Flash Flood Warning 18, NWS Jackson, KY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
350 AM EDT SAT JUL 24 1999

07Z SFC ANALYSIS AND MSAS CHART SHOW A WEAK FRONT FROM THE WESTERN TIP
OF LAKE ERIE SOUTHWEST INTO SOUTHERN ILLINOIS. DEWPOINTS AND THETA E
VALUES REMAIN HIGH AHEAD OF THIS ACROSS KENTUCKY. ON SATELLITE AND
RADAR A LARGE CLUSTER OF THUNDERSTORMS ARE COMING OUT OF SOUTHEASTERN
ILLINOIS. THESE ARE ASSOCIATED WITH A DECENT 500 MB SHORTWAVE THAT WILL
MOVE THROUGH THE OHIO VALLEY TODAY.

THE MODELS ARE IN DECENT AGREEMENT WITH THE LONG WAVE PATTERN AS THIS
INITIAL SHORTWAVE KNOCKS DOWN HEIGHTS OVER EAST KENTUCKY TODAY. FURTHER
NORTH...ENERGY COMING OVER THE MIDWEST RIDGE WILL CARVE OUT A
SUBSTANTIAL TROUGH OVER QUEBEC AND NEW ENGLAND. THE LEAD SHORTWAVE WILL
PASS THROUGH KENTUCKY TODAY ALONG WITH ITS WEAK SFC FRONT FOLLOWED BY
DRIER AIR AND A BUBBLE HIGH SETTING UP OVERHEAD ON SUNDAY.

THUNDERSTORMS WILL CONTINUE TO PROGRESS EAST ACROSS THE OHIO VALLEY
TODAY AHEAD OF THE WAVE. THESE WILL CROSS INTO EAST KENTUCKY LATE THIS
MORNING...COMBINING WITH DAYTIME HEATING...OLD OUT FLOW BOUNDARIES AND
CAPES TO 3000 J/KG...BY AFTERNOON TO PRODUCE A DECENT COVERAGE OF
THUNDERSTORMS ACROSS EAST KENTUCKY. THESE STORMS WILL BE SIMILAR TO
THOSE OF YESTERDAY AFTERNOON IN AS MUCH AS THEY WILL BE SLOW MOVING
WITH HEAVY RAINS AND POSSIBLY SEVERE WIND GUSTS. TONIGHT...THE WAVE
PASSES TO THE EAST AND COMBINED WITH THE LOSS OF DAYTIME HEATING ALLOWS
THE SKY TO CLEAR. IT WILL STILL BE MUGGY WITH AREAS OF FOG IN PLACES
THAT SAW RAIN. FOR SUNDAY...ALL THE MODELS DRY US OUT THOUGH...THIS
WILL ALLOW TEMPERATURES TO BE EVEN HIGHER WITH SLIGHTLY LOWER
HUMIDITIES. DEWPOINTS DROP FROM THE MIDDLE 70S TODAY INTO THE MIDDLE
60S BY SUNDAY AFTERNOON.

TEMPERATURES WILL AGAIN BE JUST BELOW ADVISORY CRITERIA SO WILL ISSUE
ANOTHER SPS AS HEAT INDICES RISE ABOVE 100 THIS AFTERNOON...THOUGH
THERE WILL BE A BETTER CHANCE OF COOLING RAINS DURING THE DAY.

AS FOR TEMPERATURES WILL TWEAK MOS SLIGHTLY TODAY...KEEP TONIGHT/S
VALUES AND GO BELOW MOS TOMORROW AS IT APPEARS TO OVERDUE THE DRYING
WHEN COMPARED TO THE ETA MODEL. WILL GO ABOVE MOS POPS FOR TODAY GIVEN
YESTERDAY/S ACTIVITY AND EVEN MORE FAVORABLE CONDITIONS FOR
THUNDERSTORMS TODAY.

WORK ZONES ARE AVAILABLE IN THE AFOS PRODUCT SDFOZFJKL.

.JKL...NONE.

GREIF