AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
AFDSDF 330 AM EST THU JAN 18 2001
A VERY CHALLENGING FORECAST AS WE MOVE INTO A VERY ACTIVE WEATHER
PATTERN THROUGH THE REMAINDER OF THE WORK WEEK. THE OVERALL SYNOPTIC
TRENDS ARE IN DECENT AGREEMENT THROUGH THE PERIOD...HOWEVER EACH
PRODUCE A SOMEWHAT DIFFERENT SENSIBLE WEATHER PATTERN FOR OUR
LOCATION. NONETHELESS...THE MODELS ARE CONSISTENT IN DEVELOPING THE
SURFACE LOW A BIT FURTHER SOUTH AND EAST THAN THE PREVIOUS RUN.
BASED ON THE ETA/MESO ETA...THERE SHOULD BE A COUPLE OF ROUNDS OF
PRECIPITATION TO MOVE ACROSS THE FORECAST AREA TODAY...ESPECIALLY FOR
OUR SOUTHERN/SOUTHEASTERN LOCALES. REGIONAL RADAR LOOPS INDICATE A
LARGE MASS OF PRECIPITATION ACROSS THE TENNESSEE VALLEY...FEEDING
INTO SOUTH CENTRAL KENTUCKY ON THE NOSE OF A LEVEL JET. THIS APPEARS
TO BE IN THE FORM OF RAIN NEAR THE KENTUCKY/TENNESSEE BORDER...
HOWEVER FURTHER NORTH...ACARS SOUNDINGS INDICATE THE THERMAL PROFILE
IS HOVERING RIGHT AROUND ZERO...AND THUS AN AREA OF LIGHT RAIN WITH
SLEET OR SNOW MIXED IN IS MOVING THROUGH CENTRAL PORTIONS OF
KENTUCKY.
THE MODELS ARE CONSISTENT WITH CONTINUED WARM AIR ADVECTION IN THE
LOWER LEVELS TODAY...WHICH SHOULD CHANGE THE PRECIPITATION TO ALL
RAIN THROUGH THE DAY ACROSS THE ENTIRE AREA. AS THE FIRST SLUG OF
MOISTURE MOVES TO SOUTHEAST KENTUCKY...ANOTHER ROUND OF MOISTURE
WILL MOVE IN FROM THE TENNESSEE VALLEY THIS AFTERNOON AND EVENING.
ALL THE WHILE...THE FORECAST AREA WILL REMAIN IN THE RIGHT ENTRANCE
REGION OF AN INTENSIFYING UPPER LEVEL JET...AND THUS...UPPER LEVEL
DIVERGENCE SHOULD CONTINUE TO INCREASE THROUGH THE PERIOD. WILL RUN
LIKELY POPS FOR OUR NORTHWEST COUNTIES...INCREASING TO 80 TO 90
PERCENT IN OUR SOUTHEAST ZONES.
THE PROBLEMS BEGIN TO DEVELOP LATE TONIGHT AS THE THERMAL PROFILES BEGIN
TO COLLAPSE FROM NORTHWEST TO SOUTHEAST. THUS...THERE WILL LIKELY BE
A CHANGEOVER FROM RAIN TO SNOW ACROSS SOUTH CENTRAL INDIANA...AND
THIS TREND SHOULD SPREAD SOUTHEAST THROUGH THE DAY FRIDAY. BOTH THE
ETA/AVN DO INDICATE DRYING IN THE 850 LAYER...ESPECIALLY THE AVN...
AND THIS WILL HELP TO CUT THE PRECIPITATION ACROSS OUR NORTHWESTERN
CWA. THUS...WILL RUN LIKELY POPS IN THE NORTHWEST...TRANSITIONING TO
CATEGORICAL AGAIN IN THE SOUTHEAST.
THE GREATEST THREAT FOR ANY ACCUMULATING SNOWS WOULD BE IN OUR
EASTERN AND SOUTHEASTERN COUNTIES WHERE THE PRECIPITATION COULD
LINGER INTO FRIDAY NIGHT AND SATURDAY MORNING. WILL HOLD OFF ON ANY
HEADLINES AT THIS TIME GIVEN DISPARATE MODEL SOLUTIONS AT THAT
POINT...BUT WILL ISSUE A SPECIAL WEATHER STATEMENT TO HIGHLIGHT THE
CHANGING WEATHER PATTERN.
.SDF...NONE.
VLD