000 FXUS63 KJKL 241556 AFDJKL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 1056 AM EST TUE NOV 24 2009 .SHORT TERM.../THE REST OF TODAY/...UPDATED REMOVED SOME OUTDATED WORDING FROM THE TODAY PERIOD. LATEST VIS SATELLITE IMAGERY SHOWS A LARGE SWATH OF LOW AND MIDDLE LEVEL CLOUDS ENSHROUDING MOST OF THE EASTERN UNITED STATES AND AN AREA OF CLEARING JUST EAST AND SOUTH OF THE FORECAST AREA. FEEL LIKE WITH THE AMOUNT OF LOW LEVEL MOISTURE IN PLACE...AND ANOTHER WEATHER SYSTEM APPROACHING QUICKLY FROM THE WEST...THAT THE CURRENT CLOUD COVER WILL BE SLOW TO EXIT EASTERN KENTUCKY...AND THAT THE CLEAR AREA CURRENTLY SHOWING UP ON RADAR WILL FILL IN SOMEWHAT AS THE DAY PROGRESSES. AFTER INGESTING HOURLY TEMPERATURE OBS INTO THE FORECAST GRIDS IT HAS BECOME APPARENT THAT TODAYS TEMPERATURES ARE A FEW DEGREES COOLER THAN THE FORECAST TEMPS. WITH THAT IN MIND...AND WITH PARTLY TO MOSTLY CLOUDY SKIES EXPECTED TO PERSIST THROUGHOUT THE DAY...DECIDED TO DECREASE TODAYS HIGHS BY A DEGREE OR SO ACROSS THE BOARD. ALSO CONTINUED WITH THE TREND OF GENERALLY MOSTLY CLOUDY SKIES FOR MOST OF THE DAY. THE UPDATED ZONE FORECAST TEXT PRODUCT WILL BE ISSUED SHORTLY. THE PREVIOUS SHORT TERM FORECAST DISCUSSION FOLLOWS... /TODAY THROUGH WEDNESDAY/ 07Z SFC ANALYSIS SHOWS A WEAK PRESSURE PATTERN OVER EAST KENTUCKY AS A BROAD AND INEFFECTUAL AREA OF HIGH PRESSURE IS STRADDLING THE SOUTHERN APPALACHIANS. TO THE WEST...A LOW PRESSURE CENTER IS FOUND SPINNING OUT OF THE PLAINS AND INTO THE MID MISSISSIPPI VALLEY. PLENTY OF LOW LEVEL MOISTURE IN PLACE THROUGH EAST KENTUCKY HAS RESULTED IN A LAYER OF STRATUS BLANKETING THE CWA...KEEPING TEMPERATURES ABNORMALLY MILD OVERNIGHT WITH NARY A STIRRING OF THE WIND. PATCHY FOG IS FOUND IN THE CUMBERLAND VALLEY AND THIS MAY BE A SIGN OF WHAT IS TO COME FOR THE REST OF THE AREA TOWARDS DAWN. FOR NOW...THOUGH...WILL CONTINUE TO PLAY IT BY EAR AS FOR HOW HARD TO HIT THE FOG OVER THE COMING HOURS...BUT LIKELY WILL HANDLE IT MAINLY WITH JUST A NOWCAST SHOULD IT BE DEEMED SIGNIFICANT IN ANY PARTICULAR AREA. THE MODELS ARE IN RELATIVELY GOOD AGREEMENT ALOFT WITH THE CLOSED LOW OVER THE PLAINS ROLLING INTO THE MIDWEST ON A NORTHEAST TRAJECTORY... OPENING UP LATER TONIGHT. THIS WAVE WILL LOSE MUCH OF ITS PUNCH AS IT SETTLES INTO THE WESTERN GREAT LAKES AND OHIO VALLEY BY WEDNESDAY MORNING. IT WILL ULTIMATELY FADE OUT IN THE FACE OF A DEEPER... DEVELOPING...AND REINFORCING LOW DROPPING SOUTH THROUGH THE NORTHERN PLAINS AND INTO THE CORN BELT BY WEDNESDAY EVENING. HAVE FOLLOWED A BLEND OF THE MOST SIMILAR NAM AND ECMWF SOLUTIONS FOR THESE UPPER LOWS. AS A RESULT...ANTICIPATE TROUGHING TO SPREAD OVER KENTUCKY LATER TONIGHT WITH A WEAKENING STREAM OF ENERGY PASSING THROUGH AROUND DAWN WEDNESDAY. THE TROUGH THEN EASES UP SOMEWHAT LATER WEDNESDAY AS HEIGHTS TEMPORALLY RISE AHEAD OF THE NEXT PLUNGING UPPER LOW. SENSIBLE WEATHER WILL FEATURE A MILDER DAY THANKS TO A RETURN OF SOME SUNSHINE ANTICIPATED DURING THE MIDDAY AND AFTERNOON HOURS... ONCE THE MORNING FOG AND STRATUS BURNS OFF. SOUTH WINDS AHEAD OF THE APPROACHING...BUT WEAKENING COLD FRONT WILL KEEP READINGS MILD FOR THE MOST PART TONIGHT WITH A SMALL...5 TO 7 DEGREE...RIDGE TO VALLEY TEMPERATURE SPLIT ANTICIPATED. THIS BOUNDARY PASSES THROUGH LATE TONIGHT AND INTO EARLY WEDNESDAY MORNING WITH A SMALL CHANCE OF SHOWERS FOLLOWED BY RENEWED CAA IN ITS WAKE. AS A RESULT...HAVE GONE WITH A MODEL DERIVED DIURNAL CURVE FOR TEMPERATURES TONIGHT AND WEDNESDAY...THOUGH STILL EXPECT A BIT OF A RISE IN THE EARLY AFTERNOON WITH SOME RETURNING SUNSHINE LIKELY TO COUNTERACT THE COOLER AIR BROUGHT IN ON MORE WESTERLY WINDS. UNDERCUT MOS GUIDANCE FOR HIGHS TODAY DUE TO A START OF THE DAY FEATURING FOG AND PLENTY OF CLOUDS. FOR TONIGHT...WAS SIMILAR TO GUIDANCE AT THE CCF POINTS...THOUGH WITH MORE OF A RIDGE AND VALLEY TEMPERATURE DIFFERENCE REPRESENTED...PARTICULARLY IN THE EAST. ALSO UNDERCUT MOS HIGHS ON WEDNESDAY DUE PRIMARILY TO UNDERREPRESENTED CAA BEHIND THE FRONT. AS FOR POPS...ENDED UP A TAD ABOVE GUIDANCE FOR LATE TONIGHT INTO WEDNESDAY GIVEN THE HEIGHT FALLS AND EXPECTATION OF ISOLATED TO SCATTERED SHOWERS ACCOMPANYING THE BOUNDARY. .LONG TERM.../WEDNESDAY NIGHT THROUGH MONDAY/ TWO STORM SYSTEMS ARE POISED TO AFFECT THE AREA OVER THE PERIOD AS A PROGRESSIVE PATTERN OVERTAKES THE CONUS TO END THE MONTH. FORECAST MODELS ARE IN GOOD AGREEMENT WITH THE SYNOPTIC PATTERN EARLY IN THE PERIOD BEFORE MODEL SPREAD INCREASES LATE IN THE WEEKEND AND EARLY NEXT WEEK. WE ARE FAIRLY CONFIDENT HOWEVER THAT THE MONTH WILL END WITH A COOL AND RATHER UNSETTLED WEATHER PATTERN IN PLACE ACROSS EAST KENTUCKY. THE FIRST SYSTEM CONTINUES TO LOOK MOISTURE STARVED AND THE BEST CHANCES FOR PRECIP WILL ACTUALLY BE POST-FRONTAL... THURSDAY NIGHT INTO FRIDAY MORNING AS UPSLOPE FLOW COMBINES WITH PASSING UPPER TROUGH TO SQUEEZE OUT ISOLATED TO SCATTERED SHOWERS. DECENT COLD AIR ADVECTION BEHIND THE FRONT THURSDAY AFTERNOON/EVENING SHOULD RESULT IN FALLING TEMPS FROM THE MORNING HIGHS. MODEL TIME/HEIGHTS INDICATE CLOUD TOP TEMPS WILL SUPPORT SNOW GROWTH BY THURSDAY EVENING BUT I AM NOT SURE JUST HOW COLD BOUNDARY LAYER TEMPS WILL GET THURSDAY NIGHT/FRIDAY MORNING WITH A LOT OF MIXING AND CLOUD COVER. THUS PRECIP TYPE MAY TEND TO FAVOR RAIN IN OUR VALLEYS THROUGH MUCH OF THE NIGHT... BUT A TREND TOWARD SNOW SHOULD TAKE OVER QUICKLY WITH ANY ELEVATION AFTER SUNSET THURSDAY. ANY RAIN AND/OR SNOW SHOWERS WILL THEN END QUICKLY FRIDAY EVENING AS MOISTURE THINS OUT RAPIDLY AND RIDGING BUILDS IN SURFACE AND ALOFT. RIDGING WILL THEN PROVIDE A DRY SATURDAY BUT PROGS INDICATE THE NEXT SYSTEM DIGGING INTO THE PLAINS WILL BRING INCREASINGLY MOIST SOUTHWEST FLOW INTO THE TENNESSEE/OHIO VALLEYS BY SUNDAY. TEND TO FAVOR A QUICKER ONSET TO RAIN CHANCES... A LA THE 24/00Z ECMWF AND EARLIER NCEP ENSEMBLE MEAN... THUS WILL OFFER RAIN CHANCES AS EARLY AS SUNDAY WITH SOLID RAIN CHANCES SUNDAY NIGHT AND MONDAY. EXPECT CLOUD COVER TO HINDER OUR WEEKEND WARM UP AND HELD DAYTIME TEMPS SATURDAY THROUGH MONDAY BELOW 24/00Z GFSX GUIDANCE NUMBERS. A LESS PROGRESSIVE SYSTEM LEADING TO MORE/LONGER RIDGING OVER OUR AREA LATE IN THE PERIOD WOULD HURT THIS FORECAST. && .AVIATION.../12Z TO 12Z/ PLENTY OF RESIDUAL LOW LEVEL MOISTURE REMAINS ACROSS THE AREA. THE LOWER CIGS AND BR HAS CREPT INTO THE WESTERN FRINGE OF THE CWA DURING THE PREDAWN HOURS...BUT THE FOG HAS NOT GOTTEN DENSE AS FAR AS WE CAN TELL VIA THE OBS AND WEB CAMS. DO NOT EXPECT TO SEE THIS AREA MAKE MUCH MORE PROGRESS EAST BEFORE CIGS AND VIS IMPROVE ACROSS THE BOARD. THOUGH...HAVE INCLUDED A TEMPO FOR THIS TRANSITION AT THE TAF SITES THROUGH 14Z. EVENTUALLY VFR CONDITIONS ARE EXPECTED TO RETURN EVERYWHERE DURING THE AFTERNOON. LATER THIS EVENING...JUST SCT CLOUDS ARE ANTICIPATED FOR SEVERAL HOURS BEFORE THE SKY CLOUDS UP AGAIN WITH THE APPROACH AND PASSAGE OF A MOISTURE CHALLENGED COLD FRONT. HAVE BROUGHT CIGS BACK INTO THE FORECAST FOR THIS AS WELL AS ADDED A VCSH TO THE TAFS FROM 06Z ON TO THE END OF THE PERIOD. WINDS WILL BE LIGHT AND VARIABLE THROUGH MOST OF THE DAY WITH AN INCREASE EXPECTED FROM THE SOUTH AT NEAR 10 KTS DURING THE EVENING ASSOCIATED WITH THE APPROACHING COLD FRONT. ACCOMPANYING THE FRONT...AND JUST BEHIND IT...WINDS COULD GET GUSTY...APPROACHING 20 KTS DURING THE PREDAWN HOURS OF WEDNESDAY. && .JKL WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...GREIF/AR LONG TERM....ABE AVIATION...GREIF