DIFFERENCES FOR OUR AREA. FORTUNATELY THERE IS NO SIGNIFICANT COLD AIRMASS FOR THIS POTENTIAL LOW TO WORK WITH...SO ANY SNOW POTENTIAL WILL LIKELY BE TIED TO THE IMMEDIATE TRACK OF THE UPPER LOW. HAVE DECIDED TO FOLLOW HPC GUIDANCE FAIRLY CLOSELY. WILL HAVE A FRONTAL PASSAGE SUNDAY NIGHT INTO MONDAY...AND WILL HAVE HIGHEST POPS FOR THOSE 2 PERIODS. FOR NOW WILL HAVE 40S NORTHWEST INCREASING TO 50S IN THE SOUTHEAST BOTH PERIODS. GIVEN THE POSSIBILITY FOR AN UPPER LOW TO BE SPINNING OFF TO THE EAST/NORTHEAST OF THE AREA...WILL LEAVE LOWER CHANCE POPS IN FOR MONDAY NIGHT AND TUESDAY...FOR POTENTIAL COMMA HEAD/WRAP AROUND PRECIPITATION. HPC POP GUIDANCE IS MUCH TOO HIGH GIVEN THE UNCERTAINTY OF THE DETAILS IN THE FORECAST. EVEN IF THAT EVOLUTION TURNS OUT TO BE CLOSE...THE GOOD MOISTURE RETURN MAY BE ROBBED BY CONVECTION NEAR THE GULF COAST. THEREFORE RAISING SOME DOUBT AS TO THE AMOUNT OF MOISTURE THAT WILL BE AVAILABLE FOR THE FRONT IN OUR AREA. && .AVIATION... PRECIPITATION SHIELD CURRENTLY MOVING THROUGH THE WFO PAH TAF SITES SHOULD EXIT EAST OF THE LAST SITE...KOWB...AFTER 03Z. BY THAT TIME...EACH SITE SHOULD GRADUALLY RISE FROM MVFR TO VFR CEILINGS FOR THE REMAINDER OF THE FORECAST PERIOD. VISIBILITIES SHOULD RETURN TO VFR CATEGORY WITHIN 1-2 HOURS AFTER THE PASSAGE OF THE CONVECTIVE LINE. && .PAH WATCHES/WARNINGS/ADVISORIES... KY...NONE. MO...NONE. IL...NONE. IN...NONE. && $$ LONG TERM PUBLIC...DRS SHORT TERM PUBLIC/AVIATION/FIRE WEATHER...SMITH
