Flash Flooding in Kentucky, April 4, 2008

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
333 AM EDT FRI APR 4 2008

.SHORT TERM.../TODAY THROUGH TUESDAY/...UPDATED
THE LATEST MODEL RUNS HAVE BEEN CONVERGING ON A SOLUTION THAT PUTS
LESS RAINFALL OVER EASTERN KENTUCKY THAN PREVIOUS RUNS. THE ONLY
CONSOLATION IS THAT THE MODELS HAVE NOT INITIALIZED VERY WELL IN THAT
THE CURRENT HEAVY PRECIPITATION IS WELL SOUTH OF WHERE THE MODELS SAY
IT SHOULD BE. THE LOW LEVEL CONVERGENCE OVER CENTRAL KY IS MUCH
BETTER THAN OVER EASTERN KY AND AS THE FRONT PROGRESSES SOUTH...MUCH
OF THAT LOW LEVEL CONVERGENCE IS DIMINISHED AS IT MOVES INTO EASTERN
KENTUCKY. AS SUCH HAVE SORT OF GONE WITH A BLEND OF THE OLD RUN AND
THE NEW RUN AND BLENDED THE OLD QPF FORECAST WITH THE NEW HPC QPF
FORECAST. MY CONFIDENCE IN THE FLOOD WARNINGS HAVE WANED SOME...BUT
NOT ENOUGH TO REALLY CHANGE THEM UP. LOOKING UP STREAM...LEX JUST GOT
POUNDED WITH WITH OVER 2 INCHES OF RAIN IN THE LAST THREE HOURS. WITH
THIS SORT OF POTENTIAL OUT THERE...IT WOULD BE ILL ADVISED TO MAKE
ANY BIG CHANGES. TWEAKED THE TIMING OF THE RAINFALL AND THUNDERSTORMS
FOR THE CURRENT FORECAST BASED ON THE LATEST MODEL GUIDANCE AND
CURRENT CONDITIONS. WENT WITH A BLEND OF THE GFS AND ETA MOS FOR THE
TEMPERATURES FOR THE FORECAST PERIOD.

THE FRONT WILL MOVE THROUGH THE AREA BY SATURDAY MORNING AND THE
PRECIPITATION SHOULD BE ENDING EVERYWHERE BY SATURDAY AFTERNOON.
HIGH PRESSURE BUILDS IN BY SATURDAY EVENING AND WILL KEEP ANY FRONTS
FROM MOVING INTO THE AREA UNTIL MONDAY. BY MONDAY NIGHT A COLD FRONT
WILL BE GETTING SHEARED APART AS IT MOVES INTO THE AREA. THE NEXT
FRONT WILL MOVE INTO THE AREA ON TUESDAY NIGHT AND WILL STAY IN THE
AREA UNTIL THURSDAY.

.LONG TERM.../SATURDAY NIGHT THROUGH THURSDAY/

WITH A BIT OF DISAGREEMENT AMONGST THE VARIOUS LONG RANGE MODELS...
DECIDED TO GO WITH A COMPROMISE BETWEEN THE GFS AND ECMWF SOLUTIONS.
THE ECMWF IS SEVERAL HOURS SLOWER THAN THE 6Z GFS RUN...SO USED A
BLEND BETWEEN THE TWO. LATEST HPC GUIDANCE AND MEXMOS ALSO DIFFER
SOMEWHAT IN THEIR RESPECTIVE HANDLING OF PRECIPITATION CHANCES FOR
NEXT MONDAY AND TUESDAY...WITH THE HPC GOING WITH 50 PERCENT CHANCE
OF RAIN ON MONDAY AND TUESDAY...WHILE THE GFS ENSEMBLE MOS AND MEX
BOTH GOING WITH POPS IN THE 20S AND 30S FOR THE SAME TIME FRAME. WITH
BOTH THE GFS AND ECMWF BRINGING A FAST MOVING CLIPPER TYPE SYSTEM
ACROSS THE LOWER GREAT LAKES MONDAY AND TUESDAY...DECIDED TO LEAVE IN
CURRENT SLIGHT CHANCE POPS FOR MON-TUE. IN FACT...ONLY A FEW VERY
MINOR CHANGES WERE MADE TO THE FORECAST FOR SUNDAY THROUGH TUESDAY AS
NO MAJOR IMPROVEMENTS TO THE PREVIOUS FORECAST WERE EVIDENT IN THE
LATEST MODEL DATA. DECIDED TO INCREASE PRECIP CHANCES FOR TUESDAY
NIGHT THROUGH WEDNESDAY NIGHT. THE LATEST GFS AND ECMWF QPF FORECASTS
SEEMED TO SUPPORT A BIT MORE WIDESPREAD PRECIP THAN SLIGHT CHANCE
POPS WOULD HAVE ACCOUNTED FOR...ESPECIALLY WITH A 30KT LOW LEVEL JET
MOVING ACROSS THE AREA...AND PLENTY OF LOW AND MIDDLE LEVEL MOISTURE
AND OMEGA SHOWING UP IN THE MODEL CROSS SECTIONS AND SOUNDINGS. IN
FACT...THIS MORNINGS LONG RANGE FORECAST SOUNDINGS EVEN HAD ENOUGH
SURFACE BASED INSTABILITY IN THEM TO WARRANT MENTION OF THUNDERSTORMS
FOR WEDNESDAY MORNING AND AFTERNOON...ALBEIT ONLY A SLIGHT CHANCE.

TEMPERATURES WERE IN PRETTY GOOD SHAPE OVERALL WITH A FEW MINOR
TWEAKS MADE HERE AND THERE. GENERALLY TRENDED TOWARD THE WARMER HPC
AND MEXMOS NUMBERS ACROSS THE BOARD FOR DAYTIME HIGHS...AND VERY
CLOSE TO THE LONG RANGE MOS FOR OVERNIGHT LOWS. PERSISTENT SOUTHERLY
WINDS AND LESS CLOUD COVER IN THE FORECAST WERE THE PRIMARY
SUPPORTING FEATURES FOR THE CHANGE IN THE TEMPERATURE FORECAST FOR
SUNDAY...MONDAY...AND THURSDAY. DEWPOINTS WERE CHANGED ONLY SLIGHTLY
PER LATEST MOS DATA. QPF FORECAST WAS ALSO TWEAKED ONLY TO MATCH UP
TO CHANGES IN POP FORECAST. INCLUDED A CHANCE OF RAIN EACH DAY MONDAY
THROUGH THURSDAY...WITH A BRIEF LULL BETWEEN SYSTEMS LATE WEDNESDAY
NIGHT THROUGH THURSDAY EVENING.

&&

.AVIATION.../06Z TO 06Z/

A WAVY FRONTAL BOUNDARY DRAPED ROUGHLY ALONG THE OHIO RIVER VALLEY
HAS EXTENSIVE BAND OF RAIN...THUNDERSTORMS ASSOCIATED WITH IT. THE
PORTION OF THIS BAND OVER EASTERN KENTUCKY APPEARS TO HAVE A SLIGHT
NORTHWARD DRIFT...SIGNS OF WAVE OF LOW PRESSURE ENTERING THE REGION.
THE PRECIPITATION SHIELD IS EXPECTED TO CONTINUE IT/S SLIGHT
NORTHWARD TREND....KEEPING OUR MORE SOUTHERN TERMINALS FURTHER FROM
THE MAIN SHOWER ACTIVITY. HOWEVER...BY SUNRISE THE FRONTAL BOUNDARY
WILL BE MAKING A STRONGER MOVE TO THE SOUTHEAST. MULTIPLE WAVES OF
LOW PRESSURE RIDING NORTHEAST ALONG THE FRONT WILL CAUSE THE OVERALL
PROGRESSION OF THE BOUNDARY TO BE VERY SLOW. AS A RESULT...THIS
WEATHER SYSTEM WILL BRING PERIODS OF SHOWERS AND THUNDERSTORMS TO THE
AREA...WITH RAIN BECOMING HEAVY AT TIMES.

AT TAF ISSUANCE WINDS ARE LIGHT OUT OF THE SOUTH...WITH OCCASIONAL
SOUTHWEST WINDS...GUSTS MIXING DOWN TO THE SURFACE. VAD WIND PROFILES
ARE SHOWING A STRENGTHENING SW LOW LEVEL JET DEVELOPING OVER THE
AREA. INDICATIONS ARE THAT THERE IS A POTENTIAL FOR SOME LLWS AND
INCLUDED THIS IN THE TAF FOR FIRST 6 TO 7 HOURS...UNTIL NOCTURNAL
INVERSION HAS LIFTED...OR MIXED OUT TOTALLY.

EXPECTING GENERALLY MVFR CONDITIONS UNTIL LATE IN THE FORECAST
PERIOD WHEN LOWER...IFR CIGS ARE EXPECTED BEHIND A PASSING COLD
FRONT. EXPECT ALL STATIONS WILL EXPERIENCE THUNDER DURING THE DAY
FRIDAY...BUT WILL NOT INCLUDE THUNDER UNTIL A MORE EXACT TIMING OR
WINDOW BECOMES APPARENT.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH THROUGH LATE TONIGHT FOR KYZ044-050>052-058>060-068-
069-079-080-083>088-104-106>120.

&&

SHORT TERM...JJ
LONG TERM...JJ/AR
AVIATION...RAY

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE JACKSON KY
450 PM EDT THU APR 3 2008

KYZ044-050>052-058>060-068-069-079-080-083>088-104-106>120-041200-
FLEMING-MONTGOMERY-BATH-ROWAN-ESTILL-POWELL-MENIFEE-ROCKCASTLE-
JACKSON-PULASKI-LAUREL-WAYNE-MCCREARY-WHITLEY-KNOX-BELL-HARLAN-
ELLIOTT-MORGAN-JOHNSON-WOLFE-MAGOFFIN-FLOYD-LEE-BREATHITT-KNOTT-
OWSLEY-PERRY-CLAY-LESLIE-LETCHER-MARTIN-PIKE-
INCLUDING THE CITIES OF...FLEMINGSBURG...MOUNT STERLING...
OWINGSVILLE...MOREHEAD...IRVINE...STANTON...FRENCHBURG...
MOUNT VERNON...MCKEE...SOMERSET...LONDON...MONTICELLO...
WHITLEY CITY...CORBIN...WILLIAMSBURG...BARBOURVILLE...MIDDLESBORO...
PINEVILLE...HARLAN...SANDY HOOK...WEST LIBERTY...PAINTSVILLE...
CAMPTON...SALYERSVILLE...PRESTONSBURG...BEATTYVILLE...JACKSON...
HINDMAN...BOONEVILLE...HAZARD...MANCHESTER...HYDEN...WHITESBURG...
INEZ...PIKEVILLE
450 PM EDT THU APR 3 2008

...FLOOD WATCH IN EFFECT THROUGH LATE FRIDAY NIGHT...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF EASTERN KENTUCKY.

.DAY ONE...TONIGHT.

SEVERAL ROUNDS OF SHOWERS AND THUNDERSTORMS...SOME CONTAINING
LOCALLY HEAVY RAINFALL...WILL MOVE ACROSS THE AREA TONIGHT. THIS
RAINFALL WILL LIKELY RESULT IN SOME FLOODING PROBLEMS...PARTICULARLY
FOR LOW LYING AREAS AND SMALL CREEKS AND STREAMS.

A THUNDERSTORM IS ALSO POSSIBLE OVERNIGHT.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY.

SEVERAL ROUNDS OF SHOWERS AND THUNDERSTORMS...SOME CONTAINING
LOCALLY HEAVY RAINFALL...WILL CONTINUE TO MOVE ACROSS THE AREA
FRIDAY AND FRIDAY NIGHT. THIS RAINFALL WILL LIKELY RESULT IN SOME
FLOODING PROBLEMS FOR LOW LYING AREAS AND SMALL CREEKS AND STREAMS.
RAPID RISES ON THE LARGER RIVERS WILL THEN LIKELY OCCUR FROM LATE
FRIDAY INTO THE WEEKEND AS RAINFALL RUNOFF CONTINUES.

THUNDERSTORMS ARE POSSIBLE ON FRIDAY INTO FRIDAY EVENING.
THUNDERSTORMS ARE AGAIN POSSIBLE ON WEDNESDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS ARE ENCOURAGED TO REPORT INSTANCES OF FLOODING AND RAINFALL
AMOUNTS IN EXCESS OF ONE INCH TO THE NATIONAL WEATHER SERVICE IN
JACKSON.

ABE