FXUS63 KLMK 281047
AFDLMK
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
547 AM EST SAT NOV 28 2009
...UPDATED AVIATION DISCUSSION...
.SHORT TERM (TODAY AND TONIGHT)...
QUIET SHORT TERM PERIOD AS SFC HIGH PRESSURE OVER THE AREA THIS
MORNING GRADUALLY MOVES EAST TODAY...AND AN UPPER LEVEL RIDGE
FLATTENS AND MOVES OVER THE AREA LATE TODAY. PLENTY OF SUNSHINE IN
STORE FOR TODAY WITH HIGH TEMPERATURES RANGING FROM THE LOW 60S OVER
SOUTH CENTRAL KENTUCKY TO MID 50S OVER THE BLUEGRASS.
TONIGHT...EXPECT MOSTLY CLEAR SKIES WITH CLOUDS BEGINNING TO
INCREASE TOWARD SUNRISE. LOW TEMPERATURES WILL BOTTOM OUT IN THE
LOW 40S WITH A FEW STRAY UPPER 30S POSSIBLE NEAR THE LAKE CUMBERLAND
REGION.
.LONG TERM (SUNDAY - FRIDAY)...
SUNDAY AND MONDAY...
SHARPENING SHRTWV TROF WILL DIG SEWD FROM THE UPR MS VLY SUN INTO
OUR FA MON. ASSOCIATED FRONTAL SYS WILL APPROACH AND MOVE THRU OUR
FA SUN NIGHT WITH A WAVE ON THE BNDRY MOVG THRU THE TN VLY. OUR
CURRENT CATEGORICAL POP FORECAST FOR SUN NIGHT LOOKS GOOD AND
MATCHES UP WELL WITH OUR NEIGHBORS. RAINFALL AMOUNTS SHUD NOT BE
EXCESSIVE WITH THIS PROGRESSIVE SYS...HOWEVER WE HAVE NOT HAD A
SIGNIFICANT RAIN IN A WHILE...THIS SYS LOOKS TO PRODUCE FROM .25 TO
.75 INCH AMOUNTS. WILL MAKE A SUBTLE CHANGE TO SPEED UP THE SYS AND
INCREASE POPS A BIT FOR SUN AFTN BASED ON THE FASTER GFS/HIGH
RESOLUTION NAM/SREF. BY MON MORNING...RAINS SHUD BE MOVG OFF TO OUR
S AND E WITH SFC RIDGE BUILDING IN RAPIDLY FROM THE LOWER/MID MS
VLY.
TEMPS WILL BE MILD ON SUN WITH SW FLO..DESPITE INCREASING
CLOUDS...THEN DROP OFF MON BY SOME 10-15 DEGS IN POST FRONTAL NW
FLO.
FOR THE FOLLOWING PERIOD (TUE-FRI)...NEW RUNS OF THE GFS/EURO ARE
SHOWING THE SAME TRENDS/CONSISTENCY AS THE PREVIOUS RUNS. OUR
CURRENT FCST FAVORS THE MORE CONSISTENT EURO/NOT THE MUCH FASTER
GFS. RAINFALL SHUD NOT REACH OUR FA TIL WED BASED ON BOTH MODELS AS
LOW PRES DEEPENS ACRS THE GULF STATES AND THEN TAKES A TRACK INTO KY
WED NIGHT (EURO) AND CONTS TO DEEPEN WED NIGHT ON ITS NEWD TRACK.
WILL MAKE ONLY SUBTLE CHANGES FOR THE PERIOD...TO LOWER POPS A BIT
FOR WED/WED NIGHT...GIVING SOME CREDENCE TO THE GFS WITH THE LOW
TAKING A MUCH FARTHER E/S TRACK. THIS PUTS OUR FA MORE IN LINE WITH
OUR NEIGHBORS AS WELL. PREVIOUS DISCUSSION FOR THIS PERIOD FOLLOWS:
TUESDAY THROUGH FRIDAY...
FAIRLY ACTIVE WEATHER PATTERN SETTING UP FOR THIS TIME FRAME WITH
THE POTENTIAL FOR A SIGNIFICANT LOW PRESSURE SYSTEM TO MOVE UP THE
WEST SIDE OF THE APPALACHIANS. IN THE UPPER LEVELS THE MODELS ARE
ADVERTISING A FAIRLY FAST NORTHERN BRANCH ACROSS THE NORTHERN CONUS
WITH A CUT OFF LOW DOWN IN THE SOUTHERN STREAM. BY EARLY WEDNESDAY
THE NORTHERN BRANCH QUICKLY DEEPENS AS SHARP HEIGHT RISES OCCUR OVER
THE WESTERN COAST OF CANADA. BY LATE WEDNESDAY THE POTENTIAL IS
THERE FOR THE BRANCHES TO PHASE WITH EACH OTHER AND LEAD TO A STRONG
LOW PRESSURE SYSTEM TO DEVELOP OVER THE SOUTHEAST STATES AND MOVE UP
ALONG THE WEST SIDE OF THE APPALACHIANS.
THE 12Z GFS AND EURO RUNS HANDLE THIS PHASING VERY DIFFERENTLY AS
THE GFS IS FAR MORE PROGRESSIVE AND RESULTS A LOW THAT MOVES ACROSS
THE SOUTHEAST AND THEN OFF THE COAST...A VERY COMMON BIAS OF THE GFS
MODEL. ON THE OTHER HAND...THE 12Z EURO HAS BEEN VERY CONSISTENT
OVER THE LAST FEW RUNS WITH THE PHASING COMING TOGETHER NEAR THE MS
RIVER. WE HAVE TRENDED THE FORECAST CLEARLY ON THE SIDE OF THE EURO
HERE TO MAINTAIN FORECAST CONSISTENCY AND TRENDS.
THE CRUX OF THIS FORECAST WILL HINGE ON THE TIMING AND LOCATION OF
WHERE THE UPPER LEVEL PHASING OCCURS. RIGHT NOW THE 12Z EURO HAS
THE PHASING OCCURING EAST OF THE MISSISSIPPI RIVER WHICH RESULTS IN
A LOW GOING UP THE WESTERN SIDE OF THE APPALACHIANS. THERMAL
PROFILES STAY WARM THROUGH MUCH OF THE EVENT WITH RAIN AS THE MAIN
PRECIPITATION TYPE. HOWEVER...MUCH COLDER AIR LOOKS TO RUSH IN
BEHIND THE SYSTEM RESULTING IN A CHANGEOVER TO SNOW. THE LOW THEN
BOMBS OUT ACROSS WESTERN NY STATE BY THU MORNING. IT SHOULD BE
NOTED THAT IF THE PHASING IS DELAYED AND OCCURS A BIT MORE SOUTH IT
WOULD RESULT IN A SFC TRACK A BIT MORE EAST WITH A BETTER CHANCE OF
THE COLD AIR GETTING IN HERE MORE QUICKLY RESULTING IN A QUICKER
CHANGEOVER TO SNOW. OBVIOUSLY SOMETHING TO WATCH IN THE COMING
DAYS. AFTER THIS SYSTEM PASSES...THE EURO IS STILL ON BOARD WITH A
DECENT COLD SHOT BUILDING INTO THE REGION.
AGAIN...GENERALLY TRENDED TEMPS CLOSE TO THE 2M RAW TEMPS FROM THE
GFS AND EURO SOLUTIONS. HIGHS TUESDAY LOOK TO WARM INTO THE
MID-UPPER 40S WITH LOWS TUE NIGHT IN THE LOWER 30S. AS THE ABOVE
MENTIONED SYSTEM MOVES TOWARD THE REGION HIGH TEMPS ON WED WILL WARM
INTO THE UPPER 40S TO THE LOWER 50S. TEMPERATURES FOR THU MORNING
WILL DEPEND ON THE EXACT TRACK OF THE LOW...SO HAVE GONE WITH BIT OF
A COMPROMISE OF THE 27/00Z AND 27/12Z EURO 2M TEMPS HERE WITH LOWS
IN THE LOWER 30S. CURRENTLY HAVE LOWER 40S IN FOR THU FOR
CONSISTENCY SAKE...BUT IF THE EURO IS RIGHT...WE'LL NEED TO KNOCK
THESE DOWN SIGNIFICANTLY IN LATER FORECASTS. LOWS THU NIGHT LOOK TO
DROP INTO THE UPPER 20S WITH HIGHS ON FRIDAY IN THE MID 30S.
&&
.AVIATION (12Z TAF ISSUANCE)...
SUBSIDENCE AND A DRY AIRMASS WILL ALLOW MOSTLY CLEAR SKIES TO
CONTINUE TODAY. VFR FLYING EXPECTED THROUGH THE TAF PERIOD. EXPECT
LIGHT SOUTH WINDS UP TO 5 MPH THIS MORNING. WINDS WILL INCREASE TO
SSW 8 TO 12 MPH BY EARLY AFTERNOON. EXPECT INCREASING CIRRUS
OVERNIGHT AS THE NEXT SYSTEM APPROACHES FOR LATE SUNDAY AFTERNOON
AND SUNDAY NIGHT.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
SHORT TERM........AML
LONG TERM.........DK
AVIATION..........AML
