HAMweather.com Area Forecast Discussion for County Warning Area JKL

Thu, 16 Feb 2012 11:30:55 GMT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
345 AM EST THU FEB 16 2012

.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 345 AM EST THU FEB 16 2012

WIDESPREAD RAIN SHOWERS HAVE BROKEN OUT ACROSS THE AREA AS A LOW
LEVEL JET RAMPS UP OUT AHEAD OF THE A COLD FRONT CURRENTLY ALIGNED
FROM THE GREAT LAKES DOWN THROUGH TEXAS...WHILE A STRONG UPPER LEVEL
JET RESIDES ACROSS THE OHIO VALLEY.

EXPECT THESE WIDESPREAD SHOWERS TO CONTINUE THROUGH DAWN...AND THEN 
TAPER OFF FROM WEST TO EAST THROUGH THE REST OF THE MORNING. CLOUDS
SHOULD LINGER THROUGH THE REST OF THE DAY AS LOW LEVEL NORTHWEST FLOW
ENSUES BEHIND THE DEPARTING COLD FRONT. GRADUAL CLEARING SHOULD TAKE
PLACE TONIGHT AS HIGH PRESSURE BUILDS IN...ALTHOUGH IF THE POST-
FRONTAL INVERSION IS STRONG ENOUGH...THEN STRATOCU COULD LINGER
THROUGH THE NIGHT. WILL USE A BLEND OF THE GUIDANCE FOR NOW.

HIGH PRESSURE WILL CONTINUE TO CONTROL THROUGH FRIDAY...WITH MOSTLY
SUNNY SKIES AND TEMPERATURES LOOKING TO RECOVER TO THE UPPER 40S AND
LOWER 50S. 

.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 345 AM EST THU FEB 16 2012

THE MODELS...WITH THE ADDITION OF THE LATEST ECMWF...HAVE COME INTO 
BETTER AGREEMENT ALOFT WITH THE CONVERGING STREAMS THIS WEEKEND AND 
BEYOND. THREE SEPARATE WAVES ARE MOVING THROUGH THE EASTERN TWO 
THIRDS OF THE NATION AT THE START OF THE WEEKEND.  A SIGNIFICANT 
ONE DROPPING THROUGH THE GREAT LAKES...A SOUTHERN STREAM ONE MOVING 
THROUGH SOUTHERN TEXAS...AND ANOTHER WEAKER ONE COMING OUT OF THE 
NORTHERN PLAINS. THE NORTHERN STREAM WILL FEED SOME OF ITS ENERGY 
INTO THE APPROACHING SOUTHERN UPPER LOW WHILE THE PLAINS LOW TRAILS 
JUST A TAD BEHIND...AS SEEN IN THE LATEST ECMWF. THERE IS STILL A 
FAIR AMOUNT OF DIFFERENCE SEEN AMONG THE MODELS WITH HOW THIS ALL 
EVOLVES OVER OUR LOCAL AREA EARLY SUNDAY...BUT THE RECENT MODEL 
TRENDS...SUPPORTED BY CLIMATOLOGY...ARE POINTING TOWARD SOMEWHAT 
HIGHER CONFIDENCE IN A MORE INTENSE MID LEVEL LOW CROSSING THE 
SOUTHERN APPALACHIANS. AS SUCH...HAVE GUIDED THE FIRST PART OF THE 
EXTENDED FORECAST SOMEWHAT TOWARDS THE LATEST ECMWF. RIDGING WILL 
THEN FOLLOW THE EXITING TROUGH TO START THE NEW WORK WEEK...BUT A 
PROGRESSIVE PATTERN WILL ALLOW ENERGY FROM THE NEXT FULL LATITUDE 
TROUGH...OVER THE SOUTHERN ROCKIES AND HIGH PLAINS...TO SPREAD 
QUICKLY INTO THE OHIO VALLEY ON TUESDAY. THE SOUTHERN PORTION OF 
THIS WESTERN TROUGH THEN SHARPENS UP AND SWEEPS INTO THE MISSISSIPPI 
VALLEY BY WEDNESDAY MORNING AND THEN INTO THE TENNESSEE AND OHIO 
VALLEY LATER IN THE DAY. THE LATEST ECMWF IS FASTER THAN THE GFS 
WITH THIS DEVELOPMENT...BUT WAS GIVEN A BIT MORE CREDENCE 
CONSIDERING RECENT TRENDS. 

SENSIBLE WEATHER WILL FEATURE A SFC REFLECTION FROM THE APPROACHING 
SOUTHERN STREAM UPPER LOW DEVELOPING AND DEEPENING AS IT CROSSES THE 
SOUTHERN APPALACHIANS FROM MIDDAY SATURDAY THROUGH THE DAY SUNDAY. 
WHILE THE EVENT WOULD LIKELY START OUT AS RAIN...THIS LOW WOULD PULL 
IN ENOUGH COLD AIR BY EARLY SUNDAY TO SWITCH ALL ITS REMAINING PCPN 
OVER TO SNOW WITH SOME ACCUMULATIONS EXPECTED. SHOULD THE LATEST 
ECMWF VERIFY AS IT CAME IN THEN PARTS OF EAST KENTUCKY...FURTHER 
EAST AND AT HIGHER ELEVATIONS...WILL PICK UP SOME SIGNIFICANT SNOW 
ON THE ORDER OF SEVERAL INCHES TO A SOLID HALF FOOT. THE BULK OF ANY 
ACCUMULATING SNOW WOULD BE FROM MIDNIGHT SATURDAY NIGHT INTO NOON 
SUNDAY...BUT THE SNOWS WILL LINGER INTO SUNDAY EVENING IN THE FAR 
EAST AS THE MAIN LOW HITS THE EAST COAST AND UPSLOPE/NORTHWEST FLOW 
CONTRIBUTE TO THE WRAP AROUND PCPN. FOR NOW THOUGH WILL JUST START 
TO INTRODUCE THE IDEA OF ACCUMULATING SNOW BEING A POSSIBILITY AND 
WATCH FUTURE MODEL RUNS FOR THE POTENTIAL NEED TO FIRM UP THE 
DETAILS AND AMOUNTS. CONFIDENCE IS A BIT HIGHER NOW THAT THE ECMWF 
IS COMING ON BOARD...BUT STILL BELOW AVERAGE. WILL LEAVE ANY 
HIGHLIGHTS TO THE HWO FOR NOW. 

HIGH PRESSURE FOLLOWS THE COASTAL LOW AND WILL ALLOW FOR QUIETER... 
DRIER...AND MILDER WEATHER THROUGH THE START OF THE NEW WORK WEEK 
BEFORE RAIN SHOWERS START TO MOVE INTO THE AREA FROM THE WEST LATER 
TUESDAY AHEAD OF A NEW DEVELOPING AREA OF LOW PRESSURE ACROSS THE 
MID MISSISSIPPI VALLEY. THIS LOW LOOKS WEAKER AT THIS POINT THAN THE 
WEEKEND ONE AND IS COMING IN FURTHER NORTH IMPLYING A MORE RAINY 
P-TYPE SCENARIO AS THE COLD AIR REMAINS TOO FAR TO THE NORTH AND 
NORTHWEST. 

THE GRID LOAD CAME IN QUITE REASONABLE FOR MOST ELEMENTS...THOUGH 
WITH THE STRONG JUMP OF THE LATEST ECMWF TOWARD THE FAVORED ENSEMBLE 
SUPPORTED SOLUTION...HAVE ALSO LEANED HARDER THAT WAY WITH THE POP 
AND WX PORTION OF THE EXTENDED. OTHERWISE...MADE JUST SOME MINOR 
CHANGES TO THE TEMPERATURE AND WIND GRIDS...AGAIN MORE TOWARD THE 
LATEST ECMWF.  

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT
1247 AM EST THU FEB 16 2012

RAIN WILL OVERSPREAD THE AREA FROM WEST TO EAST DURING THE
OVERNIGHT...HOWEVER VFR CONDITIONS WILL PREVAIL THROUGH DAWN. A LOW
LEVEL JET WILL BRING THE THREAT OF LOW LEVEL WIND SHEAR DURING THE
OVERNIGHT AND HAVE INCLUDED IN THE 06Z TAF ISSUANCE. CEILINGS WILL
DROP INTO THE MVFR AND EVENTUALLY IFR RANGE THROUGH THE MORNING AS
A COLD FRONT MOVES ACROSS THE AREA. CEILINGS WILL IMPROVE TO MVFR
DURING THE AFTERNOON AND THEN EVENTUALLY SCATTER OUT TOWARDS DUSK OR
SLIGHTLY THEREAFTER. 

.JKL WATCHES/WARNINGS/ADVISORIES...NONE.