FXUS63 KLMK 100809
AFDLMK
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
309 AM EST THU DEC 10 2009
.SHORT TERM (TODAY AND TONIGHT)...
HIGH PRESSURE WILL BUILD IN FROM THE WEST OVER THE COURSE OF THE
SHORT TERM...AND WILL BE CENTERED OVER KENTUCKY AND TENNESSEE BY 12Z
FRIDAY.
SCATTERED CLOUDS AND A FLURRY OR TWO WILL STILL BE POSSIBLE THROUGH
MID MORNING...ESPECIALLY IN THE BLUE GRASS...BUT FROM LATE THIS
MORNING THROUGH TONIGHT EVERYONE SHOULD SEE CLEAR SKIES.
THE GRADIENT BETWEEN HIGH PRESSURE OVER THE OZARKS TODAY AND LOW
PRESSURE OVER QUEBEC WILL REMAIN TIGHT THIS MORNING AND THEN RELAX
QUITE A BIT THIS AFTERNOON. HOWEVER WITH FULL SUNSHINE MIXING
HEIGHTS WILL REACH THREE TO FOUR THOUSAND FEET AND WILL BE ABLE TO
MIX DOWN BRISK WINDS EVEN AS THE SURFACE GRADIENT LESSENS. SO WILL
KEEP WEST WINDS UP THROUGH THE DAY AT SUSTAINED SPEEDS OF 10 TO 20
MPH IN THE NORTH...10 TO 15 MPH IN THE SOUTH...WITH WIND GUSTS OF 24
TO 29 MPH IN THE NORTH...18 TO 24 MPH IN THE SOUTH. WIND CHILLS
WILL MOSTLY BE IN THE TEENS TODAY...WITH SOME SINGLE DIGITS POSSIBLE
IN THE NORTH ESPECIALLY THIS MORNING.
THE WINDS WILL DROP OFF DRAMATICALLY ONCE THE SUN SETS THIS EVENING.
THERE WILL BE PLENTY OF SUNSHINE TODAY AND WINDS WILL BE FROM THE
WEST...RATHER THAN FROM THE NORTHWEST OFF THE MIDWEST SNOWPACK.
CLOUDS AND WINDS PREVENTED TEMPERATURES THIS MORNING FROM COMPLETELY
BOTTOMING OUT. SO...WILL ALLOW THE MERCURY TO CLIMB SEVERAL DEGREES
TODAY GENERALLY INTO THE UPPER 20S AND LOWER 30S...WHICH IS IN LINE
WITH THE SPC WRF PROG.
THE NEXT QUESTION BECOMES HOW COLD IT WILL GET TONIGHT. HIGH
PRESSURE WILL BE CENTERING ITSELF RIGHT OVERHEAD LATE TONIGHT AND
WILL BRING WINDS DOWN TO ZERO IN THE SOUTH AND AROUND 5 TO 10 MPH IN
THE NORTH WITH CLEAR SKIES OTHER THAN A FEW PATCHES OF HIGH THIN
CIRRUS TOWARDS DAWN. THIS WILL LEAD TO EXCELLENT RADIATIONAL COOLING
CONDITIONS. HOWEVER THE HIGH WILL BE COMING TO US FROM THE SNOW-FREE
OZARKS RATHER THAN FROM OFF OF THE DEEP SNOWPACK TO OUR NORTHWEST.
STILL...IN GOOD RADIATIONAL COOLING SCENARIOS IT CAN BE DIFFICULT TO
GO TOO COLD...AND MOS RARELY GOES COLD ENOUGH. DEW POINTS ARE
PROGGED DOWN INTO THE SINGLE DIGITS. SO...WILL TAKE
TEMPERATURES DOWN INTO THE LOWER AND MIDDLE TEENS WHICH IS COLDER
THAN MOS GUIDANCE AND THE SPC WRF. AT LMK WE HAVE A TOOL THAT WE USE
TO DELINEATE FOG AREAS WHEN RADIATIONAL FOG IS EXPECTED TO FORM IN
VALLEYS AND OTHER FOG PRONE SPOTS. WHILE FOG IS NOT EXPECTED TONIGHT
THANKS TO THE VERY DRY AIR COMING IN...WE USED THE FOG TOOL INSTEAD
TO TAKE TEMPERATURES DOWN A COUPLE EXTRA DEGREES IN THOSE AREAS
WHERE SHELTERED VALLEYS WILL GET COLDER THAN THE REST OF THE AREA AS
A WHOLE.
.LONG TERM (FRIDAY - WEDNESDAY)...
FRIDAY THROUGH SUNDAY NIGHT...
SHORT TO MEDIUM RANGE GUIDANCE SEEMS TO BE CONVERGING ON AN
AGREEABLE FORECAST SOLUTION IN THIS TIME PERIOD OF THE FCST. SFC
HIGH PRESSURE IS FCST TO BE OVER THE TOP OF THE OHIO VALLEY FRIDAY
MORNING AND WILL SLOWLY DRIFT EASTWARD DURING THE DAY AND INTO
SATURDAY. AFTER A COLD START TO THE MORNING...TEMPERATURES WILL
MODERATE SOME OVER THURSDAY'S HIGHS. WE WILL CONTINUE TO GO BELOW
GUIDANCE HERE AND STICK CLOSE TO THE RAW 2M TEMPS FROM THE
GFS...THOUGH WE WILL MIX IN A LITTLE OF THE EURO HERE AS WELL.
HIGHS FRIDAY AFTERNOON SHOULD WARM INTO THE LOWER 30S IN THE NORTH
WITH MID TO UPPER 30S ACROSS THE SOUTH. LOWS FRIDAY NIGHT WILL SEE
A GRADIENT OF TEMPERATURE AS SOUTHERLY SFC FLOW BECOMES MORE
ESTABLISHED TO OUR WEST AND SLIDES EASTWARD. LOWS WILL RANGE FROM
THE UPPER TEENS TO THE LOWER 20S OVER THE BLUEGRASS TO THE MID 20S
OVER THE SOUTHWEST.
BY SATURDAY...LOWERING H5 HEIGHTS ACROSS THE WESTERN UNITED STATES
WITH LEAD TO A DOWNSTREAM INCREASE IN HEIGHTS ACROSS THE EASTERN
THIRD OF THE NATION...INCLUDING THE OHIO VALLEY. WITH RISING
HEIGHTS AND MORE OF A SOUTHWESTERLY FLOW ALOFT...WE'LL BE AWAITING
THE APPROACH OF A SOUTHERN STREAM SYSTEM. THE TRENDS IN THE MODEL
DATA HAVE BEEN FOR A SLOW APPROACH OF PRECIPITATION INTO OUR REGION
WITH THIS SYSTEM. BOTH THE 10/00Z GFS AND EURO ARE IN GENERAL
AGREEMENT IN KEEPING THINGS DRY THROUGH MUCH OF SATURDAY WITH
INCREASING PRECIPITATION CHANCES BEGINNING SATURDAY EVENING. WITH
THE INCREASING SOUTHERLY FLOW...TEMPERATURES WILL REALLY MODERATE
RATHER SWIFTLY WITH HIGHS SATURDAY WARMING INTO THE UPPER 30S TO THE
LOWER 40S. PRECIPITATION WILL GRADUALLY INCREASE IN COVERAGE
SATURDAY NIGHT AND EARLY SUNDAY. HAVE INCREASED POPS SLIGHTLY HERE
BASED ON THE LATEST TRENDS. PRECIPITATION TYPE ISSUES SEEM TO BE
MORE RESOLVED HERE IN THE MODELING DATA ARGUING FOR A WARMER
SOLUTION. CRITICAL THICKNESSES AND NEAR SFC TEMPS APPEAR TO BE
WARM ENOUGH FOR ALL RAIN WITH THIS SYSTEM. HIGHEST POPS WILL BE SAT
NIGHT AND EARLY SUNDAY WITH A GRADUAL WINDING DOWN OF PRECIP ON
SUNDAY. LOWS SAT NIGHT ARE FORECAST TO COOL INTO THE LOWER-MID 30S
WITH HIGHS ON SUNDAY WARMING INTO THE LOWER-MID 40S IN THE NORTH AND
MID 40S ACROSS THE SOUTH. NEXT WEATHER SYSTEM WILL APPROACH THE
REGION LATE IN THE PERIOD. SOUTHWESTERLY FLOW AT THE SFC AND ALOFT
WILL KEEP TEMPS FROM DROPPING OFF TOO MUCH SUNDAY NIGHT WITH LOWS
ONLY DROPPING INTO THE UPPER 30S TO THE LOWER 40S.
MONDAY THROUGH WEDNESDAY...
ANOTHER SYSTEM IS FORECAST TO TRAVERSE THE CONUS IN THE SOUTHERN
STREAM AT THE BEGINNING OF THE PD. AT THE SAME TIME...NORTHERN
STREAM TROUGH WILL SEND A COLD FRONT SOUTHEAST TOWARD THE REGION.
MOSTLY CLOUDY CONDITIONS SEEM REASONABLE FOR MONDAY AS WARM AIR
ADVECTION SCHEME SHOULD KEEP LOTS OF MID-HIGH LEVEL CLOUDS IN THE
REGION. SOME ISO-SCT SHOWERS WILL BE POSSIBLE AS WELL...BUT BETTER
CHANCES OF PRECIPITATION LOOK TO OCCUR MONDAY NIGHT AND TUESDAY AS
SFC FRONT PUSHES THROUGH AND MOISTURE TRANSPORT OUT OF THE SOUTH
THANKS TO THE SOUTHERN STREAM SYSTEM CONVERGE ON THE AREA. WILL
KEEP CHC POPS IN THE FCST FOR MON NIGHT AND TUESDAY WITH DRYING
CONDITIONS FOR TUE NIGHT AND WED. LATEST MODEL TRENDS HAVE
CONTINUED TO TREND WARMER DURING THIS TIME FRAME AND MUCH...IF
NOT ALL PRECIP WILL FALL IN THE FORM OF RAIN. THERE IS SOME SPREAD
BETWEEN THE GFS AND EURO WITH RESPECT TO THE COOL DOWN BEHIND THIS
FRONT FOR LATE TUE/WED. FOR NOW...HAVE TRENDED THE FCST CLOSER TO
THE 10/00Z EURO AND DID NOT GO AS BULLISH ON COOLER TEMPS FROM THE
GFS...AS ITS UPPER LEVEL SOLUTION SEEMS A BIT TOO AMPLIFIED.
FOR NOW WILL KEEP HIGHS TUESDAY IN THE LOWER 40S IN THE NORTH AND
MID-UPPER 40S ACROSS THE FAR SOUTH. HAVE RAISED LOWS FOR WED
MORNING BASED ON THE EURO SOLNS WITH LOWS IN THE LOWER-MID 30S.
HIGHS ON WED LOOK TO BE A LITTLE WARMER WITH HIGHS IN THE LOWER 40S
IN THE NORTH WITH MID-UPPER 40S IN THE SOUTH.
&&
.AVIATION (06Z TAF ISSUANCE)...
STRONG AREA OF SFC LOW PRESSURE CONTINUES TO MOVE NORTHEAST INTO
SOUTHERN CANADA THIS EVENING. STRONG PRESSURE GRADIENT CONTINUES TO
KEEP WINDS UP TONIGHT...BUT THE OVERALL TRENDS SHOW THAT SPEEDS AND
GUSTS HAVE COME DOWN IN THE LAST FEW HOURS. GRADIENT IS EXPECTED TO
STAY TIGHT TONIGHT...SO SUSTAINED WEST TO WEST-SOUTHWEST WINDS OF
12-16KTS WITH GUSTS OF 18-22KTS WILL BE POSSIBLE THROUGH THE NIGHT.
IN TERMS OF SKY COVER...KBWG WILL LIKELY BE THE FIRST TO BREAK OUT
INTO THE CLEAR LATER THIS MORNING AS DEEPER MOISTURE PULLS NORTHEAST
WITH TIME. CIGS AT KSDF AND KLEX ARE FORECAST TO REMAIN IN THE VFR
CATEGORY OVERNIGHT WITH CIGS RUNNING BETWEEN 030-035. A FEW LIGHT
SNOW FLURRIES WILL ALSO BE POSSIBLE...BUT NOTHING THAT WOULD REDUCE
VSBYS AT THE TERMINALS. CIGS LOOK TO BREAK OUT IN TO SCT-BKN THU
MORNING PROBABLY AFTER 14-15Z WITH SKIES GOING MOSTLY CLEAR BY
LATE AFTERNOON EVENING. GOOD MIXING AND A DECENT PRESSURE GRADIENT
WILL KEEP WINDS UP TOMORROW WITH SFC WINDS OUT OF THE WEST AT
15-18KTS AND GUSTS IN THE 25-28KTS RANGE. WINDS AND PRESSURE
GRADIENT ARE FORECAST TO RELAX QUICKLY AFTER 11/00Z.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
SHORT TERM........13
LONG TERM.........MJ
AVIATION..........MJ
