FXUS63 KLMK 220214
AFDLMK
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
914 PM EST MON DEC 21 2009
...FORECAST UPDATE...
11-3.9 MICRON IR SAT IMAGERY SHOWING SOME CLEARING TRYING TO WORK
INTO PORTIONS OF FAR SOUTH CENTRAL KY. AREA OF CLEARING IS
GENERALLY BETWEEN BOWLING GREEN AND SOMERSET. NORTHWARD EXTENT
SEEMS TO HAVE GOTTEN AS FAR NORTH AS THE NUNN/CUMBERLAND
PARKWAY...BUT THAT'S ABOUT IT. FURTHER WEST...THE LOW CLOUDS HAD
TEMPORARILY CLEAR OUT ACROSS SOUTHWEST KY...BUT IR SAT IMAGERY IS
SHOWING THIS BUILDING BACK TO THE SOUTH. FURTHER UP...SOME MID-HIGH
LEVEL CIRRUS IS CURRENTLY SPREADING EASTWARD ACROSS THE REGION.
THE REAL FORECAST CHALLENGE IS HOW MUCH CLEARING WILL TAKE PLACE AND
WHAT THE NORTHWARD EXTENT WILL BE. LOW-LEVEL MOISTURE IS ABUNDANT
VERY CLOSE TO THE SURFACE...AOB 1500KFT AGL. BASED ON MODEL
SOUNDINGS AND CURRENT DATA...THAT MOSTLY CLOUDY SKIES SHOULD HOLD
TOUGH ACROSS MUCH OF THE REGION. AREAS DOWN ALONG THE KY TN BORDER
WILL LIKELY HAVE THE BEST CHANCE OF CLEARING OUT TONIGHT.
TEMPERATURES HAVE PRETTY MUCH BEEN IN A STEADY STATE OVER THE LAST
FEW HOURS. READINGS ARE IN THE 33-35 DEGREE RANGE. THE TEMPS
SHOULD SLOWLY FALL OVERNIGHT WITH TEMPS LOWER 30S. AREAS DOWN ALONG
THE KY/TN BORDER MAY DROP INTO THE UPPER 20S AS CLEARING TAKES
PLACE. LOTS OF PATCHY FOG AND MIST HAVE BEEN NOTED ACROSS THE
REGION AS WELL...SO WILL BE ADDING THAT TO THE GRIDS. WITH TEMPS
EXPECTED TO DROP TO NEAR OR SLIGHTLY BELOW FREEZING...WILL ALSO
MENTION SOME PATCHY FREEZING FOG AS WELL. SHOULD THE FOG GET DENSE
ENOUGH...SOME SLICK SPOTS ON AREA BRIDGES AND OVERPASSES WILL BE
POSSIBLE. WILL MENTION THIS IN THE OVERNIGHT HWO PRODUCT.
UPDATED GRIDS AND FORECAST PRODUCTS WILL BE AVAILABLE BY 930 PM EST.
.SHORT TERM (TONIGHT AND TUESDAY)...
CLOUD COVER HAS FAILED TO BREAK UP TODAY AND WILL LIKELY STICK
AROUND FOR THE OVERNIGHT HOURS AS WELL GIVEN ABUNDANT LOW LEVEL
MOISTURE AND INCREASING MID/UPPER LEVEL MOISTURE OVERNIGHT. DRY
CONDITIONS WILL PREVAIL THROUGH TUESDAY AFTERNOON WITH MAINLY
WESTERLY FLOW ALOFT AS HEIGHTS INCREASE WITH A RIDGE BUILDING TO THE
WEST.
WARM AIR ADVECTION OVER THE REGION WILL HELP KEEP TEMPERATURES IN
THE UPPER 20S TO LOW 30S OVERNIGHT AND WARMER TEMPERATURES WILL BE
IN STORE FOR TOMORROW. EXPECT HIGHS TO REACH INTO THE LOW 50S SOUTH
TO MID 40S NORTH WITH SOME BREAKS IN CLOUD COVER DURING THE LATE
MORNING/EARLY AFTERNOON.
.LONG TERM (TUESDAY NIGHT - MONDAY)...
A DEEP UPPER LEVEL LOW WILL DEVELOP OVER THE FOUR CORNERS STATES AT
THE BEGINNING OF THIS FORECAST PERIOD AND TRACK NORTHEAST...
BECOMING VERTICALLY STACKED OVER THE MID MISSISSIPPI VALLEY
THURSDAY. THIS SYSTEM WILL THEN SHIFT INTO THE NEW ENGLAND STATES
OVER THE WEEKEND.
THE TRACK OF THIS STORM SYSTEM WILL KEEP THE FORECAST AREA IN THE
WARM SECTOR UNTIL COLD AIR BEGINS TO FILTER INTO THE AREA CHRISTMAS
DAY. SO A WHITE CHRISTMAS IS NOT LOOKING VERY LIKELY OTHER
THAN THE POSSIBILITY OF SOME VERY LIGHT SNOW OR FLURRIES CHRISTMAS
DAY AFTERNOON.
A SURFACE LOW ASSOCIATED WITH THE AFOREMENTIONED SYSTEM WILL DEVELOP
OVER TEXAS AND TRACK INTO MISSOURI THURSDAY AFTERNOON. A COLD FRONT
WILL SWEEP ACROSS THE LOWER OHIO VALLEY LATE DAY THURSDAY INTO
CHRISTMAS MORNING. AN AREA OF RAIN WILL ACCOMPANY THE FRONTAL
BOUNDARY. AT THE PRESENT TIME THE ATMOSPHERE LOOKS TOO STABLE TO
PRODUCE EVEN ANY ELEVATED THUNDERSTORMS ALONG THE FRONT.
THURSDAY AND FRIDAY WILL BE WINDY WITH THIS DEEP LOW MOVING THROUGH
THE MID MISSISSIPPI VALLEY. WINDS BEHIND THE COLD FRONT WILL
ACTUALLY REMAIN FROM THE SOUTH AND SOUTHWEST... DELAYING THE COLD
AIR ADVECTION INTO THE REGION UNTIL THE SYSTEM BEGINS TO MOVE TO THE
NORTHEAST.
THE COLDEST AIR WILL ARRIVE OVER THE WEEKEND WHEN WE WILL SEE
TEMPERATURES IN THE 20S AND 30S. READINGS WILL BEGIN TO MODERATE
SOME MONDAY AS A SOUTHWEST FLOW RETURNS.
THIS WEDNESDAY AND THURSDAY WILL BE WARM WITH HIGHS IN THE 40S AND
LOWER 50S.
&&
.AVIATION (00Z TAF ISSUANCE)...
LATEST SUITE OF MODEL DATA SUGGEST THAT MOSTLY CLOUDY CONDITIONS
WILL CONTINUE THROUGH MUCH OF THE OVERNIGHT PERIOD. CIGS WILL RUN
MVFR EARLY IN THE PERIOD AND GRADUALLY RISE ABOVE VFR THRESHOLDS
DURING THE OVERNIGHT PERIOD. LOW-LEVEL MOISTURE LOOKS TO STAY
LOCKED IN NEAR THE SFC. THUS...VSBYS WILL LIKELY STAY IN THE MVFR
RANGE AND MAY BORDER ON THE IFR RANGE BETWEEN 22/06-12Z AT ALL THE
LOCATIONS. IF SIGNIFICANT CLEARING DOES COMMENCE...LIGHT WINDS
WOULD LIKELY RESULT IN FOG DEVELOPING. AT THIS TIME...THE GFS
GUIDANCE SEEMS A LITTLE OVERDONE WITH DROPPING VSBYS AT THIS TIME.
THEREFORE...HAVE LEANED CLOSER TO THE NAM-WRF PROFILES OVERNIGHT.
MORE SIGNIFICANT CLEARING LOOKS TO BEGIN AFTER 22/13Z.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
UPDATE.........MJ
SHORT TERM.....LMS
LONG TERM......JA
AVIATION.......MJ
