Severe Thunderstorm Warning 325, NWS Louisville, KY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
210 PM EDT WED MAY 31 2006

.SHORT TERM (TONIGHT AND THURSDAY)...

.FOR THE REST OF THIS AFTERNOON AND THIS EVENING...

WILL PROBABLY LOWER PRECIP CHANCES WITH THIS AFTERNOON
PACKAGE...ESPECIALLY ALONG THE OHIO RIVER. WIDESPREAD CLOUD COVER
EARLIER TODAY WILL LIMIT AFTERNOON HIGH TEMPERATURES ACROSS SOUTHERN
INDIANA AND KENTUCKY NEAR THE OHIO RIVER. UNDER FULL
SUN...TEMPERATURES ACROSS THE BLUEGRASS AND OUR SOUTHERN COUNTIES
WERE WARMING MORE QUICKLY THROUGH EARLY AFTERNOON. AS OF THIS
TIME...LITTLE SURFACE BASED CU HAS DEVELOPED EXCEPT ACROSS THE
HIGHER TERRAIN OF SOUTHEASTERN KENTUCKY. CURRENTLY...THE GREATEST
INSTABILITY AND POSSIBLE IGNITION POINT FOR CONVECTION LIES ACROSS
THE SOUTHERN BLUEGRASS REGION...AND OUR COUNTIES ALONG THE TENNESSEE
BORDER.

CONVECTION(SHOULD IT DEVELOP) WILL DECAY DURING THE EVENING HOURS.
LIGHT WINDS OVERNIGHT MAY LEAD TO TYPICAL PATCHY FOG DURING THE
EARLY MORNING HOURS...BUT HIGH AND MID LEVEL CLOUDINESS MAY LIMIT
THIS.

.THURSDAY...

A PROGRESSIVE UPPER AIR DISTURBANCE NOW OVER MONTANA WILL MOVE EAST
TO THE WESTERN GREAT LAKES BY LATE WEDNESDAY. AT THE SURFACE A WEAK
TROUGH CHARACTERIZED BY A WIND SHIFT LINE WILL SAG SOUTHEAST TOWARDS
THE OHIO RIVER BY LATE TOMORROW. THE GFS IS FASTER IN BRINGING THIS
BOUNDARY INTO NORTHERN KENTUCKY...BUT PREFER THE SLOWER NAM...WHICH
BRINGS THIS ACROSS THE RIVER BY MIDNIGHT. WEAK SOUTHWEST FLOW WILL
STILL PREVAIL AHEAD OF THIS WIND SHIFT LINE...BUT A VERY MOIST
AIRMASS WILL ADVECT FROM THE LOWER MISSISSIPPI VALLEY. FORECAST
SOUNDINGS SHOW PRECIPITABLE WATER AT 1.7 INCHES FOR TOMORROW
AFTERNOON...WELL ABOVE NORMAL.  SEVERE WEATHER CHANCES WILL BE QUITE
LIMITED TOMORROW BY LESSER INSTABILITY...AND HIGH MOISTURE
THROUGHOUT THE DEPTH OF THE SOUNDING. SCATTERED STORMS THAT DO
DEVELOP TOMORROW WILL SLOWLY MOVE TO THE NORTHEAST AND...WITH HIGH
FREEZING LEVELS...BE VERY EFFICIENT PRECIPITATION PRODUCERS.
LOCALIZED HEAVY RAINFALL MAY OCCUR...ESPECIALLY SHOULD STORMS
TRAIN OVER A SINGLE LOCATION.

.LONG TERM (THURSDAY NIGHT - WEDNESDAY)...

WELL...THE HEAT AND SULTRY AIR IS GONE THE MAJORITY OF THIS
FORECAST PERIOD WILL SEE TEMPS RETURN TO NEAR NORMAL.

THE FORECAST BEGINS WITH SLOW MOVING FRONTAL BOUNDARY THU
NIGHT...WITH LIKELY POPS CONTINUING AND TAPERING OFF FROM NW-SE
THROUGHOUT THE NIGHT...WITH THE EXTREME SE THE LAST AREA FOR PRECIP.
DUE TO THE SLOWNESS OF THE MID LEVEL FLOW AND HIGH PWS (150% OF
NORMAL)...LOCALLY HEAVY RAIN IS POSSIBLE THU EVENING.

BY FRIDAY...THE FRONT IS ACROSS THE VOLUNTEER STATE AND OUR DEW
POINTS WILL DROP TO <60. BRISK NWLY WINDS WILL DROP RHS TO MORE
COMFORTABLE LEVELS. TEMPS LOOK GOOD ON THE GRIDS WITH THE LOWEST
1000-850 MB THICKNESS ARE STILL TO THE N. THE COOLER TEMPS WILL BE
USHERED IN HERE ON SATURDAY WHICH SHOULD BE THE PICK DAY OF THE
WEEKEND...WITH H8 TEMPS DROPPING TO +10 IN THE FAR NERN CWA...SO
UPPER 70S ARE REALISTIC. I WILL CONTINUE WHAT THE MID SHIFT CHOSE BY
FOLLOWING THE ETA MORE SO THAN THE GFS THRU THE EARLY PORTIONS OF
THE EXTENDED FORECAST THURSDAY AND FRIDAY.

TWO MAIN FEATURES DOMINATE THE WEATHER WITH 1) DEEP TROUGH ACROSS
THE EASTERN THIRD OF USA...2) LARGE UPPER 591 HIGH OVER THE 4
CORNERS. THE MODELS ARE HANDLING HIGH AMPLITUDE RIDGE FINE...BUT
HAVE VARIOUS SOLUTIONS TO THE EAST COAST TROUGH ALONG WITH THE UPPER
LOW THAT FORMS IN THE APPALACHIANS AND DROPS SOUTHWARD.  I PLAN TO
KEEP THE FORECAST DRY...BUT HAVE SOME CONCERN OF A POTENTIAL BACK
DOOR COLD FRONT LATE MONDAY. I HAVE INCREASED THE CLOUD COVER
GRID...AND WILL WAIT TO LATER RUNS TO HAVE ENOUGH CONFIDENCE TO
INCLUDE POPS.

UPPER LEVEL HEIGHTS AND LOW LEVEL THICKNESS BEGIN RISING ON MONDAY
AS THE UPPER TROUGH SLIDES MORE EASTWARD...SO EACH DAY SHOULD SEE A
1-3 DEGREE RISE IN MERCURY READINGS. BY THE MIDDLE OF NEXT
WEEK...THINGS BECOME MORE COMPLEX WITH NWLY FLOW ALOFT AND SHORT
WAVES RIDING THE RIDGE.  AS IVE ALWAYS SAID...NW FLOW IT WILL GRAB
YOU. HOWEVER...THIS IS WAY TOO FAR OUT TO ADD POPS...BUT BEARS
WATCHING.
JDG

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&