579 FXUS63 KPAH 100855 AFDPAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PADUCAH KY 355 AM CDT FRI AUG 10 2012 .UPDATE... ISSUED AT 355 AM CDT FRI AUG 10 2012 A LARGE AREA OF LOW CLOUDS HAS DEVELOPED OVER CENTRAL ILLINOIS AND IS CURRENTLY JUST BEGINNING TO OVERSPREAD THE I-64 CORRIDOR. FIGURE THAT THIS WILL CONTINUE TO PUSH SOUTH THROUGH SUNRISE...AND THEN MIXING SHOULD STOP ITS PROGRESS AND EVENTUALLY SCATTER IT OUT. TRIED TO ADJUST SKY GRIDS FOR THIS OCCURRENCE. REDUCED POPS TO SLIGHT CHANCES ALONG THE SOUTHERN BORDER AND KILLED THEM OFF A COUPLE HOURS AFTER SUNRISE. ALSO TRENDED UPWARD WITH TEMPERATURES AS PLENTY OF CLOUD COVER AND WIND TO KEEP TEMPERATURES FROM DROPPING MUCH. THE AVIATION SECTION HAS BEEN UPDATED. && .SHORT TERM...(TODAY THROUGH SUNDAY NIGHT) ISSUED AT 355 AM CDT FRI AUG 10 2012 THE DROUGHT CERTAINLY WON ANOTHER BATTLE LAST NIGHT...AS MUCH OF THE AREA RECEIVED LITTLE IF ANY RAINFALL. THE MODELS ARE IN PRETTY GOOD AGREEMENT IN KEEPING THE AREA VERY DRY THROUGH SUNDAY...BUT THEY DIVERGE IN TIMING A MID/UPPER LEVEL SYSTEM THROUGH THE REGION IN THE SUNDAY NIGHT TO MONDAY TIME FRAME. SURFACE HIGH PRESSURE WILL BUILD INTO THE REGION AS THE UPPER LEVEL STORM SYSTEM WRAPS UP OVER THE SOUTHERN GREAT LAKES. THIS WILL RESULT IN NORTH NORTHWEST WINDS GUSTING WELL INTO THE TEENS FOR MUCH OF THE DAY...AND THEY WILL USHER IN A VERY DRY AND COOLER AIR MASS. AS STATED ABOVE...A SWATH OF LOW CLOUDS WILL OVERSPREAD MUCH OF THE AREA EAST OF THE MISSISSIPPI EARLY THIS MORNING...AND THEN SCATTER AND PUSH EAST BY MIDDAY. THIS CERTAINLY COULD HAVE AN ADDITIONAL COOLING INFLUENCE ON TEMPERATURES TODAY. HOWEVER...FOR NOW WILL KEEP LEANING TOWARD THE WARMER NAM AND ECMWF TEMPERATURES...WHICH RESULTS IN A PRETTY GOOD GRADIENT FROM NORTHEAST TO SOUTHWEST THROUGH THE FORECAST AREA. THE MODELS BRING AN IMPULSE AROUND THE UPPER LOW AND THROUGH THE EVANSVILLE TRI STATE AREA LATE THIS AFTERNOON AND EARLY THIS EVENING. MODEL SOUNDINGS FROM THE 00Z NAM INDICATE A SHALLOW LAYER OF INSTABILITY FROM AROUND 850MB TO 650MB...BUT DEEP LAYER INSTABILITY IS NOT EXPECTED. CANNOT RULE OUT A FEW LIGHT SHOWERS OR SPRINKLES OVER THE NORTHEAST...BUT WILL NOT MENTION IN THE FORECAST AT THIS TIME. THE NAM IS THE MOST AGGRESSIVE IN TRYING TO GENERATE ANY SHOWERS...AND IT IS IFFY. SKIES SHOULD CLEAR QUICKLY THIS EVENING...AS THE IMPULSE PUSHES EAST OF THE AREA...AND SURFACE HIGH PRESSURE SETTLES OVERHEAD. DEWPOINTS WILL BE WELL INTO THE 50S TONIGHT...SO WITH GOOD RADIATIONAL COOLING EXPECTED OVERNIGHT...TEMPERATURES SHOULD PLUMMET INTO THE 50S IN THE VICINITY OF CONSENSUS GUIDANCE. WOULD NOT BE AT ALL SURPRISED TO SEE LOW TO MID 50S IF THE WINDS DIE OFF FAST ENOUGH. SATURDAY WILL BE VERY DRY WITH LIGHTER NORTH WINDS. PUSHED THE FORECAST TOWARD THE WARMER AND DRIER NAM AND ECMWF ONCE AGAIN. MUCH OF THE AREA SHOULD SEE DEWPOINTS WELL INTO THE 40S IN THE AFTERNOON. WITH DRY FUELS AND RH/S IN THE 20S IT IS QUITE FORTUNATE THAT THE WINDS WILL BE UNDER 10 MPH...OR WE WOULD BE LOOKING AT A RED FLAG DAY. AS IT IS...FIRE DANGER WILL BE ELEVATED. SURFACE HIGH PRESSURE WILL BEGIN TO SHIFT EAST OF THE AREA SATURDAY NIGHT...BUT WINDS WILL STILL BE LIGHT...SO TEMPERATURES SHOULD PLUMMET INTO THE 50S ONCE AGAIN...ESPECIALLY IN THE EAST. CONSENSUS GUIDANCE SHOULD NOT BE FAR OFF. CLOUDS WILL BE ON THE INCREASE AS THE FLOW ALOFT BECOMES MORE ZONAL AND A MID/UPPER LEVEL DISTURBANCE SHIFTS EASTWARD TOWARD THE REGION SUNDAY. WITH SOUTHERLY WINDS DEVELOPING OVER THE AREA...AND STILL PLENTY OF SUNSHINE...TEMPERATURES SHOULD SOAR TOWARD THE WARM NAM/ECMWF ONCE AGAIN. MANY AREAS WILL SEE TEMPERATURES BACK INTO THE LOWER 90S. THE GFS...GEM AND ECMWF DIFFER IN THE TIMING OF THE DISTURBANCE...AND THE PLACEMENT OF QPF SUNDAY NIGHT. WITH THE DRY AIRMASS PLUNGING WELL TO OUR SOUTH...WOULD EXPECT MOISTURE TO BE LACKING AHEAD OF THIS SYSTEM. WILL LEAVE A SLIGHT CHANCE ALONG THE WEST/NORTHWEST EDGE OF THE FORECAST AREA...BUT INDICATE MAINLY AN INCREASE IN MID AND UPPER LEVEL CLOUDS. SOUTH WINDS AND INCREASED CLOUD COVER SHOULD LEAD TO A MUCH MILDER NIGHT. .LONG TERM...(MONDAY THROUGH THURSDAY) ISSUED AT 355 AM CDT FRI AUG 10 2012 NEXT WEEK WILL START OFF WITH A RETURNING SOUTHERLY FLOW AS SURFACE HIGH PRESSURE DEPARTS TO THE EAST. ZONAL TO NORTHWEST FLOW ALOFT WILL PREVAIL THROUGH MUCH OF THE WEEK...SO THIS SHOULD KEEP TEMPERATURES FROM CLIMBING TOO DRASTICALLY. WEAK SHORTWAVE ENERGY OVER THE PLAINS WILL DRIFT EAST...BRINGING A SMALL CHANCE OF SHOWERS AND THUNDERSTORMS TO PORTIONS OF THE AREA MONDAY...LINGERING ACROSS THE SOUTHEAST SECTIONS MONDAY NIGHT. UNFORTUNATELY THIS SYSTEM DOES NOT APPEAR TO BE A SIGNIFICANT RAIN MAKER AS FORECAST SOUNDINGS SUGGEST THE BEST MOISTURE WILL REMAIN ALOFT...AND MID LEVEL FORCING WILL BE QUITE MEAGER. WITH THE DEPARTURE OF THIS SYSTEM...A PERIOD OF DRY WEATHER SHOULD TAKE HOLD STARTING MONDAY NIGHT AND CONTINUING INTO WEDNESDAY ACROSS MUCH OF THE AREA. THE PASSAGE OF A WEAK FRONT MONDAY NIGHT MAY ACTUALLY SERVE TO KEEP A LID ON TEMPERATURES TUESDAY. HOWEVER... MOS GUIDANCE STILL LOOKS SEVERAL DEGREES TOO COOL. WEDNESDAY HAS THE POTENTIAL TO BE THE WARMEST DAY OF THE WEEK...AS HIGHS MAY REACH THE LOWER 90S IN MOST LOCATIONS. I SAY...HAS THE POTENTIAL...BECAUSE THERE IS SOME DISAGREEMENT AMONG MODELS AS TO HOW QUICKLY THE MID WEEK SYSTEM ARRIVES. THE LATEST 10/00Z ECMWF HAS JOINED ITS GEM/CANADIAN COUNTERPART IN ACCELERATING SHORTWAVE ENERGY INTO THE REGION AS EARLY AS LATE TUESDAY NIGHT. MEANWHILE...THE 10/00Z GFS AND 09/12Z ECMWF...IN CONCERT WITH THE GFS...ECMWF...AND GEM ENSEMBLE MEAN...MAINTAIN A SLOWER SOLUTION. WE GENERALLY UTILIZED THE LATTER IN THE COMPOSITION OF THIS FORECAST PACKAGE. AS A RESULT...SMALL PRECIPITATION CHANCES EXIST MAINLY ALONG AND WEST OF THE MISSISSIPPI RIVER ON WEDNESDAY...WITH A BETTER CHANCE FOR SHOWERS AND THUNDERSTORMS AREA WIDE WEDNESDAY NIGHT AND THURSDAY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 355 AM CDT FRI AUG 10 2012 AMENDED KEVV TO ADD IFR CEILINGS THAT ARE MARCHING QUICKLY SOUTHWARD AND EXPANDING. SHOULD ARRIVE AT KEVV AROUND 0930Z...LINGER TIL AROUND 14Z AND THEN BEGIN TO SCATTER OUT AND LIFT. OWENSBORO MAY ALSO NEED UPDATING PRIOR TO THE 12Z TAF ISSUANCE...BUT WILL GIVE IT ANOTHER HOUR BEFORE MAKING THAT DECISION. OTHER THAN GUSTY NORTH OR NORTHWEST WINDS MIXING DOWN LATER TODAY...THE FATE OF THIS LOW CLOUD DECK IS THE ONLY MAJOR CONCERN TO AVIATION FOR THE 12Z TAFS. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...NONE. MO...NONE. IN...NONE. KY...NONE. && $$ UPDATE...DRS SHORT TERM...DRS LONG TERM....RP AVIATION...DRS