Heat in Kentucky, August 19, 2006

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
319 AM CDT SAT AUG 19 2006

.DISCUSSION...

FOR THE LAST SEVERAL MONTHS THE WFO PAH FORECAST AREA HAS BEEN
PLACED NEAR THE INFLECTION POINT OF A WESTERN U.S. MEAN RIDGE AND
A LOWER AMPLITUDE TROUGH IN THE NERN U.S. THIS HAS LED TO A
VARYING DEGREE OF SUCCESS FOR THE PASSAGE OF SURFACE FRONTAL
BOUNDARIES THROUGH THE FORECAST AREA. THIS FORECAST PACKAGE IS NO
DIFFERENT.

ON THE SYNOPTIC SCALE...ALL OF THE MODELS ARE IN PRETTY GOOD
AGREEMENT WITH THE UPPER RIDGE POSITION IN THE LOWER MS VALLEY AND
THE DAMPENING OF THE MID LEVEL SHORTWAVE OVER THE NORTHERN PLAINS
THIS PAST EVENING. HOWEVER...THE NECESSARY DETAILS FOR POP/WX
FORECASTS ARE COMPLICATED BY MESO AND STORM SCALE ALTERATIONS TO
THE ATMOSPHERE /MCV AND OUTFLOW BOUNDARY INTERACTIONS/ IN AND NEAR
THE WFO PAH FORECAST AREA.

IN COMPARISON TO THE 00Z UPPER AIR ANALYSIS...THE GFS AND ECWMF
00Z SAT MODEL RUNS WERE MORE ACCURATE IN HEIGHT FIELDS...BUT THE
GFS WAS A LITTLE FAST WITH THE POSITION AND LOCATION OF THE MAIN
SHORTWAVES MOVING AROUND THE PERIPHERARY OF THE UPPER RIDGE.
THE 00Z THU RUNS OF THE NAM AND GFS...WHICH PREVIOUSLY DISCOUNTED
THE POTENTIAL FOR PRECIPITATION INTO MONDAY NIGHT...HAVE REVERSED
POSITION AND ARE IN LINE WITH THE PREVIOUS RUNS OF THE ECWMF.

FOR THE WFO PAH FORECAST AREA...THIS INDICATES THAT THE FRONTAL
BOUNDARY WORKING SOUTHWARD TODAY WILL STALL OUT OVER THE
REGION...WITH EMBEDDED WAVES EXPECTED TO PERIODICALLY DEVELOP AND
RIDE OVER THE BOUNDARY. THIS LEADS TO DIURNAL CHANCES FOR
PRECIPITATION DURING MAX HEATING...AS WELL AS THE POTENTIAL FOR
NON-DIURNAL ORGANIZED CONVECTION AS SLIGHTLY STRONGER WIND FIELDS
ALOFT WORK TOWARD THE FORECAST AREA AS THE UPPER RIDGE SHIFTS TO
THE WEST OF THE REGION. THE POP/WX FORECAST WAS MODIFIED TO THE
ACCOUNT FOR THE SLOWER MOVEMENT OF THE FRONTAL BOUNDARY...WITH
GREATER EMPHASIS PLACED ON THE 00Z SAT ECMWF/NAM LOW LEVEL WIND
AND SURFACE PRESSURE FIELDS.

THE SURFACE WIND FORECAST WAS THE MOST PROBLEMATIC FEATURE OF THIS
FORECAST PACKAGE...ESPECIALLY WITH THE VARIABLE WIND FIELDS AROUND
THE SURFACE FRONTAL BOUNDARY. ALTHOUGH DIRECTIONAL WIND CHANGES
MAY BE QUESTIONABLE...I LEANED CLOSER TO THE GFS MOS GUIDANCE
VALUES FOR INPUT INTO THE GRIDDED FORECAST PACKAGE TODAY.

FOR MAX/MIN TEMPERATURE FORECASTS...SLIGHTLY UNDERCUT TEMPERATURES
BY 1-2 DEGREES FROM NAM GUIDANCE VALUES. THIS GUIDANCE REMAINS AT
OR BELOW THE ELEVATED GFS MOS GUIDANCE VALUES AND WAS PREFERRED
BASED ON RECENT TEMPERATURE VERIFICATION.

WITH THE FRONTAL BOUNDARY EXPECTED NEARBY...ANY CLOUDS OR PRECIPITATION
CHANCES WILL PRECLUDE ELEVATED HEAT INDEX VALUES FOR THE REMAINDER
OF THE 7 DAY FORECAST PERIOD.

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
MO...NONE.
IL...NONE.
IN...NONE.
&&

SMITH

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE PADUCAH KY
416 AM CDT SAT AUG 19 2006

ILZ075>078-080>094-INZ081-082-085>088-KYZ001>022-MOZ076-086-087-
100-107>112-114-201000-
JEFFERSON-WAYNE IL-EDWARDS-WABASH-PERRY IL-FRANKLIN-HAMILTON-
WHITE-JACKSON-WILLIAMSON-SALINE-GALLATIN-UNION IL-JOHNSON-POPE-
HARDIN-ALEXANDER-PULASKI-MASSAC-GIBSON-PIKE-POSEY-VANDERBURGH-
WARRICK-SPENCER-FULTON-HICKMAN-CARLISLE-BALLARD-MCCRACKEN-GRAVES-
LIVINGSTON-MARSHALL-CALLOWAY-CRITTENDEN-LYON-TRIGG-CALDWELL-
UNION KY-WEBSTER-HOPKINS-CHRISTIAN-HENDERSON-DAVIESS-MCLEAN-
MUHLENBERG-TODD-PERRY MO-BOLLINGER-CAPE GIRARDEAU-WAYNE MO-CARTER-
RIPLEY-BUTLER-STODDARD-SCOTT-MISSISSIPPI-NEW MADRID-
416 AM CDT SAT AUG 19 2006

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHERN
ILLINOIS...SOUTHWEST INDIANA...WESTERN KENTUCKY AND SOUTHEAST
MISSOURI.

.DAY ONE...TODAY AND TONIGHT

A WEAK COLD FRONT WILL MOVE SOUTH ACROSS THE REGION TODAY. SCATTERED
THUNDERSTORMS ARE EXPECTED TO FORM ALONG THE FRONT. THE ATMOSPHERE
IS FORECAST TO BECOME VERY UNSTABLE TODAY. THIS COUPLED WITH A
SLIGHT INCREASE IN UPPER LEVEL WIND SPEEDS...MEANS A FEW OF THE
STORMS COULD PRODUCE DAMAGING WINDS. LOCALLY HEAVY RAIN WILL ALSO
BE POSSIBLE.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

THE COLD FRONT IS FORECAST TO STALL ACROSS SOUTHERN SECTIONS OF
THE FOUR STATE AREA SUNDAY...THEN MOVE A LITTLE FURTHER SOUTH ON
MONDAY. A WAVE OF LOW PRESSURE FORECAST TO MOVE EAST ALONG THE
FRONT...SHOULD TRIGGER WIDELY SCATTERED THUNDERSTORMS SUNDAY AND
AGAIN MONDAY. WHILE SEVERE THUNDERSTORMS ARE NOT EXPECTED...A FEW
OF THE STRONGER STORMS MAY BE CAPABLE OF GUSTY WINDS AND LOCALLY
HEAVY RAIN...ESPECIALLY ACROSS SOUTHEAST MISSOURI AND WESTERN
KENTUCKY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE REQUESTED TODAY AND EARLY TONIGHT.